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freebsd-skq/sys/kern/vfs_bio.c
Kirk McKusick 75e3597abb Continuing efforts to provide hardening of FFS, this change adds a 
check hash to cylinder groups. If a check hash fails when a cylinder
group is read, no further allocations are attempted in that cylinder
group until it has been fixed by fsck. This avoids a class of
filesystem panics related to corrupted cylinder group maps. The
hash is done using crc32c.

Check hases are added only to UFS2 and not to UFS1 as UFS1 is primarily
used in embedded systems with small memories and low-powered processors
which need as light-weight a filesystem as possible.

Specifics of the changes:

sys/sys/buf.h:
    Add BX_FSPRIV to reserve a set of eight b_xflags that may be used
    by individual filesystems for their own purpose. Their specific
    definitions are found in the header files for each filesystem
    that uses them. Also add fields to struct buf as noted below.

sys/kern/vfs_bio.c:
    It is only necessary to compute a check hash for a cylinder
    group when it is actually read from disk. When calling bread,
    you do not know whether the buffer was found in the cache or
    read. So a new flag (GB_CKHASH) and a pointer to a function to
    perform the hash has been added to breadn_flags to say that the
    function should be called to calculate a hash if the data has
    been read. The check hash is placed in b_ckhash and the B_CKHASH
    flag is set to indicate that a read was done and a check hash
    calculated. Though a rather elaborate mechanism, it should
    also work for check hashing other metadata in the future. A
    kernel internal API change was to change breada into a static
    fucntion and add flags and a function pointer to a check-hash
    function.

sys/ufs/ffs/fs.h:
    Add flags for types of check hashes; stored in a new word in the
    superblock. Define corresponding BX_ flags for the different types
    of check hashes. Add a check hash word in the cylinder group.

sys/ufs/ffs/ffs_alloc.c:
    In ffs_getcg do the dance with breadn_flags to get a check hash and
    if one is provided, check it.

sys/ufs/ffs/ffs_vfsops.c:
    Copy across the BX_FFSTYPES flags in background writes.
    Update the check hash when writing out buffers that need them.

sys/ufs/ffs/ffs_snapshot.c:
    Recompute check hash when updating snapshot cylinder groups.

sys/libkern/crc32.c:
lib/libufs/Makefile:
lib/libufs/libufs.h:
lib/libufs/cgroup.c:
    Include libkern/crc32.c in libufs and use it to compute check
    hashes when updating cylinder groups.

Four utilities are affected:

sbin/newfs/mkfs.c:
    Add the check hashes when building the cylinder groups.

sbin/fsck_ffs/fsck.h:
sbin/fsck_ffs/fsutil.c:
    Verify and update check hashes when checking and writing cylinder groups.

sbin/fsck_ffs/pass5.c:
    Offer to add check hashes to existing filesystems.
    Precompute check hashes when rebuilding cylinder group
    (although this will be done when it is written in fsutil.c
    it is necessary to do it early before comparing with the old
    cylinder group)

sbin/dumpfs/dumpfs.c
    Print out the new check hash flag(s)

sbin/fsdb/Makefile:
    Needs to add libufs now used by pass5.c imported from fsck_ffs.

Reviewed by: kib
Tested by: Peter Holm (pho)
2017-09-22 12:45:15 +00:00

5049 lines
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/*-
* Copyright (c) 2004 Poul-Henning Kamp
* Copyright (c) 1994,1997 John S. Dyson
* Copyright (c) 2013 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* this file contains a new buffer I/O scheme implementing a coherent
* VM object and buffer cache scheme. Pains have been taken to make
* sure that the performance degradation associated with schemes such
* as this is not realized.
*
* Author: John S. Dyson
* Significant help during the development and debugging phases
* had been provided by David Greenman, also of the FreeBSD core team.
*
* see man buf(9) for more info.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/conf.h>
#include <sys/buf.h>
#include <sys/devicestat.h>
#include <sys/eventhandler.h>
#include <sys/fail.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/vmem.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <sys/watchdog.h>
#include <geom/geom.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include <vm/swap_pager.h>
#include "opt_compat.h"
#include "opt_swap.h"
static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
struct bio_ops bioops; /* I/O operation notification */
struct buf_ops buf_ops_bio = {
.bop_name = "buf_ops_bio",
.bop_write = bufwrite,
.bop_strategy = bufstrategy,
.bop_sync = bufsync,
.bop_bdflush = bufbdflush,
};
static struct buf *buf; /* buffer header pool */
extern struct buf *swbuf; /* Swap buffer header pool. */
caddr_t unmapped_buf;
/* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
struct proc *bufdaemonproc;
struct proc *bufspacedaemonproc;
static int inmem(struct vnode *vp, daddr_t blkno);
static void vm_hold_free_pages(struct buf *bp, int newbsize);
static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
vm_offset_t to);
static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
vm_page_t m);
static void vfs_clean_pages_dirty_buf(struct buf *bp);
static void vfs_setdirty_locked_object(struct buf *bp);
static void vfs_vmio_invalidate(struct buf *bp);
static void vfs_vmio_truncate(struct buf *bp, int npages);
static void vfs_vmio_extend(struct buf *bp, int npages, int size);
static int vfs_bio_clcheck(struct vnode *vp, int size,
daddr_t lblkno, daddr_t blkno);
static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int,
void (*)(struct buf *));
static int buf_flush(struct vnode *vp, int);
static int buf_recycle(bool);
static int buf_scan(bool);
static int flushbufqueues(struct vnode *, int, int);
static void buf_daemon(void);
static void bremfreel(struct buf *bp);
static __inline void bd_wakeup(void);
static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
static void bufkva_reclaim(vmem_t *, int);
static void bufkva_free(struct buf *);
static int buf_import(void *, void **, int, int);
static void buf_release(void *, void **, int);
static void maxbcachebuf_adjust(void);
#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
#endif
int vmiodirenable = TRUE;
SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
"Use the VM system for directory writes");
long runningbufspace;
SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
"Amount of presently outstanding async buffer io");
static long bufspace;
#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
&bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
#else
SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
"Physical memory used for buffers");
#endif
static long bufkvaspace;
SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0,
"Kernel virtual memory used for buffers");
static long maxbufspace;
SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0,
"Maximum allowed value of bufspace (including metadata)");
static long bufmallocspace;
SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
"Amount of malloced memory for buffers");
static long maxbufmallocspace;
SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace,
0, "Maximum amount of malloced memory for buffers");
static long lobufspace;
SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0,
"Minimum amount of buffers we want to have");
long hibufspace;
SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0,
"Maximum allowed value of bufspace (excluding metadata)");
long bufspacethresh;
SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh,
0, "Bufspace consumed before waking the daemon to free some");
static int buffreekvacnt;
SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
"Number of times we have freed the KVA space from some buffer");
static int bufdefragcnt;
SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
"Number of times we have had to repeat buffer allocation to defragment");
static long lorunningspace;
SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
"Minimum preferred space used for in-progress I/O");
static long hirunningspace;
SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
"Maximum amount of space to use for in-progress I/O");
int dirtybufferflushes;
SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
int bdwriteskip;
SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
int altbufferflushes;
SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
0, "Number of fsync flushes to limit dirty buffers");
static int recursiveflushes;
SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
0, "Number of flushes skipped due to being recursive");
static int numdirtybuffers;
SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
"Number of buffers that are dirty (has unwritten changes) at the moment");
static int lodirtybuffers;
SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
"How many buffers we want to have free before bufdaemon can sleep");
static int hidirtybuffers;
SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
"When the number of dirty buffers is considered severe");
int dirtybufthresh;
SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
static int numfreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
"Number of free buffers");
static int lofreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
"Target number of free buffers");
static int hifreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
"Threshold for clean buffer recycling");
static int getnewbufcalls;
SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
"Number of calls to getnewbuf");
static int getnewbufrestarts;
SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
"Number of times getnewbuf has had to restart a buffer acquisition");
static int mappingrestarts;
SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
"Number of times getblk has had to restart a buffer mapping for "
"unmapped buffer");
static int numbufallocfails;
SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0,
"Number of times buffer allocations failed");
static int flushbufqtarget = 100;
SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
"Amount of work to do in flushbufqueues when helping bufdaemon");
static long notbufdflushes;
SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, &notbufdflushes, 0,
"Number of dirty buffer flushes done by the bufdaemon helpers");
static long barrierwrites;
SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
"Number of barrier writes");
SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
&unmapped_buf_allowed, 0,
"Permit the use of the unmapped i/o");
int maxbcachebuf = MAXBCACHEBUF;
SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0,
"Maximum size of a buffer cache block");
/*
* This lock synchronizes access to bd_request.
*/
static struct mtx_padalign __exclusive_cache_line bdlock;
/*
* This lock protects the runningbufreq and synchronizes runningbufwakeup and
* waitrunningbufspace().
*/
static struct mtx_padalign __exclusive_cache_line rbreqlock;
/*
* Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
*/
static struct rwlock_padalign __exclusive_cache_line nblock;
/*
* Lock that protects bdirtywait.
*/
static struct mtx_padalign __exclusive_cache_line bdirtylock;
/*
* Wakeup point for bufdaemon, as well as indicator of whether it is already
* active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
* is idling.
*/
static int bd_request;
/*
* Request/wakeup point for the bufspace daemon.
*/
static int bufspace_request;
/*
* Request for the buf daemon to write more buffers than is indicated by
* lodirtybuf. This may be necessary to push out excess dependencies or
* defragment the address space where a simple count of the number of dirty
* buffers is insufficient to characterize the demand for flushing them.
*/
static int bd_speedupreq;
/*
* Synchronization (sleep/wakeup) variable for active buffer space requests.
* Set when wait starts, cleared prior to wakeup().
* Used in runningbufwakeup() and waitrunningbufspace().
*/
static int runningbufreq;
/*
* Synchronization (sleep/wakeup) variable for buffer requests.
* Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
* by and/or.
* Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(),
* getnewbuf(), and getblk().
*/
static volatile int needsbuffer;
/*
* Synchronization for bwillwrite() waiters.
*/
static int bdirtywait;
/*
* Definitions for the buffer free lists.
*/
#define QUEUE_NONE 0 /* on no queue */
#define QUEUE_EMPTY 1 /* empty buffer headers */
#define QUEUE_DIRTY 2 /* B_DELWRI buffers */
#define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
/* Maximum number of clean buffer queues. */
#define CLEAN_QUEUES 16
/* Configured number of clean queues. */
static int clean_queues;
/* Maximum number of buffer queues. */
#define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES)
/* Queues for free buffers with various properties */
static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
#ifdef INVARIANTS
static int bq_len[BUFFER_QUEUES];
#endif
/*
* Lock for each bufqueue
*/
static struct mtx_padalign __exclusive_cache_line bqlocks[BUFFER_QUEUES];
/*
* per-cpu empty buffer cache.
*/
uma_zone_t buf_zone;
/*
* Single global constant for BUF_WMESG, to avoid getting multiple references.
* buf_wmesg is referred from macros.
*/
const char *buf_wmesg = BUF_WMESG;
static int
sysctl_runningspace(SYSCTL_HANDLER_ARGS)
{
long value;
int error;
value = *(long *)arg1;
error = sysctl_handle_long(oidp, &value, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
mtx_lock(&rbreqlock);
if (arg1 == &hirunningspace) {
if (value < lorunningspace)
error = EINVAL;
else
hirunningspace = value;
} else {
KASSERT(arg1 == &lorunningspace,
("%s: unknown arg1", __func__));
if (value > hirunningspace)
error = EINVAL;
else
lorunningspace = value;
}
mtx_unlock(&rbreqlock);
return (error);
}
#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
static int
sysctl_bufspace(SYSCTL_HANDLER_ARGS)
{
long lvalue;
int ivalue;
if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
return (sysctl_handle_long(oidp, arg1, arg2, req));
lvalue = *(long *)arg1;
if (lvalue > INT_MAX)
/* On overflow, still write out a long to trigger ENOMEM. */
return (sysctl_handle_long(oidp, &lvalue, 0, req));
ivalue = lvalue;
return (sysctl_handle_int(oidp, &ivalue, 0, req));
}
#endif
static int
bqcleanq(void)
{
static int nextq;
return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN);
}
static int
bqisclean(int qindex)
{
return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES);
}
/*
* bqlock:
*
* Return the appropriate queue lock based on the index.
*/
static inline struct mtx *
bqlock(int qindex)
{
return (struct mtx *)&bqlocks[qindex];
}
/*
* bdirtywakeup:
*
* Wakeup any bwillwrite() waiters.
*/
static void
bdirtywakeup(void)
{
mtx_lock(&bdirtylock);
if (bdirtywait) {
bdirtywait = 0;
wakeup(&bdirtywait);
}
mtx_unlock(&bdirtylock);
}
/*
* bdirtysub:
*
* Decrement the numdirtybuffers count by one and wakeup any
* threads blocked in bwillwrite().
*/
static void
bdirtysub(void)
{
if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
(lodirtybuffers + hidirtybuffers) / 2)
bdirtywakeup();
}
/*
* bdirtyadd:
*
* Increment the numdirtybuffers count by one and wakeup the buf
* daemon if needed.
*/
static void
bdirtyadd(void)
{
/*
* Only do the wakeup once as we cross the boundary. The
* buf daemon will keep running until the condition clears.
*/
if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
(lodirtybuffers + hidirtybuffers) / 2)
bd_wakeup();
}
/*
* bufspace_wakeup:
*
* Called when buffer space is potentially available for recovery.
* getnewbuf() will block on this flag when it is unable to free
* sufficient buffer space. Buffer space becomes recoverable when
* bp's get placed back in the queues.
*/
static void
bufspace_wakeup(void)
{
/*
* If someone is waiting for bufspace, wake them up.
*
* Since needsbuffer is set prior to doing an additional queue
* scan it is safe to check for the flag prior to acquiring the
* lock. The thread that is preparing to scan again before
* blocking would discover the buf we released.
*/
if (needsbuffer) {
rw_rlock(&nblock);
if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1)
wakeup(__DEVOLATILE(void *, &needsbuffer));
rw_runlock(&nblock);
}
}
/*
* bufspace_daemonwakeup:
*
* Wakeup the daemon responsible for freeing clean bufs.
*/
static void
bufspace_daemonwakeup(void)
{
rw_rlock(&nblock);
if (bufspace_request == 0) {
bufspace_request = 1;
wakeup(&bufspace_request);
}
rw_runlock(&nblock);
}
/*
* bufspace_adjust:
*
* Adjust the reported bufspace for a KVA managed buffer, possibly
* waking any waiters.
*/
static void
bufspace_adjust(struct buf *bp, int bufsize)
{
long space;
int diff;
KASSERT((bp->b_flags & B_MALLOC) == 0,
("bufspace_adjust: malloc buf %p", bp));
diff = bufsize - bp->b_bufsize;
if (diff < 0) {
atomic_subtract_long(&bufspace, -diff);
bufspace_wakeup();
} else {
space = atomic_fetchadd_long(&bufspace, diff);
/* Wake up the daemon on the transition. */
if (space < bufspacethresh && space + diff >= bufspacethresh)
bufspace_daemonwakeup();
}
bp->b_bufsize = bufsize;
}
/*
* bufspace_reserve:
*
* Reserve bufspace before calling allocbuf(). metadata has a
* different space limit than data.
*/
static int
bufspace_reserve(int size, bool metadata)
{
long limit;
long space;
if (metadata)
limit = maxbufspace;
else
limit = hibufspace;
do {
space = bufspace;
if (space + size > limit)
return (ENOSPC);
} while (atomic_cmpset_long(&bufspace, space, space + size) == 0);
/* Wake up the daemon on the transition. */
if (space < bufspacethresh && space + size >= bufspacethresh)
bufspace_daemonwakeup();
return (0);
}
/*
* bufspace_release:
*
* Release reserved bufspace after bufspace_adjust() has consumed it.
*/
static void
bufspace_release(int size)
{
atomic_subtract_long(&bufspace, size);
bufspace_wakeup();
}
/*
* bufspace_wait:
*
* Wait for bufspace, acting as the buf daemon if a locked vnode is
* supplied. needsbuffer must be set in a safe fashion prior to
* polling for space. The operation must be re-tried on return.
*/
static void
bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo)
{
struct thread *td;
int error, fl, norunbuf;
if ((gbflags & GB_NOWAIT_BD) != 0)
return;
td = curthread;
rw_wlock(&nblock);
while (needsbuffer != 0) {
if (vp != NULL && vp->v_type != VCHR &&
(td->td_pflags & TDP_BUFNEED) == 0) {
rw_wunlock(&nblock);
/*
* getblk() is called with a vnode locked, and
* some majority of the dirty buffers may as
* well belong to the vnode. Flushing the
* buffers there would make a progress that
* cannot be achieved by the buf_daemon, that
* cannot lock the vnode.
*/
norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
(td->td_pflags & TDP_NORUNNINGBUF);
/*
* Play bufdaemon. The getnewbuf() function
* may be called while the thread owns lock
* for another dirty buffer for the same
* vnode, which makes it impossible to use
* VOP_FSYNC() there, due to the buffer lock
* recursion.
*/
td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
fl = buf_flush(vp, flushbufqtarget);
td->td_pflags &= norunbuf;
rw_wlock(&nblock);
if (fl != 0)
continue;
if (needsbuffer == 0)
break;
}
error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
(PRIBIO + 4) | slpflag, "newbuf", slptimeo);
if (error != 0)
break;
}
rw_wunlock(&nblock);
}
/*
* bufspace_daemon:
*
* buffer space management daemon. Tries to maintain some marginal
* amount of free buffer space so that requesting processes neither
* block nor work to reclaim buffers.
*/
static void
bufspace_daemon(void)
{
for (;;) {
kproc_suspend_check(bufspacedaemonproc);
/*
* Free buffers from the clean queue until we meet our
* targets.
*
* Theory of operation: The buffer cache is most efficient
* when some free buffer headers and space are always
* available to getnewbuf(). This daemon attempts to prevent
* the excessive blocking and synchronization associated
* with shortfall. It goes through three phases according
* demand:
*
* 1) The daemon wakes up voluntarily once per-second
* during idle periods when the counters are below
* the wakeup thresholds (bufspacethresh, lofreebuffers).
*
* 2) The daemon wakes up as we cross the thresholds
* ahead of any potential blocking. This may bounce
* slightly according to the rate of consumption and
* release.
*
* 3) The daemon and consumers are starved for working
* clean buffers. This is the 'bufspace' sleep below
* which will inefficiently trade bufs with bqrelse
* until we return to condition 2.
*/
while (bufspace > lobufspace ||
numfreebuffers < hifreebuffers) {
if (buf_recycle(false) != 0) {
atomic_set_int(&needsbuffer, 1);
if (buf_recycle(false) != 0) {
rw_wlock(&nblock);
if (needsbuffer)
rw_sleep(__DEVOLATILE(void *,
&needsbuffer), &nblock,
PRIBIO|PDROP, "bufspace",
hz/10);
else
rw_wunlock(&nblock);
}
}
maybe_yield();
}
/*
* Re-check our limits under the exclusive nblock.
*/
rw_wlock(&nblock);
if (bufspace < bufspacethresh &&
numfreebuffers > lofreebuffers) {
bufspace_request = 0;
rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP,
"-", hz);
} else
rw_wunlock(&nblock);
}
}
static struct kproc_desc bufspace_kp = {
"bufspacedaemon",
bufspace_daemon,
&bufspacedaemonproc
};
SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start,
&bufspace_kp);
/*
* bufmallocadjust:
*
* Adjust the reported bufspace for a malloc managed buffer, possibly
* waking any waiters.
*/
static void
bufmallocadjust(struct buf *bp, int bufsize)
{
int diff;
KASSERT((bp->b_flags & B_MALLOC) != 0,
("bufmallocadjust: non-malloc buf %p", bp));
diff = bufsize - bp->b_bufsize;
if (diff < 0)
atomic_subtract_long(&bufmallocspace, -diff);
else
atomic_add_long(&bufmallocspace, diff);
bp->b_bufsize = bufsize;
}
/*
* runningwakeup:
*
* Wake up processes that are waiting on asynchronous writes to fall
* below lorunningspace.
*/
static void
runningwakeup(void)
{
mtx_lock(&rbreqlock);
if (runningbufreq) {
runningbufreq = 0;
wakeup(&runningbufreq);
}
mtx_unlock(&rbreqlock);
}
/*
* runningbufwakeup:
*
* Decrement the outstanding write count according.
*/
void
runningbufwakeup(struct buf *bp)
{
long space, bspace;
bspace = bp->b_runningbufspace;
if (bspace == 0)
return;
space = atomic_fetchadd_long(&runningbufspace, -bspace);
KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
space, bspace));
bp->b_runningbufspace = 0;
/*
* Only acquire the lock and wakeup on the transition from exceeding
* the threshold to falling below it.
*/
if (space < lorunningspace)
return;
if (space - bspace > lorunningspace)
return;
runningwakeup();
}
/*
* waitrunningbufspace()
*
* runningbufspace is a measure of the amount of I/O currently
* running. This routine is used in async-write situations to
* prevent creating huge backups of pending writes to a device.
* Only asynchronous writes are governed by this function.
*
* This does NOT turn an async write into a sync write. It waits
* for earlier writes to complete and generally returns before the
* caller's write has reached the device.
*/
void
waitrunningbufspace(void)
{
mtx_lock(&rbreqlock);
while (runningbufspace > hirunningspace) {
runningbufreq = 1;
msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
}
mtx_unlock(&rbreqlock);
}
/*
* vfs_buf_test_cache:
*
* Called when a buffer is extended. This function clears the B_CACHE
* bit if the newly extended portion of the buffer does not contain
* valid data.
*/
static __inline void
vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off,
vm_offset_t size, vm_page_t m)
{
VM_OBJECT_ASSERT_LOCKED(m->object);
if (bp->b_flags & B_CACHE) {
int base = (foff + off) & PAGE_MASK;
if (vm_page_is_valid(m, base, size) == 0)
bp->b_flags &= ~B_CACHE;
}
}
/* Wake up the buffer daemon if necessary */
static __inline void
bd_wakeup(void)
{
mtx_lock(&bdlock);
if (bd_request == 0) {
bd_request = 1;
wakeup(&bd_request);
}
mtx_unlock(&bdlock);
}
/*
* Adjust the maxbcachbuf tunable.
*/
static void
maxbcachebuf_adjust(void)
{
int i;
/*
* maxbcachebuf must be a power of 2 >= MAXBSIZE.
*/
i = 2;
while (i * 2 <= maxbcachebuf)
i *= 2;
maxbcachebuf = i;
if (maxbcachebuf < MAXBSIZE)
maxbcachebuf = MAXBSIZE;
if (maxbcachebuf > MAXPHYS)
maxbcachebuf = MAXPHYS;
if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF)
printf("maxbcachebuf=%d\n", maxbcachebuf);
}
/*
* bd_speedup - speedup the buffer cache flushing code
*/
void
bd_speedup(void)
{
int needwake;
mtx_lock(&bdlock);
needwake = 0;
if (bd_speedupreq == 0 || bd_request == 0)
needwake = 1;
bd_speedupreq = 1;
bd_request = 1;
if (needwake)
wakeup(&bd_request);
mtx_unlock(&bdlock);
}
#ifndef NSWBUF_MIN
#define NSWBUF_MIN 16
#endif
#ifdef __i386__
#define TRANSIENT_DENOM 5
#else
#define TRANSIENT_DENOM 10
#endif
/*
* Calculating buffer cache scaling values and reserve space for buffer
* headers. This is called during low level kernel initialization and
* may be called more then once. We CANNOT write to the memory area
* being reserved at this time.
*/
caddr_t
kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
{
int tuned_nbuf;
long maxbuf, maxbuf_sz, buf_sz, biotmap_sz;
/*
* physmem_est is in pages. Convert it to kilobytes (assumes
* PAGE_SIZE is >= 1K)
*/
physmem_est = physmem_est * (PAGE_SIZE / 1024);
maxbcachebuf_adjust();
/*
* The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
* For the first 64MB of ram nominally allocate sufficient buffers to
* cover 1/4 of our ram. Beyond the first 64MB allocate additional
* buffers to cover 1/10 of our ram over 64MB. When auto-sizing
* the buffer cache we limit the eventual kva reservation to
* maxbcache bytes.
*
* factor represents the 1/4 x ram conversion.
*/
if (nbuf == 0) {
int factor = 4 * BKVASIZE / 1024;
nbuf = 50;
if (physmem_est > 4096)
nbuf += min((physmem_est - 4096) / factor,
65536 / factor);
if (physmem_est > 65536)
nbuf += min((physmem_est - 65536) * 2 / (factor * 5),
32 * 1024 * 1024 / (factor * 5));
if (maxbcache && nbuf > maxbcache / BKVASIZE)
nbuf = maxbcache / BKVASIZE;
tuned_nbuf = 1;
} else
tuned_nbuf = 0;
/* XXX Avoid unsigned long overflows later on with maxbufspace. */
maxbuf = (LONG_MAX / 3) / BKVASIZE;
if (nbuf > maxbuf) {
if (!tuned_nbuf)
printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
maxbuf);
nbuf = maxbuf;
}
/*
* Ideal allocation size for the transient bio submap is 10%
* of the maximal space buffer map. This roughly corresponds
* to the amount of the buffer mapped for typical UFS load.
*
* Clip the buffer map to reserve space for the transient
* BIOs, if its extent is bigger than 90% (80% on i386) of the
* maximum buffer map extent on the platform.
*
* The fall-back to the maxbuf in case of maxbcache unset,
* allows to not trim the buffer KVA for the architectures
* with ample KVA space.
*/
if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
buf_sz = (long)nbuf * BKVASIZE;
if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
(TRANSIENT_DENOM - 1)) {
/*
* There is more KVA than memory. Do not
* adjust buffer map size, and assign the rest
* of maxbuf to transient map.
*/
biotmap_sz = maxbuf_sz - buf_sz;
} else {
/*
* Buffer map spans all KVA we could afford on
* this platform. Give 10% (20% on i386) of
* the buffer map to the transient bio map.
*/
biotmap_sz = buf_sz / TRANSIENT_DENOM;
buf_sz -= biotmap_sz;
}
if (biotmap_sz / INT_MAX > MAXPHYS)
bio_transient_maxcnt = INT_MAX;
else
bio_transient_maxcnt = biotmap_sz / MAXPHYS;
/*
* Artificially limit to 1024 simultaneous in-flight I/Os
* using the transient mapping.
*/
if (bio_transient_maxcnt > 1024)
bio_transient_maxcnt = 1024;
if (tuned_nbuf)
nbuf = buf_sz / BKVASIZE;
}
/*
* swbufs are used as temporary holders for I/O, such as paging I/O.
* We have no less then 16 and no more then 256.
*/
nswbuf = min(nbuf / 4, 256);
TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
if (nswbuf < NSWBUF_MIN)
nswbuf = NSWBUF_MIN;
/*
* Reserve space for the buffer cache buffers
*/
swbuf = (void *)v;
v = (caddr_t)(swbuf + nswbuf);
buf = (void *)v;
v = (caddr_t)(buf + nbuf);
return(v);
}
/* Initialize the buffer subsystem. Called before use of any buffers. */
void
bufinit(void)
{
struct buf *bp;
int i;
KASSERT(maxbcachebuf >= MAXBSIZE,
("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf,
MAXBSIZE));
mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF);
mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF);
for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++)
mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF);
mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
rw_init(&nblock, "needsbuffer lock");
mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF);
/* next, make a null set of free lists */
for (i = 0; i < BUFFER_QUEUES; i++)
TAILQ_INIT(&bufqueues[i]);
unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
/* finally, initialize each buffer header and stick on empty q */
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
bzero(bp, sizeof *bp);
bp->b_flags = B_INVAL;
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = QUEUE_EMPTY;
bp->b_xflags = 0;
bp->b_data = bp->b_kvabase = unmapped_buf;
LIST_INIT(&bp->b_dep);
BUF_LOCKINIT(bp);
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
#ifdef INVARIANTS
bq_len[QUEUE_EMPTY]++;
#endif
}
/*
* maxbufspace is the absolute maximum amount of buffer space we are
* allowed to reserve in KVM and in real terms. The absolute maximum
* is nominally used by metadata. hibufspace is the nominal maximum
* used by most other requests. The differential is required to
* ensure that metadata deadlocks don't occur.
*
* maxbufspace is based on BKVASIZE. Allocating buffers larger then
* this may result in KVM fragmentation which is not handled optimally
* by the system. XXX This is less true with vmem. We could use
* PAGE_SIZE.
*/
maxbufspace = (long)nbuf * BKVASIZE;
hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10);
lobufspace = (hibufspace / 20) * 19; /* 95% */
bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
/*
* Note: The 16 MiB upper limit for hirunningspace was chosen
* arbitrarily and may need further tuning. It corresponds to
* 128 outstanding write IO requests (if IO size is 128 KiB),
* which fits with many RAID controllers' tagged queuing limits.
* The lower 1 MiB limit is the historical upper limit for
* hirunningspace.
*/
hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf),
16 * 1024 * 1024), 1024 * 1024);
lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf);
/*
* Limit the amount of malloc memory since it is wired permanently into
* the kernel space. Even though this is accounted for in the buffer
* allocation, we don't want the malloced region to grow uncontrolled.
* The malloc scheme improves memory utilization significantly on
* average (small) directories.
*/
maxbufmallocspace = hibufspace / 20;
/*
* Reduce the chance of a deadlock occurring by limiting the number
* of delayed-write dirty buffers we allow to stack up.
*/
hidirtybuffers = nbuf / 4 + 20;
dirtybufthresh = hidirtybuffers * 9 / 10;
numdirtybuffers = 0;
/*
* To support extreme low-memory systems, make sure hidirtybuffers
* cannot eat up all available buffer space. This occurs when our
* minimum cannot be met. We try to size hidirtybuffers to 3/4 our
* buffer space assuming BKVASIZE'd buffers.
*/
while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
hidirtybuffers >>= 1;
}
lodirtybuffers = hidirtybuffers / 2;
/*
* lofreebuffers should be sufficient to avoid stalling waiting on
* buf headers under heavy utilization. The bufs in per-cpu caches
* are counted as free but will be unavailable to threads executing
* on other cpus.
*
* hifreebuffers is the free target for the bufspace daemon. This
* should be set appropriately to limit work per-iteration.
*/
lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
hifreebuffers = (3 * lofreebuffers) / 2;
numfreebuffers = nbuf;
/* Setup the kva and free list allocators. */
vmem_set_reclaim(buffer_arena, bufkva_reclaim);
buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
/*
* Size the clean queue according to the amount of buffer space.
* One queue per-256mb up to the max. More queues gives better
* concurrency but less accurate LRU.
*/
clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES);
}
#ifdef INVARIANTS
static inline void
vfs_buf_check_mapped(struct buf *bp)
{
KASSERT(bp->b_kvabase != unmapped_buf,
("mapped buf: b_kvabase was not updated %p", bp));
KASSERT(bp->b_data != unmapped_buf,
("mapped buf: b_data was not updated %p", bp));
KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
MAXPHYS, ("b_data + b_offset unmapped %p", bp));
}
static inline void
vfs_buf_check_unmapped(struct buf *bp)
{
KASSERT(bp->b_data == unmapped_buf,
("unmapped buf: corrupted b_data %p", bp));
}
#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
#else
#define BUF_CHECK_MAPPED(bp) do {} while (0)
#define BUF_CHECK_UNMAPPED(bp) do {} while (0)
#endif
static int
isbufbusy(struct buf *bp)
{
if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
return (1);
return (0);
}
/*
* Shutdown the system cleanly to prepare for reboot, halt, or power off.
*/
void
bufshutdown(int show_busybufs)
{
static int first_buf_printf = 1;
struct buf *bp;
int iter, nbusy, pbusy;
#ifndef PREEMPTION
int subiter;
#endif
/*
* Sync filesystems for shutdown
*/
wdog_kern_pat(WD_LASTVAL);
sys_sync(curthread, NULL);
/*
* With soft updates, some buffers that are
* written will be remarked as dirty until other
* buffers are written.
*/
for (iter = pbusy = 0; iter < 20; iter++) {
nbusy = 0;
for (bp = &buf[nbuf]; --bp >= buf; )
if (isbufbusy(bp))
nbusy++;
if (nbusy == 0) {
if (first_buf_printf)
printf("All buffers synced.");
break;
}
if (first_buf_printf) {
printf("Syncing disks, buffers remaining... ");
first_buf_printf = 0;
}
printf("%d ", nbusy);
if (nbusy < pbusy)
iter = 0;
pbusy = nbusy;
wdog_kern_pat(WD_LASTVAL);
sys_sync(curthread, NULL);
#ifdef PREEMPTION
/*
* Drop Giant and spin for a while to allow
* interrupt threads to run.
*/
DROP_GIANT();
DELAY(50000 * iter);
PICKUP_GIANT();
#else
/*
* Drop Giant and context switch several times to
* allow interrupt threads to run.
*/
DROP_GIANT();
for (subiter = 0; subiter < 50 * iter; subiter++) {
thread_lock(curthread);
mi_switch(SW_VOL, NULL);
thread_unlock(curthread);
DELAY(1000);
}
PICKUP_GIANT();
#endif
}
printf("\n");
/*
* Count only busy local buffers to prevent forcing
* a fsck if we're just a client of a wedged NFS server
*/
nbusy = 0;
for (bp = &buf[nbuf]; --bp >= buf; ) {
if (isbufbusy(bp)) {
#if 0
/* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
if (bp->b_dev == NULL) {
TAILQ_REMOVE(&mountlist,
bp->b_vp->v_mount, mnt_list);
continue;
}
#endif
nbusy++;
if (show_busybufs > 0) {
printf(
"%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
nbusy, bp, bp->b_vp, bp->b_flags,
(intmax_t)bp->b_blkno,
(intmax_t)bp->b_lblkno);
BUF_LOCKPRINTINFO(bp);
if (show_busybufs > 1)
vn_printf(bp->b_vp,
"vnode content: ");
}
}
}
if (nbusy) {
/*
* Failed to sync all blocks. Indicate this and don't
* unmount filesystems (thus forcing an fsck on reboot).
*/
printf("Giving up on %d buffers\n", nbusy);
DELAY(5000000); /* 5 seconds */
} else {
if (!first_buf_printf)
printf("Final sync complete\n");
/*
* Unmount filesystems
*/
if (panicstr == NULL)
vfs_unmountall();
}
swapoff_all();
DELAY(100000); /* wait for console output to finish */
}
static void
bpmap_qenter(struct buf *bp)
{
BUF_CHECK_MAPPED(bp);
/*
* bp->b_data is relative to bp->b_offset, but
* bp->b_offset may be offset into the first page.
*/
bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data);
pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
(vm_offset_t)(bp->b_offset & PAGE_MASK));
}
/*
* binsfree:
*
* Insert the buffer into the appropriate free list.
*/
static void
binsfree(struct buf *bp, int qindex)
{
struct mtx *olock, *nlock;
if (qindex != QUEUE_EMPTY) {
BUF_ASSERT_XLOCKED(bp);
}
/*
* Stick to the same clean queue for the lifetime of the buf to
* limit locking below. Otherwise pick ont sequentially.
*/
if (qindex == QUEUE_CLEAN) {
if (bqisclean(bp->b_qindex))
qindex = bp->b_qindex;
else
qindex = bqcleanq();
}
/*
* Handle delayed bremfree() processing.
*/
nlock = bqlock(qindex);
if (bp->b_flags & B_REMFREE) {
olock = bqlock(bp->b_qindex);
mtx_lock(olock);
bremfreel(bp);
if (olock != nlock) {
mtx_unlock(olock);
mtx_lock(nlock);
}
} else
mtx_lock(nlock);
if (bp->b_qindex != QUEUE_NONE)
panic("binsfree: free buffer onto another queue???");
bp->b_qindex = qindex;
if (bp->b_flags & B_AGE)
TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
else
TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
#ifdef INVARIANTS
bq_len[bp->b_qindex]++;
#endif
mtx_unlock(nlock);
}
/*
* buf_free:
*
* Free a buffer to the buf zone once it no longer has valid contents.
*/
static void
buf_free(struct buf *bp)
{
if (bp->b_flags & B_REMFREE)
bremfreef(bp);
if (bp->b_vflags & BV_BKGRDINPROG)
panic("losing buffer 1");
if (bp->b_rcred != NOCRED) {
crfree(bp->b_rcred);
bp->b_rcred = NOCRED;
}
if (bp->b_wcred != NOCRED) {
crfree(bp->b_wcred);
bp->b_wcred = NOCRED;
}
if (!LIST_EMPTY(&bp->b_dep))
buf_deallocate(bp);
bufkva_free(bp);
BUF_UNLOCK(bp);
uma_zfree(buf_zone, bp);
atomic_add_int(&numfreebuffers, 1);
bufspace_wakeup();
}
/*
* buf_import:
*
* Import bufs into the uma cache from the buf list. The system still
* expects a static array of bufs and much of the synchronization
* around bufs assumes type stable storage. As a result, UMA is used
* only as a per-cpu cache of bufs still maintained on a global list.
*/
static int
buf_import(void *arg, void **store, int cnt, int flags)
{
struct buf *bp;
int i;
mtx_lock(&bqlocks[QUEUE_EMPTY]);
for (i = 0; i < cnt; i++) {
bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
if (bp == NULL)
break;
bremfreel(bp);
store[i] = bp;
}
mtx_unlock(&bqlocks[QUEUE_EMPTY]);
return (i);
}
/*
* buf_release:
*
* Release bufs from the uma cache back to the buffer queues.
*/
static void
buf_release(void *arg, void **store, int cnt)
{
int i;
for (i = 0; i < cnt; i++)
binsfree(store[i], QUEUE_EMPTY);
}
/*
* buf_alloc:
*
* Allocate an empty buffer header.
*/
static struct buf *
buf_alloc(void)
{
struct buf *bp;
bp = uma_zalloc(buf_zone, M_NOWAIT);
if (bp == NULL) {
bufspace_daemonwakeup();
atomic_add_int(&numbufallocfails, 1);
return (NULL);
}
/*
* Wake-up the bufspace daemon on transition.
*/
if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers)
bufspace_daemonwakeup();
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
KASSERT(bp->b_vp == NULL,
("bp: %p still has vnode %p.", bp, bp->b_vp));
KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
("invalid buffer %p flags %#x", bp, bp->b_flags));
KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
KASSERT(bp->b_npages == 0,
("bp: %p still has %d vm pages\n", bp, bp->b_npages));
KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
bp->b_flags = 0;
bp->b_ioflags = 0;
bp->b_xflags = 0;
bp->b_vflags = 0;
bp->b_vp = NULL;
bp->b_blkno = bp->b_lblkno = 0;
bp->b_offset = NOOFFSET;
bp->b_iodone = 0;
bp->b_error = 0;
bp->b_resid = 0;
bp->b_bcount = 0;
bp->b_npages = 0;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_bufobj = NULL;
bp->b_data = bp->b_kvabase = unmapped_buf;
bp->b_fsprivate1 = NULL;
bp->b_fsprivate2 = NULL;
bp->b_fsprivate3 = NULL;
LIST_INIT(&bp->b_dep);
return (bp);
}
/*
* buf_qrecycle:
*
* Free a buffer from the given bufqueue. kva controls whether the
* freed buf must own some kva resources. This is used for
* defragmenting.
*/
static int
buf_qrecycle(int qindex, bool kva)
{
struct buf *bp, *nbp;
if (kva)
atomic_add_int(&bufdefragcnt, 1);
nbp = NULL;
mtx_lock(&bqlocks[qindex]);
nbp = TAILQ_FIRST(&bufqueues[qindex]);
/*
* Run scan, possibly freeing data and/or kva mappings on the fly
* depending.
*/
while ((bp = nbp) != NULL) {
/*
* Calculate next bp (we can only use it if we do not
* release the bqlock).
*/
nbp = TAILQ_NEXT(bp, b_freelist);
/*
* If we are defragging then we need a buffer with
* some kva to reclaim.
*/
if (kva && bp->b_kvasize == 0)
continue;
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
continue;
/*
* Skip buffers with background writes in progress.
*/
if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
BUF_UNLOCK(bp);
continue;
}
KASSERT(bp->b_qindex == qindex,
("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
/*
* NOTE: nbp is now entirely invalid. We can only restart
* the scan from this point on.
*/
bremfreel(bp);
mtx_unlock(&bqlocks[qindex]);
/*
* Requeue the background write buffer with error and
* restart the scan.
*/
if ((bp->b_vflags & BV_BKGRDERR) != 0) {
bqrelse(bp);
mtx_lock(&bqlocks[qindex]);
nbp = TAILQ_FIRST(&bufqueues[qindex]);
continue;
}
bp->b_flags |= B_INVAL;
brelse(bp);
return (0);
}
mtx_unlock(&bqlocks[qindex]);
return (ENOBUFS);
}
/*
* buf_recycle:
*
* Iterate through all clean queues until we find a buf to recycle or
* exhaust the search.
*/
static int
buf_recycle(bool kva)
{
int qindex, first_qindex;
qindex = first_qindex = bqcleanq();
do {
if (buf_qrecycle(qindex, kva) == 0)
return (0);
if (++qindex == QUEUE_CLEAN + clean_queues)
qindex = QUEUE_CLEAN;
} while (qindex != first_qindex);
return (ENOBUFS);
}
/*
* buf_scan:
*
* Scan the clean queues looking for a buffer to recycle. needsbuffer
* is set on failure so that the caller may optionally bufspace_wait()
* in a race-free fashion.
*/
static int
buf_scan(bool defrag)
{
int error;
/*
* To avoid heavy synchronization and wakeup races we set
* needsbuffer and re-poll before failing. This ensures that
* no frees can be missed between an unsuccessful poll and
* going to sleep in a synchronized fashion.
*/
if ((error = buf_recycle(defrag)) != 0) {
atomic_set_int(&needsbuffer, 1);
bufspace_daemonwakeup();
error = buf_recycle(defrag);
}
if (error == 0)
atomic_add_int(&getnewbufrestarts, 1);
return (error);
}
/*
* bremfree:
*
* Mark the buffer for removal from the appropriate free list.
*
*/
void
bremfree(struct buf *bp)
{
CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT((bp->b_flags & B_REMFREE) == 0,
("bremfree: buffer %p already marked for delayed removal.", bp));
KASSERT(bp->b_qindex != QUEUE_NONE,
("bremfree: buffer %p not on a queue.", bp));
BUF_ASSERT_XLOCKED(bp);
bp->b_flags |= B_REMFREE;
}
/*
* bremfreef:
*
* Force an immediate removal from a free list. Used only in nfs when
* it abuses the b_freelist pointer.
*/
void
bremfreef(struct buf *bp)
{
struct mtx *qlock;
qlock = bqlock(bp->b_qindex);
mtx_lock(qlock);
bremfreel(bp);
mtx_unlock(qlock);
}
/*
* bremfreel:
*
* Removes a buffer from the free list, must be called with the
* correct qlock held.
*/
static void
bremfreel(struct buf *bp)
{
CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_qindex != QUEUE_NONE,
("bremfreel: buffer %p not on a queue.", bp));
if (bp->b_qindex != QUEUE_EMPTY) {
BUF_ASSERT_XLOCKED(bp);
}
mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
#ifdef INVARIANTS
KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
bp->b_qindex));
bq_len[bp->b_qindex]--;
#endif
bp->b_qindex = QUEUE_NONE;
bp->b_flags &= ~B_REMFREE;
}
/*
* bufkva_free:
*
* Free the kva allocation for a buffer.
*
*/
static void
bufkva_free(struct buf *bp)
{
#ifdef INVARIANTS
if (bp->b_kvasize == 0) {
KASSERT(bp->b_kvabase == unmapped_buf &&
bp->b_data == unmapped_buf,
("Leaked KVA space on %p", bp));
} else if (buf_mapped(bp))
BUF_CHECK_MAPPED(bp);
else
BUF_CHECK_UNMAPPED(bp);
#endif
if (bp->b_kvasize == 0)
return;
vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
atomic_subtract_long(&bufkvaspace, bp->b_kvasize);
atomic_add_int(&buffreekvacnt, 1);
bp->b_data = bp->b_kvabase = unmapped_buf;
bp->b_kvasize = 0;
}
/*
* bufkva_alloc:
*
* Allocate the buffer KVA and set b_kvasize and b_kvabase.
*/
static int
bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
{
vm_offset_t addr;
int error;
KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
("Invalid gbflags 0x%x in %s", gbflags, __func__));
bufkva_free(bp);
addr = 0;
error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
if (error != 0) {
/*
* Buffer map is too fragmented. Request the caller
* to defragment the map.
*/
return (error);
}
bp->b_kvabase = (caddr_t)addr;
bp->b_kvasize = maxsize;
atomic_add_long(&bufkvaspace, bp->b_kvasize);
if ((gbflags & GB_UNMAPPED) != 0) {
bp->b_data = unmapped_buf;
BUF_CHECK_UNMAPPED(bp);
} else {
bp->b_data = bp->b_kvabase;
BUF_CHECK_MAPPED(bp);
}
return (0);
}
/*
* bufkva_reclaim:
*
* Reclaim buffer kva by freeing buffers holding kva. This is a vmem
* callback that fires to avoid returning failure.
*/
static void
bufkva_reclaim(vmem_t *vmem, int flags)
{
int i;
for (i = 0; i < 5; i++)
if (buf_scan(true) != 0)
break;
return;
}
/*
* Attempt to initiate asynchronous I/O on read-ahead blocks. We must
* clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
* the buffer is valid and we do not have to do anything.
*/
static void
breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt,
struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *))
{
struct buf *rabp;
int i;
for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
if (inmem(vp, *rablkno))
continue;
rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
if ((rabp->b_flags & B_CACHE) != 0) {
brelse(rabp);
continue;
}
if (!TD_IS_IDLETHREAD(curthread)) {
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
racct_add_buf(curproc, rabp, 0);
PROC_UNLOCK(curproc);
}
#endif /* RACCT */
curthread->td_ru.ru_inblock++;
}
rabp->b_flags |= B_ASYNC;
rabp->b_flags &= ~B_INVAL;
if ((flags & GB_CKHASH) != 0) {
rabp->b_flags |= B_CKHASH;
rabp->b_ckhashcalc = ckhashfunc;
}
rabp->b_ioflags &= ~BIO_ERROR;
rabp->b_iocmd = BIO_READ;
if (rabp->b_rcred == NOCRED && cred != NOCRED)
rabp->b_rcred = crhold(cred);
vfs_busy_pages(rabp, 0);
BUF_KERNPROC(rabp);
rabp->b_iooffset = dbtob(rabp->b_blkno);
bstrategy(rabp);
}
}
/*
* Entry point for bread() and breadn() via #defines in sys/buf.h.
*
* Get a buffer with the specified data. Look in the cache first. We
* must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
* is set, the buffer is valid and we do not have to do anything, see
* getblk(). Also starts asynchronous I/O on read-ahead blocks.
*
* Always return a NULL buffer pointer (in bpp) when returning an error.
*/
int
breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
int *rabsize, int cnt, struct ucred *cred, int flags,
void (*ckhashfunc)(struct buf *), struct buf **bpp)
{
struct buf *bp;
int readwait, rv;
CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
/*
* Can only return NULL if GB_LOCK_NOWAIT flag is specified.
*/
*bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
if (bp == NULL)
return (EBUSY);
/*
* If not found in cache, do some I/O
*/
readwait = 0;
if ((bp->b_flags & B_CACHE) == 0) {
if (!TD_IS_IDLETHREAD(curthread)) {
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
racct_add_buf(curproc, bp, 0);
PROC_UNLOCK(curproc);
}
#endif /* RACCT */
curthread->td_ru.ru_inblock++;
}
bp->b_iocmd = BIO_READ;
bp->b_flags &= ~B_INVAL;
if ((flags & GB_CKHASH) != 0) {
bp->b_flags |= B_CKHASH;
bp->b_ckhashcalc = ckhashfunc;
}
bp->b_ioflags &= ~BIO_ERROR;
if (bp->b_rcred == NOCRED && cred != NOCRED)
bp->b_rcred = crhold(cred);
vfs_busy_pages(bp, 0);
bp->b_iooffset = dbtob(bp->b_blkno);
bstrategy(bp);
++readwait;
}
/*
* Attempt to initiate asynchronous I/O on read-ahead blocks.
*/
breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc);
rv = 0;
if (readwait) {
rv = bufwait(bp);
if (rv != 0) {
brelse(bp);
*bpp = NULL;
}
}
return (rv);
}
/*
* Write, release buffer on completion. (Done by iodone
* if async). Do not bother writing anything if the buffer
* is invalid.
*
* Note that we set B_CACHE here, indicating that buffer is
* fully valid and thus cacheable. This is true even of NFS
* now so we set it generally. This could be set either here
* or in biodone() since the I/O is synchronous. We put it
* here.
*/
int
bufwrite(struct buf *bp)
{
int oldflags;
struct vnode *vp;
long space;
int vp_md;
CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) {
bp->b_flags |= B_INVAL | B_RELBUF;
bp->b_flags &= ~B_CACHE;
brelse(bp);
return (ENXIO);
}
if (bp->b_flags & B_INVAL) {
brelse(bp);
return (0);
}
if (bp->b_flags & B_BARRIER)
barrierwrites++;
oldflags = bp->b_flags;
BUF_ASSERT_HELD(bp);
KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
("FFS background buffer should not get here %p", bp));
vp = bp->b_vp;
if (vp)
vp_md = vp->v_vflag & VV_MD;
else
vp_md = 0;
/*
* Mark the buffer clean. Increment the bufobj write count
* before bundirty() call, to prevent other thread from seeing
* empty dirty list and zero counter for writes in progress,
* falsely indicating that the bufobj is clean.
*/
bufobj_wref(bp->b_bufobj);
bundirty(bp);
bp->b_flags &= ~B_DONE;
bp->b_ioflags &= ~BIO_ERROR;
bp->b_flags |= B_CACHE;
bp->b_iocmd = BIO_WRITE;
vfs_busy_pages(bp, 1);
/*
* Normal bwrites pipeline writes
*/
bp->b_runningbufspace = bp->b_bufsize;
space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace);
if (!TD_IS_IDLETHREAD(curthread)) {
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
racct_add_buf(curproc, bp, 1);
PROC_UNLOCK(curproc);
}
#endif /* RACCT */
curthread->td_ru.ru_oublock++;
}
if (oldflags & B_ASYNC)
BUF_KERNPROC(bp);
bp->b_iooffset = dbtob(bp->b_blkno);
buf_track(bp, __func__);
bstrategy(bp);
if ((oldflags & B_ASYNC) == 0) {
int rtval = bufwait(bp);
brelse(bp);
return (rtval);
} else if (space > hirunningspace) {
/*
* don't allow the async write to saturate the I/O
* system. We will not deadlock here because
* we are blocking waiting for I/O that is already in-progress
* to complete. We do not block here if it is the update
* or syncer daemon trying to clean up as that can lead
* to deadlock.
*/
if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
waitrunningbufspace();
}
return (0);
}
void
bufbdflush(struct bufobj *bo, struct buf *bp)
{
struct buf *nbp;
if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
(void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
altbufferflushes++;
} else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
BO_LOCK(bo);
/*
* Try to find a buffer to flush.
*/
TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
if ((nbp->b_vflags & BV_BKGRDINPROG) ||
BUF_LOCK(nbp,
LK_EXCLUSIVE | LK_NOWAIT, NULL))
continue;
if (bp == nbp)
panic("bdwrite: found ourselves");
BO_UNLOCK(bo);
/* Don't countdeps with the bo lock held. */
if (buf_countdeps(nbp, 0)) {
BO_LOCK(bo);
BUF_UNLOCK(nbp);
continue;
}
if (nbp->b_flags & B_CLUSTEROK) {
vfs_bio_awrite(nbp);
} else {
bremfree(nbp);
bawrite(nbp);
}
dirtybufferflushes++;
break;
}
if (nbp == NULL)
BO_UNLOCK(bo);
}
}
/*
* Delayed write. (Buffer is marked dirty). Do not bother writing
* anything if the buffer is marked invalid.
*
* Note that since the buffer must be completely valid, we can safely
* set B_CACHE. In fact, we have to set B_CACHE here rather then in
* biodone() in order to prevent getblk from writing the buffer
* out synchronously.
*/
void
bdwrite(struct buf *bp)
{
struct thread *td = curthread;
struct vnode *vp;
struct bufobj *bo;
CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
KASSERT((bp->b_flags & B_BARRIER) == 0,
("Barrier request in delayed write %p", bp));
BUF_ASSERT_HELD(bp);
if (bp->b_flags & B_INVAL) {
brelse(bp);
return;
}
/*
* If we have too many dirty buffers, don't create any more.
* If we are wildly over our limit, then force a complete
* cleanup. Otherwise, just keep the situation from getting
* out of control. Note that we have to avoid a recursive
* disaster and not try to clean up after our own cleanup!
*/
vp = bp->b_vp;
bo = bp->b_bufobj;
if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
td->td_pflags |= TDP_INBDFLUSH;
BO_BDFLUSH(bo, bp);
td->td_pflags &= ~TDP_INBDFLUSH;
} else
recursiveflushes++;
bdirty(bp);
/*
* Set B_CACHE, indicating that the buffer is fully valid. This is
* true even of NFS now.
*/
bp->b_flags |= B_CACHE;
/*
* This bmap keeps the system from needing to do the bmap later,
* perhaps when the system is attempting to do a sync. Since it
* is likely that the indirect block -- or whatever other datastructure
* that the filesystem needs is still in memory now, it is a good
* thing to do this. Note also, that if the pageout daemon is
* requesting a sync -- there might not be enough memory to do
* the bmap then... So, this is important to do.
*/
if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
}
buf_track(bp, __func__);
/*
* Set the *dirty* buffer range based upon the VM system dirty
* pages.
*
* Mark the buffer pages as clean. We need to do this here to
* satisfy the vnode_pager and the pageout daemon, so that it
* thinks that the pages have been "cleaned". Note that since
* the pages are in a delayed write buffer -- the VFS layer
* "will" see that the pages get written out on the next sync,
* or perhaps the cluster will be completed.
*/
vfs_clean_pages_dirty_buf(bp);
bqrelse(bp);
/*
* note: we cannot initiate I/O from a bdwrite even if we wanted to,
* due to the softdep code.
*/
}
/*
* bdirty:
*
* Turn buffer into delayed write request. We must clear BIO_READ and
* B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
* itself to properly update it in the dirty/clean lists. We mark it
* B_DONE to ensure that any asynchronization of the buffer properly
* clears B_DONE ( else a panic will occur later ).
*
* bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
* might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
* should only be called if the buffer is known-good.
*
* Since the buffer is not on a queue, we do not update the numfreebuffers
* count.
*
* The buffer must be on QUEUE_NONE.
*/
void
bdirty(struct buf *bp)
{
CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
BUF_ASSERT_HELD(bp);
bp->b_flags &= ~(B_RELBUF);
bp->b_iocmd = BIO_WRITE;
if ((bp->b_flags & B_DELWRI) == 0) {
bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
reassignbuf(bp);
bdirtyadd();
}
}
/*
* bundirty:
*
* Clear B_DELWRI for buffer.
*
* Since the buffer is not on a queue, we do not update the numfreebuffers
* count.
*
* The buffer must be on QUEUE_NONE.
*/
void
bundirty(struct buf *bp)
{
CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
BUF_ASSERT_HELD(bp);
if (bp->b_flags & B_DELWRI) {
bp->b_flags &= ~B_DELWRI;
reassignbuf(bp);
bdirtysub();
}
/*
* Since it is now being written, we can clear its deferred write flag.
*/
bp->b_flags &= ~B_DEFERRED;
}
/*
* bawrite:
*
* Asynchronous write. Start output on a buffer, but do not wait for
* it to complete. The buffer is released when the output completes.
*
* bwrite() ( or the VOP routine anyway ) is responsible for handling
* B_INVAL buffers. Not us.
*/
void
bawrite(struct buf *bp)
{
bp->b_flags |= B_ASYNC;
(void) bwrite(bp);
}
/*
* babarrierwrite:
*
* Asynchronous barrier write. Start output on a buffer, but do not
* wait for it to complete. Place a write barrier after this write so
* that this buffer and all buffers written before it are committed to
* the disk before any buffers written after this write are committed
* to the disk. The buffer is released when the output completes.
*/
void
babarrierwrite(struct buf *bp)
{
bp->b_flags |= B_ASYNC | B_BARRIER;
(void) bwrite(bp);
}
/*
* bbarrierwrite:
*
* Synchronous barrier write. Start output on a buffer and wait for
* it to complete. Place a write barrier after this write so that
* this buffer and all buffers written before it are committed to
* the disk before any buffers written after this write are committed
* to the disk. The buffer is released when the output completes.
*/
int
bbarrierwrite(struct buf *bp)
{
bp->b_flags |= B_BARRIER;
return (bwrite(bp));
}
/*
* bwillwrite:
*
* Called prior to the locking of any vnodes when we are expecting to
* write. We do not want to starve the buffer cache with too many
* dirty buffers so we block here. By blocking prior to the locking
* of any vnodes we attempt to avoid the situation where a locked vnode
* prevents the various system daemons from flushing related buffers.
*/
void
bwillwrite(void)
{
if (numdirtybuffers >= hidirtybuffers) {
mtx_lock(&bdirtylock);
while (numdirtybuffers >= hidirtybuffers) {
bdirtywait = 1;
msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
"flswai", 0);
}
mtx_unlock(&bdirtylock);
}
}
/*
* Return true if we have too many dirty buffers.
*/
int
buf_dirty_count_severe(void)
{
return(numdirtybuffers >= hidirtybuffers);
}
/*
* brelse:
*
* Release a busy buffer and, if requested, free its resources. The
* buffer will be stashed in the appropriate bufqueue[] allowing it
* to be accessed later as a cache entity or reused for other purposes.
*/
void
brelse(struct buf *bp)
{
int qindex;
/*
* Many functions erroneously call brelse with a NULL bp under rare
* error conditions. Simply return when called with a NULL bp.
*/
if (bp == NULL)
return;
CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
("brelse: non-VMIO buffer marked NOREUSE"));
if (BUF_LOCKRECURSED(bp)) {
/*
* Do not process, in particular, do not handle the
* B_INVAL/B_RELBUF and do not release to free list.
*/
BUF_UNLOCK(bp);
return;
}
if (bp->b_flags & B_MANAGED) {
bqrelse(bp);
return;
}
if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
BO_LOCK(bp->b_bufobj);
bp->b_vflags &= ~BV_BKGRDERR;
BO_UNLOCK(bp->b_bufobj);
bdirty(bp);
}
if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
(bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) &&
!(bp->b_flags & B_INVAL)) {
/*
* Failed write, redirty. All errors except ENXIO (which
* means the device is gone) are expected to be potentially
* transient - underlying media might work if tried again
* after EIO, and memory might be available after an ENOMEM.
*
* Do this also for buffers that failed with ENXIO, but have
* non-empty dependencies - the soft updates code might need
* to access the buffer to untangle them.
*
* Must clear BIO_ERROR to prevent pages from being scrapped.
*/
bp->b_ioflags &= ~BIO_ERROR;
bdirty(bp);
} else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
(bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
/*
* Either a failed read I/O, or we were asked to free or not
* cache the buffer, or we failed to write to a device that's
* no longer present.
*/
bp->b_flags |= B_INVAL;
if (!LIST_EMPTY(&bp->b_dep))
buf_deallocate(bp);
if (bp->b_flags & B_DELWRI)
bdirtysub();
bp->b_flags &= ~(B_DELWRI | B_CACHE);
if ((bp->b_flags & B_VMIO) == 0) {
allocbuf(bp, 0);
if (bp->b_vp)
brelvp(bp);
}
}
/*
* We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
* is called with B_DELWRI set, the underlying pages may wind up
* getting freed causing a previous write (bdwrite()) to get 'lost'
* because pages associated with a B_DELWRI bp are marked clean.
*
* We still allow the B_INVAL case to call vfs_vmio_truncate(), even
* if B_DELWRI is set.
*/
if (bp->b_flags & B_DELWRI)
bp->b_flags &= ~B_RELBUF;
/*
* VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
* constituted, not even NFS buffers now. Two flags effect this. If
* B_INVAL, the struct buf is invalidated but the VM object is kept
* around ( i.e. so it is trivial to reconstitute the buffer later ).
*
* If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
* invalidated. BIO_ERROR cannot be set for a failed write unless the
* buffer is also B_INVAL because it hits the re-dirtying code above.
*
* Normally we can do this whether a buffer is B_DELWRI or not. If
* the buffer is an NFS buffer, it is tracking piecemeal writes or
* the commit state and we cannot afford to lose the buffer. If the
* buffer has a background write in progress, we need to keep it
* around to prevent it from being reconstituted and starting a second
* background write.
*/
if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE ||
(bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
!(bp->b_vp->v_mount != NULL &&
(bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
!vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) {
vfs_vmio_invalidate(bp);
allocbuf(bp, 0);
}
if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
(bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
allocbuf(bp, 0);
bp->b_flags &= ~B_NOREUSE;
if (bp->b_vp != NULL)
brelvp(bp);
}
/*
* If the buffer has junk contents signal it and eventually
* clean up B_DELWRI and diassociate the vnode so that gbincore()
* doesn't find it.
*/
if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
(bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
bp->b_flags |= B_INVAL;
if (bp->b_flags & B_INVAL) {
if (bp->b_flags & B_DELWRI)
bundirty(bp);
if (bp->b_vp)
brelvp(bp);
}
buf_track(bp, __func__);
/* buffers with no memory */
if (bp->b_bufsize == 0) {
buf_free(bp);
return;
}
/* buffers with junk contents */
if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
(bp->b_ioflags & BIO_ERROR)) {
bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
if (bp->b_vflags & BV_BKGRDINPROG)
panic("losing buffer 2");
qindex = QUEUE_CLEAN;
bp->b_flags |= B_AGE;
/* remaining buffers */
} else if (bp->b_flags & B_DELWRI)
qindex = QUEUE_DIRTY;
else
qindex = QUEUE_CLEAN;
binsfree(bp, qindex);
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
panic("brelse: not dirty");
/* unlock */
BUF_UNLOCK(bp);
if (qindex == QUEUE_CLEAN)
bufspace_wakeup();
}
/*
* Release a buffer back to the appropriate queue but do not try to free
* it. The buffer is expected to be used again soon.
*
* bqrelse() is used by bdwrite() to requeue a delayed write, and used by
* biodone() to requeue an async I/O on completion. It is also used when
* known good buffers need to be requeued but we think we may need the data
* again soon.
*
* XXX we should be able to leave the B_RELBUF hint set on completion.
*/
void
bqrelse(struct buf *bp)
{
int qindex;
CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
qindex = QUEUE_NONE;
if (BUF_LOCKRECURSED(bp)) {
/* do not release to free list */
BUF_UNLOCK(bp);
return;
}
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
if (bp->b_flags & B_MANAGED) {
if (bp->b_flags & B_REMFREE)
bremfreef(bp);
goto out;
}
/* buffers with stale but valid contents */
if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
BV_BKGRDERR)) == BV_BKGRDERR) {
BO_LOCK(bp->b_bufobj);
bp->b_vflags &= ~BV_BKGRDERR;
BO_UNLOCK(bp->b_bufobj);
qindex = QUEUE_DIRTY;
} else {
if ((bp->b_flags & B_DELWRI) == 0 &&
(bp->b_xflags & BX_VNDIRTY))
panic("bqrelse: not dirty");
if ((bp->b_flags & B_NOREUSE) != 0) {
brelse(bp);
return;
}
qindex = QUEUE_CLEAN;
}
binsfree(bp, qindex);
out:
buf_track(bp, __func__);
/* unlock */
BUF_UNLOCK(bp);
if (qindex == QUEUE_CLEAN)
bufspace_wakeup();
}
/*
* Complete I/O to a VMIO backed page. Validate the pages as appropriate,
* restore bogus pages.
*/
static void
vfs_vmio_iodone(struct buf *bp)
{
vm_ooffset_t foff;
vm_page_t m;
vm_object_t obj;
struct vnode *vp;
int i, iosize, resid;
bool bogus;
obj = bp->b_bufobj->bo_object;
KASSERT(obj->paging_in_progress >= bp->b_npages,
("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
obj->paging_in_progress, bp->b_npages));
vp = bp->b_vp;
KASSERT(vp->v_holdcnt > 0,
("vfs_vmio_iodone: vnode %p has zero hold count", vp));
KASSERT(vp->v_object != NULL,
("vfs_vmio_iodone: vnode %p has no vm_object", vp));
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_vmio_iodone: bp %p has no buffer offset", bp));
bogus = false;
iosize = bp->b_bcount - bp->b_resid;
VM_OBJECT_WLOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
if (resid > iosize)
resid = iosize;
/*
* cleanup bogus pages, restoring the originals
*/
m = bp->b_pages[i];
if (m == bogus_page) {
bogus = true;
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
if (m == NULL)
panic("biodone: page disappeared!");
bp->b_pages[i] = m;
} else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
/*
* In the write case, the valid and clean bits are
* already changed correctly ( see bdwrite() ), so we
* only need to do this here in the read case.
*/
KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
resid)) == 0, ("vfs_vmio_iodone: page %p "
"has unexpected dirty bits", m));
vfs_page_set_valid(bp, foff, m);
}
KASSERT(OFF_TO_IDX(foff) == m->pindex,
("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
(intmax_t)foff, (uintmax_t)m->pindex));
vm_page_sunbusy(m);
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
iosize -= resid;
}
vm_object_pip_wakeupn(obj, bp->b_npages);
VM_OBJECT_WUNLOCK(obj);
if (bogus && buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
}
/*
* Unwire a page held by a buf and place it on the appropriate vm queue.
*/
static void
vfs_vmio_unwire(struct buf *bp, vm_page_t m)
{
bool freed;
vm_page_lock(m);
if (vm_page_unwire(m, PQ_NONE)) {
/*
* Determine if the page should be freed before adding
* it to the inactive queue.
*/
if (m->valid == 0) {
freed = !vm_page_busied(m);
if (freed)
vm_page_free(m);
} else if ((bp->b_flags & B_DIRECT) != 0)
freed = vm_page_try_to_free(m);
else
freed = false;
if (!freed) {
/*
* If the page is unlikely to be reused, let the
* VM know. Otherwise, maintain LRU page
* ordering and put the page at the tail of the
* inactive queue.
*/
if ((bp->b_flags & B_NOREUSE) != 0)
vm_page_deactivate_noreuse(m);
else
vm_page_deactivate(m);
}
}
vm_page_unlock(m);
}
/*
* Perform page invalidation when a buffer is released. The fully invalid
* pages will be reclaimed later in vfs_vmio_truncate().
*/
static void
vfs_vmio_invalidate(struct buf *bp)
{
vm_object_t obj;
vm_page_t m;
int i, resid, poffset, presid;
if (buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
} else
BUF_CHECK_UNMAPPED(bp);
/*
* Get the base offset and length of the buffer. Note that
* in the VMIO case if the buffer block size is not
* page-aligned then b_data pointer may not be page-aligned.
* But our b_pages[] array *IS* page aligned.
*
* block sizes less then DEV_BSIZE (usually 512) are not
* supported due to the page granularity bits (m->valid,
* m->dirty, etc...).
*
* See man buf(9) for more information
*/
obj = bp->b_bufobj->bo_object;
resid = bp->b_bufsize;
poffset = bp->b_offset & PAGE_MASK;
VM_OBJECT_WLOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (m == bogus_page)
panic("vfs_vmio_invalidate: Unexpected bogus page.");
bp->b_pages[i] = NULL;
presid = resid > (PAGE_SIZE - poffset) ?
(PAGE_SIZE - poffset) : resid;
KASSERT(presid >= 0, ("brelse: extra page"));
while (vm_page_xbusied(m)) {
vm_page_lock(m);
VM_OBJECT_WUNLOCK(obj);
vm_page_busy_sleep(m, "mbncsh", true);
VM_OBJECT_WLOCK(obj);
}
if (pmap_page_wired_mappings(m) == 0)
vm_page_set_invalid(m, poffset, presid);
vfs_vmio_unwire(bp, m);
resid -= presid;
poffset = 0;
}
VM_OBJECT_WUNLOCK(obj);
bp->b_npages = 0;
}
/*
* Page-granular truncation of an existing VMIO buffer.
*/
static void
vfs_vmio_truncate(struct buf *bp, int desiredpages)
{
vm_object_t obj;
vm_page_t m;
int i;
if (bp->b_npages == desiredpages)
return;
if (buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) +
(desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages);
} else
BUF_CHECK_UNMAPPED(bp);
obj = bp->b_bufobj->bo_object;
if (obj != NULL)
VM_OBJECT_WLOCK(obj);
for (i = desiredpages; i < bp->b_npages; i++) {
m = bp->b_pages[i];
KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
bp->b_pages[i] = NULL;
vfs_vmio_unwire(bp, m);
}
if (obj != NULL)
VM_OBJECT_WUNLOCK(obj);
bp->b_npages = desiredpages;
}
/*
* Byte granular extension of VMIO buffers.
*/
static void
vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
{
/*
* We are growing the buffer, possibly in a
* byte-granular fashion.
*/
vm_object_t obj;
vm_offset_t toff;
vm_offset_t tinc;
vm_page_t m;
/*
* Step 1, bring in the VM pages from the object, allocating
* them if necessary. We must clear B_CACHE if these pages
* are not valid for the range covered by the buffer.
*/
obj = bp->b_bufobj->bo_object;
VM_OBJECT_WLOCK(obj);
if (bp->b_npages < desiredpages) {
/*
* We must allocate system pages since blocking
* here could interfere with paging I/O, no
* matter which process we are.
*
* Only exclusive busy can be tested here.
* Blocking on shared busy might lead to
* deadlocks once allocbuf() is called after
* pages are vfs_busy_pages().
*/
(void)vm_page_grab_pages(obj,
OFF_TO_IDX(bp->b_offset) + bp->b_npages,
VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY |
VM_ALLOC_NOBUSY | VM_ALLOC_WIRED,
&bp->b_pages[bp->b_npages], desiredpages - bp->b_npages);
bp->b_npages = desiredpages;
}
/*
* Step 2. We've loaded the pages into the buffer,
* we have to figure out if we can still have B_CACHE
* set. Note that B_CACHE is set according to the
* byte-granular range ( bcount and size ), not the
* aligned range ( newbsize ).
*
* The VM test is against m->valid, which is DEV_BSIZE
* aligned. Needless to say, the validity of the data
* needs to also be DEV_BSIZE aligned. Note that this
* fails with NFS if the server or some other client
* extends the file's EOF. If our buffer is resized,
* B_CACHE may remain set! XXX
*/
toff = bp->b_bcount;
tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
while ((bp->b_flags & B_CACHE) && toff < size) {
vm_pindex_t pi;
if (tinc > (size - toff))
tinc = size - toff;
pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT;
m = bp->b_pages[pi];
vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
toff += tinc;
tinc = PAGE_SIZE;
}
VM_OBJECT_WUNLOCK(obj);
/*
* Step 3, fixup the KVA pmap.
*/
if (buf_mapped(bp))
bpmap_qenter(bp);
else
BUF_CHECK_UNMAPPED(bp);
}
/*
* Check to see if a block at a particular lbn is available for a clustered
* write.
*/
static int
vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
{
struct buf *bpa;
int match;
match = 0;
/* If the buf isn't in core skip it */
if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
return (0);
/* If the buf is busy we don't want to wait for it */
if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
return (0);
/* Only cluster with valid clusterable delayed write buffers */
if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
(B_DELWRI | B_CLUSTEROK))
goto done;
if (bpa->b_bufsize != size)
goto done;
/*
* Check to see if it is in the expected place on disk and that the
* block has been mapped.
*/
if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
match = 1;
done:
BUF_UNLOCK(bpa);
return (match);
}
/*
* vfs_bio_awrite:
*
* Implement clustered async writes for clearing out B_DELWRI buffers.
* This is much better then the old way of writing only one buffer at
* a time. Note that we may not be presented with the buffers in the
* correct order, so we search for the cluster in both directions.
*/
int
vfs_bio_awrite(struct buf *bp)
{
struct bufobj *bo;
int i;
int j;
daddr_t lblkno = bp->b_lblkno;
struct vnode *vp = bp->b_vp;
int ncl;
int nwritten;
int size;
int maxcl;
int gbflags;
bo = &vp->v_bufobj;
gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0;
/*
* right now we support clustered writing only to regular files. If
* we find a clusterable block we could be in the middle of a cluster
* rather then at the beginning.
*/
if ((vp->v_type == VREG) &&
(vp->v_mount != 0) && /* Only on nodes that have the size info */
(bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
size = vp->v_mount->mnt_stat.f_iosize;
maxcl = MAXPHYS / size;
BO_RLOCK(bo);
for (i = 1; i < maxcl; i++)
if (vfs_bio_clcheck(vp, size, lblkno + i,
bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
break;
for (j = 1; i + j <= maxcl && j <= lblkno; j++)
if (vfs_bio_clcheck(vp, size, lblkno - j,
bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
break;
BO_RUNLOCK(bo);
--j;
ncl = i + j;
/*
* this is a possible cluster write
*/
if (ncl != 1) {
BUF_UNLOCK(bp);
nwritten = cluster_wbuild(vp, size, lblkno - j, ncl,
gbflags);
return (nwritten);
}
}
bremfree(bp);
bp->b_flags |= B_ASYNC;
/*
* default (old) behavior, writing out only one block
*
* XXX returns b_bufsize instead of b_bcount for nwritten?
*/
nwritten = bp->b_bufsize;
(void) bwrite(bp);
return (nwritten);
}
/*
* getnewbuf_kva:
*
* Allocate KVA for an empty buf header according to gbflags.
*/
static int
getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
{
if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
/*
* In order to keep fragmentation sane we only allocate kva
* in BKVASIZE chunks. XXX with vmem we can do page size.
*/
maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
if (maxsize != bp->b_kvasize &&
bufkva_alloc(bp, maxsize, gbflags))
return (ENOSPC);
}
return (0);
}
/*
* getnewbuf:
*
* Find and initialize a new buffer header, freeing up existing buffers
* in the bufqueues as necessary. The new buffer is returned locked.
*
* We block if:
* We have insufficient buffer headers
* We have insufficient buffer space
* buffer_arena is too fragmented ( space reservation fails )
* If we have to flush dirty buffers ( but we try to avoid this )
*
* The caller is responsible for releasing the reserved bufspace after
* allocbuf() is called.
*/
static struct buf *
getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
{
struct buf *bp;
bool metadata, reserved;
bp = NULL;
KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
if (!unmapped_buf_allowed)
gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
vp->v_type == VCHR)
metadata = true;
else
metadata = false;
atomic_add_int(&getnewbufcalls, 1);
reserved = false;
do {
if (reserved == false &&
bufspace_reserve(maxsize, metadata) != 0)
continue;
reserved = true;
if ((bp = buf_alloc()) == NULL)
continue;
if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
return (bp);
break;
} while(buf_scan(false) == 0);
if (reserved)
atomic_subtract_long(&bufspace, maxsize);
if (bp != NULL) {
bp->b_flags |= B_INVAL;
brelse(bp);
}
bufspace_wait(vp, gbflags, slpflag, slptimeo);
return (NULL);
}
/*
* buf_daemon:
*
* buffer flushing daemon. Buffers are normally flushed by the
* update daemon but if it cannot keep up this process starts to
* take the load in an attempt to prevent getnewbuf() from blocking.
*/
static struct kproc_desc buf_kp = {
"bufdaemon",
buf_daemon,
&bufdaemonproc
};
SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
static int
buf_flush(struct vnode *vp, int target)
{
int flushed;
flushed = flushbufqueues(vp, target, 0);
if (flushed == 0) {
/*
* Could not find any buffers without rollback
* dependencies, so just write the first one
* in the hopes of eventually making progress.
*/
if (vp != NULL && target > 2)
target /= 2;
flushbufqueues(vp, target, 1);
}
return (flushed);
}
static void
buf_daemon()
{
int lodirty;
/*
* This process needs to be suspended prior to shutdown sync.
*/
EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
SHUTDOWN_PRI_LAST);
/*
* This process is allowed to take the buffer cache to the limit
*/
curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
mtx_lock(&bdlock);
for (;;) {
bd_request = 0;
mtx_unlock(&bdlock);
kproc_suspend_check(bufdaemonproc);
lodirty = lodirtybuffers;
if (bd_speedupreq) {
lodirty = numdirtybuffers / 2;
bd_speedupreq = 0;
}
/*
* Do the flush. Limit the amount of in-transit I/O we
* allow to build up, otherwise we would completely saturate
* the I/O system.
*/
while (numdirtybuffers > lodirty) {
if (buf_flush(NULL, numdirtybuffers - lodirty) == 0)
break;
kern_yield(PRI_USER);
}
/*
* Only clear bd_request if we have reached our low water
* mark. The buf_daemon normally waits 1 second and
* then incrementally flushes any dirty buffers that have
* built up, within reason.
*
* If we were unable to hit our low water mark and couldn't
* find any flushable buffers, we sleep for a short period
* to avoid endless loops on unlockable buffers.
*/
mtx_lock(&bdlock);
if (numdirtybuffers <= lodirtybuffers) {
/*
* We reached our low water mark, reset the
* request and sleep until we are needed again.
* The sleep is just so the suspend code works.
*/
bd_request = 0;
/*
* Do an extra wakeup in case dirty threshold
* changed via sysctl and the explicit transition
* out of shortfall was missed.
*/
bdirtywakeup();
if (runningbufspace <= lorunningspace)
runningwakeup();
msleep(&bd_request, &bdlock, PVM, "psleep", hz);
} else {
/*
* We couldn't find any flushable dirty buffers but
* still have too many dirty buffers, we
* have to sleep and try again. (rare)
*/
msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
}
}
}
/*
* flushbufqueues:
*
* Try to flush a buffer in the dirty queue. We must be careful to
* free up B_INVAL buffers instead of write them, which NFS is
* particularly sensitive to.
*/
static int flushwithdeps = 0;
SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
0, "Number of buffers flushed with dependecies that require rollbacks");
static int
flushbufqueues(struct vnode *lvp, int target, int flushdeps)
{
struct buf *sentinel;
struct vnode *vp;
struct mount *mp;
struct buf *bp;
int hasdeps;
int flushed;
int queue;
int error;
bool unlock;
flushed = 0;
queue = QUEUE_DIRTY;
bp = NULL;
sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
sentinel->b_qindex = QUEUE_SENTINEL;
mtx_lock(&bqlocks[queue]);
TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqlocks[queue]);
while (flushed != target) {
maybe_yield();
mtx_lock(&bqlocks[queue]);
bp = TAILQ_NEXT(sentinel, b_freelist);
if (bp != NULL) {
TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
b_freelist);
} else {
mtx_unlock(&bqlocks[queue]);
break;
}
/*
* Skip sentinels inserted by other invocations of the
* flushbufqueues(), taking care to not reorder them.
*
* Only flush the buffers that belong to the
* vnode locked by the curthread.
*/
if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
bp->b_vp != lvp)) {
mtx_unlock(&bqlocks[queue]);
continue;
}
error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
mtx_unlock(&bqlocks[queue]);
if (error != 0)
continue;
/*
* BKGRDINPROG can only be set with the buf and bufobj
* locks both held. We tolerate a race to clear it here.
*/
if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
(bp->b_flags & B_DELWRI) == 0) {
BUF_UNLOCK(bp);
continue;
}
if (bp->b_flags & B_INVAL) {
bremfreef(bp);
brelse(bp);
flushed++;
continue;
}
if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
if (flushdeps == 0) {
BUF_UNLOCK(bp);
continue;
}
hasdeps = 1;
} else
hasdeps = 0;
/*
* We must hold the lock on a vnode before writing
* one of its buffers. Otherwise we may confuse, or
* in the case of a snapshot vnode, deadlock the
* system.
*
* The lock order here is the reverse of the normal
* of vnode followed by buf lock. This is ok because
* the NOWAIT will prevent deadlock.
*/
vp = bp->b_vp;
if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
BUF_UNLOCK(bp);
continue;
}
if (lvp == NULL) {
unlock = true;
error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
} else {
ASSERT_VOP_LOCKED(vp, "getbuf");
unlock = false;
error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
vn_lock(vp, LK_TRYUPGRADE);
}
if (error == 0) {
CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
if (curproc == bufdaemonproc) {
vfs_bio_awrite(bp);
} else {
bremfree(bp);
bwrite(bp);
notbufdflushes++;
}
vn_finished_write(mp);
if (unlock)
VOP_UNLOCK(vp, 0);
flushwithdeps += hasdeps;
flushed++;
/*
* Sleeping on runningbufspace while holding
* vnode lock leads to deadlock.
*/
if (curproc == bufdaemonproc &&
runningbufspace > hirunningspace)
waitrunningbufspace();
continue;
}
vn_finished_write(mp);
BUF_UNLOCK(bp);
}
mtx_lock(&bqlocks[queue]);
TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqlocks[queue]);
free(sentinel, M_TEMP);
return (flushed);
}
/*
* Check to see if a block is currently memory resident.
*/
struct buf *
incore(struct bufobj *bo, daddr_t blkno)
{
struct buf *bp;
BO_RLOCK(bo);
bp = gbincore(bo, blkno);
BO_RUNLOCK(bo);
return (bp);
}
/*
* Returns true if no I/O is needed to access the
* associated VM object. This is like incore except
* it also hunts around in the VM system for the data.
*/
static int
inmem(struct vnode * vp, daddr_t blkno)
{
vm_object_t obj;
vm_offset_t toff, tinc, size;
vm_page_t m;
vm_ooffset_t off;
ASSERT_VOP_LOCKED(vp, "inmem");
if (incore(&vp->v_bufobj, blkno))
return 1;
if (vp->v_mount == NULL)
return 0;
obj = vp->v_object;
if (obj == NULL)
return (0);
size = PAGE_SIZE;
if (size > vp->v_mount->mnt_stat.f_iosize)
size = vp->v_mount->mnt_stat.f_iosize;
off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
VM_OBJECT_RLOCK(obj);
for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
if (!m)
goto notinmem;
tinc = size;
if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
if (vm_page_is_valid(m,
(vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
goto notinmem;
}
VM_OBJECT_RUNLOCK(obj);
return 1;
notinmem:
VM_OBJECT_RUNLOCK(obj);
return (0);
}
/*
* Set the dirty range for a buffer based on the status of the dirty
* bits in the pages comprising the buffer. The range is limited
* to the size of the buffer.
*
* Tell the VM system that the pages associated with this buffer
* are clean. This is used for delayed writes where the data is
* going to go to disk eventually without additional VM intevention.
*
* Note that while we only really need to clean through to b_bcount, we
* just go ahead and clean through to b_bufsize.
*/
static void
vfs_clean_pages_dirty_buf(struct buf *bp)
{
vm_ooffset_t foff, noff, eoff;
vm_page_t m;
int i;
if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
return;
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_clean_pages_dirty_buf: no buffer offset"));
VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
vfs_drain_busy_pages(bp);
vfs_setdirty_locked_object(bp);
for (i = 0; i < bp->b_npages; i++) {
noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
eoff = noff;
if (eoff > bp->b_offset + bp->b_bufsize)
eoff = bp->b_offset + bp->b_bufsize;
m = bp->b_pages[i];
vfs_page_set_validclean(bp, foff, m);
/* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
foff = noff;
}
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
}
static void
vfs_setdirty_locked_object(struct buf *bp)
{
vm_object_t object;
int i;
object = bp->b_bufobj->bo_object;
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* We qualify the scan for modified pages on whether the
* object has been flushed yet.
*/
if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
vm_offset_t boffset;
vm_offset_t eoffset;
/*
* test the pages to see if they have been modified directly
* by users through the VM system.
*/
for (i = 0; i < bp->b_npages; i++)
vm_page_test_dirty(bp->b_pages[i]);
/*
* Calculate the encompassing dirty range, boffset and eoffset,
* (eoffset - boffset) bytes.
*/
for (i = 0; i < bp->b_npages; i++) {
if (bp->b_pages[i]->dirty)
break;
}
boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
for (i = bp->b_npages - 1; i >= 0; --i) {
if (bp->b_pages[i]->dirty) {
break;
}
}
eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
/*
* Fit it to the buffer.
*/
if (eoffset > bp->b_bcount)
eoffset = bp->b_bcount;
/*
* If we have a good dirty range, merge with the existing
* dirty range.
*/
if (boffset < eoffset) {
if (bp->b_dirtyoff > boffset)
bp->b_dirtyoff = boffset;
if (bp->b_dirtyend < eoffset)
bp->b_dirtyend = eoffset;
}
}
}
/*
* Allocate the KVA mapping for an existing buffer.
* If an unmapped buffer is provided but a mapped buffer is requested, take
* also care to properly setup mappings between pages and KVA.
*/
static void
bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
{
int bsize, maxsize, need_mapping, need_kva;
off_t offset;
need_mapping = bp->b_data == unmapped_buf &&
(gbflags & GB_UNMAPPED) == 0;
need_kva = bp->b_kvabase == unmapped_buf &&
bp->b_data == unmapped_buf &&
(gbflags & GB_KVAALLOC) != 0;
if (!need_mapping && !need_kva)
return;
BUF_CHECK_UNMAPPED(bp);
if (need_mapping && bp->b_kvabase != unmapped_buf) {
/*
* Buffer is not mapped, but the KVA was already
* reserved at the time of the instantiation. Use the
* allocated space.
*/
goto has_addr;
}
/*
* Calculate the amount of the address space we would reserve
* if the buffer was mapped.
*/
bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
offset = blkno * bsize;
maxsize = size + (offset & PAGE_MASK);
maxsize = imax(maxsize, bsize);
while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
if ((gbflags & GB_NOWAIT_BD) != 0) {
/*
* XXXKIB: defragmentation cannot
* succeed, not sure what else to do.
*/
panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
}
atomic_add_int(&mappingrestarts, 1);
bufspace_wait(bp->b_vp, gbflags, 0, 0);
}
has_addr:
if (need_mapping) {
/* b_offset is handled by bpmap_qenter. */
bp->b_data = bp->b_kvabase;
BUF_CHECK_MAPPED(bp);
bpmap_qenter(bp);
}
}
/*
* getblk:
*
* Get a block given a specified block and offset into a file/device.
* The buffers B_DONE bit will be cleared on return, making it almost
* ready for an I/O initiation. B_INVAL may or may not be set on
* return. The caller should clear B_INVAL prior to initiating a
* READ.
*
* For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
* an existing buffer.
*
* For a VMIO buffer, B_CACHE is modified according to the backing VM.
* If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
* and then cleared based on the backing VM. If the previous buffer is
* non-0-sized but invalid, B_CACHE will be cleared.
*
* If getblk() must create a new buffer, the new buffer is returned with
* both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
* case it is returned with B_INVAL clear and B_CACHE set based on the
* backing VM.
*
* getblk() also forces a bwrite() for any B_DELWRI buffer whos
* B_CACHE bit is clear.
*
* What this means, basically, is that the caller should use B_CACHE to
* determine whether the buffer is fully valid or not and should clear
* B_INVAL prior to issuing a read. If the caller intends to validate
* the buffer by loading its data area with something, the caller needs
* to clear B_INVAL. If the caller does this without issuing an I/O,
* the caller should set B_CACHE ( as an optimization ), else the caller
* should issue the I/O and biodone() will set B_CACHE if the I/O was
* a write attempt or if it was a successful read. If the caller
* intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
* prior to issuing the READ. biodone() will *not* clear B_INVAL.
*/
struct buf *
getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo,
int flags)
{
struct buf *bp;
struct bufobj *bo;
int bsize, error, maxsize, vmio;
off_t offset;
CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
ASSERT_VOP_LOCKED(vp, "getblk");
if (size > maxbcachebuf)
panic("getblk: size(%d) > maxbcachebuf(%d)\n", size,
maxbcachebuf);
if (!unmapped_buf_allowed)
flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
bo = &vp->v_bufobj;
loop:
BO_RLOCK(bo);
bp = gbincore(bo, blkno);
if (bp != NULL) {
int lockflags;
/*
* Buffer is in-core. If the buffer is not busy nor managed,
* it must be on a queue.
*/
lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
if (flags & GB_LOCK_NOWAIT)
lockflags |= LK_NOWAIT;
error = BUF_TIMELOCK(bp, lockflags,
BO_LOCKPTR(bo), "getblk", slpflag, slptimeo);
/*
* If we slept and got the lock we have to restart in case
* the buffer changed identities.
*/
if (error == ENOLCK)
goto loop;
/* We timed out or were interrupted. */
else if (error)
return (NULL);
/* If recursed, assume caller knows the rules. */
else if (BUF_LOCKRECURSED(bp))
goto end;
/*
* The buffer is locked. B_CACHE is cleared if the buffer is
* invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
* and for a VMIO buffer B_CACHE is adjusted according to the
* backing VM cache.
*/
if (bp->b_flags & B_INVAL)
bp->b_flags &= ~B_CACHE;
else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
bp->b_flags |= B_CACHE;
if (bp->b_flags & B_MANAGED)
MPASS(bp->b_qindex == QUEUE_NONE);
else
bremfree(bp);
/*
* check for size inconsistencies for non-VMIO case.
*/
if (bp->b_bcount != size) {
if ((bp->b_flags & B_VMIO) == 0 ||
(size > bp->b_kvasize)) {
if (bp->b_flags & B_DELWRI) {
bp->b_flags |= B_NOCACHE;
bwrite(bp);
} else {
if (LIST_EMPTY(&bp->b_dep)) {
bp->b_flags |= B_RELBUF;
brelse(bp);
} else {
bp->b_flags |= B_NOCACHE;
bwrite(bp);
}
}
goto loop;
}
}
/*
* Handle the case of unmapped buffer which should
* become mapped, or the buffer for which KVA
* reservation is requested.
*/
bp_unmapped_get_kva(bp, blkno, size, flags);
/*
* If the size is inconsistent in the VMIO case, we can resize
* the buffer. This might lead to B_CACHE getting set or
* cleared. If the size has not changed, B_CACHE remains
* unchanged from its previous state.
*/
allocbuf(bp, size);
KASSERT(bp->b_offset != NOOFFSET,
("getblk: no buffer offset"));
/*
* A buffer with B_DELWRI set and B_CACHE clear must
* be committed before we can return the buffer in
* order to prevent the caller from issuing a read
* ( due to B_CACHE not being set ) and overwriting
* it.
*
* Most callers, including NFS and FFS, need this to
* operate properly either because they assume they
* can issue a read if B_CACHE is not set, or because
* ( for example ) an uncached B_DELWRI might loop due
* to softupdates re-dirtying the buffer. In the latter
* case, B_CACHE is set after the first write completes,
* preventing further loops.
* NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
* above while extending the buffer, we cannot allow the
* buffer to remain with B_CACHE set after the write
* completes or it will represent a corrupt state. To
* deal with this we set B_NOCACHE to scrap the buffer
* after the write.
*
* We might be able to do something fancy, like setting
* B_CACHE in bwrite() except if B_DELWRI is already set,
* so the below call doesn't set B_CACHE, but that gets real
* confusing. This is much easier.
*/
if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
bp->b_flags |= B_NOCACHE;
bwrite(bp);
goto loop;
}
bp->b_flags &= ~B_DONE;
} else {
/*
* Buffer is not in-core, create new buffer. The buffer
* returned by getnewbuf() is locked. Note that the returned
* buffer is also considered valid (not marked B_INVAL).
*/
BO_RUNLOCK(bo);
/*
* If the user does not want us to create the buffer, bail out
* here.
*/
if (flags & GB_NOCREAT)
return NULL;
if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
return NULL;
bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
offset = blkno * bsize;
vmio = vp->v_object != NULL;
if (vmio) {
maxsize = size + (offset & PAGE_MASK);
} else {
maxsize = size;
/* Do not allow non-VMIO notmapped buffers. */
flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
}
maxsize = imax(maxsize, bsize);
bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
if (bp == NULL) {
if (slpflag || slptimeo)
return NULL;
/*
* XXX This is here until the sleep path is diagnosed
* enough to work under very low memory conditions.
*
* There's an issue on low memory, 4BSD+non-preempt
* systems (eg MIPS routers with 32MB RAM) where buffer
* exhaustion occurs without sleeping for buffer
* reclaimation. This just sticks in a loop and
* constantly attempts to allocate a buffer, which
* hits exhaustion and tries to wakeup bufdaemon.
* This never happens because we never yield.
*
* The real solution is to identify and fix these cases
* so we aren't effectively busy-waiting in a loop
* until the reclaimation path has cycles to run.
*/
kern_yield(PRI_USER);
goto loop;
}
/*
* This code is used to make sure that a buffer is not
* created while the getnewbuf routine is blocked.
* This can be a problem whether the vnode is locked or not.
* If the buffer is created out from under us, we have to
* throw away the one we just created.
*
* Note: this must occur before we associate the buffer
* with the vp especially considering limitations in
* the splay tree implementation when dealing with duplicate
* lblkno's.
*/
BO_LOCK(bo);
if (gbincore(bo, blkno)) {
BO_UNLOCK(bo);
bp->b_flags |= B_INVAL;
brelse(bp);
bufspace_release(maxsize);
goto loop;
}
/*
* Insert the buffer into the hash, so that it can
* be found by incore.
*/
bp->b_blkno = bp->b_lblkno = blkno;
bp->b_offset = offset;
bgetvp(vp, bp);
BO_UNLOCK(bo);
/*
* set B_VMIO bit. allocbuf() the buffer bigger. Since the
* buffer size starts out as 0, B_CACHE will be set by
* allocbuf() for the VMIO case prior to it testing the
* backing store for validity.
*/
if (vmio) {
bp->b_flags |= B_VMIO;
KASSERT(vp->v_object == bp->b_bufobj->bo_object,
("ARGH! different b_bufobj->bo_object %p %p %p\n",
bp, vp->v_object, bp->b_bufobj->bo_object));
} else {
bp->b_flags &= ~B_VMIO;
KASSERT(bp->b_bufobj->bo_object == NULL,
("ARGH! has b_bufobj->bo_object %p %p\n",
bp, bp->b_bufobj->bo_object));
BUF_CHECK_MAPPED(bp);
}
allocbuf(bp, size);
bufspace_release(maxsize);
bp->b_flags &= ~B_DONE;
}
CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
BUF_ASSERT_HELD(bp);
end:
buf_track(bp, __func__);
KASSERT(bp->b_bufobj == bo,
("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
return (bp);
}
/*
* Get an empty, disassociated buffer of given size. The buffer is initially
* set to B_INVAL.
*/
struct buf *
geteblk(int size, int flags)
{
struct buf *bp;
int maxsize;
maxsize = (size + BKVAMASK) & ~BKVAMASK;
while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) {
if ((flags & GB_NOWAIT_BD) &&
(curthread->td_pflags & TDP_BUFNEED) != 0)
return (NULL);
}
allocbuf(bp, size);
bufspace_release(maxsize);
bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
BUF_ASSERT_HELD(bp);
return (bp);
}
/*
* Truncate the backing store for a non-vmio buffer.
*/
static void
vfs_nonvmio_truncate(struct buf *bp, int newbsize)
{
if (bp->b_flags & B_MALLOC) {
/*
* malloced buffers are not shrunk
*/
if (newbsize == 0) {
bufmallocadjust(bp, 0);
free(bp->b_data, M_BIOBUF);
bp->b_data = bp->b_kvabase;
bp->b_flags &= ~B_MALLOC;
}
return;
}
vm_hold_free_pages(bp, newbsize);
bufspace_adjust(bp, newbsize);
}
/*
* Extend the backing for a non-VMIO buffer.
*/
static void
vfs_nonvmio_extend(struct buf *bp, int newbsize)
{
caddr_t origbuf;
int origbufsize;
/*
* We only use malloced memory on the first allocation.
* and revert to page-allocated memory when the buffer
* grows.
*
* There is a potential smp race here that could lead
* to bufmallocspace slightly passing the max. It
* is probably extremely rare and not worth worrying
* over.
*/
if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
bufmallocspace < maxbufmallocspace) {
bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
bp->b_flags |= B_MALLOC;
bufmallocadjust(bp, newbsize);
return;
}
/*
* If the buffer is growing on its other-than-first
* allocation then we revert to the page-allocation
* scheme.
*/
origbuf = NULL;
origbufsize = 0;
if (bp->b_flags & B_MALLOC) {
origbuf = bp->b_data;
origbufsize = bp->b_bufsize;
bp->b_data = bp->b_kvabase;
bufmallocadjust(bp, 0);
bp->b_flags &= ~B_MALLOC;
newbsize = round_page(newbsize);
}
vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize,
(vm_offset_t) bp->b_data + newbsize);
if (origbuf != NULL) {
bcopy(origbuf, bp->b_data, origbufsize);
free(origbuf, M_BIOBUF);
}
bufspace_adjust(bp, newbsize);
}
/*
* This code constitutes the buffer memory from either anonymous system
* memory (in the case of non-VMIO operations) or from an associated
* VM object (in the case of VMIO operations). This code is able to
* resize a buffer up or down.
*
* Note that this code is tricky, and has many complications to resolve
* deadlock or inconsistent data situations. Tread lightly!!!
* There are B_CACHE and B_DELWRI interactions that must be dealt with by
* the caller. Calling this code willy nilly can result in the loss of data.
*
* allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
* B_CACHE for the non-VMIO case.
*/
int
allocbuf(struct buf *bp, int size)
{
int newbsize;
BUF_ASSERT_HELD(bp);
if (bp->b_bcount == size)
return (1);
if (bp->b_kvasize != 0 && bp->b_kvasize < size)
panic("allocbuf: buffer too small");
newbsize = roundup2(size, DEV_BSIZE);
if ((bp->b_flags & B_VMIO) == 0) {
if ((bp->b_flags & B_MALLOC) == 0)
newbsize = round_page(newbsize);
/*
* Just get anonymous memory from the kernel. Don't
* mess with B_CACHE.
*/
if (newbsize < bp->b_bufsize)
vfs_nonvmio_truncate(bp, newbsize);
else if (newbsize > bp->b_bufsize)
vfs_nonvmio_extend(bp, newbsize);
} else {
int desiredpages;
desiredpages = (size == 0) ? 0 :
num_pages((bp->b_offset & PAGE_MASK) + newbsize);
if (bp->b_flags & B_MALLOC)
panic("allocbuf: VMIO buffer can't be malloced");
/*
* Set B_CACHE initially if buffer is 0 length or will become
* 0-length.
*/
if (size == 0 || bp->b_bufsize == 0)
bp->b_flags |= B_CACHE;
if (newbsize < bp->b_bufsize)
vfs_vmio_truncate(bp, desiredpages);
/* XXX This looks as if it should be newbsize > b_bufsize */
else if (size > bp->b_bcount)
vfs_vmio_extend(bp, desiredpages, size);
bufspace_adjust(bp, newbsize);
}
bp->b_bcount = size; /* requested buffer size. */
return (1);
}
extern int inflight_transient_maps;
void
biodone(struct bio *bp)
{
struct mtx *mtxp;
void (*done)(struct bio *);
vm_offset_t start, end;
biotrack(bp, __func__);
if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
bp->bio_flags |= BIO_UNMAPPED;
start = trunc_page((vm_offset_t)bp->bio_data);
end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
bp->bio_data = unmapped_buf;
pmap_qremove(start, atop(end - start));
vmem_free(transient_arena, start, end - start);
atomic_add_int(&inflight_transient_maps, -1);
}
done = bp->bio_done;
if (done == NULL) {
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
bp->bio_flags |= BIO_DONE;
wakeup(bp);
mtx_unlock(mtxp);
} else
done(bp);
}
/*
* Wait for a BIO to finish.
*/
int
biowait(struct bio *bp, const char *wchan)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
while ((bp->bio_flags & BIO_DONE) == 0)
msleep(bp, mtxp, PRIBIO, wchan, 0);
mtx_unlock(mtxp);
if (bp->bio_error != 0)
return (bp->bio_error);
if (!(bp->bio_flags & BIO_ERROR))
return (0);
return (EIO);
}
void
biofinish(struct bio *bp, struct devstat *stat, int error)
{
if (error) {
bp->bio_error = error;
bp->bio_flags |= BIO_ERROR;
}
if (stat != NULL)
devstat_end_transaction_bio(stat, bp);
biodone(bp);
}
#if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
void
biotrack_buf(struct bio *bp, const char *location)
{
buf_track(bp->bio_track_bp, location);
}
#endif
/*
* bufwait:
*
* Wait for buffer I/O completion, returning error status. The buffer
* is left locked and B_DONE on return. B_EINTR is converted into an EINTR
* error and cleared.
*/
int
bufwait(struct buf *bp)
{
if (bp->b_iocmd == BIO_READ)
bwait(bp, PRIBIO, "biord");
else
bwait(bp, PRIBIO, "biowr");
if (bp->b_flags & B_EINTR) {
bp->b_flags &= ~B_EINTR;
return (EINTR);
}
if (bp->b_ioflags & BIO_ERROR) {
return (bp->b_error ? bp->b_error : EIO);
} else {
return (0);
}
}
/*
* bufdone:
*
* Finish I/O on a buffer, optionally calling a completion function.
* This is usually called from an interrupt so process blocking is
* not allowed.
*
* biodone is also responsible for setting B_CACHE in a B_VMIO bp.
* In a non-VMIO bp, B_CACHE will be set on the next getblk()
* assuming B_INVAL is clear.
*
* For the VMIO case, we set B_CACHE if the op was a read and no
* read error occurred, or if the op was a write. B_CACHE is never
* set if the buffer is invalid or otherwise uncacheable.
*
* biodone does not mess with B_INVAL, allowing the I/O routine or the
* initiator to leave B_INVAL set to brelse the buffer out of existence
* in the biodone routine.
*/
void
bufdone(struct buf *bp)
{
struct bufobj *dropobj;
void (*biodone)(struct buf *);
buf_track(bp, __func__);
CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
dropobj = NULL;
KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
BUF_ASSERT_HELD(bp);
runningbufwakeup(bp);
if (bp->b_iocmd == BIO_WRITE)
dropobj = bp->b_bufobj;
else if ((bp->b_flags & B_CKHASH) != 0) {
KASSERT(buf_mapped(bp), ("biodone: bp %p not mapped", bp));
(*bp->b_ckhashcalc)(bp);
}
/* call optional completion function if requested */
if (bp->b_iodone != NULL) {
biodone = bp->b_iodone;
bp->b_iodone = NULL;
(*biodone) (bp);
if (dropobj)
bufobj_wdrop(dropobj);
return;
}
bufdone_finish(bp);
if (dropobj)
bufobj_wdrop(dropobj);
}
void
bufdone_finish(struct buf *bp)
{
BUF_ASSERT_HELD(bp);
if (!LIST_EMPTY(&bp->b_dep))
buf_complete(bp);
if (bp->b_flags & B_VMIO) {
/*
* Set B_CACHE if the op was a normal read and no error
* occurred. B_CACHE is set for writes in the b*write()
* routines.
*/
if (bp->b_iocmd == BIO_READ &&
!(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
!(bp->b_ioflags & BIO_ERROR))
bp->b_flags |= B_CACHE;
vfs_vmio_iodone(bp);
}
/*
* For asynchronous completions, release the buffer now. The brelse
* will do a wakeup there if necessary - so no need to do a wakeup
* here in the async case. The sync case always needs to do a wakeup.
*/
if (bp->b_flags & B_ASYNC) {
if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) ||
(bp->b_ioflags & BIO_ERROR))
brelse(bp);
else
bqrelse(bp);
} else
bdone(bp);
}
/*
* This routine is called in lieu of iodone in the case of
* incomplete I/O. This keeps the busy status for pages
* consistent.
*/
void
vfs_unbusy_pages(struct buf *bp)
{
int i;
vm_object_t obj;
vm_page_t m;
runningbufwakeup(bp);
if (!(bp->b_flags & B_VMIO))
return;
obj = bp->b_bufobj->bo_object;
VM_OBJECT_WLOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (m == bogus_page) {
m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
if (!m)
panic("vfs_unbusy_pages: page missing\n");
bp->b_pages[i] = m;
if (buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
} else
BUF_CHECK_UNMAPPED(bp);
}
vm_page_sunbusy(m);
}
vm_object_pip_wakeupn(obj, bp->b_npages);
VM_OBJECT_WUNLOCK(obj);
}
/*
* vfs_page_set_valid:
*
* Set the valid bits in a page based on the supplied offset. The
* range is restricted to the buffer's size.
*
* This routine is typically called after a read completes.
*/
static void
vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
{
vm_ooffset_t eoff;
/*
* Compute the end offset, eoff, such that [off, eoff) does not span a
* page boundary and eoff is not greater than the end of the buffer.
* The end of the buffer, in this case, is our file EOF, not the
* allocation size of the buffer.
*/
eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
if (eoff > bp->b_offset + bp->b_bcount)
eoff = bp->b_offset + bp->b_bcount;
/*
* Set valid range. This is typically the entire buffer and thus the
* entire page.
*/
if (eoff > off)
vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off);
}
/*
* vfs_page_set_validclean:
*
* Set the valid bits and clear the dirty bits in a page based on the
* supplied offset. The range is restricted to the buffer's size.
*/
static void
vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
{
vm_ooffset_t soff, eoff;
/*
* Start and end offsets in buffer. eoff - soff may not cross a
* page boundary or cross the end of the buffer. The end of the
* buffer, in this case, is our file EOF, not the allocation size
* of the buffer.
*/
soff = off;
eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
if (eoff > bp->b_offset + bp->b_bcount)
eoff = bp->b_offset + bp->b_bcount;
/*
* Set valid range. This is typically the entire buffer and thus the
* entire page.
*/
if (eoff > soff) {
vm_page_set_validclean(
m,
(vm_offset_t) (soff & PAGE_MASK),
(vm_offset_t) (eoff - soff)
);
}
}
/*
* Ensure that all buffer pages are not exclusive busied. If any page is
* exclusive busy, drain it.
*/
void
vfs_drain_busy_pages(struct buf *bp)
{
vm_page_t m;
int i, last_busied;
VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
last_busied = 0;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (vm_page_xbusied(m)) {
for (; last_busied < i; last_busied++)
vm_page_sbusy(bp->b_pages[last_busied]);
while (vm_page_xbusied(m)) {
vm_page_lock(m);
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
vm_page_busy_sleep(m, "vbpage", true);
VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
}
}
}
for (i = 0; i < last_busied; i++)
vm_page_sunbusy(bp->b_pages[i]);
}
/*
* This routine is called before a device strategy routine.
* It is used to tell the VM system that paging I/O is in
* progress, and treat the pages associated with the buffer
* almost as being exclusive busy. Also the object paging_in_progress
* flag is handled to make sure that the object doesn't become
* inconsistent.
*
* Since I/O has not been initiated yet, certain buffer flags
* such as BIO_ERROR or B_INVAL may be in an inconsistent state
* and should be ignored.
*/
void
vfs_busy_pages(struct buf *bp, int clear_modify)
{
vm_object_t obj;
vm_ooffset_t foff;
vm_page_t m;
int i;
bool bogus;
if (!(bp->b_flags & B_VMIO))
return;
obj = bp->b_bufobj->bo_object;
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_busy_pages: no buffer offset"));
VM_OBJECT_WLOCK(obj);
vfs_drain_busy_pages(bp);
if (bp->b_bufsize != 0)
vfs_setdirty_locked_object(bp);
bogus = false;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if ((bp->b_flags & B_CLUSTER) == 0) {
vm_object_pip_add(obj, 1);
vm_page_sbusy(m);
}
/*
* When readying a buffer for a read ( i.e
* clear_modify == 0 ), it is important to do
* bogus_page replacement for valid pages in
* partially instantiated buffers. Partially
* instantiated buffers can, in turn, occur when
* reconstituting a buffer from its VM backing store
* base. We only have to do this if B_CACHE is
* clear ( which causes the I/O to occur in the
* first place ). The replacement prevents the read
* I/O from overwriting potentially dirty VM-backed
* pages. XXX bogus page replacement is, uh, bogus.
* It may not work properly with small-block devices.
* We need to find a better way.
*/
if (clear_modify) {
pmap_remove_write(m);
vfs_page_set_validclean(bp, foff, m);
} else if (m->valid == VM_PAGE_BITS_ALL &&
(bp->b_flags & B_CACHE) == 0) {
bp->b_pages[i] = bogus_page;
bogus = true;
}
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
}
VM_OBJECT_WUNLOCK(obj);
if (bogus && buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
}
/*
* vfs_bio_set_valid:
*
* Set the range within the buffer to valid. The range is
* relative to the beginning of the buffer, b_offset. Note that
* b_offset itself may be offset from the beginning of the first
* page.
*/
void
vfs_bio_set_valid(struct buf *bp, int base, int size)
{
int i, n;
vm_page_t m;
if (!(bp->b_flags & B_VMIO))
return;
/*
* Fixup base to be relative to beginning of first page.
* Set initial n to be the maximum number of bytes in the
* first page that can be validated.
*/
base += (bp->b_offset & PAGE_MASK);
n = PAGE_SIZE - (base & PAGE_MASK);
VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
m = bp->b_pages[i];
if (n > size)
n = size;
vm_page_set_valid_range(m, base & PAGE_MASK, n);
base += n;
size -= n;
n = PAGE_SIZE;
}
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
}
/*
* vfs_bio_clrbuf:
*
* If the specified buffer is a non-VMIO buffer, clear the entire
* buffer. If the specified buffer is a VMIO buffer, clear and
* validate only the previously invalid portions of the buffer.
* This routine essentially fakes an I/O, so we need to clear
* BIO_ERROR and B_INVAL.
*
* Note that while we only theoretically need to clear through b_bcount,
* we go ahead and clear through b_bufsize.
*/
void
vfs_bio_clrbuf(struct buf *bp)
{
int i, j, mask, sa, ea, slide;
if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
clrbuf(bp);
return;
}
bp->b_flags &= ~B_INVAL;
bp->b_ioflags &= ~BIO_ERROR;
VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
(bp->b_offset & PAGE_MASK) == 0) {
if (bp->b_pages[0] == bogus_page)
goto unlock;
mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object);
if ((bp->b_pages[0]->valid & mask) == mask)
goto unlock;
if ((bp->b_pages[0]->valid & mask) == 0) {
pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
bp->b_pages[0]->valid |= mask;
goto unlock;
}
}
sa = bp->b_offset & PAGE_MASK;
slide = 0;
for (i = 0; i < bp->b_npages; i++, sa = 0) {
slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
ea = slide & PAGE_MASK;
if (ea == 0)
ea = PAGE_SIZE;
if (bp->b_pages[i] == bogus_page)
continue;
j = sa / DEV_BSIZE;
mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
if ((bp->b_pages[i]->valid & mask) == mask)
continue;
if ((bp->b_pages[i]->valid & mask) == 0)
pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
else {
for (; sa < ea; sa += DEV_BSIZE, j++) {
if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
pmap_zero_page_area(bp->b_pages[i],
sa, DEV_BSIZE);
}
}
}
bp->b_pages[i]->valid |= mask;
}
unlock:
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
bp->b_resid = 0;
}
void
vfs_bio_bzero_buf(struct buf *bp, int base, int size)
{
vm_page_t m;
int i, n;
if (buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
bzero(bp->b_data + base, size);
} else {
BUF_CHECK_UNMAPPED(bp);
n = PAGE_SIZE - (base & PAGE_MASK);
for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
m = bp->b_pages[i];
if (n > size)
n = size;
pmap_zero_page_area(m, base & PAGE_MASK, n);
base += n;
size -= n;
n = PAGE_SIZE;
}
}
}
/*
* Update buffer flags based on I/O request parameters, optionally releasing the
* buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM,
* where they may be placed on a page queue (VMIO) or freed immediately (direct
* I/O). Otherwise the buffer is released to the cache.
*/
static void
b_io_dismiss(struct buf *bp, int ioflag, bool release)
{
KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0,
("buf %p non-VMIO noreuse", bp));
if ((ioflag & IO_DIRECT) != 0)
bp->b_flags |= B_DIRECT;
if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) {
bp->b_flags |= B_RELBUF;
if ((ioflag & IO_NOREUSE) != 0)
bp->b_flags |= B_NOREUSE;
if (release)
brelse(bp);
} else if (release)
bqrelse(bp);
}
void
vfs_bio_brelse(struct buf *bp, int ioflag)
{
b_io_dismiss(bp, ioflag, true);
}
void
vfs_bio_set_flags(struct buf *bp, int ioflag)
{
b_io_dismiss(bp, ioflag, false);
}
/*
* vm_hold_load_pages and vm_hold_free_pages get pages into
* a buffers address space. The pages are anonymous and are
* not associated with a file object.
*/
static void
vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
{
vm_offset_t pg;
vm_page_t p;
int index;
BUF_CHECK_MAPPED(bp);
to = round_page(to);
from = round_page(from);
index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
tryagain:
/*
* note: must allocate system pages since blocking here
* could interfere with paging I/O, no matter which
* process we are.
*/
p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
if (p == NULL) {
VM_WAIT;
goto tryagain;
}
pmap_qenter(pg, &p, 1);
bp->b_pages[index] = p;
}
bp->b_npages = index;
}
/* Return pages associated with this buf to the vm system */
static void
vm_hold_free_pages(struct buf *bp, int newbsize)
{
vm_offset_t from;
vm_page_t p;
int index, newnpages;
BUF_CHECK_MAPPED(bp);
from = round_page((vm_offset_t)bp->b_data + newbsize);
newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
if (bp->b_npages > newnpages)
pmap_qremove(from, bp->b_npages - newnpages);
for (index = newnpages; index < bp->b_npages; index++) {
p = bp->b_pages[index];
bp->b_pages[index] = NULL;
p->wire_count--;
vm_page_free(p);
}
atomic_subtract_int(&vm_cnt.v_wire_count, bp->b_npages - newnpages);
bp->b_npages = newnpages;
}
/*
* Map an IO request into kernel virtual address space.
*
* All requests are (re)mapped into kernel VA space.
* Notice that we use b_bufsize for the size of the buffer
* to be mapped. b_bcount might be modified by the driver.
*
* Note that even if the caller determines that the address space should
* be valid, a race or a smaller-file mapped into a larger space may
* actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
* check the return value.
*
* This function only works with pager buffers.
*/
int
vmapbuf(struct buf *bp, int mapbuf)
{
vm_prot_t prot;
int pidx;
if (bp->b_bufsize < 0)
return (-1);
prot = VM_PROT_READ;
if (bp->b_iocmd == BIO_READ)
prot |= VM_PROT_WRITE; /* Less backwards than it looks */
if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
(vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
btoc(MAXPHYS))) < 0)
return (-1);
bp->b_npages = pidx;
bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
if (mapbuf || !unmapped_buf_allowed) {
pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
bp->b_data = bp->b_kvabase + bp->b_offset;
} else
bp->b_data = unmapped_buf;
return(0);
}
/*
* Free the io map PTEs associated with this IO operation.
* We also invalidate the TLB entries and restore the original b_addr.
*
* This function only works with pager buffers.
*/
void
vunmapbuf(struct buf *bp)
{
int npages;
npages = bp->b_npages;
if (buf_mapped(bp))
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
vm_page_unhold_pages(bp->b_pages, npages);
bp->b_data = unmapped_buf;
}
void
bdone(struct buf *bp)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
bp->b_flags |= B_DONE;
wakeup(bp);
mtx_unlock(mtxp);
}
void
bwait(struct buf *bp, u_char pri, const char *wchan)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
while ((bp->b_flags & B_DONE) == 0)
msleep(bp, mtxp, pri, wchan, 0);
mtx_unlock(mtxp);
}
int
bufsync(struct bufobj *bo, int waitfor)
{
return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread));
}
void
bufstrategy(struct bufobj *bo, struct buf *bp)
{
int i = 0;
struct vnode *vp;
vp = bp->b_vp;
KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
i = VOP_STRATEGY(vp, bp);
KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
}
void
bufobj_wrefl(struct bufobj *bo)
{
KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
ASSERT_BO_WLOCKED(bo);
bo->bo_numoutput++;
}
void
bufobj_wref(struct bufobj *bo)
{
KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
BO_LOCK(bo);
bo->bo_numoutput++;
BO_UNLOCK(bo);
}
void
bufobj_wdrop(struct bufobj *bo)
{
KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
BO_LOCK(bo);
KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
bo->bo_flag &= ~BO_WWAIT;
wakeup(&bo->bo_numoutput);
}
BO_UNLOCK(bo);
}
int
bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
{
int error;
KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
ASSERT_BO_WLOCKED(bo);
error = 0;
while (bo->bo_numoutput) {
bo->bo_flag |= BO_WWAIT;
error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
slpflag | (PRIBIO + 1), "bo_wwait", timeo);
if (error)
break;
}
return (error);
}
/*
* Set bio_data or bio_ma for struct bio from the struct buf.
*/
void
bdata2bio(struct buf *bp, struct bio *bip)
{
if (!buf_mapped(bp)) {
KASSERT(unmapped_buf_allowed, ("unmapped"));
bip->bio_ma = bp->b_pages;
bip->bio_ma_n = bp->b_npages;
bip->bio_data = unmapped_buf;
bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
bip->bio_flags |= BIO_UNMAPPED;
KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
PAGE_SIZE == bp->b_npages,
("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
(long long)bip->bio_length, bip->bio_ma_n));
} else {
bip->bio_data = bp->b_data;
bip->bio_ma = NULL;
}
}
/*
* The MIPS pmap code currently doesn't handle aliased pages.
* The VIPT caches may not handle page aliasing themselves, leading
* to data corruption.
*
* As such, this code makes a system extremely unhappy if said
* system doesn't support unaliasing the above situation in hardware.
* Some "recent" systems (eg some mips24k/mips74k cores) don't enable
* this feature at build time, so it has to be handled in software.
*
* Once the MIPS pmap/cache code grows to support this function on
* earlier chips, it should be flipped back off.
*/
#ifdef __mips__
static int buf_pager_relbuf = 1;
#else
static int buf_pager_relbuf = 0;
#endif
SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN,
&buf_pager_relbuf, 0,
"Make buffer pager release buffers after reading");
/*
* The buffer pager. It uses buffer reads to validate pages.
*
* In contrast to the generic local pager from vm/vnode_pager.c, this
* pager correctly and easily handles volumes where the underlying
* device block size is greater than the machine page size. The
* buffer cache transparently extends the requested page run to be
* aligned at the block boundary, and does the necessary bogus page
* replacements in the addends to avoid obliterating already valid
* pages.
*
* The only non-trivial issue is that the exclusive busy state for
* pages, which is assumed by the vm_pager_getpages() interface, is
* incompatible with the VMIO buffer cache's desire to share-busy the
* pages. This function performs a trivial downgrade of the pages'
* state before reading buffers, and a less trivial upgrade from the
* shared-busy to excl-busy state after the read.
*/
int
vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count,
int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
vbg_get_blksize_t get_blksize)
{
vm_page_t m;
vm_object_t object;
struct buf *bp;
struct mount *mp;
daddr_t lbn, lbnp;
vm_ooffset_t la, lb, poff, poffe;
long bsize;
int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b;
bool redo, lpart;
object = vp->v_object;
mp = vp->v_mount;
la = IDX_TO_OFF(ma[count - 1]->pindex);
if (la >= object->un_pager.vnp.vnp_size)
return (VM_PAGER_BAD);
lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size;
bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex)));
/*
* Calculate read-ahead, behind and total pages.
*/
pgsin = count;
lb = IDX_TO_OFF(ma[0]->pindex);
pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs));
pgsin += pgsin_b;
if (rbehind != NULL)
*rbehind = pgsin_b;
pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la);
if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size)
pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size,
PAGE_SIZE) - la);
pgsin += pgsin_a;
if (rahead != NULL)
*rahead = pgsin_a;
VM_CNT_INC(v_vnodein);
VM_CNT_ADD(v_vnodepgsin, pgsin);
br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS)
!= 0) ? GB_UNMAPPED : 0;
VM_OBJECT_WLOCK(object);
again:
for (i = 0; i < count; i++)
vm_page_busy_downgrade(ma[i]);
VM_OBJECT_WUNLOCK(object);
lbnp = -1;
for (i = 0; i < count; i++) {
m = ma[i];
/*
* Pages are shared busy and the object lock is not
* owned, which together allow for the pages'
* invalidation. The racy test for validity avoids
* useless creation of the buffer for the most typical
* case when invalidation is not used in redo or for
* parallel read. The shared->excl upgrade loop at
* the end of the function catches the race in a
* reliable way (protected by the object lock).
*/
if (m->valid == VM_PAGE_BITS_ALL)
continue;
poff = IDX_TO_OFF(m->pindex);
poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size);
for (; poff < poffe; poff += bsize) {
lbn = get_lblkno(vp, poff);
if (lbn == lbnp)
goto next_page;
lbnp = lbn;
bsize = get_blksize(vp, lbn);
error = bread_gb(vp, lbn, bsize, curthread->td_ucred,
br_flags, &bp);
if (error != 0)
goto end_pages;
if (LIST_EMPTY(&bp->b_dep)) {
/*
* Invalidation clears m->valid, but
* may leave B_CACHE flag if the
* buffer existed at the invalidation
* time. In this case, recycle the
* buffer to do real read on next
* bread() after redo.
*
* Otherwise B_RELBUF is not strictly
* necessary, enable to reduce buf
* cache pressure.
*/
if (buf_pager_relbuf ||
m->valid != VM_PAGE_BITS_ALL)
bp->b_flags |= B_RELBUF;
bp->b_flags &= ~B_NOCACHE;
brelse(bp);
} else {
bqrelse(bp);
}
}
KASSERT(1 /* racy, enable for debugging */ ||
m->valid == VM_PAGE_BITS_ALL || i == count - 1,
("buf %d %p invalid", i, m));
if (i == count - 1 && lpart) {
VM_OBJECT_WLOCK(object);
if (m->valid != 0 &&
m->valid != VM_PAGE_BITS_ALL)
vm_page_zero_invalid(m, TRUE);
VM_OBJECT_WUNLOCK(object);
}
next_page:;
}
end_pages:
VM_OBJECT_WLOCK(object);
redo = false;
for (i = 0; i < count; i++) {
vm_page_sunbusy(ma[i]);
ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL);
/*
* Since the pages were only sbusy while neither the
* buffer nor the object lock was held by us, or
* reallocated while vm_page_grab() slept for busy
* relinguish, they could have been invalidated.
* Recheck the valid bits and re-read as needed.
*
* Note that the last page is made fully valid in the
* read loop, and partial validity for the page at
* index count - 1 could mean that the page was
* invalidated or removed, so we must restart for
* safety as well.
*/
if (ma[i]->valid != VM_PAGE_BITS_ALL)
redo = true;
}
if (redo && error == 0)
goto again;
VM_OBJECT_WUNLOCK(object);
return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
}
#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>
/* DDB command to show buffer data */
DB_SHOW_COMMAND(buffer, db_show_buffer)
{
/* get args */
struct buf *bp = (struct buf *)addr;
#ifdef FULL_BUF_TRACKING
uint32_t i, j;
#endif
if (!have_addr) {
db_printf("usage: show buffer <addr>\n");
return;
}
db_printf("buf at %p\n", bp);
db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n",
(u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
db_printf(
"b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
"b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, "
"b_dep = %p\n",
bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
(intmax_t)bp->b_lblkno, bp->b_dep.lh_first);
db_printf("b_kvabase = %p, b_kvasize = %d\n",
bp->b_kvabase, bp->b_kvasize);
if (bp->b_npages) {
int i;
db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
for (i = 0; i < bp->b_npages; i++) {
vm_page_t m;
m = bp->b_pages[i];
if (m != NULL)
db_printf("(%p, 0x%lx, 0x%lx)", m->object,
(u_long)m->pindex,
(u_long)VM_PAGE_TO_PHYS(m));
else
db_printf("( ??? )");
if ((i + 1) < bp->b_npages)
db_printf(",");
}
db_printf("\n");
}
#if defined(FULL_BUF_TRACKING)
db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt);
i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL)
continue;
db_printf(" %2u: %s\n", j,
bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]);
}
#elif defined(BUF_TRACKING)
db_printf("b_io_tracking: %s\n", bp->b_io_tracking);
#endif
db_printf(" ");
BUF_LOCKPRINTINFO(bp);
}
DB_SHOW_COMMAND(lockedbufs, lockedbufs)
{
struct buf *bp;
int i;
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
if (BUF_ISLOCKED(bp)) {
db_show_buffer((uintptr_t)bp, 1, 0, NULL);
db_printf("\n");
if (db_pager_quit)
break;
}
}
}
DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
{
struct vnode *vp;
struct buf *bp;
if (!have_addr) {
db_printf("usage: show vnodebufs <addr>\n");
return;
}
vp = (struct vnode *)addr;
db_printf("Clean buffers:\n");
TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
db_show_buffer((uintptr_t)bp, 1, 0, NULL);
db_printf("\n");
}
db_printf("Dirty buffers:\n");
TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
db_show_buffer((uintptr_t)bp, 1, 0, NULL);
db_printf("\n");
}
}
DB_COMMAND(countfreebufs, db_coundfreebufs)
{
struct buf *bp;
int i, used = 0, nfree = 0;
if (have_addr) {
db_printf("usage: countfreebufs\n");
return;
}
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
if (bp->b_qindex == QUEUE_EMPTY)
nfree++;
else
used++;
}
db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
nfree + used);
db_printf("numfreebuffers is %d\n", numfreebuffers);
}
#endif /* DDB */
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