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

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

Specifics of the changes:

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

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

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

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

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

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

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

Four utilities are affected:

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

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

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

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

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

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

2705 lines
74 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 "opt_quota.h"
#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/fcntl.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/rwlock.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
#include "opt_ffs.h"
#ifdef NO_FFS_SNAPSHOT
int
ffs_snapshot(mp, snapfile)
struct mount *mp;
char *snapfile;
{
return (EINVAL);
}
int
ffs_snapblkfree(fs, devvp, bno, size, inum, vtype, wkhd)
struct fs *fs;
struct vnode *devvp;
ufs2_daddr_t bno;
long size;
ino_t inum;
enum vtype vtype;
struct workhead *wkhd;
{
return (EINVAL);
}
void
ffs_snapremove(vp)
struct vnode *vp;
{
}
void
ffs_snapshot_mount(mp)
struct mount *mp;
{
}
void
ffs_snapshot_unmount(mp)
struct mount *mp;
{
}
void
ffs_snapgone(ip)
struct inode *ip;
{
}
int
ffs_copyonwrite(devvp, bp)
struct vnode *devvp;
struct buf *bp;
{
return (EINVAL);
}
void
ffs_sync_snap(mp, waitfor)
struct mount *mp;
int waitfor;
{
}
#else
FEATURE(ffs_snapshot, "FFS snapshot support");
LIST_HEAD(, snapdata) snapfree;
static struct mtx snapfree_lock;
MTX_SYSINIT(ffs_snapfree, &snapfree_lock, "snapdata free list", MTX_DEF);
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, 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, 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);
static void try_free_snapdata(struct vnode *devvp);
static struct snapdata *ffs_snapdata_acquire(struct vnode *devvp);
static int ffs_bp_snapblk(struct vnode *, struct buf *);
/*
* 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 code normally only ensures
* persistence for the filesystem metadata contained within a
* snapshot. Setting the following flag allows this crash
* persistence to be enabled for file contents.
*/
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;
ufs2_daddr_t blockno;
uint64_t 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;
struct nameidata nd;
struct mount *wrtmp;
struct vattr vat;
struct vnode *vp, *xvp, *mvp, *devvp;
struct uio auio;
struct iovec aiov;
struct snapdata *sn;
struct ufsmount *ump;
ump = VFSTOUFS(mp);
fs = ump->um_fs;
sn = NULL;
/*
* At the moment, journaled soft updates cannot support
* taking snapshots.
*/
if (MOUNTEDSUJ(mp)) {
vfs_mount_error(mp, "%s: Snapshots are not yet supported when "
"running with journaled soft updates", fs->fs_fsmnt);
return (EOPNOTSUPP);
}
MNT_ILOCK(mp);
flag = mp->mnt_flag;
MNT_IUNLOCK(mp);
/*
* 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 | NOCACHE, 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");
vfs_rel(wrtmp);
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;
}
error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vat);
VOP_UNLOCK(nd.ni_dvp, 0);
if (error) {
NDFREE(&nd, NDF_ONLY_PNBUF);
vn_finished_write(wrtmp);
vrele(nd.ni_dvp);
return (error);
}
vp = nd.ni_vp;
vp->v_vflag |= VV_SYSTEM;
ip = VTOI(vp);
devvp = ITODEVVP(ip);
/*
* 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;
error = readblock(vp, bp, numblks - 1);
bawrite(bp);
if (error != 0)
goto out;
/*
* 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 = UFS_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);
if (cg % 10 == 0)
ffs_syncvnode(vp, MNT_WAIT, 0);
}
/*
* 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);
space = malloc(len, M_DEVBUF, M_WAITOK|M_ZERO);
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 (cg % 10 == 0)
ffs_syncvnode(vp, MNT_WAIT, 0);
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)) != 0)
goto out;
VOP_UNLOCK(vp, 0);
/*
* 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) {
struct proc *p;
p = td->td_proc;
PROC_LOCK(p);
saved_nice = p->p_nice;
sched_nice(p, 0);
PROC_UNLOCK(p);
}
/*
* Suspend operation on filesystem.
*/
for (;;) {
vn_finished_write(wrtmp);
if ((error = vfs_write_suspend(vp->v_mount, 0)) != 0) {
vn_start_write(NULL, &wrtmp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
goto out;
}
if (mp->mnt_kern_flag & MNTK_SUSPENDED)
break;
vn_start_write(NULL, &wrtmp, V_WAIT);
}
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (ip->i_effnlink == 0) {
error = ENOENT; /* Snapshot file unlinked */
goto out1;
}
if (collectsnapstats)
nanotime(&starttime);
/* The last block might have changed. Copy it again to be sure. */
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)(numblks - 1)),
fs->fs_bsize, KERNCRED, BA_CLRBUF, &bp);
if (error != 0)
goto out1;
error = readblock(vp, bp, numblks - 1);
bp->b_flags |= B_VALIDSUSPWRT;
bawrite(bp);
if (error != 0)
goto out1;
/*
* 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.
*/
copy_fs = malloc((u_long)fs->fs_bsize, M_UFSMNT, M_WAITOK);
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(&((char *)copy_fs)[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);
free(copy_fs, M_UFSMNT);
copy_fs = 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;
MNT_IUNLOCK(mp);
loop:
MNT_VNODE_FOREACH_ALL(xvp, mp, mvp) {
if ((xvp->v_usecount == 0 &&
(xvp->v_iflag & (VI_OWEINACT | VI_DOINGINACT)) == 0) ||
xvp->v_type == VNON ||
IS_SNAPSHOT(VTOI(xvp))) {
VI_UNLOCK(xvp);
continue;
}
/*
* We can skip parent directory vnode because it must have
* this snapshot file in it.
*/
if (xvp == nd.ni_dvp) {
VI_UNLOCK(xvp);
continue;
}
vholdl(xvp);
if (vn_lock(xvp, LK_EXCLUSIVE | LK_INTERLOCK) != 0) {
MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
vdrop(xvp);
goto loop;
}
VI_LOCK(xvp);
if (xvp->v_usecount == 0 &&
(xvp->v_iflag & (VI_OWEINACT | VI_DOINGINACT)) == 0) {
VI_UNLOCK(xvp);
VOP_UNLOCK(xvp, 0);
vdrop(xvp);
continue;
}
VI_UNLOCK(xvp);
if (snapdebug)
vn_printf(xvp, "ffs_snapshot: busy vnode ");
if (VOP_GETATTR(xvp, &vat, td->td_ucred) == 0 &&
vat.va_nlink > 0) {
VOP_UNLOCK(xvp, 0);
vdrop(xvp);
continue;
}
xp = VTOI(xvp);
if (ffs_checkfreefile(copy_fs, vp, xp->i_number)) {
VOP_UNLOCK(xvp, 0);
vdrop(xvp);
continue;
}
/*
* If there is a fragment, clear it here.
*/
blkno = 0;
loc = howmany(xp->i_size, fs->fs_bsize) - 1;
if (loc < UFS_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,
xvp->v_type, NULL);
blkno = DIP(xp, i_db[loc]);
DIP_SET(xp, i_db[loc], 0);
}
}
snaplistsize += 1;
if (I_IS_UFS1(xp))
error = expunge_ufs1(vp, xp, copy_fs, fullacct_ufs1,
BLK_NOCOPY, 1);
else
error = expunge_ufs2(vp, xp, copy_fs, fullacct_ufs2,
BLK_NOCOPY, 1);
if (blkno)
DIP_SET(xp, i_db[loc], blkno);
if (!error)
error = ffs_freefile(ump, copy_fs, vp, xp->i_number,
xp->i_mode, NULL);
VOP_UNLOCK(xvp, 0);
vdrop(xvp);
if (error) {
free(copy_fs->fs_csp, M_UFSMNT);
free(copy_fs, M_UFSMNT);
copy_fs = NULL;
MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
goto out1;
}
}
/*
* Erase the journal file from the snapshot.
*/
if (fs->fs_flags & FS_SUJ) {
error = softdep_journal_lookup(mp, &xvp);
if (error) {
free(copy_fs->fs_csp, M_UFSMNT);
free(copy_fs, M_UFSMNT);
copy_fs = NULL;
goto out1;
}
xp = VTOI(xvp);
if (I_IS_UFS1(xp))
error = expunge_ufs1(vp, xp, copy_fs, fullacct_ufs1,
BLK_NOCOPY, 0);
else
error = expunge_ufs2(vp, xp, copy_fs, fullacct_ufs2,
BLK_NOCOPY, 0);
vput(xvp);
}
/*
* Acquire a lock on the snapdata structure, creating it if necessary.
*/
sn = ffs_snapdata_acquire(devvp);
/*
* Change vnode to use shared snapshot lock instead of the original
* private lock.
*/
vp->v_vnlock = &sn->sn_lock;
lockmgr(&vp->v_lock, LK_RELEASE, NULL);
xp = TAILQ_FIRST(&sn->sn_head);
/*
* 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) {
snapblklist = malloc(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: %ju already on list",
(uintmax_t)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");
out1:
KASSERT((sn != NULL && copy_fs != NULL && error == 0) ||
(sn == NULL && copy_fs == NULL && error != 0),
("email phk@ and mckusick@"));
/*
* Resume operation on filesystem.
*/
vfs_write_resume(vp->v_mount, VR_START_WRITE | VR_NO_SUSPCLR);
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 (copy_fs == 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 (I_IS_UFS1(xp))
error = expunge_ufs1(vp, xp, fs, snapacct_ufs1,
BLK_SNAP, 0);
else
error = expunge_ufs2(vp, xp, fs, snapacct_ufs2,
BLK_SNAP, 0);
if (error == 0 && xp->i_effnlink == 0) {
error = ffs_freefile(ump,
copy_fs,
vp,
xp->i_number,
xp->i_mode, NULL);
}
if (error) {
fs->fs_snapinum[snaploc] = 0;
goto done;
}
}
/*
* Allocate space for the full list of preallocated snapshot blocks.
*/
snapblklist = malloc(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 (I_IS_UFS1(ip))
error = expunge_ufs1(vp, ip, copy_fs, mapacct_ufs1,
BLK_SNAP, 0);
else
error = expunge_ufs2(vp, ip, copy_fs, mapacct_ufs2,
BLK_SNAP, 0);
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);
}
error = bread(vp, lblkno(fs, fs->fs_sblockloc), fs->fs_bsize,
KERNCRED, &nbp);
if (error) {
brelse(nbp);
} else {
loc = blkoff(fs, fs->fs_sblockloc);
bcopy((char *)copy_fs, &nbp->b_data[loc], (u_int)fs->fs_sbsize);
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);
/*
* Preallocate all the direct blocks in the snapshot inode so
* that we never have to write the inode itself to commit an
* update to the contents of the snapshot. Note that once
* created, the size of the snapshot will never change, so
* there will never be a need to write the inode except to
* update the non-integrity-critical time fields and
* allocated-block count.
*/
for (blockno = 0; blockno < UFS_NDADDR; blockno++) {
if (DIP(ip, i_db[blockno]) != 0)
continue;
error = UFS_BALLOC(vp, lblktosize(fs, blockno),
fs->fs_bsize, KERNCRED, BA_CLRBUF, &bp);
if (error)
break;
error = readblock(vp, bp, blockno);
bawrite(bp);
if (error != 0)
break;
}
done:
free(copy_fs->fs_csp, M_UFSMNT);
free(copy_fs, M_UFSMNT);
copy_fs = NULL;
out:
NDFREE(&nd, NDF_ONLY_PNBUF);
if (saved_nice > 0) {
struct proc *p;
p = td->td_proc;
PROC_LOCK(p);
sched_nice(td->td_proc, saved_nice);
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);
MNT_ILOCK(mp);
mp->mnt_flag = (mp->mnt_flag & MNT_QUOTA) | (flag & ~MNT_QUOTA);
MNT_IUNLOCK(mp);
if (error)
(void) ffs_truncate(vp, (off_t)0, 0, NOCRED);
(void) ffs_syncvnode(vp, MNT_WAIT, 0);
if (error)
vput(vp);
else
VOP_UNLOCK(vp, 0);
vrele(nd.ni_dvp);
vn_finished_write(wrtmp);
process_deferred_inactive(mp);
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 = ITOFS(ip);
if ((error = ffs_getcg(fs, ITODEVVP(ip), cg, &bp, &cgp)) != 0)
return (error);
UFS_LOCK(ITOUMP(ip));
ACTIVESET(fs, cg);
/*
* Recomputation of summary information might not have been performed
* at mount time. Sync up summary information for current cylinder
* group while data is in memory to ensure that result of background
* fsck is slightly more consistent.
*/
fs->fs_cs(fs, cg) = cgp->cg_cs;
UFS_UNLOCK(ITOUMP(ip));
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);
cgp = (struct cg *)nbp->b_data;
bqrelse(bp);
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 < UFS_NDADDR) {
for ( ; loc < UFS_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) {
goto out;
}
indiroff = (base + loc - UFS_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) {
goto out;
}
indiroff = 0;
}
if (I_IS_UFS1(ip)) {
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");
}
if (passno == 2)
ibp->b_flags |= B_VALIDSUSPWRT;
bdwrite(ibp);
out:
/*
* We have to calculate the crc32c here rather than just setting the
* BX_CYLGRP b_xflags because the allocation of the block for the
* the cylinder group map will always be a full size block (fs_bsize)
* even though the cylinder group may be smaller (fs_cgsize). The
* crc32c must be computed only over fs_cgsize whereas the BX_CYLGRP
* flag causes it to be computed over the size of the buffer.
*/
if ((fs->fs_metackhash & CK_CYLGRP) != 0) {
((struct cg *)nbp->b_data)->cg_ckhash = 0;
((struct cg *)nbp->b_data)->cg_ckhash =
calculate_crc32c(~0L, nbp->b_data, fs->fs_cgsize);
}
return (error);
}
/*
* 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, clearmode)
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 clearmode;
{
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 < UFS_NDADDR) {
blkno = VTOI(snapvp)->i_din1->di_db[lbn];
} else {
if (DOINGSOFTDEP(snapvp))
softdep_prealloc(snapvp, MNT_WAIT);
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 - UFS_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
* or unlinked snapshots to be completely unallocated.
*/
dip = (struct ufs1_dinode *)bp->b_data +
ino_to_fsbo(fs, cancelip->i_number);
if (clearmode || cancelip->i_effnlink == 0)
dip->di_mode = 0;
dip->di_size = 0;
dip->di_blocks = 0;
dip->di_flags &= ~SF_SNAPSHOT;
bzero(&dip->di_db[0], (UFS_NDADDR + UFS_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[UFS_NDADDR], fs, 0, expungetype)))
return (error);
if ((error = (*acctfunc)(snapvp, &cancelip->i_din1->di_ib[0],
&cancelip->i_din1->di_ib[UFS_NIADDR], fs, -1, expungetype)))
return (error);
blksperindir = 1;
lbn = -UFS_NDADDR;
len = numblks - UFS_NDADDR;
rlbn = UFS_NDADDR;
for (i = 0; len > 0 && i < UFS_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[UFS_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);
bap = malloc(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 < UFS_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 - UFS_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 >= UFS_NDADDR)
brelse(ibp);
} else {
if (*blkp != 0)
panic("snapacct_ufs1: bad block");
*blkp = expungetype;
if (lbn >= UFS_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(ITOUMP(ip), fs, vp, blkno, fs->fs_bsize, inum,
vp->v_type, NULL);
}
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, clearmode)
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 clearmode;
{
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 < UFS_NDADDR) {
blkno = VTOI(snapvp)->i_din2->di_db[lbn];
} else {
if (DOINGSOFTDEP(snapvp))
softdep_prealloc(snapvp, MNT_WAIT);
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 - UFS_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 (clearmode || cancelip->i_effnlink == 0)
dip->di_mode = 0;
dip->di_size = 0;
dip->di_blocks = 0;
dip->di_flags &= ~SF_SNAPSHOT;
bzero(&dip->di_db[0], (UFS_NDADDR + UFS_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[UFS_NDADDR], fs, 0, expungetype)))
return (error);
if ((error = (*acctfunc)(snapvp, &cancelip->i_din2->di_ib[0],
&cancelip->i_din2->di_ib[UFS_NIADDR], fs, -1, expungetype)))
return (error);
blksperindir = 1;
lbn = -UFS_NDADDR;
len = numblks - UFS_NDADDR;
rlbn = UFS_NDADDR;
for (i = 0; len > 0 && i < UFS_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[UFS_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_CACHE) == 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);
bap = malloc(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 < UFS_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 - UFS_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 >= UFS_NDADDR)
brelse(ibp);
} else {
if (*blkp != 0)
panic("snapacct_ufs2: bad block");
*blkp = expungetype;
if (lbn >= UFS_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(ITOUMP(ip), fs, vp, blkno, fs->fs_bsize, inum,
vp->v_type, NULL);
}
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 = ITODEVVP(ip)->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 %ju\n",
(uintmax_t)ip->i_number);
/*
* Delete snapshot inode from superblock. Keep list dense.
*/
ump = ITOUMP(ip);
fs = ump->um_fs;
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 buf *ibp;
struct fs *fs;
ufs2_daddr_t numblks, blkno, dblk;
int error, i, last, loc;
struct snapdata *sn;
ip = VTOI(vp);
fs = ITOFS(ip);
devvp = ITODEVVP(ip);
/*
* 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.
*/
VI_LOCK(devvp);
if (ip->i_nextsnap.tqe_prev != 0) {
sn = devvp->v_rdev->si_snapdata;
TAILQ_REMOVE(&sn->sn_head, ip, i_nextsnap);
ip->i_nextsnap.tqe_prev = 0;
VI_UNLOCK(devvp);
lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL);
for (i = 0; i < sn->sn_lock.lk_recurse; i++)
lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL);
KASSERT(vp->v_vnlock == &sn->sn_lock,
("ffs_snapremove: lost lock mutation"));
vp->v_vnlock = &vp->v_lock;
VI_LOCK(devvp);
while (sn->sn_lock.lk_recurse > 0)
lockmgr(&sn->sn_lock, LK_RELEASE, NULL);
lockmgr(&sn->sn_lock, LK_RELEASE, NULL);
try_free_snapdata(devvp);
} else
VI_UNLOCK(devvp);
/*
* Clear all BLK_NOCOPY fields. Pass any block claims to other
* snapshots that want them (see ffs_snapblkfree below).
*/
for (blkno = 1; blkno < UFS_NDADDR; blkno++) {
dblk = DIP(ip, i_db[blkno]);
if (dblk == 0)
continue;
if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
DIP_SET(ip, i_db[blkno], 0);
else if ((dblk == blkstofrags(fs, blkno) &&
ffs_snapblkfree(fs, ITODEVVP(ip), dblk, fs->fs_bsize,
ip->i_number, vp->v_type, NULL))) {
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 = UFS_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 (I_IS_UFS1(ip)) {
dblk = ((ufs1_daddr_t *)(ibp->b_data))[loc];
if (dblk == 0)
continue;
if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
((ufs1_daddr_t *)(ibp->b_data))[loc]= 0;
else if ((dblk == blkstofrags(fs, blkno) &&
ffs_snapblkfree(fs, ITODEVVP(ip), dblk,
fs->fs_bsize, ip->i_number, vp->v_type,
NULL))) {
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 == 0)
continue;
if (dblk == BLK_NOCOPY || dblk == BLK_SNAP)
((ufs2_daddr_t *)(ibp->b_data))[loc] = 0;
else if ((dblk == blkstofrags(fs, blkno) &&
ffs_snapblkfree(fs, ITODEVVP(ip), dblk,
fs->fs_bsize, ip->i_number, vp->v_type, NULL))) {
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;
/*
* The dirtied indirects must be written out before
* softdep_setup_freeblocks() is called. Otherwise indir_trunc()
* may find indirect pointers using the magic BLK_* values.
*/
if (DOINGSOFTDEP(vp))
ffs_syncvnode(vp, MNT_WAIT, 0);
#ifdef QUOTA
/*
* Reenable disk quotas for ex-snapshot file.
*/
if (!getinoquota(ip))
(void) chkdq(ip, DIP(ip, i_blocks), KERNCRED, FORCE);
#endif
}
/*
* 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, vtype, wkhd)
struct fs *fs;
struct vnode *devvp;
ufs2_daddr_t bno;
long size;
ino_t inum;
enum vtype vtype;
struct workhead *wkhd;
{
struct buf *ibp, *cbp, *savedcbp = NULL;
struct thread *td = curthread;
struct inode *ip;
struct vnode *vp = NULL;
ufs_lbn_t lbn;
ufs2_daddr_t blkno;
int indiroff = 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);
}
if (lockmgr(&sn->sn_lock, LK_INTERLOCK | LK_EXCLUSIVE | LK_SLEEPFAIL,
VI_MTX(devvp)) != 0)
goto retry;
TAILQ_FOREACH(ip, &sn->sn_head, i_nextsnap) {
vp = ITOV(ip);
if (DOINGSOFTDEP(vp))
softdep_prealloc(vp, MNT_WAIT);
/*
* Lookup block being written.
*/
if (lbn < UFS_NDADDR) {
blkno = DIP(ip, i_db[lbn]);
} else {
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 - UFS_NDADDR) % NINDIR(fs);
if (I_IS_UFS1(ip))
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 (lbn < UFS_NDADDR) {
DIP_SET(ip, i_db[lbn], BLK_NOCOPY);
ip->i_flag |= IN_CHANGE | IN_UPDATE;
} else if (I_IS_UFS1(ip)) {
((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 >= UFS_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 (size == fs->fs_bsize) {
#ifdef DEBUG
if (snapdebug)
printf("%s %ju lbn %jd from inum %ju\n",
"Grabonremove: snapino",
(uintmax_t)ip->i_number,
(intmax_t)lbn, (uintmax_t)inum);
#endif
/*
* If journaling is tracking this write we must add
* the work to the inode or indirect being written.
*/
if (wkhd != NULL) {
if (lbn < UFS_NDADDR)
softdep_inode_append(ip,
curthread->td_ucred, wkhd);
else
softdep_buf_append(ibp, wkhd);
}
if (lbn < UFS_NDADDR) {
DIP_SET(ip, i_db[lbn], bno);
} else if (I_IS_UFS1(ip)) {
((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;
lockmgr(vp->v_vnlock, LK_RELEASE, NULL);
return (1);
}
if (lbn >= UFS_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%ju lbn %jd %s %ju size %ld to blkno %jd\n",
"Copyonremove: snapino ", (uintmax_t)ip->i_number,
(intmax_t)lbn, "for inum", (uintmax_t)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. At a minimum we ensure the
* integrity of the filesystem metadata, but use the
* dopersistence sysctl-setable flag to decide on the
* persistence needed for file content data.
*/
if (savedcbp != NULL) {
bcopy(savedcbp->b_data, cbp->b_data, fs->fs_bsize);
bawrite(cbp);
if ((vtype == VDIR || dopersistence) &&
ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT, NO_INO_UPDT);
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 ((vtype == VDIR || dopersistence) &&
ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT, NO_INO_UPDT);
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. At a minimum we
* ensure the integrity of the filesystem metadata, but
* use the dopersistence sysctl-setable flag to decide on
* the persistence needed for file content data.
*/
if (savedcbp) {
vp = savedcbp->b_vp;
bawrite(savedcbp);
if ((vtype == VDIR || dopersistence) &&
VTOI(vp)->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT, NO_INO_UPDT);
}
/*
* 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 (error != 0 && wkhd != NULL)
softdep_freework(wkhd);
lockmgr(&sn->sn_lock, LK_RELEASE, NULL);
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 vnode *lastvp;
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;
lastvp = NULL;
sn = NULL;
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 (!IS_SNAPSHOT(ip) || ip->i_size ==
lblktosize(fs, howmany(fs->fs_size, fs->fs_frag))) {
if (!IS_SNAPSHOT(ip)) {
reason = "non-snapshot";
} else {
reason = "old format snapshot";
(void)ffs_truncate(vp, (off_t)0, 0, NOCRED);
(void)ffs_syncvnode(vp, MNT_WAIT, 0);
}
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;
}
/*
* Acquire a lock on the snapdata structure, creating it if
* necessary.
*/
sn = ffs_snapdata_acquire(devvp);
/*
* Change vnode to use shared snapshot lock instead of the
* original private lock.
*/
vp->v_vnlock = &sn->sn_lock;
lockmgr(&vp->v_lock, LK_RELEASE, NULL);
/*
* Link it onto the active snapshot list.
*/
VI_LOCK(devvp);
if (ip->i_nextsnap.tqe_prev != 0)
panic("ffs_snapshot_mount: %ju already on list",
(uintmax_t)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);
lastvp = vp;
}
vp = lastvp;
/*
* No usable snapshots found.
*/
if (sn == NULL || 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);
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);
return;
}
snapblklist = malloc(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);
free(snapblklist, M_UFSMNT);
return;
}
VOP_UNLOCK(vp, 0);
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;
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
while (sn != NULL && (xp = TAILQ_FIRST(&sn->sn_head)) != NULL) {
vp = ITOV(xp);
TAILQ_REMOVE(&sn->sn_head, xp, i_nextsnap);
xp->i_nextsnap.tqe_prev = 0;
lockmgr(&sn->sn_lock, LK_INTERLOCK | LK_EXCLUSIVE,
VI_MTX(devvp));
lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL);
KASSERT(vp->v_vnlock == &sn->sn_lock,
("ffs_snapshot_unmount: lost lock mutation"));
vp->v_vnlock = &vp->v_lock;
lockmgr(&vp->v_lock, LK_RELEASE, NULL);
lockmgr(&sn->sn_lock, LK_RELEASE, NULL);
if (xp->i_effnlink > 0)
vrele(vp);
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
}
try_free_snapdata(devvp);
ASSERT_VOP_LOCKED(devvp, "ffs_snapshot_unmount");
}
/*
* Check the buffer block to be belong to device buffer that shall be
* locked after snaplk. devvp shall be locked on entry, and will be
* leaved locked upon exit.
*/
static int
ffs_bp_snapblk(devvp, bp)
struct vnode *devvp;
struct buf *bp;
{
struct snapdata *sn;
struct fs *fs;
ufs2_daddr_t lbn, *snapblklist;
int lower, upper, mid;
ASSERT_VI_LOCKED(devvp, "ffs_bp_snapblk");
KASSERT(devvp->v_type == VCHR, ("Not a device %p", devvp));
sn = devvp->v_rdev->si_snapdata;
if (sn == NULL || TAILQ_FIRST(&sn->sn_head) == NULL)
return (0);
fs = ITOFS(TAILQ_FIRST(&sn->sn_head));
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)
return (1);
return (0);
}
void
ffs_bdflush(bo, bp)
struct bufobj *bo;
struct buf *bp;
{
struct thread *td;
struct vnode *vp, *devvp;
struct buf *nbp;
int bp_bdskip;
if (bo->bo_dirty.bv_cnt <= dirtybufthresh)
return;
td = curthread;
vp = bp->b_vp;
devvp = bo2vnode(bo);
KASSERT(vp == devvp, ("devvp != vp %p %p", bo, bp));
VI_LOCK(devvp);
bp_bdskip = ffs_bp_snapblk(devvp, bp);
if (bp_bdskip)
bdwriteskip++;
VI_UNLOCK(devvp);
if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10 && !bp_bdskip) {
(void) VOP_FSYNC(vp, MNT_NOWAIT, td);
altbufferflushes++;
} else {
BO_LOCK(bo);
/*
* Try to find a buffer to flush.
*/
TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
if ((nbp->b_vflags & BV_BKGRDINPROG) ||
BUF_LOCK(nbp,
LK_EXCLUSIVE | LK_NOWAIT, NULL))
continue;
if (bp == nbp)
panic("bdwrite: found ourselves");
BO_UNLOCK(bo);
/*
* Don't countdeps with the bo lock
* held.
*/
if (buf_countdeps(nbp, 0)) {
BO_LOCK(bo);
BUF_UNLOCK(nbp);
continue;
}
if (bp_bdskip) {
VI_LOCK(devvp);
if (!ffs_bp_snapblk(vp, nbp)) {
VI_UNLOCK(devvp);
BO_LOCK(bo);
BUF_UNLOCK(nbp);
continue;
}
VI_UNLOCK(devvp);
}
if (nbp->b_flags & B_CLUSTEROK) {
vfs_bio_awrite(nbp);
} else {
bremfree(nbp);
bawrite(nbp);
}
dirtybufferflushes++;
break;
}
if (nbp == NULL)
BO_UNLOCK(bo);
}
}
/*
* 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 = NULL;
struct thread *td = curthread;
struct fs *fs;
struct inode *ip;
struct vnode *vp = NULL;
ufs2_daddr_t lbn, blkno, *snapblklist;
int lower, upper, mid, indiroff, error = 0;
int launched_async_io, prev_norunningbuf;
long saved_runningbufspace;
if (devvp != bp->b_vp && IS_SNAPSHOT(VTOI(bp->b_vp)))
return (0); /* Update on a snapshot file */
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;
if (sn == NULL ||
TAILQ_EMPTY(&sn->sn_head)) {
VI_UNLOCK(devvp);
return (0); /* No snapshot */
}
ip = TAILQ_FIRST(&sn->sn_head);
fs = ITOFS(ip);
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);
}
launched_async_io = 0;
prev_norunningbuf = td->td_pflags & TDP_NORUNNINGBUF;
/*
* Since I/O on bp isn't yet in progress and it may be blocked
* for a long time waiting on snaplk, back it out of
* runningbufspace, possibly waking other threads waiting for space.
*/
saved_runningbufspace = bp->b_runningbufspace;
if (saved_runningbufspace != 0)
runningbufwakeup(bp);
/*
* Not in the precomputed list, so check the snapshots.
*/
while (lockmgr(&sn->sn_lock, LK_INTERLOCK | LK_EXCLUSIVE | LK_SLEEPFAIL,
VI_MTX(devvp)) != 0) {
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
if (sn == NULL ||
TAILQ_EMPTY(&sn->sn_head)) {
VI_UNLOCK(devvp);
if (saved_runningbufspace != 0) {
bp->b_runningbufspace = saved_runningbufspace;
atomic_add_long(&runningbufspace,
bp->b_runningbufspace);
}
return (0); /* Snapshot gone */
}
}
TAILQ_FOREACH(ip, &sn->sn_head, i_nextsnap) {
vp = ITOV(ip);
if (DOINGSOFTDEP(vp))
softdep_prealloc(vp, MNT_WAIT);
/*
* 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 < UFS_NDADDR) {
blkno = DIP(ip, i_db[lbn]);
} else {
td->td_pflags |= TDP_COWINPROGRESS | TDP_NORUNNINGBUF;
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 - UFS_NDADDR) % NINDIR(fs);
if (I_IS_UFS1(ip))
blkno=((ufs1_daddr_t *)(ibp->b_data))[indiroff];
else
blkno=((ufs2_daddr_t *)(ibp->b_data))[indiroff];
bqrelse(ibp);
}
#ifdef INVARIANTS
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.
*/
td->td_pflags |= TDP_COWINPROGRESS | TDP_NORUNNINGBUF;
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 %ju lbn %jd for ",
(uintmax_t)ip->i_number, (intmax_t)lbn);
if (bp->b_vp == devvp)
printf("fs metadata");
else
printf("inum %ju",
(uintmax_t)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. At a minimum we ensure the
* integrity of the filesystem metadata, but use the
* dopersistence sysctl-setable flag to decide on the
* persistence needed for file content data.
*/
if (savedcbp != NULL) {
bcopy(savedcbp->b_data, cbp->b_data, fs->fs_bsize);
bawrite(cbp);
if ((devvp == bp->b_vp || bp->b_vp->v_type == VDIR ||
dopersistence) && ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT, NO_INO_UPDT);
else
launched_async_io = 1;
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 ((devvp == bp->b_vp || bp->b_vp->v_type == VDIR ||
dopersistence) && ip->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT, NO_INO_UPDT);
else
launched_async_io = 1;
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. At a minimum we
* ensure the integrity of the filesystem metadata, but
* use the dopersistence sysctl-setable flag to decide on
* the persistence needed for file content data.
*/
if (savedcbp) {
vp = savedcbp->b_vp;
bawrite(savedcbp);
if ((devvp == bp->b_vp || bp->b_vp->v_type == VDIR ||
dopersistence) && VTOI(vp)->i_effnlink > 0)
(void) ffs_syncvnode(vp, MNT_WAIT, NO_INO_UPDT);
else
launched_async_io = 1;
}
lockmgr(vp->v_vnlock, LK_RELEASE, NULL);
td->td_pflags = (td->td_pflags & ~TDP_NORUNNINGBUF) |
prev_norunningbuf;
if (launched_async_io && (td->td_pflags & TDP_NORUNNINGBUF) == 0)
waitrunningbufspace();
/*
* I/O on bp will now be started, so count it in runningbufspace.
*/
if (saved_runningbufspace != 0) {
bp->b_runningbufspace = saved_runningbufspace;
atomic_add_long(&runningbufspace, bp->b_runningbufspace);
}
return (error);
}
/*
* sync snapshots to force freework records waiting on snapshots to claim
* blocks to free.
*/
void
ffs_sync_snap(mp, waitfor)
struct mount *mp;
int waitfor;
{
struct snapdata *sn;
struct vnode *devvp;
struct vnode *vp;
struct inode *ip;
devvp = VFSTOUFS(mp)->um_devvp;
if ((devvp->v_vflag & VV_COPYONWRITE) == 0)
return;
for (;;) {
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
if (sn == NULL) {
VI_UNLOCK(devvp);
return;
}
if (lockmgr(&sn->sn_lock,
LK_INTERLOCK | LK_EXCLUSIVE | LK_SLEEPFAIL,
VI_MTX(devvp)) == 0)
break;
}
TAILQ_FOREACH(ip, &sn->sn_head, i_nextsnap) {
vp = ITOV(ip);
ffs_syncvnode(vp, waitfor, NO_INO_UPDT);
}
lockmgr(&sn->sn_lock, LK_RELEASE, NULL);
}
/*
* 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;
struct fs *fs;
ip = VTOI(vp);
fs = ITOFS(ip);
bip = g_alloc_bio();
bip->bio_cmd = BIO_READ;
bip->bio_offset = dbtob(fsbtodb(fs, blkstofrags(fs, lbn)));
bip->bio_data = bp->b_data;
bip->bio_length = bp->b_bcount;
bip->bio_done = NULL;
g_io_request(bip, ITODEVVP(ip)->v_bufobj.bo_private);
bp->b_error = biowait(bip, "snaprdb");
g_destroy_bio(bip);
return (bp->b_error);
}
#endif
/*
* Process file deletes that were deferred by ufs_inactive() due to
* the file system being suspended. Transfer IN_LAZYACCESS into
* IN_MODIFIED for vnodes that were accessed during suspension.
*/
void
process_deferred_inactive(struct mount *mp)
{
struct vnode *vp, *mvp;
struct inode *ip;
struct thread *td;
int error;
td = curthread;
(void) vn_start_secondary_write(NULL, &mp, V_WAIT);
loop:
MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
/*
* IN_LAZYACCESS is checked here without holding any
* vnode lock, but this flag is set only while holding
* vnode interlock.
*/
if (vp->v_type == VNON ||
((VTOI(vp)->i_flag & IN_LAZYACCESS) == 0 &&
((vp->v_iflag & VI_OWEINACT) == 0 || vp->v_usecount > 0))) {
VI_UNLOCK(vp);
continue;
}
vholdl(vp);
error = vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK);
if (error != 0) {
vdrop(vp);
if (error == ENOENT)
continue; /* vnode recycled */
MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
goto loop;
}
ip = VTOI(vp);
if ((ip->i_flag & IN_LAZYACCESS) != 0) {
ip->i_flag &= ~IN_LAZYACCESS;
ip->i_flag |= IN_MODIFIED;
}
VI_LOCK(vp);
if ((vp->v_iflag & VI_OWEINACT) == 0 || vp->v_usecount > 0) {
VI_UNLOCK(vp);
VOP_UNLOCK(vp, 0);
vdrop(vp);
continue;
}
vinactive(vp, td);
VNASSERT((vp->v_iflag & VI_OWEINACT) == 0, vp,
("process_deferred_inactive: got VI_OWEINACT"));
VI_UNLOCK(vp);
VOP_UNLOCK(vp, 0);
vdrop(vp);
}
vn_finished_secondary_write(mp);
}
#ifndef NO_FFS_SNAPSHOT
static struct snapdata *
ffs_snapdata_alloc(void)
{
struct snapdata *sn;
/*
* Fetch a snapdata from the free list if there is one available.
*/
mtx_lock(&snapfree_lock);
sn = LIST_FIRST(&snapfree);
if (sn != NULL)
LIST_REMOVE(sn, sn_link);
mtx_unlock(&snapfree_lock);
if (sn != NULL)
return (sn);
/*
* If there were no free snapdatas allocate one.
*/
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_NOSHARE);
return (sn);
}
/*
* The snapdata is never freed because we can not be certain that
* there are no threads sleeping on the snap lock. Persisting
* them permanently avoids costly synchronization in ffs_lock().
*/
static void
ffs_snapdata_free(struct snapdata *sn)
{
mtx_lock(&snapfree_lock);
LIST_INSERT_HEAD(&snapfree, sn, sn_link);
mtx_unlock(&snapfree_lock);
}
/* Try to free snapdata associated with devvp */
static void
try_free_snapdata(struct vnode *devvp)
{
struct snapdata *sn;
ufs2_daddr_t *snapblklist;
ASSERT_VI_LOCKED(devvp, "try_free_snapdata");
sn = devvp->v_rdev->si_snapdata;
if (sn == NULL || TAILQ_FIRST(&sn->sn_head) != NULL ||
(devvp->v_vflag & VV_COPYONWRITE) == 0) {
VI_UNLOCK(devvp);
return;
}
devvp->v_rdev->si_snapdata = NULL;
devvp->v_vflag &= ~VV_COPYONWRITE;
lockmgr(&sn->sn_lock, LK_DRAIN|LK_INTERLOCK, VI_MTX(devvp));
snapblklist = sn->sn_blklist;
sn->sn_blklist = NULL;
sn->sn_listsize = 0;
lockmgr(&sn->sn_lock, LK_RELEASE, NULL);
if (snapblklist != NULL)
free(snapblklist, M_UFSMNT);
ffs_snapdata_free(sn);
}
static struct snapdata *
ffs_snapdata_acquire(struct vnode *devvp)
{
struct snapdata *nsn, *sn;
int error;
/*
* Allocate a free snapdata. This is done before acquiring the
* devvp lock to avoid allocation while the devvp interlock is
* held.
*/
nsn = ffs_snapdata_alloc();
for (;;) {
VI_LOCK(devvp);
sn = devvp->v_rdev->si_snapdata;
if (sn == NULL) {
/*
* This is the first snapshot on this
* filesystem and we use our pre-allocated
* snapdata. Publish sn with the sn_lock
* owned by us, to avoid the race.
*/
error = lockmgr(&nsn->sn_lock, LK_EXCLUSIVE |
LK_NOWAIT, NULL);
if (error != 0)
panic("leaked sn, lockmgr error %d", error);
sn = devvp->v_rdev->si_snapdata = nsn;
VI_UNLOCK(devvp);
nsn = NULL;
break;
}
/*
* There is a snapshots which already exists on this
* filesystem, grab a reference to the common lock.
*/
error = lockmgr(&sn->sn_lock, LK_INTERLOCK |
LK_EXCLUSIVE | LK_SLEEPFAIL, VI_MTX(devvp));
if (error == 0)
break;
}
/*
* Free any unused snapdata.
*/
if (nsn != NULL)
ffs_snapdata_free(nsn);
return (sn);
}
#endif
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