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freebsd-nq/sys/ufs/ffs/ffs_snapshot.c
Xin LI d5128ab2af When clearing a fragment, it's possible that the length is zero. 
Reviewed by:	mckusick
MFC After:	1 week
2005-02-19 07:31:33 +00:00

2158 lines
60 KiB
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/*-
* Copyright 2000 Marshall Kirk McKusick. All Rights Reserved.
*
* Further information about snapshots can be obtained from:
*
* Marshall Kirk McKusick http://www.mckusick.com/softdep/
* 1614 Oxford Street mckusick@mckusick.com
* Berkeley, CA 94709-1608 +1-510-843-9542
* USA
*
* 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 MARSHALL KIRK MCKUSICK ``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 MARSHALL KIRK MCKUSICK 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_snapshot.c 8.11 (McKusick) 7/23/00
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/sched.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <sys/vnode.h>
#include <geom/geom.h>
#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufs_extern.h>
#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>
#define KERNCRED thread0.td_ucred
#define DEBUG 1
TAILQ_HEAD(snaphead, inode);
struct snapdata {
struct snaphead sn_head;
daddr_t sn_listsize;
daddr_t *sn_blklist;
struct lock sn_lock;
};
static int cgaccount(int, struct vnode *, struct buf *, int);
static int expunge_ufs1(struct vnode *, struct inode *, struct fs *,
int (*)(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *, struct fs *,
ufs_lbn_t, int), int);
static int indiracct_ufs1(struct vnode *, struct vnode *, int,
ufs1_daddr_t, ufs_lbn_t, ufs_lbn_t, ufs_lbn_t, ufs_lbn_t, struct fs *,
int (*)(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *, struct fs *,
ufs_lbn_t, int), int);
static int fullacct_ufs1(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *,
struct fs *, ufs_lbn_t, int);
static int snapacct_ufs1(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *,
struct fs *, ufs_lbn_t, int);
static int mapacct_ufs1(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *,
struct fs *, ufs_lbn_t, int);
static int expunge_ufs2(struct vnode *, struct inode *, struct fs *,
int (*)(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *, struct fs *,
ufs_lbn_t, int), int);
static int indiracct_ufs2(struct vnode *, struct vnode *, int,
ufs2_daddr_t, ufs_lbn_t, ufs_lbn_t, ufs_lbn_t, ufs_lbn_t, struct fs *,
int (*)(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *, struct fs *,
ufs_lbn_t, int), int);
static int fullacct_ufs2(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
struct fs *, ufs_lbn_t, int);
static int snapacct_ufs2(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
struct fs *, ufs_lbn_t, int);
static int mapacct_ufs2(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
struct fs *, ufs_lbn_t, int);
static int readblock(struct vnode *vp, struct buf *, ufs2_daddr_t);
/*
* To ensure the consistency of snapshots across crashes, we must
* synchronously write out copied blocks before allowing the
* originals to be modified. Because of the rather severe speed
* penalty that this imposes, the following flag allows this
* crash persistence to be disabled.
*/
int dopersistence = 0;
#ifdef DEBUG
#include <sys/sysctl.h>
SYSCTL_INT(_debug, OID_AUTO, dopersistence, CTLFLAG_RW, &dopersistence, 0, "");
static int snapdebug = 0;
SYSCTL_INT(_debug, OID_AUTO, snapdebug, CTLFLAG_RW, &snapdebug, 0, "");
int collectsnapstats = 0;
SYSCTL_INT(_debug, OID_AUTO, collectsnapstats, CTLFLAG_RW, &collectsnapstats,
0, "");
#endif /* DEBUG */
/*
* Create a snapshot file and initialize it for the filesystem.
*/
int
ffs_snapshot(mp, snapfile)
struct mount *mp;
char *snapfile;
{
ufs2_daddr_t numblks, blkno, *blkp, *snapblklist;
int error, cg, snaploc;
int i, size, len, loc;
int flag = mp->mnt_flag;
struct timespec starttime = {0, 0}, endtime;
char saved_nice = 0;
long redo = 0, snaplistsize = 0;
int32_t *lp;
void *space;
struct fs *copy_fs = NULL, *fs;
struct thread *td = curthread;
struct inode *ip, *xp;
struct buf *bp, *nbp, *ibp, *sbp = NULL;
struct nameidata nd;
struct mount *wrtmp;
struct vattr vat;
struct vnode *vp, *xvp, *nvp, *devvp;
struct uio auio;
struct iovec aiov;
struct snapdata *sn;
struct ufsmount *ump;
ump = VFSTOUFS(mp);
fs = ump->um_fs;
/*
* XXX: make sure we don't go to out1 before we setup sn
*/
sn = (void *)0xdeadbeef;
/*
* Need to serialize access to snapshot code per filesystem.
*/
/*
* Assign a snapshot slot in the superblock.
*/
UFS_LOCK(ump);
for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++)
if (fs->fs_snapinum[snaploc] == 0)
break;
UFS_UNLOCK(ump);
if (snaploc == FSMAXSNAP)
return (ENOSPC);
/*
* Create the snapshot file.
*/
restart:
NDINIT(&nd, CREATE, LOCKPARENT | LOCKLEAF, UIO_SYSSPACE, snapfile, td);
if ((error = namei(&nd)) != 0)
return (error);
if (nd.ni_vp != NULL) {
vput(nd.ni_vp);
error = EEXIST;
}
if (nd.ni_dvp->v_mount != mp)
error = EXDEV;
if (error) {
NDFREE(&nd, NDF_ONLY_PNBUF);
if (nd.ni_dvp == nd.ni_vp)
vrele(nd.ni_dvp);
else
vput(nd.ni_dvp);
return (error);
}
VATTR_NULL(&vat);
vat.va_type = VREG;
vat.va_mode = S_IRUSR;
vat.va_vaflags |= VA_EXCLUSIVE;
if (VOP_GETWRITEMOUNT(nd.ni_dvp, &wrtmp))
wrtmp = NULL;
if (wrtmp != mp)
panic("ffs_snapshot: mount mismatch");
if (vn_start_write(NULL, &wrtmp, V_NOWAIT) != 0) {
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(nd.ni_dvp);
if ((error = vn_start_write(NULL, &wrtmp,
V_XSLEEP | PCATCH)) != 0)
return (error);
goto restart;
}
VOP_LEASE(nd.ni_dvp, td, KERNCRED, LEASE_WRITE);
error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vat);
vput(nd.ni_dvp);
if (error) {
NDFREE(&nd, NDF_ONLY_PNBUF);
vn_finished_write(wrtmp);
return (error);
}
vp = nd.ni_vp;
ip = VTOI(vp);
devvp = ip->i_devvp;
/*
* Allocate and copy the last block contents so as to be able
* to set size to that of the filesystem.
*/
numblks = howmany(fs->fs_size, fs->fs_frag);
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)(numblks - 1)),
fs->fs_bsize, KERNCRED, BA_CLRBUF, &bp);
if (error)
goto out;
ip->i_size = lblktosize(fs, (off_t)numblks);
DIP_SET(ip, i_size, ip->i_size);
ip->i_flag |= IN_CHANGE | IN_UPDATE;
if ((error = readblock(vp, bp, numblks - 1)) != 0)
goto out;
bawrite(bp);
/*
* Preallocate critical data structures so that we can copy
* them in without further allocation after we suspend all
* operations on the filesystem. We would like to just release
* the allocated buffers without writing them since they will
* be filled in below once we are ready to go, but this upsets
* the soft update code, so we go ahead and write the new buffers.
*
* Allocate all indirect blocks and mark all of them as not
* needing to be copied.
*/
for (blkno = NDADDR; blkno < numblks; blkno += NINDIR(fs)) {
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)blkno),
fs->fs_bsize, td->td_ucred, BA_METAONLY, &ibp);
if (error)
goto out;
bawrite(ibp);
}
/*
* Allocate copies for the superblock and its summary information.
*/
error = UFS_BALLOC(vp, fs->fs_sblockloc, fs->fs_sbsize, KERNCRED,
0, &nbp);
if (error)
goto out;
bawrite(nbp);
blkno = fragstoblks(fs, fs->fs_csaddr);
len = howmany(fs->fs_cssize, fs->fs_bsize);
for (loc = 0; loc < len; loc++) {
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)(blkno + loc)),
fs->fs_bsize, KERNCRED, 0, &nbp);
if (error)
goto out;
bawrite(nbp);
}
/*
* Allocate all cylinder group blocks.
*/
for (cg = 0; cg < fs->fs_ncg; cg++) {
error = UFS_BALLOC(vp, lfragtosize(fs, cgtod(fs, cg)),
fs->fs_bsize, KERNCRED, 0, &nbp);
if (error)
goto out;
bawrite(nbp);
}
/*
* Copy all the cylinder group maps. Although the
* filesystem is still active, we hope that only a few
* cylinder groups will change between now and when we
* suspend operations. Thus, we will be able to quickly
* touch up the few cylinder groups that changed during
* the suspension period.
*/
len = howmany(fs->fs_ncg, NBBY);
MALLOC(space, void *, len, M_DEVBUF, M_WAITOK);
bzero(space, len);
UFS_LOCK(ump);
fs->fs_active = space;
UFS_UNLOCK(ump);
for (cg = 0; cg < fs->fs_ncg; cg++) {
error = UFS_BALLOC(vp, lfragtosize(fs, cgtod(fs, cg)),
fs->fs_bsize, KERNCRED, 0, &nbp);
if (error)
goto out;
error = cgaccount(cg, vp, nbp, 1);
bawrite(nbp);
if (error)
goto out;
}
/*
* Change inode to snapshot type file.
*/
ip->i_flags |= SF_SNAPSHOT;
DIP_SET(ip, i_flags, ip->i_flags);
ip->i_flag |= IN_CHANGE | IN_UPDATE;
/*
* Ensure that the snapshot is completely on disk.
* Since we have marked it as a snapshot it is safe to
* unlock it as no process will be allowed to write to it.
*/
if ((error = ffs_syncvnode(vp, MNT_WAIT)) != 0)
goto out;
VOP_UNLOCK(vp, 0, td);
/*
* All allocations are done, so we can now snapshot the system.
*
* Recind nice scheduling while running with the filesystem suspended.
*/
if (td->td_proc->p_nice > 0) {
PROC_LOCK(td->td_proc);
mtx_lock_spin(&sched_lock);
saved_nice = td->td_proc->p_nice;
sched_nice(td->td_proc, 0);
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(td->td_proc);
}
/*
* Suspend operation on filesystem.
*/
for (;;) {
vn_finished_write(wrtmp);
if ((error = vfs_write_suspend(vp->v_mount)) != 0) {
vn_start_write(NULL, &wrtmp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
goto out;
}
if (mp->mnt_kern_flag & MNTK_SUSPENDED)
break;
vn_start_write(NULL, &wrtmp, V_WAIT);
}
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (collectsnapstats)
nanotime(&starttime);
/*
* First, copy all the cylinder group maps that have changed.
*/
for (cg = 0; cg < fs->fs_ncg; cg++) {
if ((ACTIVECGNUM(fs, cg) & ACTIVECGOFF(cg)) != 0)
continue;
redo++;
error = UFS_BALLOC(vp, lfragtosize(fs, cgtod(fs, cg)),
fs->fs_bsize, KERNCRED, 0, &nbp);
if (error)
goto out1;
error = cgaccount(cg, vp, nbp, 2);
bawrite(nbp);
if (error)
goto out1;
}
/*
* Grab a copy of the superblock and its summary information.
* We delay writing it until the suspension is released below.
*/
error = bread(vp, lblkno(fs, fs->fs_sblockloc), fs->fs_bsize,
KERNCRED, &sbp);
if (error) {
brelse(sbp);
sbp = NULL;
goto out1;
}
loc = blkoff(fs, fs->fs_sblockloc);
copy_fs = (struct fs *)(sbp->b_data + loc);
bcopy(fs, copy_fs, fs->fs_sbsize);
if ((fs->fs_flags & (FS_UNCLEAN | FS_NEEDSFSCK)) == 0)
copy_fs->fs_clean = 1;
size = fs->fs_bsize < SBLOCKSIZE ? fs->fs_bsize : SBLOCKSIZE;
if (fs->fs_sbsize < size)
bzero(&sbp->b_data[loc + fs->fs_sbsize], size - fs->fs_sbsize);
size = blkroundup(fs, fs->fs_cssize);
if (fs->fs_contigsumsize > 0)
size += fs->fs_ncg * sizeof(int32_t);
space = malloc((u_long)size, M_UFSMNT, M_WAITOK);
copy_fs->fs_csp = space;
bcopy(fs->fs_csp, copy_fs->fs_csp, fs->fs_cssize);
space = (char *)space + fs->fs_cssize;
loc = howmany(fs->fs_cssize, fs->fs_fsize);
i = fs->fs_frag - loc % fs->fs_frag;
len = (i == fs->fs_frag) ? 0 : i * fs->fs_fsize;
if (len > 0) {
if ((error = bread(devvp, fsbtodb(fs, fs->fs_csaddr + loc),
len, KERNCRED, &bp)) != 0) {
brelse(bp);
free(copy_fs->fs_csp, M_UFSMNT);
bawrite(sbp);
sbp = NULL;
goto out1;
}
bcopy(bp->b_data, space, (u_int)len);
space = (char *)space + len;
bp->b_flags |= B_INVAL | B_NOCACHE;
brelse(bp);
}
if (fs->fs_contigsumsize > 0) {
copy_fs->fs_maxcluster = lp = space;
for (i = 0; i < fs->fs_ncg; i++)
*lp++ = fs->fs_contigsumsize;
}
/*
* We must check for active files that have been unlinked
* (e.g., with a zero link count). We have to expunge all
* trace of these files from the snapshot so that they are
* not reclaimed prematurely by fsck or unnecessarily dumped.
* We turn off the MNTK_SUSPENDED flag to avoid a panic from
* spec_strategy about writing on a suspended filesystem.
* Note that we skip unlinked snapshot files as they will
* be handled separately below.
*
* We also calculate the needed size for the snapshot list.
*/
snaplistsize = fs->fs_ncg + howmany(fs->fs_cssize, fs->fs_bsize) +
FSMAXSNAP + 1 /* superblock */ + 1 /* last block */ + 1 /* size */;
MNT_ILOCK(mp);
mp->mnt_kern_flag &= ~MNTK_SUSPENDED;
loop:
MNT_VNODE_FOREACH(xvp, mp, nvp) {
VI_LOCK(xvp);
MNT_IUNLOCK(mp);
if ((xvp->v_iflag & VI_XLOCK) ||
xvp->v_usecount == 0 || xvp->v_type == VNON ||
(VTOI(xvp)->i_flags & SF_SNAPSHOT)) {
VI_UNLOCK(xvp);
MNT_ILOCK(mp);
continue;
}
/*
* We can skip parent directory vnode because it must have
* this snapshot file in it.
*/
if (xvp == nd.ni_dvp) {
VI_UNLOCK(xvp);
MNT_ILOCK(mp);
continue;
}
if (vn_lock(xvp, LK_EXCLUSIVE | LK_INTERLOCK, td) != 0) {
MNT_ILOCK(mp);
goto loop;
}
if (snapdebug)
vprint("ffs_snapshot: busy vnode", xvp);
if (VOP_GETATTR(xvp, &vat, td->td_ucred, td) == 0 &&
vat.va_nlink > 0) {
VOP_UNLOCK(xvp, 0, td);
MNT_ILOCK(mp);
continue;
}
xp = VTOI(xvp);
if (ffs_checkfreefile(copy_fs, vp, xp->i_number)) {
VOP_UNLOCK(xvp, 0, td);
MNT_ILOCK(mp);
continue;
}
/*
* If there is a fragment, clear it here.
*/
blkno = 0;
loc = howmany(xp->i_size, fs->fs_bsize) - 1;
if (loc < NDADDR) {
len = fragroundup(fs, blkoff(fs, xp->i_size));
if (len != 0 && len < fs->fs_bsize) {
ffs_blkfree(ump, copy_fs, vp,
DIP(xp, i_db[loc]), len, xp->i_number);
blkno = DIP(xp, i_db[loc]);
DIP_SET(xp, i_db[loc], 0);
}
}
snaplistsize += 1;
if (xp->i_ump->um_fstype == UFS1)
error = expunge_ufs1(vp, xp, copy_fs, fullacct_ufs1,
BLK_NOCOPY);
else
error = expunge_ufs2(vp, xp, copy_fs, fullacct_ufs2,
BLK_NOCOPY);
if (blkno)
DIP_SET(xp, i_db[loc], blkno);
if (!error)
error = ffs_freefile(ump, copy_fs, vp, xp->i_number,
xp->i_mode);
VOP_UNLOCK(xvp, 0, td);
if (error) {
free(copy_fs->fs_csp, M_UFSMNT);
bawrite(sbp);
sbp = NULL;
goto out1;
}
MNT_ILOCK(mp);
}
MNT_IUNLOCK(mp);
/*
* If there already exist snapshots on this filesystem, grab a
* reference to their shared lock. If this is the first snapshot
* on this filesystem, we need to allocate a lock for the snapshots
* to share. In either case, acquire the snapshot lock and give
* up our original private lock.
*/
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
if (sn != NULL) {
xp = TAILQ_FIRST(&sn->sn_head);
VI_UNLOCK(devvp);
VI_LOCK(vp);
vp->v_vnlock = &sn->sn_lock;
} else {
VI_UNLOCK(devvp);
sn = malloc(sizeof *sn, M_UFSMNT, M_WAITOK | M_ZERO);
TAILQ_INIT(&sn->sn_head);
lockinit(&sn->sn_lock, PVFS, "snaplk", VLKTIMEOUT,
LK_CANRECURSE | LK_NOPAUSE);
VI_LOCK(vp);
vp->v_vnlock = &sn->sn_lock;
devvp->v_rdev->si_snapdata = sn;
xp = NULL;
}
vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE | LK_RETRY, td);
transferlockers(&vp->v_lock, vp->v_vnlock);
lockmgr(&vp->v_lock, LK_RELEASE, NULL, td);
/*
* If this is the first snapshot on this filesystem, then we need
* to allocate the space for the list of preallocated snapshot blocks.
* This list will be refined below, but this preliminary one will
* keep us out of deadlock until the full one is ready.
*/
if (xp == NULL) {
MALLOC(snapblklist, daddr_t *, snaplistsize * sizeof(daddr_t),
M_UFSMNT, M_WAITOK);
blkp = &snapblklist[1];
*blkp++ = lblkno(fs, fs->fs_sblockloc);
blkno = fragstoblks(fs, fs->fs_csaddr);
for (cg = 0; cg < fs->fs_ncg; cg++) {
if (fragstoblks(fs, cgtod(fs, cg) > blkno))
break;
*blkp++ = fragstoblks(fs, cgtod(fs, cg));
}
len = howmany(fs->fs_cssize, fs->fs_bsize);
for (loc = 0; loc < len; loc++)
*blkp++ = blkno + loc;
for (; cg < fs->fs_ncg; cg++)
*blkp++ = fragstoblks(fs, cgtod(fs, cg));
snapblklist[0] = blkp - snapblklist;
VI_LOCK(devvp);
if (sn->sn_blklist != NULL)
panic("ffs_snapshot: non-empty list");
sn->sn_blklist = snapblklist;
sn->sn_listsize = blkp - snapblklist;
VI_UNLOCK(devvp);
}
/*
* Record snapshot inode. Since this is the newest snapshot,
* it must be placed at the end of the list.
*/
VI_LOCK(devvp);
fs->fs_snapinum[snaploc] = ip->i_number;
if (ip->i_nextsnap.tqe_prev != 0)
panic("ffs_snapshot: %d already on list", ip->i_number);
TAILQ_INSERT_TAIL(&sn->sn_head, ip, i_nextsnap);
devvp->v_vflag |= VV_COPYONWRITE;
VI_UNLOCK(devvp);
ASSERT_VOP_LOCKED(vp, "ffs_snapshot vp");
vp->v_vflag |= VV_SYSTEM;
out1:
KASSERT(sn != (void *)0xdeadbeef, ("email phk@ and mckusick@"));
/*
* Resume operation on filesystem.
*/
vfs_write_resume(vp->v_mount);
vn_start_write(NULL, &wrtmp, V_WAIT);
if (collectsnapstats && starttime.tv_sec > 0) {
nanotime(&endtime);
timespecsub(&endtime, &starttime);
printf("%s: suspended %ld.%03ld sec, redo %ld of %d\n",
vp->v_mount->mnt_stat.f_mntonname, (long)endtime.tv_sec,
endtime.tv_nsec / 1000000, redo, fs->fs_ncg);
}
if (sbp == NULL)
goto out;
/*
* Copy allocation information from all the snapshots in
* this snapshot and then expunge them from its view.
*/
TAILQ_FOREACH(xp, &sn->sn_head, i_nextsnap) {
if (xp == ip)
break;
if (xp->i_ump->um_fstype == UFS1)
error = expunge_ufs1(vp, xp, fs, snapacct_ufs1,
BLK_SNAP);
else
error = expunge_ufs2(vp, xp, fs, snapacct_ufs2,
BLK_SNAP);
if (error) {
fs->fs_snapinum[snaploc] = 0;
goto done;
}
}
/*
* Allocate space for the full list of preallocated snapshot blocks.
*/
MALLOC(snapblklist, daddr_t *, snaplistsize * sizeof(daddr_t),
M_UFSMNT, M_WAITOK);
ip->i_snapblklist = &snapblklist[1];
/*
* Expunge the blocks used by the snapshots from the set of
* blocks marked as used in the snapshot bitmaps. Also, collect
* the list of allocated blocks in i_snapblklist.
*/
if (ip->i_ump->um_fstype == UFS1)
error = expunge_ufs1(vp, ip, copy_fs, mapacct_ufs1, BLK_SNAP);
else
error = expunge_ufs2(vp, ip, copy_fs, mapacct_ufs2, BLK_SNAP);
if (error) {
fs->fs_snapinum[snaploc] = 0;
FREE(snapblklist, M_UFSMNT);
goto done;
}
if (snaplistsize < ip->i_snapblklist - snapblklist)
panic("ffs_snapshot: list too small");
snaplistsize = ip->i_snapblklist - snapblklist;
snapblklist[0] = snaplistsize;
ip->i_snapblklist = 0;
/*
* Write out the list of allocated blocks to the end of the snapshot.
*/
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
aiov.iov_base = (void *)snapblklist;
aiov.iov_len = snaplistsize * sizeof(daddr_t);
auio.uio_resid = aiov.iov_len;;
auio.uio_offset = ip->i_size;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_rw = UIO_WRITE;
auio.uio_td = td;
if ((error = VOP_WRITE(vp, &auio, IO_UNIT, td->td_ucred)) != 0) {
fs->fs_snapinum[snaploc] = 0;
FREE(snapblklist, M_UFSMNT);
goto done;
}
/*
* Write the superblock and its summary information
* to the snapshot.
*/
blkno = fragstoblks(fs, fs->fs_csaddr);
len = howmany(fs->fs_cssize, fs->fs_bsize);
space = copy_fs->fs_csp;
for (loc = 0; loc < len; loc++) {
error = bread(vp, blkno + loc, fs->fs_bsize, KERNCRED, &nbp);
if (error) {
brelse(nbp);
fs->fs_snapinum[snaploc] = 0;
FREE(snapblklist, M_UFSMNT);
goto done;
}
bcopy(space, nbp->b_data, fs->fs_bsize);
space = (char *)space + fs->fs_bsize;
bawrite(nbp);
}
/*
* As this is the newest list, it is the most inclusive, so
* should replace the previous list.
*/
VI_LOCK(devvp);
space = sn->sn_blklist;
sn->sn_blklist = snapblklist;
sn->sn_listsize = snaplistsize;
VI_UNLOCK(devvp);
if (space != NULL)
FREE(space, M_UFSMNT);
done:
FREE(copy_fs->fs_csp, M_UFSMNT);
bawrite(sbp);
out:
if (saved_nice > 0) {
PROC_LOCK(td->td_proc);
mtx_lock_spin(&sched_lock);
sched_nice(td->td_proc, saved_nice);
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(td->td_proc);
}
UFS_LOCK(ump);
if (fs->fs_active != 0) {
FREE(fs->fs_active, M_DEVBUF);
fs->fs_active = 0;
}
UFS_UNLOCK(ump);
mp->mnt_flag = flag;
if (error)
(void) ffs_truncate(vp, (off_t)0, 0, NOCRED, td);
(void) ffs_syncvnode(vp, MNT_WAIT);
if (error)
vput(vp);
else
VOP_UNLOCK(vp, 0, td);
vn_finished_write(wrtmp);
return (error);
}
/*
* Copy a cylinder group map. All the unallocated blocks are marked
* BLK_NOCOPY so that the snapshot knows that it need not copy them
* if they are later written. If passno is one, then this is a first
* pass, so only setting needs to be done. If passno is 2, then this
* is a revision to a previous pass which must be undone as the
* replacement pass is done.
*/
static int
cgaccount(cg, vp, nbp, passno)
int cg;
struct vnode *vp;
struct buf *nbp;
int passno;
{
struct buf *bp, *ibp;
struct inode *ip;
struct cg *cgp;
struct fs *fs;
ufs2_daddr_t base, numblks;
int error, len, loc, indiroff;
ip = VTOI(vp);
fs = ip->i_fs;
error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
(int)fs->fs_cgsize, KERNCRED, &bp);
if (error) {
brelse(bp);
return (error);
}
cgp = (struct cg *)bp->b_data;
if (!cg_chkmagic(cgp)) {
brelse(bp);
return (EIO);
}
UFS_LOCK(ip->i_ump);
ACTIVECLEAR(fs, cg);
UFS_UNLOCK(ip->i_ump);
bcopy(bp->b_data, nbp->b_data, fs->fs_cgsize);
if (fs->fs_cgsize < fs->fs_bsize)
bzero(&nbp->b_data[fs->fs_cgsize],
fs->fs_bsize - fs->fs_cgsize);
if (passno == 2)
nbp->b_flags |= B_VALIDSUSPWRT;
numblks = howmany(fs->fs_size, fs->fs_frag);
len = howmany(fs->fs_fpg, fs->fs_frag);
base = cgbase(fs, cg) / fs->fs_frag;
if (base + len >= numblks)
len = numblks - base - 1;
loc = 0;
if (base < NDADDR) {
for ( ; loc < NDADDR; loc++) {
if (ffs_isblock(fs, cg_blksfree(cgp), loc))
DIP_SET(ip, i_db[loc], BLK_NOCOPY);
else if (passno == 2 && DIP(ip, i_db[loc])== BLK_NOCOPY)
DIP_SET(ip, i_db[loc], 0);
else if (passno == 1 && DIP(ip, i_db[loc])== BLK_NOCOPY)
panic("ffs_snapshot: lost direct block");
}
}
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)(base + loc)),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
if (error) {
brelse(bp);
return (error);
}
indiroff = (base + loc - NDADDR) % NINDIR(fs);
for ( ; loc < len; loc++, indiroff++) {
if (indiroff >= NINDIR(fs)) {
if (passno == 2)
ibp->b_flags |= B_VALIDSUSPWRT;
bawrite(ibp);
error = UFS_BALLOC(vp,
lblktosize(fs, (off_t)(base + loc)),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
if (error) {
brelse(bp);
return (error);
}
indiroff = 0;
}
if (ip->i_ump->um_fstype == UFS1) {
if (ffs_isblock(fs, cg_blksfree(cgp), loc))
((ufs1_daddr_t *)(ibp->b_data))[indiroff] =
BLK_NOCOPY;
else if (passno == 2 && ((ufs1_daddr_t *)(ibp->b_data))
[indiroff] == BLK_NOCOPY)
((ufs1_daddr_t *)(ibp->b_data))[indiroff] = 0;
else if (passno == 1 && ((ufs1_daddr_t *)(ibp->b_data))
[indiroff] == BLK_NOCOPY)
panic("ffs_snapshot: lost indirect block");
continue;
}
if (ffs_isblock(fs, cg_blksfree(cgp), loc))
((ufs2_daddr_t *)(ibp->b_data))[indiroff] = BLK_NOCOPY;
else if (passno == 2 &&
((ufs2_daddr_t *)(ibp->b_data)) [indiroff] == BLK_NOCOPY)
((ufs2_daddr_t *)(ibp->b_data))[indiroff] = 0;
else if (passno == 1 &&
((ufs2_daddr_t *)(ibp->b_data)) [indiroff] == BLK_NOCOPY)
panic("ffs_snapshot: lost indirect block");
}
bqrelse(bp);
if (passno == 2)
ibp->b_flags |= B_VALIDSUSPWRT;
bdwrite(ibp);
return (0);
}
/*
* Before expunging a snapshot inode, note all the
* blocks that it claims with BLK_SNAP so that fsck will
* be able to account for those blocks properly and so
* that this snapshot knows that it need not copy them
* if the other snapshot holding them is freed. This code
* is reproduced once each for UFS1 and UFS2.
*/
static int
expunge_ufs1(snapvp, cancelip, fs, acctfunc, expungetype)
struct vnode *snapvp;
struct inode *cancelip;
struct fs *fs;
int (*acctfunc)(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *,
struct fs *, ufs_lbn_t, int);
int expungetype;
{
int i, error, indiroff;
ufs_lbn_t lbn, rlbn;
ufs2_daddr_t len, blkno, numblks, blksperindir;
struct ufs1_dinode *dip;
struct thread *td = curthread;
struct buf *bp;
/*
* Prepare to expunge the inode. If its inode block has not
* yet been copied, then allocate and fill the copy.
*/
lbn = fragstoblks(fs, ino_to_fsba(fs, cancelip->i_number));
blkno = 0;
if (lbn < NDADDR) {
blkno = VTOI(snapvp)->i_din1->di_db[lbn];
} else {
td->td_pflags |= TDP_COWINPROGRESS;
error = ffs_balloc_ufs1(snapvp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, BA_METAONLY, &bp);
td->td_pflags &= ~TDP_COWINPROGRESS;
if (error)
return (error);
indiroff = (lbn - NDADDR) % NINDIR(fs);
blkno = ((ufs1_daddr_t *)(bp->b_data))[indiroff];
bqrelse(bp);
}
if (blkno != 0) {
if ((error = bread(snapvp, lbn, fs->fs_bsize, KERNCRED, &bp)))
return (error);
} else {
error = ffs_balloc_ufs1(snapvp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, 0, &bp);
if (error)
return (error);
if ((error = readblock(snapvp, bp, lbn)) != 0)
return (error);
}
/*
* Set a snapshot inode to be a zero length file, regular files
* to be completely unallocated.
*/
dip = (struct ufs1_dinode *)bp->b_data +
ino_to_fsbo(fs, cancelip->i_number);
if (expungetype == BLK_NOCOPY)
dip->di_mode = 0;
dip->di_size = 0;
dip->di_blocks = 0;
dip->di_flags &= ~SF_SNAPSHOT;
bzero(&dip->di_db[0], (NDADDR + NIADDR) * sizeof(ufs1_daddr_t));
bdwrite(bp);
/*
* Now go through and expunge all the blocks in the file
* using the function requested.
*/
numblks = howmany(cancelip->i_size, fs->fs_bsize);
if ((error = (*acctfunc)(snapvp, &cancelip->i_din1->di_db[0],
&cancelip->i_din1->di_db[NDADDR], fs, 0, expungetype)))
return (error);
if ((error = (*acctfunc)(snapvp, &cancelip->i_din1->di_ib[0],
&cancelip->i_din1->di_ib[NIADDR], fs, -1, expungetype)))
return (error);
blksperindir = 1;
lbn = -NDADDR;
len = numblks - NDADDR;
rlbn = NDADDR;
for (i = 0; len > 0 && i < NIADDR; i++) {
error = indiracct_ufs1(snapvp, ITOV(cancelip), i,
cancelip->i_din1->di_ib[i], lbn, rlbn, len,
blksperindir, fs, acctfunc, expungetype);
if (error)
return (error);
blksperindir *= NINDIR(fs);
lbn -= blksperindir + 1;
len -= blksperindir;
rlbn += blksperindir;
}
return (0);
}
/*
* Descend an indirect block chain for vnode cancelvp accounting for all
* its indirect blocks in snapvp.
*/
static int
indiracct_ufs1(snapvp, cancelvp, level, blkno, lbn, rlbn, remblks,
blksperindir, fs, acctfunc, expungetype)
struct vnode *snapvp;
struct vnode *cancelvp;
int level;
ufs1_daddr_t blkno;
ufs_lbn_t lbn;
ufs_lbn_t rlbn;
ufs_lbn_t remblks;
ufs_lbn_t blksperindir;
struct fs *fs;
int (*acctfunc)(struct vnode *, ufs1_daddr_t *, ufs1_daddr_t *,
struct fs *, ufs_lbn_t, int);
int expungetype;
{
int error, num, i;
ufs_lbn_t subblksperindir;
struct indir indirs[NIADDR + 2];
ufs1_daddr_t last, *bap;
struct buf *bp;
if (blkno == 0) {
if (expungetype == BLK_NOCOPY)
return (0);
panic("indiracct_ufs1: missing indir");
}
if ((error = ufs_getlbns(cancelvp, rlbn, indirs, &num)) != 0)
return (error);
if (lbn != indirs[num - 1 - level].in_lbn || num < 2)
panic("indiracct_ufs1: botched params");
/*
* We have to expand bread here since it will deadlock looking
* up the block number for any blocks that are not in the cache.
*/
bp = getblk(cancelvp, lbn, fs->fs_bsize, 0, 0, 0);
bp->b_blkno = fsbtodb(fs, blkno);
if ((bp->b_flags & (B_DONE | B_DELWRI)) == 0 &&
(error = readblock(cancelvp, bp, fragstoblks(fs, blkno)))) {
brelse(bp);
return (error);
}
/*
* Account for the block pointers in this indirect block.
*/
last = howmany(remblks, blksperindir);
if (last > NINDIR(fs))
last = NINDIR(fs);
MALLOC(bap, ufs1_daddr_t *, fs->fs_bsize, M_DEVBUF, M_WAITOK);
bcopy(bp->b_data, (caddr_t)bap, fs->fs_bsize);
bqrelse(bp);
error = (*acctfunc)(snapvp, &bap[0], &bap[last], fs,
level == 0 ? rlbn : -1, expungetype);
if (error || level == 0)
goto out;
/*
* Account for the block pointers in each of the indirect blocks
* in the levels below us.
*/
subblksperindir = blksperindir / NINDIR(fs);
for (lbn++, level--, i = 0; i < last; i++) {
error = indiracct_ufs1(snapvp, cancelvp, level, bap[i], lbn,
rlbn, remblks, subblksperindir, fs, acctfunc, expungetype);
if (error)
goto out;
rlbn += blksperindir;
lbn -= blksperindir;
remblks -= blksperindir;
}
out:
FREE(bap, M_DEVBUF);
return (error);
}
/*
* Do both snap accounting and map accounting.
*/
static int
fullacct_ufs1(vp, oldblkp, lastblkp, fs, lblkno, exptype)
struct vnode *vp;
ufs1_daddr_t *oldblkp, *lastblkp;
struct fs *fs;
ufs_lbn_t lblkno;
int exptype; /* BLK_SNAP or BLK_NOCOPY */
{
int error;
if ((error = snapacct_ufs1(vp, oldblkp, lastblkp, fs, lblkno, exptype)))
return (error);
return (mapacct_ufs1(vp, oldblkp, lastblkp, fs, lblkno, exptype));
}
/*
* Identify a set of blocks allocated in a snapshot inode.
*/
static int
snapacct_ufs1(vp, oldblkp, lastblkp, fs, lblkno, expungetype)
struct vnode *vp;
ufs1_daddr_t *oldblkp, *lastblkp;
struct fs *fs;
ufs_lbn_t lblkno;
int expungetype; /* BLK_SNAP or BLK_NOCOPY */
{
struct inode *ip = VTOI(vp);
ufs1_daddr_t blkno, *blkp;
ufs_lbn_t lbn;
struct buf *ibp;
int error;
for ( ; oldblkp < lastblkp; oldblkp++) {
blkno = *oldblkp;
if (blkno == 0 || blkno == BLK_NOCOPY || blkno == BLK_SNAP)
continue;
lbn = fragstoblks(fs, blkno);
if (lbn < NDADDR) {
blkp = &ip->i_din1->di_db[lbn];
ip->i_flag |= IN_CHANGE | IN_UPDATE;
} else {
error = ffs_balloc_ufs1(vp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
if (error)
return (error);
blkp = &((ufs1_daddr_t *)(ibp->b_data))
[(lbn - NDADDR) % NINDIR(fs)];
}
/*
* If we are expunging a snapshot vnode and we
* find a block marked BLK_NOCOPY, then it is
* one that has been allocated to this snapshot after
* we took our current snapshot and can be ignored.
*/
if (expungetype == BLK_SNAP && *blkp == BLK_NOCOPY) {
if (lbn >= NDADDR)
brelse(ibp);
} else {
if (*blkp != 0)
panic("snapacct_ufs1: bad block");
*blkp = expungetype;
if (lbn >= NDADDR)
bdwrite(ibp);
}
}
return (0);
}
/*
* Account for a set of blocks allocated in a snapshot inode.
*/
static int
mapacct_ufs1(vp, oldblkp, lastblkp, fs, lblkno, expungetype)
struct vnode *vp;
ufs1_daddr_t *oldblkp, *lastblkp;
struct fs *fs;
ufs_lbn_t lblkno;
int expungetype;
{
ufs1_daddr_t blkno;
struct inode *ip;
ino_t inum;
int acctit;
ip = VTOI(vp);
inum = ip->i_number;
if (lblkno == -1)
acctit = 0;
else
acctit = 1;
for ( ; oldblkp < lastblkp; oldblkp++, lblkno++) {
blkno = *oldblkp;
if (blkno == 0 || blkno == BLK_NOCOPY)
continue;
if (acctit && expungetype == BLK_SNAP && blkno != BLK_SNAP)
*ip->i_snapblklist++ = lblkno;
if (blkno == BLK_SNAP)
blkno = blkstofrags(fs, lblkno);
ffs_blkfree(ip->i_ump, fs, vp, blkno, fs->fs_bsize, inum);
}
return (0);
}
/*
* Before expunging a snapshot inode, note all the
* blocks that it claims with BLK_SNAP so that fsck will
* be able to account for those blocks properly and so
* that this snapshot knows that it need not copy them
* if the other snapshot holding them is freed. This code
* is reproduced once each for UFS1 and UFS2.
*/
static int
expunge_ufs2(snapvp, cancelip, fs, acctfunc, expungetype)
struct vnode *snapvp;
struct inode *cancelip;
struct fs *fs;
int (*acctfunc)(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
struct fs *, ufs_lbn_t, int);
int expungetype;
{
int i, error, indiroff;
ufs_lbn_t lbn, rlbn;
ufs2_daddr_t len, blkno, numblks, blksperindir;
struct ufs2_dinode *dip;
struct thread *td = curthread;
struct buf *bp;
/*
* Prepare to expunge the inode. If its inode block has not
* yet been copied, then allocate and fill the copy.
*/
lbn = fragstoblks(fs, ino_to_fsba(fs, cancelip->i_number));
blkno = 0;
if (lbn < NDADDR) {
blkno = VTOI(snapvp)->i_din2->di_db[lbn];
} else {
td->td_pflags |= TDP_COWINPROGRESS;
error = ffs_balloc_ufs2(snapvp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, BA_METAONLY, &bp);
td->td_pflags &= ~TDP_COWINPROGRESS;
if (error)
return (error);
indiroff = (lbn - NDADDR) % NINDIR(fs);
blkno = ((ufs2_daddr_t *)(bp->b_data))[indiroff];
bqrelse(bp);
}
if (blkno != 0) {
if ((error = bread(snapvp, lbn, fs->fs_bsize, KERNCRED, &bp)))
return (error);
} else {
error = ffs_balloc_ufs2(snapvp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, 0, &bp);
if (error)
return (error);
if ((error = readblock(snapvp, bp, lbn)) != 0)
return (error);
}
/*
* Set a snapshot inode to be a zero length file, regular files
* to be completely unallocated.
*/
dip = (struct ufs2_dinode *)bp->b_data +
ino_to_fsbo(fs, cancelip->i_number);
if (expungetype == BLK_NOCOPY)
dip->di_mode = 0;
dip->di_size = 0;
dip->di_blocks = 0;
dip->di_flags &= ~SF_SNAPSHOT;
bzero(&dip->di_db[0], (NDADDR + NIADDR) * sizeof(ufs2_daddr_t));
bdwrite(bp);
/*
* Now go through and expunge all the blocks in the file
* using the function requested.
*/
numblks = howmany(cancelip->i_size, fs->fs_bsize);
if ((error = (*acctfunc)(snapvp, &cancelip->i_din2->di_db[0],
&cancelip->i_din2->di_db[NDADDR], fs, 0, expungetype)))
return (error);
if ((error = (*acctfunc)(snapvp, &cancelip->i_din2->di_ib[0],
&cancelip->i_din2->di_ib[NIADDR], fs, -1, expungetype)))
return (error);
blksperindir = 1;
lbn = -NDADDR;
len = numblks - NDADDR;
rlbn = NDADDR;
for (i = 0; len > 0 && i < NIADDR; i++) {
error = indiracct_ufs2(snapvp, ITOV(cancelip), i,
cancelip->i_din2->di_ib[i], lbn, rlbn, len,
blksperindir, fs, acctfunc, expungetype);
if (error)
return (error);
blksperindir *= NINDIR(fs);
lbn -= blksperindir + 1;
len -= blksperindir;
rlbn += blksperindir;
}
return (0);
}
/*
* Descend an indirect block chain for vnode cancelvp accounting for all
* its indirect blocks in snapvp.
*/
static int
indiracct_ufs2(snapvp, cancelvp, level, blkno, lbn, rlbn, remblks,
blksperindir, fs, acctfunc, expungetype)
struct vnode *snapvp;
struct vnode *cancelvp;
int level;
ufs2_daddr_t blkno;
ufs_lbn_t lbn;
ufs_lbn_t rlbn;
ufs_lbn_t remblks;
ufs_lbn_t blksperindir;
struct fs *fs;
int (*acctfunc)(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
struct fs *, ufs_lbn_t, int);
int expungetype;
{
int error, num, i;
ufs_lbn_t subblksperindir;
struct indir indirs[NIADDR + 2];
ufs2_daddr_t last, *bap;
struct buf *bp;
if (blkno == 0) {
if (expungetype == BLK_NOCOPY)
return (0);
panic("indiracct_ufs2: missing indir");
}
if ((error = ufs_getlbns(cancelvp, rlbn, indirs, &num)) != 0)
return (error);
if (lbn != indirs[num - 1 - level].in_lbn || num < 2)
panic("indiracct_ufs2: botched params");
/*
* We have to expand bread here since it will deadlock looking
* up the block number for any blocks that are not in the cache.
*/
bp = getblk(cancelvp, lbn, fs->fs_bsize, 0, 0, 0);
bp->b_blkno = fsbtodb(fs, blkno);
if ((bp->b_flags & (B_DONE | B_DELWRI)) == 0 &&
(error = readblock(cancelvp, bp, fragstoblks(fs, blkno)))) {
brelse(bp);
return (error);
}
/*
* Account for the block pointers in this indirect block.
*/
last = howmany(remblks, blksperindir);
if (last > NINDIR(fs))
last = NINDIR(fs);
MALLOC(bap, ufs2_daddr_t *, fs->fs_bsize, M_DEVBUF, M_WAITOK);
bcopy(bp->b_data, (caddr_t)bap, fs->fs_bsize);
bqrelse(bp);
error = (*acctfunc)(snapvp, &bap[0], &bap[last], fs,
level == 0 ? rlbn : -1, expungetype);
if (error || level == 0)
goto out;
/*
* Account for the block pointers in each of the indirect blocks
* in the levels below us.
*/
subblksperindir = blksperindir / NINDIR(fs);
for (lbn++, level--, i = 0; i < last; i++) {
error = indiracct_ufs2(snapvp, cancelvp, level, bap[i], lbn,
rlbn, remblks, subblksperindir, fs, acctfunc, expungetype);
if (error)
goto out;
rlbn += blksperindir;
lbn -= blksperindir;
remblks -= blksperindir;
}
out:
FREE(bap, M_DEVBUF);
return (error);
}
/*
* Do both snap accounting and map accounting.
*/
static int
fullacct_ufs2(vp, oldblkp, lastblkp, fs, lblkno, exptype)
struct vnode *vp;
ufs2_daddr_t *oldblkp, *lastblkp;
struct fs *fs;
ufs_lbn_t lblkno;
int exptype; /* BLK_SNAP or BLK_NOCOPY */
{
int error;
if ((error = snapacct_ufs2(vp, oldblkp, lastblkp, fs, lblkno, exptype)))
return (error);
return (mapacct_ufs2(vp, oldblkp, lastblkp, fs, lblkno, exptype));
}
/*
* Identify a set of blocks allocated in a snapshot inode.
*/
static int
snapacct_ufs2(vp, oldblkp, lastblkp, fs, lblkno, expungetype)
struct vnode *vp;
ufs2_daddr_t *oldblkp, *lastblkp;
struct fs *fs;
ufs_lbn_t lblkno;
int expungetype; /* BLK_SNAP or BLK_NOCOPY */
{
struct inode *ip = VTOI(vp);
ufs2_daddr_t blkno, *blkp;
ufs_lbn_t lbn;
struct buf *ibp;
int error;
for ( ; oldblkp < lastblkp; oldblkp++) {
blkno = *oldblkp;
if (blkno == 0 || blkno == BLK_NOCOPY || blkno == BLK_SNAP)
continue;
lbn = fragstoblks(fs, blkno);
if (lbn < NDADDR) {
blkp = &ip->i_din2->di_db[lbn];
ip->i_flag |= IN_CHANGE | IN_UPDATE;
} else {
error = ffs_balloc_ufs2(vp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
if (error)
return (error);
blkp = &((ufs2_daddr_t *)(ibp->b_data))
[(lbn - NDADDR) % NINDIR(fs)];
}
/*
* If we are expunging a snapshot vnode and we
* find a block marked BLK_NOCOPY, then it is
* one that has been allocated to this snapshot after
* we took our current snapshot and can be ignored.
*/
if (expungetype == BLK_SNAP && *blkp == BLK_NOCOPY) {
if (lbn >= NDADDR)
brelse(ibp);
} else {
if (*blkp != 0)
panic("snapacct_ufs2: bad block");
*blkp = expungetype;
if (lbn >= NDADDR)
bdwrite(ibp);
}
}
return (0);
}
/*
* Account for a set of blocks allocated in a snapshot inode.
*/
static int
mapacct_ufs2(vp, oldblkp, lastblkp, fs, lblkno, expungetype)
struct vnode *vp;
ufs2_daddr_t *oldblkp, *lastblkp;
struct fs *fs;
ufs_lbn_t lblkno;
int expungetype;
{
ufs2_daddr_t blkno;
struct inode *ip;
ino_t inum;
int acctit;
ip = VTOI(vp);
inum = ip->i_number;
if (lblkno == -1)
acctit = 0;
else
acctit = 1;
for ( ; oldblkp < lastblkp; oldblkp++, lblkno++) {
blkno = *oldblkp;
if (blkno == 0 || blkno == BLK_NOCOPY)
continue;
if (acctit && expungetype == BLK_SNAP && blkno != BLK_SNAP)
*ip->i_snapblklist++ = lblkno;
if (blkno == BLK_SNAP)
blkno = blkstofrags(fs, lblkno);
ffs_blkfree(ip->i_ump, fs, vp, blkno, fs->fs_bsize, inum);
}
return (0);
}
/*
* Decrement extra reference on snapshot when last name is removed.
* It will not be freed until the last open reference goes away.
*/
void
ffs_snapgone(ip)
struct inode *ip;
{
struct inode *xp;
struct fs *fs;
int snaploc;
struct snapdata *sn;
struct ufsmount *ump;
/*
* Find snapshot in incore list.
*/
xp = NULL;
sn = ip->i_devvp->v_rdev->si_snapdata;
if (sn != NULL)
TAILQ_FOREACH(xp, &sn->sn_head, i_nextsnap)
if (xp == ip)
break;
if (xp != NULL)
vrele(ITOV(ip));
else if (snapdebug)
printf("ffs_snapgone: lost snapshot vnode %d\n",
ip->i_number);
/*
* Delete snapshot inode from superblock. Keep list dense.
*/
fs = ip->i_fs;
ump = ip->i_ump;
UFS_LOCK(ump);
for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++)
if (fs->fs_snapinum[snaploc] == ip->i_number)
break;
if (snaploc < FSMAXSNAP) {
for (snaploc++; snaploc < FSMAXSNAP; snaploc++) {
if (fs->fs_snapinum[snaploc] == 0)
break;
fs->fs_snapinum[snaploc - 1] = fs->fs_snapinum[snaploc];
}
fs->fs_snapinum[snaploc - 1] = 0;
}
UFS_UNLOCK(ump);
}
/*
* Prepare a snapshot file for being removed.
*/
void
ffs_snapremove(vp)
struct vnode *vp;
{
struct inode *ip;
struct vnode *devvp;
struct lock *lkp;
struct buf *ibp;
struct fs *fs;
struct thread *td = curthread;
ufs2_daddr_t numblks, blkno, dblk, *snapblklist;
int error, loc, last;
struct snapdata *sn;
ip = VTOI(vp);
fs = ip->i_fs;
devvp = ip->i_devvp;
sn = devvp->v_rdev->si_snapdata;
/*
* If active, delete from incore list (this snapshot may
* already have been in the process of being deleted, so
* would not have been active).
*
* Clear copy-on-write flag if last snapshot.
*/
if (ip->i_nextsnap.tqe_prev != 0) {
VI_LOCK(devvp);
lockmgr(&vp->v_lock, LK_INTERLOCK | LK_EXCLUSIVE,
VI_MTX(devvp), td);
VI_LOCK(devvp);
TAILQ_REMOVE(&sn->sn_head, ip, i_nextsnap);
ip->i_nextsnap.tqe_prev = 0;
lkp = vp->v_vnlock;
vp->v_vnlock = &vp->v_lock;
lockmgr(lkp, LK_RELEASE, NULL, td);
if (TAILQ_FIRST(&sn->sn_head) != 0) {
VI_UNLOCK(devvp);
} else {
snapblklist = sn->sn_blklist;
sn->sn_blklist = 0;
sn->sn_listsize = 0;
devvp->v_rdev->si_snapdata = NULL;
devvp->v_vflag &= ~VV_COPYONWRITE;
lockmgr(lkp, LK_DRAIN|LK_INTERLOCK, VI_MTX(devvp), td);
lockmgr(lkp, LK_RELEASE, NULL, td);
lockdestroy(lkp);
free(sn, M_UFSMNT);
FREE(snapblklist, M_UFSMNT);
}
}
/*
* Clear all BLK_NOCOPY fields. Pass any block claims to other
* snapshots that want them (see ffs_snapblkfree below).
*/
for (blkno = 1; blkno < NDADDR; blkno++) {
dblk = DIP(ip, i_db[blkno]);
if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
DIP_SET(ip, i_db[blkno], 0);
else if ((dblk == blkstofrags(fs, blkno) &&
ffs_snapblkfree(fs, ip->i_devvp, dblk, fs->fs_bsize,
ip->i_number))) {
DIP_SET(ip, i_blocks, DIP(ip, i_blocks) -
btodb(fs->fs_bsize));
DIP_SET(ip, i_db[blkno], 0);
}
}
numblks = howmany(ip->i_size, fs->fs_bsize);
for (blkno = NDADDR; blkno < numblks; blkno += NINDIR(fs)) {
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)blkno),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
if (error)
continue;
if (fs->fs_size - blkno > NINDIR(fs))
last = NINDIR(fs);
else
last = fs->fs_size - blkno;
for (loc = 0; loc < last; loc++) {
if (ip->i_ump->um_fstype == UFS1) {
dblk = ((ufs1_daddr_t *)(ibp->b_data))[loc];
if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
((ufs1_daddr_t *)(ibp->b_data))[loc]= 0;
else if ((dblk == blkstofrags(fs, blkno) &&
ffs_snapblkfree(fs, ip->i_devvp, dblk,
fs->fs_bsize, ip->i_number))) {
ip->i_din1->di_blocks -=
btodb(fs->fs_bsize);
((ufs1_daddr_t *)(ibp->b_data))[loc]= 0;
}
continue;
}
dblk = ((ufs2_daddr_t *)(ibp->b_data))[loc];
if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
((ufs2_daddr_t *)(ibp->b_data))[loc] = 0;
else if ((dblk == blkstofrags(fs, blkno) &&
ffs_snapblkfree(fs, ip->i_devvp, dblk,
fs->fs_bsize, ip->i_number))) {
ip->i_din2->di_blocks -= btodb(fs->fs_bsize);
((ufs2_daddr_t *)(ibp->b_data))[loc] = 0;
}
}
bawrite(ibp);
}
/*
* Clear snapshot flag and drop reference.
*/
ip->i_flags &= ~SF_SNAPSHOT;
DIP_SET(ip, i_flags, ip->i_flags);
ip->i_flag |= IN_CHANGE | IN_UPDATE;
}
/*
* Notification that a block is being freed. Return zero if the free
* should be allowed to proceed. Return non-zero if the snapshot file
* wants to claim the block. The block will be claimed if it is an
* uncopied part of one of the snapshots. It will be freed if it is
* either a BLK_NOCOPY or has already been copied in all of the snapshots.
* If a fragment is being freed, then all snapshots that care about
* it must make a copy since a snapshot file can only claim full sized
* blocks. Note that if more than one snapshot file maps the block,
* we can pick one at random to claim it. Since none of the snapshots
* can change, we are assurred that they will all see the same unmodified
* image. When deleting a snapshot file (see ffs_snapremove above), we
* must push any of these claimed blocks to one of the other snapshots
* that maps it. These claimed blocks are easily identified as they will
* have a block number equal to their logical block number within the
* snapshot. A copied block can never have this property because they
* must always have been allocated from a BLK_NOCOPY location.
*/
int
ffs_snapblkfree(fs, devvp, bno, size, inum)
struct fs *fs;
struct vnode *devvp;
ufs2_daddr_t bno;
long size;
ino_t inum;
{
struct buf *ibp, *cbp, *savedcbp = 0;
struct thread *td = curthread;
struct inode *ip;
struct vnode *vp = NULL;
ufs_lbn_t lbn;
ufs2_daddr_t blkno;
int indiroff = 0, snapshot_locked = 0, error = 0, claimedblk = 0;
struct snapdata *sn;
lbn = fragstoblks(fs, bno);
retry:
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
if (sn == NULL) {
VI_UNLOCK(devvp);
return (0);
}
TAILQ_FOREACH(ip, &sn->sn_head, i_nextsnap) {
vp = ITOV(ip);
/*
* Lookup block being written.
*/
if (lbn < NDADDR) {
blkno = DIP(ip, i_db[lbn]);
} else {
if (snapshot_locked == 0 &&
lockmgr(vp->v_vnlock,
LK_INTERLOCK | LK_EXCLUSIVE | LK_SLEEPFAIL,
VI_MTX(devvp), td) != 0)
goto retry;
snapshot_locked = 1;
td->td_pflags |= TDP_COWINPROGRESS;
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
td->td_pflags &= ~TDP_COWINPROGRESS;
if (error)
break;
indiroff = (lbn - NDADDR) % NINDIR(fs);
if (ip->i_ump->um_fstype == UFS1)
blkno=((ufs1_daddr_t *)(ibp->b_data))[indiroff];
else
blkno=((ufs2_daddr_t *)(ibp->b_data))[indiroff];
}
/*
* Check to see if block needs to be copied.
*/
if (blkno == 0) {
/*
* A block that we map is being freed. If it has not
* been claimed yet, we will claim or copy it (below).
*/
claimedblk = 1;
} else if (blkno == BLK_SNAP) {
/*
* No previous snapshot claimed the block,
* so it will be freed and become a BLK_NOCOPY
* (don't care) for us.
*/
if (claimedblk)
panic("snapblkfree: inconsistent block type");
if (snapshot_locked == 0 &&
lockmgr(vp->v_vnlock,
LK_INTERLOCK | LK_EXCLUSIVE | LK_NOWAIT,
VI_MTX(devvp), td) != 0) {
if (lbn >= NDADDR)
bqrelse(ibp);
vn_lock(vp, LK_EXCLUSIVE | LK_SLEEPFAIL, td);
goto retry;
}
snapshot_locked = 1;
if (lbn < NDADDR) {
DIP_SET(ip, i_db[lbn], BLK_NOCOPY);
ip->i_flag |= IN_CHANGE | IN_UPDATE;
} else if (ip->i_ump->um_fstype == UFS1) {
((ufs1_daddr_t *)(ibp->b_data))[indiroff] =
BLK_NOCOPY;
bdwrite(ibp);
} else {
((ufs2_daddr_t *)(ibp->b_data))[indiroff] =
BLK_NOCOPY;
bdwrite(ibp);
}
continue;
} else /* BLK_NOCOPY or default */ {
/*
* If the snapshot has already copied the block
* (default), or does not care about the block,
* it is not needed.
*/
if (lbn >= NDADDR)
bqrelse(ibp);
continue;
}
/*
* If this is a full size block, we will just grab it
* and assign it to the snapshot inode. Otherwise we
* will proceed to copy it. See explanation for this
* routine as to why only a single snapshot needs to
* claim this block.
*/
if (snapshot_locked == 0 &&
lockmgr(vp->v_vnlock,
LK_INTERLOCK | LK_EXCLUSIVE | LK_NOWAIT,
VI_MTX(devvp), td) != 0) {
if (lbn >= NDADDR)
bqrelse(ibp);
vn_lock(vp, LK_EXCLUSIVE | LK_SLEEPFAIL, td);
goto retry;
}
snapshot_locked = 1;
if (size == fs->fs_bsize) {
#ifdef DEBUG
if (snapdebug)
printf("%s %d lbn %jd from inum %d\n",
"Grabonremove: snapino", ip->i_number,
(intmax_t)lbn, inum);
#endif
if (lbn < NDADDR) {
DIP_SET(ip, i_db[lbn], bno);
} else if (ip->i_ump->um_fstype == UFS1) {
((ufs1_daddr_t *)(ibp->b_data))[indiroff] = bno;
bdwrite(ibp);
} else {
((ufs2_daddr_t *)(ibp->b_data))[indiroff] = bno;
bdwrite(ibp);
}
DIP_SET(ip, i_blocks, DIP(ip, i_blocks) + btodb(size));
ip->i_flag |= IN_CHANGE | IN_UPDATE;
VOP_UNLOCK(vp, 0, td);
return (1);
}
if (lbn >= NDADDR)
bqrelse(ibp);
/*
* Allocate the block into which to do the copy. Note that this
* allocation will never require any additional allocations for
* the snapshot inode.
*/
td->td_pflags |= TDP_COWINPROGRESS;
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, 0, &cbp);
td->td_pflags &= ~TDP_COWINPROGRESS;
if (error)
break;
#ifdef DEBUG
if (snapdebug)
printf("%s%d lbn %jd %s %d size %ld to blkno %jd\n",
"Copyonremove: snapino ", ip->i_number,
(intmax_t)lbn, "for inum", inum, size,
(intmax_t)cbp->b_blkno);
#endif
/*
* If we have already read the old block contents, then
* simply copy them to the new block. Note that we need
* to synchronously write snapshots that have not been
* unlinked, and hence will be visible after a crash,
* to ensure their integrity.
*/
if (savedcbp != 0) {
bcopy(savedcbp->b_data, cbp->b_data, fs->fs_bsize);
bawrite(cbp);
if (dopersistence && ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT);
continue;
}
/*
* Otherwise, read the old block contents into the buffer.
*/
if ((error = readblock(vp, cbp, lbn)) != 0) {
bzero(cbp->b_data, fs->fs_bsize);
bawrite(cbp);
if (dopersistence && ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT);
break;
}
savedcbp = cbp;
}
/*
* Note that we need to synchronously write snapshots that
* have not been unlinked, and hence will be visible after
* a crash, to ensure their integrity.
*/
if (savedcbp) {
vp = savedcbp->b_vp;
bawrite(savedcbp);
if (dopersistence && VTOI(vp)->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT);
}
/*
* If we have been unable to allocate a block in which to do
* the copy, then return non-zero so that the fragment will
* not be freed. Although space will be lost, the snapshot
* will stay consistent.
*/
if (snapshot_locked)
VOP_UNLOCK(vp, 0, td);
else
VI_UNLOCK(devvp);
return (error);
}
/*
* Associate snapshot files when mounting.
*/
void
ffs_snapshot_mount(mp)
struct mount *mp;
{
struct ufsmount *ump = VFSTOUFS(mp);
struct vnode *devvp = ump->um_devvp;
struct fs *fs = ump->um_fs;
struct thread *td = curthread;
struct snapdata *sn;
struct vnode *vp;
struct inode *ip;
struct uio auio;
struct iovec aiov;
void *snapblklist;
char *reason;
daddr_t snaplistsize;
int error, snaploc, loc;
/*
* XXX The following needs to be set before ffs_truncate or
* VOP_READ can be called.
*/
mp->mnt_stat.f_iosize = fs->fs_bsize;
/*
* Process each snapshot listed in the superblock.
*/
vp = NULL;
sn = devvp->v_rdev->si_snapdata;
for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++) {
if (fs->fs_snapinum[snaploc] == 0)
break;
if ((error = ffs_vget(mp, fs->fs_snapinum[snaploc],
LK_EXCLUSIVE, &vp)) != 0){
printf("ffs_snapshot_mount: vget failed %d\n", error);
continue;
}
ip = VTOI(vp);
if ((ip->i_flags & SF_SNAPSHOT) == 0 || ip->i_size ==
lblktosize(fs, howmany(fs->fs_size, fs->fs_frag))) {
if ((ip->i_flags & SF_SNAPSHOT) == 0) {
reason = "non-snapshot";
} else {
reason = "old format snapshot";
(void)ffs_truncate(vp, (off_t)0, 0, NOCRED, td);
(void)ffs_syncvnode(vp, MNT_WAIT);
}
printf("ffs_snapshot_mount: %s inode %d\n",
reason, fs->fs_snapinum[snaploc]);
vput(vp);
vp = NULL;
for (loc = snaploc + 1; loc < FSMAXSNAP; loc++) {
if (fs->fs_snapinum[loc] == 0)
break;
fs->fs_snapinum[loc - 1] = fs->fs_snapinum[loc];
}
fs->fs_snapinum[loc - 1] = 0;
snaploc--;
continue;
}
/*
* If there already exist snapshots on this filesystem, grab a
* reference to their shared lock. If this is the first snapshot
* on this filesystem, we need to allocate a lock for the
* snapshots to share. In either case, acquire the snapshot
* lock and give up our original private lock.
*/
VI_LOCK(devvp);
if (sn != NULL) {
VI_UNLOCK(devvp);
VI_LOCK(vp);
vp->v_vnlock = &sn->sn_lock;
} else {
VI_UNLOCK(devvp);
sn = malloc(sizeof *sn, M_UFSMNT, M_WAITOK | M_ZERO);
TAILQ_INIT(&sn->sn_head);
lockinit(&sn->sn_lock, PVFS, "snaplk", VLKTIMEOUT,
LK_CANRECURSE | LK_NOPAUSE);
VI_LOCK(vp);
vp->v_vnlock = &sn->sn_lock;
devvp->v_rdev->si_snapdata = sn;
}
vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE | LK_RETRY, td);
transferlockers(&vp->v_lock, vp->v_vnlock);
lockmgr(&vp->v_lock, LK_RELEASE, NULL, td);
/*
* Link it onto the active snapshot list.
*/
VI_LOCK(devvp);
if (ip->i_nextsnap.tqe_prev != 0)
panic("ffs_snapshot_mount: %d already on list",
ip->i_number);
else
TAILQ_INSERT_TAIL(&sn->sn_head, ip, i_nextsnap);
vp->v_vflag |= VV_SYSTEM;
VI_UNLOCK(devvp);
VOP_UNLOCK(vp, 0, td);
}
/*
* No usable snapshots found.
*/
if (vp == NULL)
return;
/*
* Allocate the space for the block hints list. We always want to
* use the list from the newest snapshot.
*/
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
aiov.iov_base = (void *)&snaplistsize;
aiov.iov_len = sizeof(snaplistsize);
auio.uio_resid = aiov.iov_len;
auio.uio_offset =
lblktosize(fs, howmany(fs->fs_size, fs->fs_frag));
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_rw = UIO_READ;
auio.uio_td = td;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if ((error = VOP_READ(vp, &auio, IO_UNIT, td->td_ucred)) != 0) {
printf("ffs_snapshot_mount: read_1 failed %d\n", error);
VOP_UNLOCK(vp, 0, td);
return;
}
MALLOC(snapblklist, void *, snaplistsize * sizeof(daddr_t),
M_UFSMNT, M_WAITOK);
auio.uio_iovcnt = 1;
aiov.iov_base = snapblklist;
aiov.iov_len = snaplistsize * sizeof (daddr_t);
auio.uio_resid = aiov.iov_len;
auio.uio_offset -= sizeof(snaplistsize);
if ((error = VOP_READ(vp, &auio, IO_UNIT, td->td_ucred)) != 0) {
printf("ffs_snapshot_mount: read_2 failed %d\n", error);
VOP_UNLOCK(vp, 0, td);
FREE(snapblklist, M_UFSMNT);
return;
}
VOP_UNLOCK(vp, 0, td);
VI_LOCK(devvp);
ASSERT_VOP_LOCKED(devvp, "ffs_snapshot_mount");
sn->sn_listsize = snaplistsize;
sn->sn_blklist = (daddr_t *)snapblklist;
devvp->v_vflag |= VV_COPYONWRITE;
VI_UNLOCK(devvp);
}
/*
* Disassociate snapshot files when unmounting.
*/
void
ffs_snapshot_unmount(mp)
struct mount *mp;
{
struct vnode *devvp = VFSTOUFS(mp)->um_devvp;
struct snapdata *sn;
struct inode *xp;
struct vnode *vp;
sn = devvp->v_rdev->si_snapdata;
VI_LOCK(devvp);
while ((xp = TAILQ_FIRST(&sn->sn_head)) != 0) {
vp = ITOV(xp);
vp->v_vnlock = &vp->v_lock;
TAILQ_REMOVE(&sn->sn_head, xp, i_nextsnap);
xp->i_nextsnap.tqe_prev = 0;
if (xp->i_effnlink > 0) {
VI_UNLOCK(devvp);
vrele(vp);
VI_LOCK(devvp);
}
}
if (sn->sn_blklist != NULL) {
FREE(sn->sn_blklist, M_UFSMNT);
sn->sn_blklist = NULL;
sn->sn_listsize = 0;
}
lockdestroy(&sn->sn_lock);
free(sn, M_UFSMNT);
ASSERT_VOP_LOCKED(devvp, "ffs_snapshot_unmount");
devvp->v_rdev->si_snapdata = NULL;
devvp->v_vflag &= ~VV_COPYONWRITE;
VI_UNLOCK(devvp);
}
/*
* Check for need to copy block that is about to be written,
* copying the block if necessary.
*/
int
ffs_copyonwrite(devvp, bp)
struct vnode *devvp;
struct buf *bp;
{
struct snapdata *sn;
struct buf *ibp, *cbp, *savedcbp = 0;
struct thread *td = curthread;
struct fs *fs;
struct inode *ip;
struct vnode *vp = 0;
ufs2_daddr_t lbn, blkno, *snapblklist;
int lower, upper, mid, indiroff, snapshot_locked = 0, error = 0;
if (td->td_pflags & TDP_COWINPROGRESS)
panic("ffs_copyonwrite: recursive call");
/*
* First check to see if it is in the preallocated list.
* By doing this check we avoid several potential deadlocks.
*/
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
ip = TAILQ_FIRST(&sn->sn_head);
fs = ip->i_fs;
lbn = fragstoblks(fs, dbtofsb(fs, bp->b_blkno));
snapblklist = sn->sn_blklist;
upper = sn->sn_listsize - 1;
lower = 1;
while (lower <= upper) {
mid = (lower + upper) / 2;
if (snapblklist[mid] == lbn)
break;
if (snapblklist[mid] < lbn)
lower = mid + 1;
else
upper = mid - 1;
}
if (lower <= upper) {
VI_UNLOCK(devvp);
return (0);
}
/*
* Not in the precomputed list, so check the snapshots.
*/
retry:
TAILQ_FOREACH(ip, &sn->sn_head, i_nextsnap) {
vp = ITOV(ip);
/*
* We ensure that everything of our own that needs to be
* copied will be done at the time that ffs_snapshot is
* called. Thus we can skip the check here which can
* deadlock in doing the lookup in UFS_BALLOC.
*/
if (bp->b_vp == vp)
continue;
/*
* Check to see if block needs to be copied. We do not have
* to hold the snapshot lock while doing this lookup as it
* will never require any additional allocations for the
* snapshot inode.
*/
if (lbn < NDADDR) {
blkno = DIP(ip, i_db[lbn]);
} else {
if (snapshot_locked == 0 &&
lockmgr(vp->v_vnlock,
LK_INTERLOCK | LK_EXCLUSIVE | LK_SLEEPFAIL,
VI_MTX(devvp), td) != 0) {
VI_LOCK(devvp);
goto retry;
}
snapshot_locked = 1;
td->td_pflags |= TDP_COWINPROGRESS;
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, BA_METAONLY, &ibp);
td->td_pflags &= ~TDP_COWINPROGRESS;
if (error)
break;
indiroff = (lbn - NDADDR) % NINDIR(fs);
if (ip->i_ump->um_fstype == UFS1)
blkno=((ufs1_daddr_t *)(ibp->b_data))[indiroff];
else
blkno=((ufs2_daddr_t *)(ibp->b_data))[indiroff];
bqrelse(ibp);
}
#ifdef DIAGNOSTIC
if (blkno == BLK_SNAP && bp->b_lblkno >= 0)
panic("ffs_copyonwrite: bad copy block");
#endif
if (blkno != 0)
continue;
/*
* Allocate the block into which to do the copy. Since
* multiple processes may all try to copy the same block,
* we have to recheck our need to do a copy if we sleep
* waiting for the lock.
*
* Because all snapshots on a filesystem share a single
* lock, we ensure that we will never be in competition
* with another process to allocate a block.
*/
if (snapshot_locked == 0 &&
lockmgr(vp->v_vnlock,
LK_INTERLOCK | LK_EXCLUSIVE | LK_SLEEPFAIL,
VI_MTX(devvp), td) != 0) {
VI_LOCK(devvp);
goto retry;
}
snapshot_locked = 1;
td->td_pflags |= TDP_COWINPROGRESS;
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)lbn),
fs->fs_bsize, KERNCRED, 0, &cbp);
td->td_pflags &= ~TDP_COWINPROGRESS;
if (error)
break;
#ifdef DEBUG
if (snapdebug) {
printf("Copyonwrite: snapino %d lbn %jd for ",
ip->i_number, (intmax_t)lbn);
if (bp->b_vp == devvp)
printf("fs metadata");
else
printf("inum %d", VTOI(bp->b_vp)->i_number);
printf(" lblkno %jd to blkno %jd\n",
(intmax_t)bp->b_lblkno, (intmax_t)cbp->b_blkno);
}
#endif
/*
* If we have already read the old block contents, then
* simply copy them to the new block. Note that we need
* to synchronously write snapshots that have not been
* unlinked, and hence will be visible after a crash,
* to ensure their integrity.
*/
if (savedcbp != 0) {
bcopy(savedcbp->b_data, cbp->b_data, fs->fs_bsize);
bawrite(cbp);
if (dopersistence && ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT);
continue;
}
/*
* Otherwise, read the old block contents into the buffer.
*/
if ((error = readblock(vp, cbp, lbn)) != 0) {
bzero(cbp->b_data, fs->fs_bsize);
bawrite(cbp);
if (dopersistence && ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT);
break;
}
savedcbp = cbp;
}
/*
* Note that we need to synchronously write snapshots that
* have not been unlinked, and hence will be visible after
* a crash, to ensure their integrity.
*/
if (savedcbp) {
vp = savedcbp->b_vp;
bawrite(savedcbp);
if (dopersistence && VTOI(vp)->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT);
}
if (snapshot_locked)
VOP_UNLOCK(vp, 0, td);
else
VI_UNLOCK(devvp);
return (error);
}
/*
* Read the specified block into the given buffer.
* Much of this boiler-plate comes from bwrite().
*/
static int
readblock(vp, bp, lbn)
struct vnode *vp;
struct buf *bp;
ufs2_daddr_t lbn;
{
struct inode *ip = VTOI(vp);
struct bio *bip;
bip = g_alloc_bio();
bip->bio_cmd = BIO_READ;
bip->bio_offset = dbtob(fsbtodb(ip->i_fs, blkstofrags(ip->i_fs, lbn)));
bip->bio_data = bp->b_data;
bip->bio_length = bp->b_bcount;
g_io_request(bip, ip->i_devvp->v_bufobj.bo_private);
do
msleep(bip, NULL, PRIBIO, "snaprdb", hz/10);
while (!(bip->bio_flags & BIO_DONE));
bp->b_error = bip->bio_error;
g_destroy_bio(bip);
return (bp->b_error);
}
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