freebsd-dev/sys/vm/swap_pager.c
Gleb Smirnoff b0cd20172d A change to KPI of vm_pager_get_pages() and underlying VOP_GETPAGES().
o With new KPI consumers can request contiguous ranges of pages, and
  unlike before, all pages will be kept busied on return, like it was
  done before with the 'reqpage' only. Now the reqpage goes away. With
  new interface it is easier to implement code protected from race
  conditions.

  Such arrayed requests for now should be preceeded by a call to
  vm_pager_haspage() to make sure that request is possible. This
  could be improved later, making vm_pager_haspage() obsolete.

  Strenghtening the promises on the business of the array of pages
  allows us to remove such hacks as swp_pager_free_nrpage() and
  vm_pager_free_nonreq().

o New KPI accepts two integer pointers that may optionally point at
  values for read ahead and read behind, that a pager may do, if it
  can. These pages are completely owned by pager, and not controlled
  by the caller.

  This shifts the UFS-specific readahead logic from vm_fault.c, which
  should be file system agnostic, into vnode_pager.c. It also removes
  one VOP_BMAP() request per hard fault.

Discussed with:	kib, alc, jeff, scottl
Sponsored by:	Nginx, Inc.
Sponsored by:	Netflix
2015-12-16 21:30:45 +00:00

2771 lines
69 KiB
C

/*-
* Copyright (c) 1998 Matthew Dillon,
* Copyright (c) 1994 John S. Dyson
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* New Swap System
* Matthew Dillon
*
* Radix Bitmap 'blists'.
*
* - The new swapper uses the new radix bitmap code. This should scale
* to arbitrarily small or arbitrarily large swap spaces and an almost
* arbitrary degree of fragmentation.
*
* Features:
*
* - on the fly reallocation of swap during putpages. The new system
* does not try to keep previously allocated swap blocks for dirty
* pages.
*
* - on the fly deallocation of swap
*
* - No more garbage collection required. Unnecessarily allocated swap
* blocks only exist for dirty vm_page_t's now and these are already
* cycled (in a high-load system) by the pager. We also do on-the-fly
* removal of invalidated swap blocks when a page is destroyed
* or renamed.
*
* from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
*
* @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
* @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_swap.h"
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/disk.h>
#include <sys/fcntl.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/racct.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/blist.h>
#include <sys/lock.h>
#include <sys/sx.h>
#include <sys/vmmeter.h>
#include <security/mac/mac_framework.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_pageout.h>
#include <vm/vm_param.h>
#include <vm/swap_pager.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
#include <geom/geom.h>
/*
* SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, 16
* or 32 pages per allocation.
* The 32-page limit is due to the radix code (kern/subr_blist.c).
*/
#ifndef MAX_PAGEOUT_CLUSTER
#define MAX_PAGEOUT_CLUSTER 16
#endif
#if !defined(SWB_NPAGES)
#define SWB_NPAGES MAX_PAGEOUT_CLUSTER
#endif
/*
* The swblock structure maps an object and a small, fixed-size range
* of page indices to disk addresses within a swap area.
* The collection of these mappings is implemented as a hash table.
* Unused disk addresses within a swap area are allocated and managed
* using a blist.
*/
#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
#define SWAP_META_PAGES (SWB_NPAGES * 2)
#define SWAP_META_MASK (SWAP_META_PAGES - 1)
struct swblock {
struct swblock *swb_hnext;
vm_object_t swb_object;
vm_pindex_t swb_index;
int swb_count;
daddr_t swb_pages[SWAP_META_PAGES];
};
static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data");
static struct mtx sw_dev_mtx;
static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq);
static struct swdevt *swdevhd; /* Allocate from here next */
static int nswapdev; /* Number of swap devices */
int swap_pager_avail;
static int swdev_syscall_active = 0; /* serialize swap(on|off) */
static vm_ooffset_t swap_total;
SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0,
"Total amount of available swap storage.");
static vm_ooffset_t swap_reserved;
SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0,
"Amount of swap storage needed to back all allocated anonymous memory.");
static int overcommit = 0;
SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0,
"Configure virtual memory overcommit behavior. See tuning(7) "
"for details.");
static unsigned long swzone;
SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0,
"Actual size of swap metadata zone");
static unsigned long swap_maxpages;
SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0,
"Maximum amount of swap supported");
/* bits from overcommit */
#define SWAP_RESERVE_FORCE_ON (1 << 0)
#define SWAP_RESERVE_RLIMIT_ON (1 << 1)
#define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2)
int
swap_reserve(vm_ooffset_t incr)
{
return (swap_reserve_by_cred(incr, curthread->td_ucred));
}
int
swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred)
{
vm_ooffset_t r, s;
int res, error;
static int curfail;
static struct timeval lastfail;
struct uidinfo *uip;
uip = cred->cr_ruidinfo;
if (incr & PAGE_MASK)
panic("swap_reserve: & PAGE_MASK");
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
error = racct_add(curproc, RACCT_SWAP, incr);
PROC_UNLOCK(curproc);
if (error != 0)
return (0);
}
#endif
res = 0;
mtx_lock(&sw_dev_mtx);
r = swap_reserved + incr;
if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) {
s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count;
s *= PAGE_SIZE;
} else
s = 0;
s += swap_total;
if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s ||
(error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) {
res = 1;
swap_reserved = r;
}
mtx_unlock(&sw_dev_mtx);
if (res) {
UIDINFO_VMSIZE_LOCK(uip);
if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 &&
uip->ui_vmsize + incr > lim_cur(curthread, RLIMIT_SWAP) &&
priv_check(curthread, PRIV_VM_SWAP_NORLIMIT))
res = 0;
else
uip->ui_vmsize += incr;
UIDINFO_VMSIZE_UNLOCK(uip);
if (!res) {
mtx_lock(&sw_dev_mtx);
swap_reserved -= incr;
mtx_unlock(&sw_dev_mtx);
}
}
if (!res && ppsratecheck(&lastfail, &curfail, 1)) {
printf("uid %d, pid %d: swap reservation for %jd bytes failed\n",
uip->ui_uid, curproc->p_pid, incr);
}
#ifdef RACCT
if (!res) {
PROC_LOCK(curproc);
racct_sub(curproc, RACCT_SWAP, incr);
PROC_UNLOCK(curproc);
}
#endif
return (res);
}
void
swap_reserve_force(vm_ooffset_t incr)
{
struct uidinfo *uip;
mtx_lock(&sw_dev_mtx);
swap_reserved += incr;
mtx_unlock(&sw_dev_mtx);
#ifdef RACCT
PROC_LOCK(curproc);
racct_add_force(curproc, RACCT_SWAP, incr);
PROC_UNLOCK(curproc);
#endif
uip = curthread->td_ucred->cr_ruidinfo;
PROC_LOCK(curproc);
UIDINFO_VMSIZE_LOCK(uip);
uip->ui_vmsize += incr;
UIDINFO_VMSIZE_UNLOCK(uip);
PROC_UNLOCK(curproc);
}
void
swap_release(vm_ooffset_t decr)
{
struct ucred *cred;
PROC_LOCK(curproc);
cred = curthread->td_ucred;
swap_release_by_cred(decr, cred);
PROC_UNLOCK(curproc);
}
void
swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred)
{
struct uidinfo *uip;
uip = cred->cr_ruidinfo;
if (decr & PAGE_MASK)
panic("swap_release: & PAGE_MASK");
mtx_lock(&sw_dev_mtx);
if (swap_reserved < decr)
panic("swap_reserved < decr");
swap_reserved -= decr;
mtx_unlock(&sw_dev_mtx);
UIDINFO_VMSIZE_LOCK(uip);
if (uip->ui_vmsize < decr)
printf("negative vmsize for uid = %d\n", uip->ui_uid);
uip->ui_vmsize -= decr;
UIDINFO_VMSIZE_UNLOCK(uip);
racct_sub_cred(cred, RACCT_SWAP, decr);
}
#define SWM_FREE 0x02 /* free, period */
#define SWM_POP 0x04 /* pop out */
int swap_pager_full = 2; /* swap space exhaustion (task killing) */
static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
static int nsw_rcount; /* free read buffers */
static int nsw_wcount_sync; /* limit write buffers / synchronous */
static int nsw_wcount_async; /* limit write buffers / asynchronous */
static int nsw_wcount_async_max;/* assigned maximum */
static int nsw_cluster_max; /* maximum VOP I/O allowed */
static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW,
NULL, 0, sysctl_swap_async_max, "I", "Maximum running async swap ops");
static struct swblock **swhash;
static int swhash_mask;
static struct mtx swhash_mtx;
static struct sx sw_alloc_sx;
/*
* "named" and "unnamed" anon region objects. Try to reduce the overhead
* of searching a named list by hashing it just a little.
*/
#define NOBJLISTS 8
#define NOBJLIST(handle) \
(&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
static struct mtx sw_alloc_mtx; /* protect list manipulation */
static struct pagerlst swap_pager_object_list[NOBJLISTS];
static uma_zone_t swap_zone;
/*
* pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
* calls hooked from other parts of the VM system and do not appear here.
* (see vm/swap_pager.h).
*/
static vm_object_t
swap_pager_alloc(void *handle, vm_ooffset_t size,
vm_prot_t prot, vm_ooffset_t offset, struct ucred *);
static void swap_pager_dealloc(vm_object_t object);
static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *,
int *);
static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
int *, pgo_getpages_iodone_t, void *);
static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
static boolean_t
swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
static void swap_pager_init(void);
static void swap_pager_unswapped(vm_page_t);
static void swap_pager_swapoff(struct swdevt *sp);
struct pagerops swappagerops = {
.pgo_init = swap_pager_init, /* early system initialization of pager */
.pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
.pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
.pgo_getpages = swap_pager_getpages, /* pagein */
.pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */
.pgo_putpages = swap_pager_putpages, /* pageout */
.pgo_haspage = swap_pager_haspage, /* get backing store status for page */
.pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
};
/*
* dmmax is in page-sized chunks with the new swap system. It was
* dev-bsized chunks in the old. dmmax is always a power of 2.
*
* swap_*() routines are externally accessible. swp_*() routines are
* internal.
*/
static int dmmax;
static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
SYSCTL_INT(_vm, OID_AUTO, dmmax,
CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block");
static void swp_sizecheck(void);
static void swp_pager_async_iodone(struct buf *bp);
static int swapongeom(struct thread *, struct vnode *);
static int swaponvp(struct thread *, struct vnode *, u_long);
static int swapoff_one(struct swdevt *sp, struct ucred *cred);
/*
* Swap bitmap functions
*/
static void swp_pager_freeswapspace(daddr_t blk, int npages);
static daddr_t swp_pager_getswapspace(int npages);
/*
* Metadata functions
*/
static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index);
static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t);
static void swp_pager_meta_free_all(vm_object_t);
static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
/*
* SWP_SIZECHECK() - update swap_pager_full indication
*
* update the swap_pager_almost_full indication and warn when we are
* about to run out of swap space, using lowat/hiwat hysteresis.
*
* Clear swap_pager_full ( task killing ) indication when lowat is met.
*
* No restrictions on call
* This routine may not block.
*/
static void
swp_sizecheck(void)
{
if (swap_pager_avail < nswap_lowat) {
if (swap_pager_almost_full == 0) {
printf("swap_pager: out of swap space\n");
swap_pager_almost_full = 1;
}
} else {
swap_pager_full = 0;
if (swap_pager_avail > nswap_hiwat)
swap_pager_almost_full = 0;
}
}
/*
* SWP_PAGER_HASH() - hash swap meta data
*
* This is an helper function which hashes the swapblk given
* the object and page index. It returns a pointer to a pointer
* to the object, or a pointer to a NULL pointer if it could not
* find a swapblk.
*/
static struct swblock **
swp_pager_hash(vm_object_t object, vm_pindex_t index)
{
struct swblock **pswap;
struct swblock *swap;
index &= ~(vm_pindex_t)SWAP_META_MASK;
pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask];
while ((swap = *pswap) != NULL) {
if (swap->swb_object == object &&
swap->swb_index == index
) {
break;
}
pswap = &swap->swb_hnext;
}
return (pswap);
}
/*
* SWAP_PAGER_INIT() - initialize the swap pager!
*
* Expected to be started from system init. NOTE: This code is run
* before much else so be careful what you depend on. Most of the VM
* system has yet to be initialized at this point.
*/
static void
swap_pager_init(void)
{
/*
* Initialize object lists
*/
int i;
for (i = 0; i < NOBJLISTS; ++i)
TAILQ_INIT(&swap_pager_object_list[i]);
mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF);
mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
/*
* Device Stripe, in PAGE_SIZE'd blocks
*/
dmmax = SWB_NPAGES * 2;
}
/*
* SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
*
* Expected to be started from pageout process once, prior to entering
* its main loop.
*/
void
swap_pager_swap_init(void)
{
unsigned long n, n2;
/*
* Number of in-transit swap bp operations. Don't
* exhaust the pbufs completely. Make sure we
* initialize workable values (0 will work for hysteresis
* but it isn't very efficient).
*
* The nsw_cluster_max is constrained by the bp->b_pages[]
* array (MAXPHYS/PAGE_SIZE) and our locally defined
* MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
* constrained by the swap device interleave stripe size.
*
* Currently we hardwire nsw_wcount_async to 4. This limit is
* designed to prevent other I/O from having high latencies due to
* our pageout I/O. The value 4 works well for one or two active swap
* devices but is probably a little low if you have more. Even so,
* a higher value would probably generate only a limited improvement
* with three or four active swap devices since the system does not
* typically have to pageout at extreme bandwidths. We will want
* at least 2 per swap devices, and 4 is a pretty good value if you
* have one NFS swap device due to the command/ack latency over NFS.
* So it all works out pretty well.
*/
nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
mtx_lock(&pbuf_mtx);
nsw_rcount = (nswbuf + 1) / 2;
nsw_wcount_sync = (nswbuf + 3) / 4;
nsw_wcount_async = 4;
nsw_wcount_async_max = nsw_wcount_async;
mtx_unlock(&pbuf_mtx);
/*
* Initialize our zone. Right now I'm just guessing on the number
* we need based on the number of pages in the system. Each swblock
* can hold 32 pages, so this is probably overkill. This reservation
* is typically limited to around 32MB by default.
*/
n = vm_cnt.v_page_count / 2;
if (maxswzone && n > maxswzone / sizeof(struct swblock))
n = maxswzone / sizeof(struct swblock);
n2 = n;
swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL,
NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM);
if (swap_zone == NULL)
panic("failed to create swap_zone.");
do {
if (uma_zone_reserve_kva(swap_zone, n))
break;
/*
* if the allocation failed, try a zone two thirds the
* size of the previous attempt.
*/
n -= ((n + 2) / 3);
} while (n > 0);
if (n2 != n)
printf("Swap zone entries reduced from %lu to %lu.\n", n2, n);
swap_maxpages = n * SWAP_META_PAGES;
swzone = n * sizeof(struct swblock);
n2 = n;
/*
* Initialize our meta-data hash table. The swapper does not need to
* be quite as efficient as the VM system, so we do not use an
* oversized hash table.
*
* n: size of hash table, must be power of 2
* swhash_mask: hash table index mask
*/
for (n = 1; n < n2 / 8; n *= 2)
;
swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO);
swhash_mask = n - 1;
mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF);
}
/*
* SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
* its metadata structures.
*
* This routine is called from the mmap and fork code to create a new
* OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
* and then converting it with swp_pager_meta_build().
*
* This routine may block in vm_object_allocate() and create a named
* object lookup race, so we must interlock.
*
* MPSAFE
*/
static vm_object_t
swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t offset, struct ucred *cred)
{
vm_object_t object;
vm_pindex_t pindex;
pindex = OFF_TO_IDX(offset + PAGE_MASK + size);
if (handle) {
mtx_lock(&Giant);
/*
* Reference existing named region or allocate new one. There
* should not be a race here against swp_pager_meta_build()
* as called from vm_page_remove() in regards to the lookup
* of the handle.
*/
sx_xlock(&sw_alloc_sx);
object = vm_pager_object_lookup(NOBJLIST(handle), handle);
if (object == NULL) {
if (cred != NULL) {
if (!swap_reserve_by_cred(size, cred)) {
sx_xunlock(&sw_alloc_sx);
mtx_unlock(&Giant);
return (NULL);
}
crhold(cred);
}
object = vm_object_allocate(OBJT_DEFAULT, pindex);
VM_OBJECT_WLOCK(object);
object->handle = handle;
if (cred != NULL) {
object->cred = cred;
object->charge = size;
}
swp_pager_meta_build(object, 0, SWAPBLK_NONE);
VM_OBJECT_WUNLOCK(object);
}
sx_xunlock(&sw_alloc_sx);
mtx_unlock(&Giant);
} else {
if (cred != NULL) {
if (!swap_reserve_by_cred(size, cred))
return (NULL);
crhold(cred);
}
object = vm_object_allocate(OBJT_DEFAULT, pindex);
VM_OBJECT_WLOCK(object);
if (cred != NULL) {
object->cred = cred;
object->charge = size;
}
swp_pager_meta_build(object, 0, SWAPBLK_NONE);
VM_OBJECT_WUNLOCK(object);
}
return (object);
}
/*
* SWAP_PAGER_DEALLOC() - remove swap metadata from object
*
* The swap backing for the object is destroyed. The code is
* designed such that we can reinstantiate it later, but this
* routine is typically called only when the entire object is
* about to be destroyed.
*
* The object must be locked.
*/
static void
swap_pager_dealloc(vm_object_t object)
{
/*
* Remove from list right away so lookups will fail if we block for
* pageout completion.
*/
if (object->handle != NULL) {
mtx_lock(&sw_alloc_mtx);
TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list);
mtx_unlock(&sw_alloc_mtx);
}
VM_OBJECT_ASSERT_WLOCKED(object);
vm_object_pip_wait(object, "swpdea");
/*
* Free all remaining metadata. We only bother to free it from
* the swap meta data. We do not attempt to free swapblk's still
* associated with vm_page_t's for this object. We do not care
* if paging is still in progress on some objects.
*/
swp_pager_meta_free_all(object);
object->handle = NULL;
object->type = OBJT_DEAD;
}
/************************************************************************
* SWAP PAGER BITMAP ROUTINES *
************************************************************************/
/*
* SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
*
* Allocate swap for the requested number of pages. The starting
* swap block number (a page index) is returned or SWAPBLK_NONE
* if the allocation failed.
*
* Also has the side effect of advising that somebody made a mistake
* when they configured swap and didn't configure enough.
*
* This routine may not sleep.
*
* We allocate in round-robin fashion from the configured devices.
*/
static daddr_t
swp_pager_getswapspace(int npages)
{
daddr_t blk;
struct swdevt *sp;
int i;
blk = SWAPBLK_NONE;
mtx_lock(&sw_dev_mtx);
sp = swdevhd;
for (i = 0; i < nswapdev; i++) {
if (sp == NULL)
sp = TAILQ_FIRST(&swtailq);
if (!(sp->sw_flags & SW_CLOSING)) {
blk = blist_alloc(sp->sw_blist, npages);
if (blk != SWAPBLK_NONE) {
blk += sp->sw_first;
sp->sw_used += npages;
swap_pager_avail -= npages;
swp_sizecheck();
swdevhd = TAILQ_NEXT(sp, sw_list);
goto done;
}
}
sp = TAILQ_NEXT(sp, sw_list);
}
if (swap_pager_full != 2) {
printf("swap_pager_getswapspace(%d): failed\n", npages);
swap_pager_full = 2;
swap_pager_almost_full = 1;
}
swdevhd = NULL;
done:
mtx_unlock(&sw_dev_mtx);
return (blk);
}
static int
swp_pager_isondev(daddr_t blk, struct swdevt *sp)
{
return (blk >= sp->sw_first && blk < sp->sw_end);
}
static void
swp_pager_strategy(struct buf *bp)
{
struct swdevt *sp;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
mtx_unlock(&sw_dev_mtx);
if ((sp->sw_flags & SW_UNMAPPED) != 0 &&
unmapped_buf_allowed) {
bp->b_data = unmapped_buf;
bp->b_offset = 0;
} else {
pmap_qenter((vm_offset_t)bp->b_data,
&bp->b_pages[0], bp->b_bcount / PAGE_SIZE);
}
sp->sw_strategy(bp, sp);
return;
}
}
panic("Swapdev not found");
}
/*
* SWP_PAGER_FREESWAPSPACE() - free raw swap space
*
* This routine returns the specified swap blocks back to the bitmap.
*
* This routine may not sleep.
*/
static void
swp_pager_freeswapspace(daddr_t blk, int npages)
{
struct swdevt *sp;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
if (blk >= sp->sw_first && blk < sp->sw_end) {
sp->sw_used -= npages;
/*
* If we are attempting to stop swapping on
* this device, we don't want to mark any
* blocks free lest they be reused.
*/
if ((sp->sw_flags & SW_CLOSING) == 0) {
blist_free(sp->sw_blist, blk - sp->sw_first,
npages);
swap_pager_avail += npages;
swp_sizecheck();
}
mtx_unlock(&sw_dev_mtx);
return;
}
}
panic("Swapdev not found");
}
/*
* SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
* range within an object.
*
* This is a globally accessible routine.
*
* This routine removes swapblk assignments from swap metadata.
*
* The external callers of this routine typically have already destroyed
* or renamed vm_page_t's associated with this range in the object so
* we should be ok.
*
* The object must be locked.
*/
void
swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
{
swp_pager_meta_free(object, start, size);
}
/*
* SWAP_PAGER_RESERVE() - reserve swap blocks in object
*
* Assigns swap blocks to the specified range within the object. The
* swap blocks are not zeroed. Any previous swap assignment is destroyed.
*
* Returns 0 on success, -1 on failure.
*/
int
swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
{
int n = 0;
daddr_t blk = SWAPBLK_NONE;
vm_pindex_t beg = start; /* save start index */
VM_OBJECT_WLOCK(object);
while (size) {
if (n == 0) {
n = BLIST_MAX_ALLOC;
while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
n >>= 1;
if (n == 0) {
swp_pager_meta_free(object, beg, start - beg);
VM_OBJECT_WUNLOCK(object);
return (-1);
}
}
}
swp_pager_meta_build(object, start, blk);
--size;
++start;
++blk;
--n;
}
swp_pager_meta_free(object, start, n);
VM_OBJECT_WUNLOCK(object);
return (0);
}
/*
* SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
* and destroy the source.
*
* Copy any valid swapblks from the source to the destination. In
* cases where both the source and destination have a valid swapblk,
* we keep the destination's.
*
* This routine is allowed to sleep. It may sleep allocating metadata
* indirectly through swp_pager_meta_build() or if paging is still in
* progress on the source.
*
* The source object contains no vm_page_t's (which is just as well)
*
* The source object is of type OBJT_SWAP.
*
* The source and destination objects must be locked.
* Both object locks may temporarily be released.
*/
void
swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
vm_pindex_t offset, int destroysource)
{
vm_pindex_t i;
VM_OBJECT_ASSERT_WLOCKED(srcobject);
VM_OBJECT_ASSERT_WLOCKED(dstobject);
/*
* If destroysource is set, we remove the source object from the
* swap_pager internal queue now.
*/
if (destroysource) {
if (srcobject->handle != NULL) {
mtx_lock(&sw_alloc_mtx);
TAILQ_REMOVE(
NOBJLIST(srcobject->handle),
srcobject,
pager_object_list
);
mtx_unlock(&sw_alloc_mtx);
}
}
/*
* transfer source to destination.
*/
for (i = 0; i < dstobject->size; ++i) {
daddr_t dstaddr;
/*
* Locate (without changing) the swapblk on the destination,
* unless it is invalid in which case free it silently, or
* if the destination is a resident page, in which case the
* source is thrown away.
*/
dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
if (dstaddr == SWAPBLK_NONE) {
/*
* Destination has no swapblk and is not resident,
* copy source.
*/
daddr_t srcaddr;
srcaddr = swp_pager_meta_ctl(
srcobject,
i + offset,
SWM_POP
);
if (srcaddr != SWAPBLK_NONE) {
/*
* swp_pager_meta_build() can sleep.
*/
vm_object_pip_add(srcobject, 1);
VM_OBJECT_WUNLOCK(srcobject);
vm_object_pip_add(dstobject, 1);
swp_pager_meta_build(dstobject, i, srcaddr);
vm_object_pip_wakeup(dstobject);
VM_OBJECT_WLOCK(srcobject);
vm_object_pip_wakeup(srcobject);
}
} else {
/*
* Destination has valid swapblk or it is represented
* by a resident page. We destroy the sourceblock.
*/
swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE);
}
}
/*
* Free left over swap blocks in source.
*
* We have to revert the type to OBJT_DEFAULT so we do not accidently
* double-remove the object from the swap queues.
*/
if (destroysource) {
swp_pager_meta_free_all(srcobject);
/*
* Reverting the type is not necessary, the caller is going
* to destroy srcobject directly, but I'm doing it here
* for consistency since we've removed the object from its
* queues.
*/
srcobject->type = OBJT_DEFAULT;
}
}
/*
* SWAP_PAGER_HASPAGE() - determine if we have good backing store for
* the requested page.
*
* We determine whether good backing store exists for the requested
* page and return TRUE if it does, FALSE if it doesn't.
*
* If TRUE, we also try to determine how much valid, contiguous backing
* store exists before and after the requested page within a reasonable
* distance. We do not try to restrict it to the swap device stripe
* (that is handled in getpages/putpages). It probably isn't worth
* doing here.
*/
static boolean_t
swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after)
{
daddr_t blk0;
VM_OBJECT_ASSERT_LOCKED(object);
/*
* do we have good backing store at the requested index ?
*/
blk0 = swp_pager_meta_ctl(object, pindex, 0);
if (blk0 == SWAPBLK_NONE) {
if (before)
*before = 0;
if (after)
*after = 0;
return (FALSE);
}
/*
* find backwards-looking contiguous good backing store
*/
if (before != NULL) {
int i;
for (i = 1; i < (SWB_NPAGES/2); ++i) {
daddr_t blk;
if (i > pindex)
break;
blk = swp_pager_meta_ctl(object, pindex - i, 0);
if (blk != blk0 - i)
break;
}
*before = (i - 1);
}
/*
* find forward-looking contiguous good backing store
*/
if (after != NULL) {
int i;
for (i = 1; i < (SWB_NPAGES/2); ++i) {
daddr_t blk;
blk = swp_pager_meta_ctl(object, pindex + i, 0);
if (blk != blk0 + i)
break;
}
*after = (i - 1);
}
return (TRUE);
}
/*
* SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
*
* This removes any associated swap backing store, whether valid or
* not, from the page.
*
* This routine is typically called when a page is made dirty, at
* which point any associated swap can be freed. MADV_FREE also
* calls us in a special-case situation
*
* NOTE!!! If the page is clean and the swap was valid, the caller
* should make the page dirty before calling this routine. This routine
* does NOT change the m->dirty status of the page. Also: MADV_FREE
* depends on it.
*
* This routine may not sleep.
*
* The object containing the page must be locked.
*/
static void
swap_pager_unswapped(vm_page_t m)
{
swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
}
/*
* SWAP_PAGER_GETPAGES() - bring pages in from swap
*
* Attempt to retrieve (m, count) pages from backing store, but make
* sure we retrieve at least m[reqpage]. We try to load in as large
* a chunk surrounding m[reqpage] as is contiguous in swap and which
* belongs to the same object.
*
* The code is designed for asynchronous operation and
* immediate-notification of 'reqpage' but tends not to be
* used that way. Please do not optimize-out this algorithmic
* feature, I intend to improve on it in the future.
*
* The parent has a single vm_object_pip_add() reference prior to
* calling us and we should return with the same.
*
* The parent has BUSY'd the pages. We should return with 'm'
* left busy, but the others adjusted.
*/
static int
swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
int *rahead)
{
struct buf *bp;
daddr_t blk;
/*
* Calculate range to retrieve. The pages have already been assigned
* their swapblks. We require a *contiguous* range but we know it to
* not span devices. If we do not supply it, bad things
* happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the
* loops are set up such that the case(s) are handled implicitly.
*
* The swp_*() calls must be made with the object locked.
*/
blk = swp_pager_meta_ctl(m[0]->object, m[0]->pindex, 0);
if (blk == SWAPBLK_NONE)
return (VM_PAGER_FAIL);
#ifdef INVARIANTS
for (int i = 0; i < count; i++)
KASSERT(blk + i ==
swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0),
("%s: range is not contiguous", __func__));
#endif
/*
* Getpbuf() can sleep.
*/
VM_OBJECT_WUNLOCK(object);
/*
* Get a swap buffer header to perform the IO
*/
bp = getpbuf(&nsw_rcount);
bp->b_flags |= B_PAGING;
bp->b_iocmd = BIO_READ;
bp->b_iodone = swp_pager_async_iodone;
bp->b_rcred = crhold(thread0.td_ucred);
bp->b_wcred = crhold(thread0.td_ucred);
bp->b_blkno = blk;
bp->b_bcount = PAGE_SIZE * count;
bp->b_bufsize = PAGE_SIZE * count;
bp->b_npages = count;
VM_OBJECT_WLOCK(object);
for (int i = 0; i < count; i++) {
bp->b_pages[i] = m[i];
m[i]->oflags |= VPO_SWAPINPROG;
}
PCPU_INC(cnt.v_swapin);
PCPU_ADD(cnt.v_swappgsin, bp->b_npages);
/*
* We still hold the lock on mreq, and our automatic completion routine
* does not remove it.
*/
vm_object_pip_add(object, bp->b_npages);
VM_OBJECT_WUNLOCK(object);
/*
* perform the I/O. NOTE!!! bp cannot be considered valid after
* this point because we automatically release it on completion.
* Instead, we look at the one page we are interested in which we
* still hold a lock on even through the I/O completion.
*
* The other pages in our m[] array are also released on completion,
* so we cannot assume they are valid anymore either.
*
* NOTE: b_blkno is destroyed by the call to swapdev_strategy
*/
BUF_KERNPROC(bp);
swp_pager_strategy(bp);
/*
* wait for the page we want to complete. VPO_SWAPINPROG is always
* cleared on completion. If an I/O error occurs, SWAPBLK_NONE
* is set in the meta-data.
*/
VM_OBJECT_WLOCK(object);
while ((m[0]->oflags & VPO_SWAPINPROG) != 0) {
m[0]->oflags |= VPO_SWAPSLEEP;
PCPU_INC(cnt.v_intrans);
if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP,
"swread", hz * 20)) {
printf(
"swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
}
}
/*
* If we had an unrecoverable read error pages will not be valid.
*/
for (int i = 0; i < count; i++)
if (m[i]->valid != VM_PAGE_BITS_ALL)
return (VM_PAGER_ERROR);
if (rbehind)
*rbehind = 0;
if (rahead)
*rahead = 0;
return (VM_PAGER_OK);
/*
* A final note: in a low swap situation, we cannot deallocate swap
* and mark a page dirty here because the caller is likely to mark
* the page clean when we return, causing the page to possibly revert
* to all-zero's later.
*/
}
/*
* swap_pager_getpages_async():
*
* Right now this is emulation of asynchronous operation on top of
* swap_pager_getpages().
*/
static int
swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
{
int r, error;
r = swap_pager_getpages(object, m, count, rbehind, rahead);
VM_OBJECT_WUNLOCK(object);
switch (r) {
case VM_PAGER_OK:
error = 0;
break;
case VM_PAGER_ERROR:
error = EIO;
break;
case VM_PAGER_FAIL:
error = EINVAL;
break;
default:
panic("unhandled swap_pager_getpages() error %d", r);
}
(iodone)(arg, m, count, error);
VM_OBJECT_WLOCK(object);
return (r);
}
/*
* swap_pager_putpages:
*
* Assign swap (if necessary) and initiate I/O on the specified pages.
*
* We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
* are automatically converted to SWAP objects.
*
* In a low memory situation we may block in VOP_STRATEGY(), but the new
* vm_page reservation system coupled with properly written VFS devices
* should ensure that no low-memory deadlock occurs. This is an area
* which needs work.
*
* The parent has N vm_object_pip_add() references prior to
* calling us and will remove references for rtvals[] that are
* not set to VM_PAGER_PEND. We need to remove the rest on I/O
* completion.
*
* The parent has soft-busy'd the pages it passes us and will unbusy
* those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
* We need to unbusy the rest on I/O completion.
*/
static void
swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
int flags, int *rtvals)
{
int i, n;
boolean_t sync;
if (count && m[0]->object != object) {
panic("swap_pager_putpages: object mismatch %p/%p",
object,
m[0]->object
);
}
/*
* Step 1
*
* Turn object into OBJT_SWAP
* check for bogus sysops
* force sync if not pageout process
*/
if (object->type != OBJT_SWAP)
swp_pager_meta_build(object, 0, SWAPBLK_NONE);
VM_OBJECT_WUNLOCK(object);
n = 0;
if (curproc != pageproc)
sync = TRUE;
else
sync = (flags & VM_PAGER_PUT_SYNC) != 0;
/*
* Step 2
*
* Assign swap blocks and issue I/O. We reallocate swap on the fly.
* The page is left dirty until the pageout operation completes
* successfully.
*/
for (i = 0; i < count; i += n) {
int j;
struct buf *bp;
daddr_t blk;
/*
* Maximum I/O size is limited by a number of factors.
*/
n = min(BLIST_MAX_ALLOC, count - i);
n = min(n, nsw_cluster_max);
/*
* Get biggest block of swap we can. If we fail, fall
* back and try to allocate a smaller block. Don't go
* overboard trying to allocate space if it would overly
* fragment swap.
*/
while (
(blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
n > 4
) {
n >>= 1;
}
if (blk == SWAPBLK_NONE) {
for (j = 0; j < n; ++j)
rtvals[i+j] = VM_PAGER_FAIL;
continue;
}
/*
* All I/O parameters have been satisfied, build the I/O
* request and assign the swap space.
*/
if (sync == TRUE) {
bp = getpbuf(&nsw_wcount_sync);
} else {
bp = getpbuf(&nsw_wcount_async);
bp->b_flags = B_ASYNC;
}
bp->b_flags |= B_PAGING;
bp->b_iocmd = BIO_WRITE;
bp->b_rcred = crhold(thread0.td_ucred);
bp->b_wcred = crhold(thread0.td_ucred);
bp->b_bcount = PAGE_SIZE * n;
bp->b_bufsize = PAGE_SIZE * n;
bp->b_blkno = blk;
VM_OBJECT_WLOCK(object);
for (j = 0; j < n; ++j) {
vm_page_t mreq = m[i+j];
swp_pager_meta_build(
mreq->object,
mreq->pindex,
blk + j
);
vm_page_dirty(mreq);
mreq->oflags |= VPO_SWAPINPROG;
bp->b_pages[j] = mreq;
}
VM_OBJECT_WUNLOCK(object);
bp->b_npages = n;
/*
* Must set dirty range for NFS to work.
*/
bp->b_dirtyoff = 0;
bp->b_dirtyend = bp->b_bcount;
PCPU_INC(cnt.v_swapout);
PCPU_ADD(cnt.v_swappgsout, bp->b_npages);
/*
* We unconditionally set rtvals[] to VM_PAGER_PEND so that we
* can call the async completion routine at the end of a
* synchronous I/O operation. Otherwise, our caller would
* perform duplicate unbusy and wakeup operations on the page
* and object, respectively.
*/
for (j = 0; j < n; j++)
rtvals[i + j] = VM_PAGER_PEND;
/*
* asynchronous
*
* NOTE: b_blkno is destroyed by the call to swapdev_strategy
*/
if (sync == FALSE) {
bp->b_iodone = swp_pager_async_iodone;
BUF_KERNPROC(bp);
swp_pager_strategy(bp);
continue;
}
/*
* synchronous
*
* NOTE: b_blkno is destroyed by the call to swapdev_strategy
*/
bp->b_iodone = bdone;
swp_pager_strategy(bp);
/*
* Wait for the sync I/O to complete.
*/
bwait(bp, PVM, "swwrt");
/*
* Now that we are through with the bp, we can call the
* normal async completion, which frees everything up.
*/
swp_pager_async_iodone(bp);
}
VM_OBJECT_WLOCK(object);
}
/*
* swp_pager_async_iodone:
*
* Completion routine for asynchronous reads and writes from/to swap.
* Also called manually by synchronous code to finish up a bp.
*
* This routine may not sleep.
*/
static void
swp_pager_async_iodone(struct buf *bp)
{
int i;
vm_object_t object = NULL;
/*
* report error
*/
if (bp->b_ioflags & BIO_ERROR) {
printf(
"swap_pager: I/O error - %s failed; blkno %ld,"
"size %ld, error %d\n",
((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
(long)bp->b_blkno,
(long)bp->b_bcount,
bp->b_error
);
}
/*
* remove the mapping for kernel virtual
*/
if (buf_mapped(bp))
pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
else
bp->b_data = bp->b_kvabase;
if (bp->b_npages) {
object = bp->b_pages[0]->object;
VM_OBJECT_WLOCK(object);
}
/*
* cleanup pages. If an error occurs writing to swap, we are in
* very serious trouble. If it happens to be a disk error, though,
* we may be able to recover by reassigning the swap later on. So
* in this case we remove the m->swapblk assignment for the page
* but do not free it in the rlist. The errornous block(s) are thus
* never reallocated as swap. Redirty the page and continue.
*/
for (i = 0; i < bp->b_npages; ++i) {
vm_page_t m = bp->b_pages[i];
m->oflags &= ~VPO_SWAPINPROG;
if (m->oflags & VPO_SWAPSLEEP) {
m->oflags &= ~VPO_SWAPSLEEP;
wakeup(&object->paging_in_progress);
}
if (bp->b_ioflags & BIO_ERROR) {
/*
* If an error occurs I'd love to throw the swapblk
* away without freeing it back to swapspace, so it
* can never be used again. But I can't from an
* interrupt.
*/
if (bp->b_iocmd == BIO_READ) {
/*
* NOTE: for reads, m->dirty will probably
* be overridden by the original caller of
* getpages so don't play cute tricks here.
*/
m->valid = 0;
} else {
/*
* If a write error occurs, reactivate page
* so it doesn't clog the inactive list,
* then finish the I/O.
*/
vm_page_dirty(m);
vm_page_lock(m);
vm_page_activate(m);
vm_page_unlock(m);
vm_page_sunbusy(m);
}
} else if (bp->b_iocmd == BIO_READ) {
/*
* NOTE: for reads, m->dirty will probably be
* overridden by the original caller of getpages so
* we cannot set them in order to free the underlying
* swap in a low-swap situation. I don't think we'd
* want to do that anyway, but it was an optimization
* that existed in the old swapper for a time before
* it got ripped out due to precisely this problem.
*/
KASSERT(!pmap_page_is_mapped(m),
("swp_pager_async_iodone: page %p is mapped", m));
KASSERT(m->dirty == 0,
("swp_pager_async_iodone: page %p is dirty", m));
m->valid = VM_PAGE_BITS_ALL;
} else {
/*
* For write success, clear the dirty
* status, then finish the I/O ( which decrements the
* busy count and possibly wakes waiter's up ).
*/
KASSERT(!pmap_page_is_write_mapped(m),
("swp_pager_async_iodone: page %p is not write"
" protected", m));
vm_page_undirty(m);
vm_page_sunbusy(m);
if (vm_page_count_severe()) {
vm_page_lock(m);
vm_page_try_to_cache(m);
vm_page_unlock(m);
}
}
}
/*
* adjust pip. NOTE: the original parent may still have its own
* pip refs on the object.
*/
if (object != NULL) {
vm_object_pip_wakeupn(object, bp->b_npages);
VM_OBJECT_WUNLOCK(object);
}
/*
* swapdev_strategy() manually sets b_vp and b_bufobj before calling
* bstrategy(). Set them back to NULL now we're done with it, or we'll
* trigger a KASSERT in relpbuf().
*/
if (bp->b_vp) {
bp->b_vp = NULL;
bp->b_bufobj = NULL;
}
/*
* release the physical I/O buffer
*/
relpbuf(
bp,
((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
((bp->b_flags & B_ASYNC) ?
&nsw_wcount_async :
&nsw_wcount_sync
)
)
);
}
/*
* swap_pager_isswapped:
*
* Return 1 if at least one page in the given object is paged
* out to the given swap device.
*
* This routine may not sleep.
*/
int
swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
{
daddr_t index = 0;
int bcount;
int i;
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->type != OBJT_SWAP)
return (0);
mtx_lock(&swhash_mtx);
for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) {
struct swblock *swap;
if ((swap = *swp_pager_hash(object, index)) != NULL) {
for (i = 0; i < SWAP_META_PAGES; ++i) {
if (swp_pager_isondev(swap->swb_pages[i], sp)) {
mtx_unlock(&swhash_mtx);
return (1);
}
}
}
index += SWAP_META_PAGES;
}
mtx_unlock(&swhash_mtx);
return (0);
}
/*
* SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
*
* This routine dissociates the page at the given index within a
* swap block from its backing store, paging it in if necessary.
* If the page is paged in, it is placed in the inactive queue,
* since it had its backing store ripped out from under it.
* We also attempt to swap in all other pages in the swap block,
* we only guarantee that the one at the specified index is
* paged in.
*
* XXX - The code to page the whole block in doesn't work, so we
* revert to the one-by-one behavior for now. Sigh.
*/
static inline void
swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
{
vm_page_t m;
vm_object_pip_add(object, 1);
m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
if (m->valid == VM_PAGE_BITS_ALL) {
vm_object_pip_wakeup(object);
vm_page_dirty(m);
vm_page_lock(m);
vm_page_activate(m);
vm_page_unlock(m);
vm_page_xunbusy(m);
vm_pager_page_unswapped(m);
return;
}
if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK)
panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
vm_object_pip_wakeup(object);
vm_page_dirty(m);
vm_page_lock(m);
vm_page_deactivate(m);
vm_page_unlock(m);
vm_page_xunbusy(m);
vm_pager_page_unswapped(m);
}
/*
* swap_pager_swapoff:
*
* Page in all of the pages that have been paged out to the
* given device. The corresponding blocks in the bitmap must be
* marked as allocated and the device must be flagged SW_CLOSING.
* There may be no processes swapped out to the device.
*
* This routine may block.
*/
static void
swap_pager_swapoff(struct swdevt *sp)
{
struct swblock *swap;
int i, j, retries;
GIANT_REQUIRED;
retries = 0;
full_rescan:
mtx_lock(&swhash_mtx);
for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
restart:
for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
vm_object_t object = swap->swb_object;
vm_pindex_t pindex = swap->swb_index;
for (j = 0; j < SWAP_META_PAGES; ++j) {
if (swp_pager_isondev(swap->swb_pages[j], sp)) {
/* avoid deadlock */
if (!VM_OBJECT_TRYWLOCK(object)) {
break;
} else {
mtx_unlock(&swhash_mtx);
swp_pager_force_pagein(object,
pindex + j);
VM_OBJECT_WUNLOCK(object);
mtx_lock(&swhash_mtx);
goto restart;
}
}
}
}
}
mtx_unlock(&swhash_mtx);
if (sp->sw_used) {
/*
* Objects may be locked or paging to the device being
* removed, so we will miss their pages and need to
* make another pass. We have marked this device as
* SW_CLOSING, so the activity should finish soon.
*/
retries++;
if (retries > 100) {
panic("swapoff: failed to locate %d swap blocks",
sp->sw_used);
}
pause("swpoff", hz / 20);
goto full_rescan;
}
}
/************************************************************************
* SWAP META DATA *
************************************************************************
*
* These routines manipulate the swap metadata stored in the
* OBJT_SWAP object.
*
* Swap metadata is implemented with a global hash and not directly
* linked into the object. Instead the object simply contains
* appropriate tracking counters.
*/
/*
* SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
*
* We first convert the object to a swap object if it is a default
* object.
*
* The specified swapblk is added to the object's swap metadata. If
* the swapblk is not valid, it is freed instead. Any previously
* assigned swapblk is freed.
*/
static void
swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
{
static volatile int exhausted;
struct swblock *swap;
struct swblock **pswap;
int idx;
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* Convert default object to swap object if necessary
*/
if (object->type != OBJT_SWAP) {
object->type = OBJT_SWAP;
object->un_pager.swp.swp_bcount = 0;
if (object->handle != NULL) {
mtx_lock(&sw_alloc_mtx);
TAILQ_INSERT_TAIL(
NOBJLIST(object->handle),
object,
pager_object_list
);
mtx_unlock(&sw_alloc_mtx);
}
}
/*
* Locate hash entry. If not found create, but if we aren't adding
* anything just return. If we run out of space in the map we wait
* and, since the hash table may have changed, retry.
*/
retry:
mtx_lock(&swhash_mtx);
pswap = swp_pager_hash(object, pindex);
if ((swap = *pswap) == NULL) {
int i;
if (swapblk == SWAPBLK_NONE)
goto done;
swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT |
(curproc == pageproc ? M_USE_RESERVE : 0));
if (swap == NULL) {
mtx_unlock(&swhash_mtx);
VM_OBJECT_WUNLOCK(object);
if (uma_zone_exhausted(swap_zone)) {
if (atomic_cmpset_int(&exhausted, 0, 1))
printf("swap zone exhausted, "
"increase kern.maxswzone\n");
vm_pageout_oom(VM_OOM_SWAPZ);
pause("swzonex", 10);
} else
VM_WAIT;
VM_OBJECT_WLOCK(object);
goto retry;
}
if (atomic_cmpset_int(&exhausted, 1, 0))
printf("swap zone ok\n");
swap->swb_hnext = NULL;
swap->swb_object = object;
swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK;
swap->swb_count = 0;
++object->un_pager.swp.swp_bcount;
for (i = 0; i < SWAP_META_PAGES; ++i)
swap->swb_pages[i] = SWAPBLK_NONE;
}
/*
* Delete prior contents of metadata
*/
idx = pindex & SWAP_META_MASK;
if (swap->swb_pages[idx] != SWAPBLK_NONE) {
swp_pager_freeswapspace(swap->swb_pages[idx], 1);
--swap->swb_count;
}
/*
* Enter block into metadata
*/
swap->swb_pages[idx] = swapblk;
if (swapblk != SWAPBLK_NONE)
++swap->swb_count;
done:
mtx_unlock(&swhash_mtx);
}
/*
* SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
*
* The requested range of blocks is freed, with any associated swap
* returned to the swap bitmap.
*
* This routine will free swap metadata structures as they are cleaned
* out. This routine does *NOT* operate on swap metadata associated
* with resident pages.
*/
static void
swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
{
VM_OBJECT_ASSERT_LOCKED(object);
if (object->type != OBJT_SWAP)
return;
while (count > 0) {
struct swblock **pswap;
struct swblock *swap;
mtx_lock(&swhash_mtx);
pswap = swp_pager_hash(object, index);
if ((swap = *pswap) != NULL) {
daddr_t v = swap->swb_pages[index & SWAP_META_MASK];
if (v != SWAPBLK_NONE) {
swp_pager_freeswapspace(v, 1);
swap->swb_pages[index & SWAP_META_MASK] =
SWAPBLK_NONE;
if (--swap->swb_count == 0) {
*pswap = swap->swb_hnext;
uma_zfree(swap_zone, swap);
--object->un_pager.swp.swp_bcount;
}
}
--count;
++index;
} else {
int n = SWAP_META_PAGES - (index & SWAP_META_MASK);
count -= n;
index += n;
}
mtx_unlock(&swhash_mtx);
}
}
/*
* SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
*
* This routine locates and destroys all swap metadata associated with
* an object.
*/
static void
swp_pager_meta_free_all(vm_object_t object)
{
daddr_t index = 0;
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->type != OBJT_SWAP)
return;
while (object->un_pager.swp.swp_bcount) {
struct swblock **pswap;
struct swblock *swap;
mtx_lock(&swhash_mtx);
pswap = swp_pager_hash(object, index);
if ((swap = *pswap) != NULL) {
int i;
for (i = 0; i < SWAP_META_PAGES; ++i) {
daddr_t v = swap->swb_pages[i];
if (v != SWAPBLK_NONE) {
--swap->swb_count;
swp_pager_freeswapspace(v, 1);
}
}
if (swap->swb_count != 0)
panic("swap_pager_meta_free_all: swb_count != 0");
*pswap = swap->swb_hnext;
uma_zfree(swap_zone, swap);
--object->un_pager.swp.swp_bcount;
}
mtx_unlock(&swhash_mtx);
index += SWAP_META_PAGES;
}
}
/*
* SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
*
* This routine is capable of looking up, popping, or freeing
* swapblk assignments in the swap meta data or in the vm_page_t.
* The routine typically returns the swapblk being looked-up, or popped,
* or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
* was invalid. This routine will automatically free any invalid
* meta-data swapblks.
*
* It is not possible to store invalid swapblks in the swap meta data
* (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
*
* When acting on a busy resident page and paging is in progress, we
* have to wait until paging is complete but otherwise can act on the
* busy page.
*
* SWM_FREE remove and free swap block from metadata
* SWM_POP remove from meta data but do not free.. pop it out
*/
static daddr_t
swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
{
struct swblock **pswap;
struct swblock *swap;
daddr_t r1;
int idx;
VM_OBJECT_ASSERT_LOCKED(object);
/*
* The meta data only exists of the object is OBJT_SWAP
* and even then might not be allocated yet.
*/
if (object->type != OBJT_SWAP)
return (SWAPBLK_NONE);
r1 = SWAPBLK_NONE;
mtx_lock(&swhash_mtx);
pswap = swp_pager_hash(object, pindex);
if ((swap = *pswap) != NULL) {
idx = pindex & SWAP_META_MASK;
r1 = swap->swb_pages[idx];
if (r1 != SWAPBLK_NONE) {
if (flags & SWM_FREE) {
swp_pager_freeswapspace(r1, 1);
r1 = SWAPBLK_NONE;
}
if (flags & (SWM_FREE|SWM_POP)) {
swap->swb_pages[idx] = SWAPBLK_NONE;
if (--swap->swb_count == 0) {
*pswap = swap->swb_hnext;
uma_zfree(swap_zone, swap);
--object->un_pager.swp.swp_bcount;
}
}
}
}
mtx_unlock(&swhash_mtx);
return (r1);
}
/*
* System call swapon(name) enables swapping on device name,
* which must be in the swdevsw. Return EBUSY
* if already swapping on this device.
*/
#ifndef _SYS_SYSPROTO_H_
struct swapon_args {
char *name;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
sys_swapon(struct thread *td, struct swapon_args *uap)
{
struct vattr attr;
struct vnode *vp;
struct nameidata nd;
int error;
error = priv_check(td, PRIV_SWAPON);
if (error)
return (error);
mtx_lock(&Giant);
while (swdev_syscall_active)
tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0);
swdev_syscall_active = 1;
/*
* Swap metadata may not fit in the KVM if we have physical
* memory of >1GB.
*/
if (swap_zone == NULL) {
error = ENOMEM;
goto done;
}
NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->name, td);
error = namei(&nd);
if (error)
goto done;
NDFREE(&nd, NDF_ONLY_PNBUF);
vp = nd.ni_vp;
if (vn_isdisk(vp, &error)) {
error = swapongeom(td, vp);
} else if (vp->v_type == VREG &&
(vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
(error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
/*
* Allow direct swapping to NFS regular files in the same
* way that nfs_mountroot() sets up diskless swapping.
*/
error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
}
if (error)
vrele(vp);
done:
swdev_syscall_active = 0;
wakeup_one(&swdev_syscall_active);
mtx_unlock(&Giant);
return (error);
}
/*
* Check that the total amount of swap currently configured does not
* exceed half the theoretical maximum. If it does, print a warning
* message and return -1; otherwise, return 0.
*/
static int
swapon_check_swzone(unsigned long npages)
{
unsigned long maxpages;
/* absolute maximum we can handle assuming 100% efficiency */
maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES;
/* recommend using no more than half that amount */
if (npages > maxpages / 2) {
printf("warning: total configured swap (%lu pages) "
"exceeds maximum recommended amount (%lu pages).\n",
npages, maxpages / 2);
printf("warning: increase kern.maxswzone "
"or reduce amount of swap.\n");
return (-1);
}
return (0);
}
static void
swaponsomething(struct vnode *vp, void *id, u_long nblks,
sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
{
struct swdevt *sp, *tsp;
swblk_t dvbase;
u_long mblocks;
/*
* nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
* First chop nblks off to page-align it, then convert.
*
* sw->sw_nblks is in page-sized chunks now too.
*/
nblks &= ~(ctodb(1) - 1);
nblks = dbtoc(nblks);
/*
* If we go beyond this, we get overflows in the radix
* tree bitmap code.
*/
mblocks = 0x40000000 / BLIST_META_RADIX;
if (nblks > mblocks) {
printf(
"WARNING: reducing swap size to maximum of %luMB per unit\n",
mblocks / 1024 / 1024 * PAGE_SIZE);
nblks = mblocks;
}
sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
sp->sw_vp = vp;
sp->sw_id = id;
sp->sw_dev = dev;
sp->sw_flags = 0;
sp->sw_nblks = nblks;
sp->sw_used = 0;
sp->sw_strategy = strategy;
sp->sw_close = close;
sp->sw_flags = flags;
sp->sw_blist = blist_create(nblks, M_WAITOK);
/*
* Do not free the first two block in order to avoid overwriting
* any bsd label at the front of the partition
*/
blist_free(sp->sw_blist, 2, nblks - 2);
dvbase = 0;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(tsp, &swtailq, sw_list) {
if (tsp->sw_end >= dvbase) {
/*
* We put one uncovered page between the devices
* in order to definitively prevent any cross-device
* I/O requests
*/
dvbase = tsp->sw_end + 1;
}
}
sp->sw_first = dvbase;
sp->sw_end = dvbase + nblks;
TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
nswapdev++;
swap_pager_avail += nblks;
swap_total += (vm_ooffset_t)nblks * PAGE_SIZE;
swapon_check_swzone(swap_total / PAGE_SIZE);
swp_sizecheck();
mtx_unlock(&sw_dev_mtx);
}
/*
* SYSCALL: swapoff(devname)
*
* Disable swapping on the given device.
*
* XXX: Badly designed system call: it should use a device index
* rather than filename as specification. We keep sw_vp around
* only to make this work.
*/
#ifndef _SYS_SYSPROTO_H_
struct swapoff_args {
char *name;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
sys_swapoff(struct thread *td, struct swapoff_args *uap)
{
struct vnode *vp;
struct nameidata nd;
struct swdevt *sp;
int error;
error = priv_check(td, PRIV_SWAPOFF);
if (error)
return (error);
mtx_lock(&Giant);
while (swdev_syscall_active)
tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
swdev_syscall_active = 1;
NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name,
td);
error = namei(&nd);
if (error)
goto done;
NDFREE(&nd, NDF_ONLY_PNBUF);
vp = nd.ni_vp;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
if (sp->sw_vp == vp)
break;
}
mtx_unlock(&sw_dev_mtx);
if (sp == NULL) {
error = EINVAL;
goto done;
}
error = swapoff_one(sp, td->td_ucred);
done:
swdev_syscall_active = 0;
wakeup_one(&swdev_syscall_active);
mtx_unlock(&Giant);
return (error);
}
static int
swapoff_one(struct swdevt *sp, struct ucred *cred)
{
u_long nblks, dvbase;
#ifdef MAC
int error;
#endif
mtx_assert(&Giant, MA_OWNED);
#ifdef MAC
(void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
error = mac_system_check_swapoff(cred, sp->sw_vp);
(void) VOP_UNLOCK(sp->sw_vp, 0);
if (error != 0)
return (error);
#endif
nblks = sp->sw_nblks;
/*
* We can turn off this swap device safely only if the
* available virtual memory in the system will fit the amount
* of data we will have to page back in, plus an epsilon so
* the system doesn't become critically low on swap space.
*/
if (vm_cnt.v_free_count + vm_cnt.v_cache_count + swap_pager_avail <
nblks + nswap_lowat) {
return (ENOMEM);
}
/*
* Prevent further allocations on this device.
*/
mtx_lock(&sw_dev_mtx);
sp->sw_flags |= SW_CLOSING;
for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) {
swap_pager_avail -= blist_fill(sp->sw_blist,
dvbase, dmmax);
}
swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE;
mtx_unlock(&sw_dev_mtx);
/*
* Page in the contents of the device and close it.
*/
swap_pager_swapoff(sp);
sp->sw_close(curthread, sp);
mtx_lock(&sw_dev_mtx);
sp->sw_id = NULL;
TAILQ_REMOVE(&swtailq, sp, sw_list);
nswapdev--;
if (nswapdev == 0) {
swap_pager_full = 2;
swap_pager_almost_full = 1;
}
if (swdevhd == sp)
swdevhd = NULL;
mtx_unlock(&sw_dev_mtx);
blist_destroy(sp->sw_blist);
free(sp, M_VMPGDATA);
return (0);
}
void
swapoff_all(void)
{
struct swdevt *sp, *spt;
const char *devname;
int error;
mtx_lock(&Giant);
while (swdev_syscall_active)
tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
swdev_syscall_active = 1;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
mtx_unlock(&sw_dev_mtx);
if (vn_isdisk(sp->sw_vp, NULL))
devname = devtoname(sp->sw_vp->v_rdev);
else
devname = "[file]";
error = swapoff_one(sp, thread0.td_ucred);
if (error != 0) {
printf("Cannot remove swap device %s (error=%d), "
"skipping.\n", devname, error);
} else if (bootverbose) {
printf("Swap device %s removed.\n", devname);
}
mtx_lock(&sw_dev_mtx);
}
mtx_unlock(&sw_dev_mtx);
swdev_syscall_active = 0;
wakeup_one(&swdev_syscall_active);
mtx_unlock(&Giant);
}
void
swap_pager_status(int *total, int *used)
{
struct swdevt *sp;
*total = 0;
*used = 0;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
*total += sp->sw_nblks;
*used += sp->sw_used;
}
mtx_unlock(&sw_dev_mtx);
}
int
swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len)
{
struct swdevt *sp;
const char *tmp_devname;
int error, n;
n = 0;
error = ENOENT;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
if (n != name) {
n++;
continue;
}
xs->xsw_version = XSWDEV_VERSION;
xs->xsw_dev = sp->sw_dev;
xs->xsw_flags = sp->sw_flags;
xs->xsw_nblks = sp->sw_nblks;
xs->xsw_used = sp->sw_used;
if (devname != NULL) {
if (vn_isdisk(sp->sw_vp, NULL))
tmp_devname = devtoname(sp->sw_vp->v_rdev);
else
tmp_devname = "[file]";
strncpy(devname, tmp_devname, len);
}
error = 0;
break;
}
mtx_unlock(&sw_dev_mtx);
return (error);
}
static int
sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
{
struct xswdev xs;
int error;
if (arg2 != 1) /* name length */
return (EINVAL);
error = swap_dev_info(*(int *)arg1, &xs, NULL, 0);
if (error != 0)
return (error);
error = SYSCTL_OUT(req, &xs, sizeof(xs));
return (error);
}
SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
"Number of swap devices");
SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
"Swap statistics by device");
/*
* vmspace_swap_count() - count the approximate swap usage in pages for a
* vmspace.
*
* The map must be locked.
*
* Swap usage is determined by taking the proportional swap used by
* VM objects backing the VM map. To make up for fractional losses,
* if the VM object has any swap use at all the associated map entries
* count for at least 1 swap page.
*/
long
vmspace_swap_count(struct vmspace *vmspace)
{
vm_map_t map;
vm_map_entry_t cur;
vm_object_t object;
long count, n;
map = &vmspace->vm_map;
count = 0;
for (cur = map->header.next; cur != &map->header; cur = cur->next) {
if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
(object = cur->object.vm_object) != NULL) {
VM_OBJECT_WLOCK(object);
if (object->type == OBJT_SWAP &&
object->un_pager.swp.swp_bcount != 0) {
n = (cur->end - cur->start) / PAGE_SIZE;
count += object->un_pager.swp.swp_bcount *
SWAP_META_PAGES * n / object->size + 1;
}
VM_OBJECT_WUNLOCK(object);
}
}
return (count);
}
/*
* GEOM backend
*
* Swapping onto disk devices.
*
*/
static g_orphan_t swapgeom_orphan;
static struct g_class g_swap_class = {
.name = "SWAP",
.version = G_VERSION,
.orphan = swapgeom_orphan,
};
DECLARE_GEOM_CLASS(g_swap_class, g_class);
static void
swapgeom_close_ev(void *arg, int flags)
{
struct g_consumer *cp;
cp = arg;
g_access(cp, -1, -1, 0);
g_detach(cp);
g_destroy_consumer(cp);
}
/*
* Add a reference to the g_consumer for an inflight transaction.
*/
static void
swapgeom_acquire(struct g_consumer *cp)
{
mtx_assert(&sw_dev_mtx, MA_OWNED);
cp->index++;
}
/*
* Remove a reference from the g_consumer. Post a close event if
* all referneces go away.
*/
static void
swapgeom_release(struct g_consumer *cp, struct swdevt *sp)
{
mtx_assert(&sw_dev_mtx, MA_OWNED);
cp->index--;
if (cp->index == 0) {
if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0)
sp->sw_id = NULL;
}
}
static void
swapgeom_done(struct bio *bp2)
{
struct swdevt *sp;
struct buf *bp;
struct g_consumer *cp;
bp = bp2->bio_caller2;
cp = bp2->bio_from;
bp->b_ioflags = bp2->bio_flags;
if (bp2->bio_error)
bp->b_ioflags |= BIO_ERROR;
bp->b_resid = bp->b_bcount - bp2->bio_completed;
bp->b_error = bp2->bio_error;
bufdone(bp);
sp = bp2->bio_caller1;
mtx_lock(&sw_dev_mtx);
swapgeom_release(cp, sp);
mtx_unlock(&sw_dev_mtx);
g_destroy_bio(bp2);
}
static void
swapgeom_strategy(struct buf *bp, struct swdevt *sp)
{
struct bio *bio;
struct g_consumer *cp;
mtx_lock(&sw_dev_mtx);
cp = sp->sw_id;
if (cp == NULL) {
mtx_unlock(&sw_dev_mtx);
bp->b_error = ENXIO;
bp->b_ioflags |= BIO_ERROR;
bufdone(bp);
return;
}
swapgeom_acquire(cp);
mtx_unlock(&sw_dev_mtx);
if (bp->b_iocmd == BIO_WRITE)
bio = g_new_bio();
else
bio = g_alloc_bio();
if (bio == NULL) {
mtx_lock(&sw_dev_mtx);
swapgeom_release(cp, sp);
mtx_unlock(&sw_dev_mtx);
bp->b_error = ENOMEM;
bp->b_ioflags |= BIO_ERROR;
bufdone(bp);
return;
}
bio->bio_caller1 = sp;
bio->bio_caller2 = bp;
bio->bio_cmd = bp->b_iocmd;
bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
bio->bio_length = bp->b_bcount;
bio->bio_done = swapgeom_done;
if (!buf_mapped(bp)) {
bio->bio_ma = bp->b_pages;
bio->bio_data = unmapped_buf;
bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
bio->bio_ma_n = bp->b_npages;
bio->bio_flags |= BIO_UNMAPPED;
} else {
bio->bio_data = bp->b_data;
bio->bio_ma = NULL;
}
g_io_request(bio, cp);
return;
}
static void
swapgeom_orphan(struct g_consumer *cp)
{
struct swdevt *sp;
int destroy;
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
if (sp->sw_id == cp) {
sp->sw_flags |= SW_CLOSING;
break;
}
}
/*
* Drop reference we were created with. Do directly since we're in a
* special context where we don't have to queue the call to
* swapgeom_close_ev().
*/
cp->index--;
destroy = ((sp != NULL) && (cp->index == 0));
if (destroy)
sp->sw_id = NULL;
mtx_unlock(&sw_dev_mtx);
if (destroy)
swapgeom_close_ev(cp, 0);
}
static void
swapgeom_close(struct thread *td, struct swdevt *sw)
{
struct g_consumer *cp;
mtx_lock(&sw_dev_mtx);
cp = sw->sw_id;
sw->sw_id = NULL;
mtx_unlock(&sw_dev_mtx);
/* XXX: direct call when Giant untangled */
if (cp != NULL)
g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
}
struct swh0h0 {
struct cdev *dev;
struct vnode *vp;
int error;
};
static void
swapongeom_ev(void *arg, int flags)
{
struct swh0h0 *swh;
struct g_provider *pp;
struct g_consumer *cp;
static struct g_geom *gp;
struct swdevt *sp;
u_long nblks;
int error;
swh = arg;
swh->error = 0;
pp = g_dev_getprovider(swh->dev);
if (pp == NULL) {
swh->error = ENODEV;
return;
}
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
cp = sp->sw_id;
if (cp != NULL && cp->provider == pp) {
mtx_unlock(&sw_dev_mtx);
swh->error = EBUSY;
return;
}
}
mtx_unlock(&sw_dev_mtx);
if (gp == NULL)
gp = g_new_geomf(&g_swap_class, "swap");
cp = g_new_consumer(gp);
cp->index = 1; /* Number of active I/Os, plus one for being active. */
cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
g_attach(cp, pp);
/*
* XXX: Everytime you think you can improve the margin for
* footshooting, somebody depends on the ability to do so:
* savecore(8) wants to write to our swapdev so we cannot
* set an exclusive count :-(
*/
error = g_access(cp, 1, 1, 0);
if (error) {
g_detach(cp);
g_destroy_consumer(cp);
swh->error = error;
return;
}
nblks = pp->mediasize / DEV_BSIZE;
swaponsomething(swh->vp, cp, nblks, swapgeom_strategy,
swapgeom_close, dev2udev(swh->dev),
(pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
swh->error = 0;
}
static int
swapongeom(struct thread *td, struct vnode *vp)
{
int error;
struct swh0h0 swh;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
swh.dev = vp->v_rdev;
swh.vp = vp;
swh.error = 0;
/* XXX: direct call when Giant untangled */
error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL);
if (!error)
error = swh.error;
VOP_UNLOCK(vp, 0);
return (error);
}
/*
* VNODE backend
*
* This is used mainly for network filesystem (read: probably only tested
* with NFS) swapfiles.
*
*/
static void
swapdev_strategy(struct buf *bp, struct swdevt *sp)
{
struct vnode *vp2;
bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
vp2 = sp->sw_id;
vhold(vp2);
if (bp->b_iocmd == BIO_WRITE) {
if (bp->b_bufobj)
bufobj_wdrop(bp->b_bufobj);
bufobj_wref(&vp2->v_bufobj);
}
if (bp->b_bufobj != &vp2->v_bufobj)
bp->b_bufobj = &vp2->v_bufobj;
bp->b_vp = vp2;
bp->b_iooffset = dbtob(bp->b_blkno);
bstrategy(bp);
return;
}
static void
swapdev_close(struct thread *td, struct swdevt *sp)
{
VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
vrele(sp->sw_vp);
}
static int
swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
{
struct swdevt *sp;
int error;
if (nblks == 0)
return (ENXIO);
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
if (sp->sw_id == vp) {
mtx_unlock(&sw_dev_mtx);
return (EBUSY);
}
}
mtx_unlock(&sw_dev_mtx);
(void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
#ifdef MAC
error = mac_system_check_swapon(td->td_ucred, vp);
if (error == 0)
#endif
error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL);
(void) VOP_UNLOCK(vp, 0);
if (error)
return (error);
swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,
NODEV, 0);
return (0);
}
static int
sysctl_swap_async_max(SYSCTL_HANDLER_ARGS)
{
int error, new, n;
new = nsw_wcount_async_max;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (new > nswbuf / 2 || new < 1)
return (EINVAL);
mtx_lock(&pbuf_mtx);
while (nsw_wcount_async_max != new) {
/*
* Adjust difference. If the current async count is too low,
* we will need to sqeeze our update slowly in. Sleep with a
* higher priority than getpbuf() to finish faster.
*/
n = new - nsw_wcount_async_max;
if (nsw_wcount_async + n >= 0) {
nsw_wcount_async += n;
nsw_wcount_async_max += n;
wakeup(&nsw_wcount_async);
} else {
nsw_wcount_async_max -= nsw_wcount_async;
nsw_wcount_async = 0;
msleep(&nsw_wcount_async, &pbuf_mtx, PSWP,
"swpsysctl", 0);
}
}
mtx_unlock(&pbuf_mtx);
return (0);
}