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freebsd/sys/ufs/ffs/ffs_vnops.c
Kirk McKusick f2a2857bb3 Add snapshots to the fast filesystem. Most of the changes support 
the gating of system calls that cause modifications to the underlying
filesystem. The gating can be enabled by any filesystem that needs
to consistently suspend operations by adding the vop_stdgetwritemount
to their set of vnops. Once gating is enabled, the function
vfs_write_suspend stops all new write operations to a filesystem,
allows any filesystem modifying system calls already in progress
to complete, then sync's the filesystem to disk and returns. The
function vfs_write_resume allows the suspended write operations to
begin again. Gating is not added by default for all filesystems as
for SMP systems it adds two extra locks to such critical kernel
paths as the write system call. Thus, gating should only be added
as needed.

Details on the use and current status of snapshots in FFS can be
found in /sys/ufs/ffs/README.snapshot so for brevity and timelyness
is not included here. Unless and until you create a snapshot file,
these changes should have no effect on your system (famous last words).
2000-07-11 22:07:57 +00:00

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/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. 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.
* 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.
*
* @(#)ffs_vnops.c 8.15 (Berkeley) 5/14/95
* $FreeBSD$
*/
#include "opt_ffs.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/stat.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/conf.h>
#include <machine/limits.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>
#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>
static int ffs_fsync __P((struct vop_fsync_args *));
static int ffs_getpages __P((struct vop_getpages_args *));
static int ffs_putpages __P((struct vop_putpages_args *));
static int ffs_read __P((struct vop_read_args *));
static int ffs_write __P((struct vop_write_args *));
/* Global vfs data structures for ufs. */
vop_t **ffs_vnodeop_p;
static struct vnodeopv_entry_desc ffs_vnodeop_entries[] = {
{ &vop_default_desc, (vop_t *) ufs_vnoperate },
{ &vop_fsync_desc, (vop_t *) ffs_fsync },
{ &vop_getpages_desc, (vop_t *) ffs_getpages },
{ &vop_putpages_desc, (vop_t *) ffs_putpages },
{ &vop_read_desc, (vop_t *) ffs_read },
{ &vop_balloc_desc, (vop_t *) ffs_balloc },
{ &vop_reallocblks_desc, (vop_t *) ffs_reallocblks },
{ &vop_write_desc, (vop_t *) ffs_write },
#ifdef FFS_EXTATTR
{ &vop_getextattr_desc, (vop_t *) ufs_vop_getextattr },
{ &vop_setextattr_desc, (vop_t *) ufs_vop_setextattr },
#endif
{ NULL, NULL }
};
static struct vnodeopv_desc ffs_vnodeop_opv_desc =
{ &ffs_vnodeop_p, ffs_vnodeop_entries };
vop_t **ffs_specop_p;
static struct vnodeopv_entry_desc ffs_specop_entries[] = {
{ &vop_default_desc, (vop_t *) ufs_vnoperatespec },
{ &vop_fsync_desc, (vop_t *) ffs_fsync },
{ &vop_copyonwrite_desc, (vop_t *) ffs_copyonwrite },
{ NULL, NULL }
};
static struct vnodeopv_desc ffs_specop_opv_desc =
{ &ffs_specop_p, ffs_specop_entries };
vop_t **ffs_fifoop_p;
static struct vnodeopv_entry_desc ffs_fifoop_entries[] = {
{ &vop_default_desc, (vop_t *) ufs_vnoperatefifo },
{ &vop_fsync_desc, (vop_t *) ffs_fsync },
{ NULL, NULL }
};
static struct vnodeopv_desc ffs_fifoop_opv_desc =
{ &ffs_fifoop_p, ffs_fifoop_entries };
VNODEOP_SET(ffs_vnodeop_opv_desc);
VNODEOP_SET(ffs_specop_opv_desc);
VNODEOP_SET(ffs_fifoop_opv_desc);
#include <ufs/ufs/ufs_readwrite.c>
/*
* Synch an open file.
*/
/* ARGSUSED */
static int
ffs_fsync(ap)
struct vop_fsync_args /* {
struct vnode *a_vp;
struct ucred *a_cred;
int a_waitfor;
struct proc *a_p;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
struct inode *ip = VTOI(vp);
struct buf *bp;
struct buf *nbp;
int s, error, wait, passes, skipmeta;
daddr_t lbn;
/*
* Snapshots have to be unlocked so they do not deadlock
* checking whether they need to copy their written buffers.
* We always hold a reference, so they cannot be removed
* out from underneath us.
*/
if (ip->i_flags & SF_SNAPSHOT)
VOP_UNLOCK(vp, 0, ap->a_p);
wait = (ap->a_waitfor == MNT_WAIT);
if (vn_isdisk(vp, NULL)) {
lbn = INT_MAX;
if (vp->v_specmountpoint != NULL &&
(vp->v_specmountpoint->mnt_flag & MNT_SOFTDEP))
softdep_fsync_mountdev(vp);
} else {
lbn = lblkno(ip->i_fs, (ip->i_size + ip->i_fs->fs_bsize - 1));
}
/*
* Flush all dirty buffers associated with a vnode.
*/
passes = NIADDR + 1;
skipmeta = 0;
if (wait)
skipmeta = 1;
s = splbio();
loop:
for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp;
bp = TAILQ_NEXT(bp, b_vnbufs))
bp->b_flags &= ~B_SCANNED;
for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
nbp = TAILQ_NEXT(bp, b_vnbufs);
/*
* Reasons to skip this buffer: it has already been considered
* on this pass, this pass is the first time through on a
* synchronous flush request and the buffer being considered
* is metadata, the buffer has dependencies that will cause
* it to be redirtied and it has not already been deferred,
* or it is already being written.
*/
if ((bp->b_flags & B_SCANNED) != 0)
continue;
bp->b_flags |= B_SCANNED;
if ((skipmeta == 1 && bp->b_lblkno < 0))
continue;
if (!wait && LIST_FIRST(&bp->b_dep) != NULL &&
(bp->b_flags & B_DEFERRED) == 0 &&
buf_countdeps(bp, 0)) {
bp->b_flags |= B_DEFERRED;
continue;
}
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT))
continue;
if ((bp->b_flags & B_DELWRI) == 0)
panic("ffs_fsync: not dirty");
if (vp != bp->b_vp)
panic("ffs_fsync: vp != vp->b_vp");
/*
* If this is a synchronous flush request, or it is not a
* file or device, start the write on this buffer immediatly.
*/
if (wait || (vp->v_type != VREG && vp->v_type != VBLK)) {
/*
* On our final pass through, do all I/O synchronously
* so that we can find out if our flush is failing
* because of write errors.
*/
if (passes > 0 || !wait) {
if ((bp->b_flags & B_CLUSTEROK) && !wait) {
BUF_UNLOCK(bp);
(void) vfs_bio_awrite(bp);
} else {
bremfree(bp);
splx(s);
(void) bawrite(bp);
s = splbio();
}
} else {
bremfree(bp);
splx(s);
if ((error = bwrite(bp)) != 0)
return (error);
s = splbio();
}
} else if ((vp->v_type == VREG) && (bp->b_lblkno >= lbn)) {
/*
* If the buffer is for data that has been truncated
* off the file, then throw it away.
*/
bremfree(bp);
bp->b_flags |= B_INVAL | B_NOCACHE;
splx(s);
brelse(bp);
s = splbio();
} else {
BUF_UNLOCK(bp);
vfs_bio_awrite(bp);
}
/*
* Since we may have slept during the I/O, we need
* to start from a known point.
*/
nbp = TAILQ_FIRST(&vp->v_dirtyblkhd);
}
/*
* If we were asked to do this synchronously, then go back for
* another pass, this time doing the metadata.
*/
if (skipmeta) {
skipmeta = 0;
goto loop;
}
if (wait) {
while (vp->v_numoutput) {
vp->v_flag |= VBWAIT;
(void) tsleep((caddr_t)&vp->v_numoutput,
PRIBIO + 4, "ffsfsn", 0);
}
/*
* Ensure that any filesystem metatdata associated
* with the vnode has been written.
*/
splx(s);
if ((error = softdep_sync_metadata(ap)) != 0)
return (error);
s = splbio();
if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
/*
* Block devices associated with filesystems may
* have new I/O requests posted for them even if
* the vnode is locked, so no amount of trying will
* get them clean. Thus we give block devices a
* good effort, then just give up. For all other file
* types, go around and try again until it is clean.
*/
if (passes > 0) {
passes -= 1;
goto loop;
}
#ifdef DIAGNOSTIC
if (!vn_isdisk(vp, NULL))
vprint("ffs_fsync: dirty", vp);
#endif
}
}
splx(s);
error = UFS_UPDATE(vp, wait);
if (ip->i_flags & SF_SNAPSHOT)
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, ap->a_p);
return (error);
}
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