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Add support for reading directly from file to userland buffer when the

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O_DIRECT descriptor status flag is set and both offset and length is a
multiple of the physical media sector size.
This commit is contained in:
Tor Egge 2003-03-26 23:40:42 +00:00
parent 6b08046175
commit 5bbb806004
6 changed files with 539 additions and 0 deletions
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13
sys/conf/NOTES
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@ -2227,6 +2227,19 @@ options SHMSEG=9
# console.
options PANIC_REBOOT_WAIT_TIME=16
# Attempt to bypass the buffer cache and put data directly into the
# userland buffer for read operation when O_DIRECT flag is set on the
# file. Both offset and length of the read operation must be
# multiples of the physical media sector size.
#
#options DIRECTIO
# Specify a lower limit for the number of swap I/O buffers. They are
# (among other things) used when bypassing the buffer cache due to
# DIRECTIO kernel option enabled and O_DIRECT flag set on file.
#
#options NSWBUF_MIN=120
#####################################################################
# More undocumented options for linting.

1
sys/conf/files
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@ -1522,6 +1522,7 @@ ufs/ffs/ffs_subr.c optional ffs
ufs/ffs/ffs_tables.c optional ffs
ufs/ffs/ffs_vfsops.c optional ffs
ufs/ffs/ffs_vnops.c optional ffs
ufs/ffs/ffs_rawread.c optional directio
ufs/ufs/ufs_acl.c optional ffs
ufs/ufs/ufs_bmap.c optional ffs
ufs/ufs/ufs_dirhash.c optional ffs

2
sys/conf/options
View File

@ -108,6 +108,7 @@ MD_ROOT_SIZE opt_md.h
NDGBPORTS opt_dgb.h
NTIMECOUNTER opt_ntp.h
NSWAPDEV opt_swap.h
NSWBUF_MIN opt_swap.h
PANIC_REBOOT_WAIT_TIME opt_panic.h
PPS_SYNC opt_ntp.h
PUC_FASTINTR opt_puc.h
@ -142,6 +143,7 @@ VFS_AIO
WLCACHE opt_wavelan.h
WLDEBUG opt_wavelan.h
TTYHOG opt_tty.h
DIRECTIO opt_directio.h
# POSIX kernel options
_KPOSIX_PRIORITY_SCHEDULING opt_posix.h

12
sys/kern/vfs_bio.c
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@ -52,6 +52,8 @@
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include "opt_directio.h"
#include "opt_swap.h"
static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
@ -246,6 +248,9 @@ const char *buf_wmesg = BUF_WMESG;
#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
#ifdef DIRECTIO
extern void ffs_rawread_setup(void);
#endif /* DIRECTIO */
/*
* numdirtywakeup:
*
@ -463,6 +468,13 @@ kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
* We have no less then 16 and no more then 256.
*/
nswbuf = max(min(nbuf/4, 256), 16);
#ifdef NSWBUF_MIN
if (nswbuf < NSWBUF_MIN)
nswbuf = NSWBUF_MIN;
#endif
#ifdef DIRECTIO
ffs_rawread_setup();
#endif
/*
* Reserve space for the buffer cache buffers

498
sys/ufs/ffs/ffs_rawread.c Normal file
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@ -0,0 +1,498 @@
/*-
* Copyright (c) 2000-2003 Tor Egge
* All rights reserved.
*
* 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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/conf.h>
#include <sys/filio.h>
#include <sys/ttycom.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ffs/fs.h>
#include <machine/limits.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_object.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
static int ffs_rawread_readahead(struct vnode *vp,
caddr_t udata,
off_t offset,
size_t len,
struct thread *td,
struct buf *bp,
caddr_t sa);
static int ffs_rawread_main(struct vnode *vp,
struct uio *uio);
static int ffs_rawread_sync(struct vnode *vp, struct thread *td);
int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
void ffs_rawread_setup(void);
static void ffs_rawreadwakeup(struct buf *bp);
SYSCTL_DECL(_vfs_ffs);
static int ffsrawbufcnt = 4;
SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
"Buffers available for raw reads");
static int allowrawread = 1;
SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
"Flag to enable raw reads");
static int rawreadahead = 1;
SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
"Flag to enable readahead for long raw reads");
void
ffs_rawread_setup(void)
{
ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
}
static int
ffs_rawread_sync(struct vnode *vp, struct thread *td)
{
int spl;
int error;
int upgraded;
GIANT_REQUIRED;
/* Check for dirty mmap, pending writes and dirty buffers */
spl = splbio();
VI_LOCK(vp);
if (vp->v_numoutput > 0 ||
!TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
(vp->v_iflag & VI_OBJDIRTY) != 0) {
splx(spl);
VI_UNLOCK(vp);
if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE) {
upgraded = 1;
/* Upgrade to exclusive lock, this might block */
VOP_LOCK(vp, LK_UPGRADE | LK_NOPAUSE, td);
} else
upgraded = 0;
/* Attempt to msync mmap() regions to clean dirty mmap */
VI_LOCK(vp);
if ((vp->v_iflag & VI_OBJDIRTY) != 0) {
struct vm_object *obj;
VI_UNLOCK(vp);
if (VOP_GETVOBJECT(vp, &obj) == 0)
vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
VI_LOCK(vp);
}
/* Wait for pending writes to complete */
spl = splbio();
while (vp->v_numoutput) {
vp->v_iflag |= VI_BWAIT;
error = msleep((caddr_t)&vp->v_numoutput,
VI_MTX(vp),
PRIBIO + 1,
"rawrdfls", 0);
if (error != 0) {
splx(spl);
VI_UNLOCK(vp);
if (upgraded != 0)
VOP_LOCK(vp, LK_DOWNGRADE, td);
return (error);
}
}
/* Flush dirty buffers */
if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
splx(spl);
VI_UNLOCK(vp);
if ((error = VOP_FSYNC(vp, NOCRED, MNT_WAIT, td)) != 0) {
if (upgraded != 0)
VOP_LOCK(vp, LK_DOWNGRADE, td);
return (error);
}
VI_LOCK(vp);
spl = splbio();
if (vp->v_numoutput > 0 ||
!TAILQ_EMPTY(&vp->v_dirtyblkhd))
panic("ffs_rawread_sync: dirty bufs");
}
splx(spl);
VI_UNLOCK(vp);
if (upgraded != 0)
VOP_LOCK(vp, LK_DOWNGRADE, td);
} else {
splx(spl);
VI_UNLOCK(vp);
}
return 0;
}
static int
ffs_rawread_readahead(struct vnode *vp,
caddr_t udata,
off_t offset,
size_t len,
struct thread *td,
struct buf *bp,
caddr_t sa)
{
int error;
u_int iolen;
off_t blockno;
int blockoff;
int bsize;
struct vnode *dp;
int bforwards;
GIANT_REQUIRED;
bsize = vp->v_mount->mnt_stat.f_iosize;
iolen = ((vm_offset_t) udata) & PAGE_MASK;
bp->b_bcount = len;
if (bp->b_bcount + iolen > bp->b_kvasize) {
bp->b_bcount = bp->b_kvasize;
if (iolen != 0)
bp->b_bcount -= PAGE_SIZE;
}
bp->b_flags = B_PHYS;
bp->b_iocmd = BIO_READ;
bp->b_iodone = ffs_rawreadwakeup;
bp->b_data = udata;
bp->b_saveaddr = sa;
bp->b_offset = offset;
blockno = bp->b_offset / bsize;
blockoff = (bp->b_offset % bsize) / DEV_BSIZE;
if ((daddr_t) blockno != blockno) {
return EINVAL; /* blockno overflow */
}
bp->b_lblkno = bp->b_blkno = blockno;
if (!useracc(bp->b_data, bp->b_bcount, VM_PROT_WRITE)) {
return EFAULT;
}
error = VOP_BMAP(vp, bp->b_lblkno, &dp, &bp->b_blkno, &bforwards,
NULL);
if (error != 0) {
return error;
}
if (bp->b_blkno == -1) {
/* Fill holes with NULs to preserve semantics */
if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
bp->b_bcount = bsize - blockoff * DEV_BSIZE;
bp->b_bufsize = bp->b_bcount;
if (vmapbuf(bp) < 0)
return EFAULT;
if (ticks - PCPU_GET(switchticks) >= hogticks)
uio_yield();
bzero(bp->b_data, bp->b_bufsize);
/* Mark operation completed (similar to bufdone()) */
bp->b_resid = 0;
bp->b_flags |= B_DONE;
return 0;
}
if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
bp->b_bufsize = bp->b_bcount;
bp->b_blkno += blockoff;
bp->b_dev = dp->v_rdev;
vmapbuf(bp);
if (vmapbuf < 0)
return EFAULT;
if (dp->v_type == VCHR)
(void) VOP_SPECSTRATEGY(dp, bp);
else
(void) VOP_STRATEGY(dp, bp);
return 0;
}
static int
ffs_rawread_main(struct vnode *vp,
struct uio *uio)
{
int error, nerror;
struct buf *bp, *nbp, *tbp;
caddr_t sa, nsa, tsa;
u_int iolen;
int spl;
caddr_t udata;
long resid;
off_t offset;
struct thread *td;
GIANT_REQUIRED;
td = uio->uio_td ? uio->uio_td : curthread;
udata = uio->uio_iov->iov_base;
resid = uio->uio_resid;
offset = uio->uio_offset;
/*
* keep the process from being swapped
*/
PHOLD(td->td_proc);
error = 0;
nerror = 0;
bp = NULL;
nbp = NULL;
sa = NULL;
nsa = NULL;
while (resid > 0) {
if (bp == NULL) { /* Setup first read */
/* XXX: Leave some bufs for swap */
bp = getpbuf(&ffsrawbufcnt);
sa = bp->b_data;
bp->b_vp = vp;
bp->b_error = 0;
error = ffs_rawread_readahead(vp, udata, offset,
resid, td, bp, sa);
if (error != 0)
break;
if (resid > bp->b_bufsize) { /* Setup fist readahead */
/* XXX: Leave bufs for swap */
if (rawreadahead != 0)
nbp = trypbuf(&ffsrawbufcnt);
else
nbp = NULL;
if (nbp != NULL) {
nsa = nbp->b_data;
nbp->b_vp = vp;
nbp->b_error = 0;
nerror = ffs_rawread_readahead(vp,
udata +
bp->b_bufsize,
offset +
bp->b_bufsize,
resid -
bp->b_bufsize,
td,
nbp,
nsa);
if (nerror) {
relpbuf(nbp, &ffsrawbufcnt);
nbp = NULL;
}
}
}
}
spl = splbio();
while ((bp->b_flags & B_DONE) == 0) {
tsleep((caddr_t)bp, PRIBIO, "rawrd", 0);
}
splx(spl);
vunmapbuf(bp);
iolen = bp->b_bcount - bp->b_resid;
if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
nerror = 0; /* Ignore possible beyond EOF error */
break; /* EOF */
}
if ((bp->b_ioflags & BIO_ERROR) != 0) {
error = bp->b_error;
break;
}
resid -= iolen;
udata += iolen;
offset += iolen;
if (iolen < bp->b_bufsize) {
/* Incomplete read. Try to read remaining part */
error = ffs_rawread_readahead(vp,
udata,
offset,
bp->b_bufsize - iolen,
td,
bp,
sa);
if (error != 0)
break;
} else if (nbp != NULL) { /* Complete read with readahead */
tbp = bp;
bp = nbp;
nbp = tbp;
tsa = sa;
sa = nsa;
nsa = tsa;
if (resid <= bp->b_bufsize) { /* No more readaheads */
relpbuf(nbp, &ffsrawbufcnt);
nbp = NULL;
} else { /* Setup next readahead */
nerror = ffs_rawread_readahead(vp,
udata +
bp->b_bufsize,
offset +
bp->b_bufsize,
resid -
bp->b_bufsize,
td,
nbp,
nsa);
if (nerror != 0) {
relpbuf(nbp, &ffsrawbufcnt);
nbp = NULL;
}
}
} else if (nerror != 0) {/* Deferred Readahead error */
break;
} else if (resid > 0) { /* More to read, no readahead */
error = ffs_rawread_readahead(vp, udata, offset,
resid, td, bp, sa);
if (error != 0)
break;
}
}
if (bp != NULL)
relpbuf(bp, &ffsrawbufcnt);
if (nbp != NULL) { /* Run down readahead buffer */
spl = splbio();
while ((nbp->b_flags & B_DONE) == 0) {
tsleep((caddr_t)nbp, PRIBIO, "rawrd", 0);
}
splx(spl);
vunmapbuf(nbp);
relpbuf(nbp, &ffsrawbufcnt);
}
if (error == 0)
error = nerror;
PRELE(td->td_proc);
uio->uio_iov->iov_base = udata;
uio->uio_resid = resid;
uio->uio_offset = offset;
return error;
}
int
ffs_rawread(struct vnode *vp,
struct uio *uio,
int *workdone)
{
if (allowrawread != 0 &&
uio->uio_iovcnt == 1 &&
uio->uio_segflg == UIO_USERSPACE &&
uio->uio_resid == uio->uio_iov->iov_len &&
(((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_flags &
TDF_DEADLKTREAT) == 0) {
int secsize; /* Media sector size */
off_t filebytes; /* Bytes left of file */
int blockbytes; /* Bytes left of file in full blocks */
int partialbytes; /* Bytes in last partial block */
int skipbytes; /* Bytes not to read in ffs_rawread */
struct inode *ip;
int error;
/* Only handle sector aligned reads */
ip = VTOI(vp);
secsize = ip->i_devvp->v_rdev->si_bsize_phys;
if ((uio->uio_offset & (secsize - 1)) == 0 &&
(uio->uio_resid & (secsize - 1)) == 0) {
/* Sync dirty pages and buffers if needed */
error = ffs_rawread_sync(vp,
(uio->uio_td != NULL) ?
uio->uio_td : curthread);
if (error != 0)
return error;
/* Check for end of file */
if (ip->i_size > uio->uio_offset) {
filebytes = ip->i_size - uio->uio_offset;
/* No special eof handling needed ? */
if (uio->uio_resid <= filebytes) {
*workdone = 1;
return ffs_rawread_main(vp, uio);
}
partialbytes = ((unsigned int) ip->i_size) %
ip->i_fs->fs_bsize;
blockbytes = (int) filebytes - partialbytes;
if (blockbytes > 0) {
skipbytes = uio->uio_resid -
blockbytes;
uio->uio_resid = blockbytes;
error = ffs_rawread_main(vp, uio);
uio->uio_resid += skipbytes;
if (error != 0)
return error;
/* Read remaining part using buffer */
}
}
}
}
*workdone = 0;
return 0;
}
static void
ffs_rawreadwakeup(struct buf *bp)
{
wakeup((caddr_t) bp);
}

13
sys/ufs/ffs/ffs_vnops.c
View File

@ -76,7 +76,11 @@
#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>
#include "opt_directio.h"
#ifdef DIRECTIO
extern int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
#endif
static int ffs_fsync(struct vop_fsync_args *);
static int ffs_getpages(struct vop_getpages_args *);
static int ffs_read(struct vop_read_args *);
@ -349,6 +353,15 @@ ffs_read(ap)
#else
panic("ffs_read+IO_EXT");
#endif
#ifdef DIRECTIO
if ((ioflag & IO_DIRECT) != 0) {
int workdone;
error = ffs_rawread(vp, uio, &workdone);
if (error != 0 || workdone != 0)
return error;
}
#endif
GIANT_REQUIRED;