/* $NetBSD: ffs_snapshot.c,v 1.83 2008/12/01 13:22:06 joerg Exp $ */ /* * 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 * * from FreeBSD: ffs_snapshot.c,v 1.79 2004/02/13 02:02:06 kuriyama Exp */ #include __KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.83 2008/12/01 13:22:06 joerg Exp $"); #if defined(_KERNEL_OPT) #include "opt_ffs.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if !defined(FFS_NO_SNAPSHOT) typedef int (*acctfunc_t) (struct vnode *, void *, int, int, struct fs *, daddr_t, int); static int snapshot_setup(struct mount *, struct vnode *); static int snapshot_copyfs(struct mount *, struct vnode *, void **); static int snapshot_expunge(struct mount *, struct vnode *, struct fs *, daddr_t *, daddr_t **); static int snapshot_expunge_snap(struct mount *, struct vnode *, struct fs *, daddr_t); static int snapshot_writefs(struct mount *, struct vnode *, void *); static int cgaccount(struct vnode *, int, int *); static int cgaccount1(int, struct vnode *, void *, int); static int expunge(struct vnode *, struct inode *, struct fs *, acctfunc_t, int); static int indiracct(struct vnode *, struct vnode *, int, daddr_t, daddr_t, daddr_t, daddr_t, daddr_t, struct fs *, acctfunc_t, int); static int fullacct(struct vnode *, void *, int, int, struct fs *, daddr_t, int); static int snapacct(struct vnode *, void *, int, int, struct fs *, daddr_t, int); static int mapacct(struct vnode *, void *, int, int, struct fs *, daddr_t, int); #endif /* !defined(FFS_NO_SNAPSHOT) */ static int ffs_copyonwrite(void *, struct buf *, bool); static int snapblkaddr(struct vnode *, daddr_t, daddr_t *); static int rwfsblk(struct vnode *, int, void *, daddr_t); static int syncsnap(struct vnode *); static int wrsnapblk(struct vnode *, void *, daddr_t); static inline daddr_t db_get(struct inode *, int); static inline void db_assign(struct inode *, int, daddr_t); static inline daddr_t ib_get(struct inode *, int); static inline void ib_assign(struct inode *, int, daddr_t); static inline daddr_t idb_get(struct inode *, void *, int); static inline void idb_assign(struct inode *, void *, int, daddr_t); struct snap_info { kmutex_t si_lock; /* Lock this snapinfo */ kmutex_t si_snaplock; /* Snapshot vnode common lock */ TAILQ_HEAD(inodelst, inode) si_snapshots; /* List of active snapshots */ daddr_t *si_snapblklist; /* Snapshot block hints list */ uint32_t si_gen; /* Incremented on change */ }; #ifdef DEBUG static int snapdebug = 0; #endif int ffs_snapshot_init(struct ufsmount *ump) { struct snap_info *si; si = ump->um_snapinfo = kmem_alloc(sizeof(*si), KM_SLEEP); if (si == NULL) return ENOMEM; TAILQ_INIT(&si->si_snapshots); mutex_init(&si->si_lock, MUTEX_DEFAULT, IPL_NONE); mutex_init(&si->si_snaplock, MUTEX_DEFAULT, IPL_NONE); si->si_gen = 0; si->si_snapblklist = NULL; return 0; } void ffs_snapshot_fini(struct ufsmount *ump) { struct snap_info *si; si = ump->um_snapinfo; ump->um_snapinfo = NULL; KASSERT(TAILQ_EMPTY(&si->si_snapshots)); mutex_destroy(&si->si_lock); mutex_destroy(&si->si_snaplock); KASSERT(si->si_snapblklist == NULL); kmem_free(si, sizeof(*si)); } /* * Create a snapshot file and initialize it for the filesystem. * Vnode is locked on entry and return. */ int ffs_snapshot(struct mount *mp, struct vnode *vp, struct timespec *ctime) { #if defined(FFS_NO_SNAPSHOT) return EOPNOTSUPP; } #else /* defined(FFS_NO_SNAPSHOT) */ bool suspended = false; bool snapshot_locked = false; int error, redo = 0, snaploc; void *sbbuf = NULL; daddr_t *snaplist = NULL, snaplistsize = 0; struct buf *bp, *nbp; struct fs *copy_fs, *fs = VFSTOUFS(mp)->um_fs; struct inode *ip = VTOI(vp); struct lwp *l = curlwp; struct snap_info *si = VFSTOUFS(mp)->um_snapinfo; struct timespec ts; struct timeval starttime; #ifdef DEBUG struct timeval endtime; #endif struct vnode *devvp = ip->i_devvp; /* * If the vnode already is a snapshot, return. */ if (VTOI(vp)->i_flags & SF_SNAPSHOT) { if (ctime) { ctime->tv_sec = DIP(VTOI(vp), mtime); ctime->tv_nsec = DIP(VTOI(vp), mtimensec); } return 0; } /* * Check for free snapshot slot in the superblock. */ for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++) if (fs->fs_snapinum[snaploc] == 0) break; if (snaploc == FSMAXSNAP) return (ENOSPC); /* * Prepare the vnode to become a snapshot. */ error = snapshot_setup(mp, vp); if (error) goto out; /* * Change inode to snapshot type file. */ ip->i_flags |= SF_SNAPSHOT; DIP_ASSIGN(ip, flags, ip->i_flags); ip->i_flag |= IN_CHANGE | IN_UPDATE; /* * 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. */ error = cgaccount(vp, 1, NULL); if (error) goto out; /* * 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. */ error = VOP_FSYNC(vp, l->l_cred, FSYNC_WAIT, 0, 0); if (error) goto out; VOP_UNLOCK(vp, 0); /* * All allocations are done, so we can now suspend the filesystem. */ error = vfs_suspend(vp->v_mount, 0); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); if (error) goto out; suspended = true; getmicrotime(&starttime); /* * First, copy all the cylinder group maps that have changed. */ error = cgaccount(vp, 2, &redo); if (error) goto out; /* * Create a copy of the superblock and its summary information. */ error = snapshot_copyfs(mp, vp, &sbbuf); copy_fs = (struct fs *)((char *)sbbuf + blkoff(fs, fs->fs_sblockloc)); if (error) goto out; /* * Expunge unlinked files from our view. */ error = snapshot_expunge(mp, vp, copy_fs, &snaplistsize, &snaplist); if (error) goto out; /* * Acquire the snapshot lock. */ mutex_enter(&si->si_snaplock); snapshot_locked = true; /* * Record snapshot inode. Since this is the newest snapshot, * it must be placed at the end of the list. */ fs->fs_snapinum[snaploc] = ip->i_number; mutex_enter(&si->si_lock); if (ip->i_nextsnap.tqe_prev != 0) panic("ffs_snapshot: %"PRIu64" already on list", ip->i_number); TAILQ_INSERT_TAIL(&si->si_snapshots, ip, i_nextsnap); if (TAILQ_FIRST(&si->si_snapshots) == ip) { /* * If this is the first snapshot on this filesystem, put the * preliminary list in place and establish the cow handler. */ si->si_snapblklist = snaplist; fscow_establish(mp, ffs_copyonwrite, devvp); } si->si_gen++; mutex_exit(&si->si_lock); vp->v_vflag |= VV_SYSTEM; /* * Set the mtime to the time the snapshot has been taken. */ TIMEVAL_TO_TIMESPEC(&starttime, &ts); if (ctime) *ctime = ts; DIP_ASSIGN(ip, mtime, ts.tv_sec); DIP_ASSIGN(ip, mtimensec, ts.tv_nsec); ip->i_flag |= IN_CHANGE | IN_UPDATE; /* * Copy allocation information from all snapshots and then * expunge them from our view. */ error = snapshot_expunge_snap(mp, vp, copy_fs, snaplistsize); if (error) goto out; /* * Write the superblock and its summary information to the snapshot. */ error = snapshot_writefs(mp, vp, sbbuf); if (error) goto out; /* * We're nearly done, ensure that the snapshot is completely on disk. */ error = VOP_FSYNC(vp, l->l_cred, FSYNC_WAIT, 0, 0); if (error) goto out; /* * Invalidate and free all pages on the snapshot vnode. * We will read and write through the buffercache. */ mutex_enter(&vp->v_interlock); error = VOP_PUTPAGES(vp, 0, 0, PGO_ALLPAGES | PGO_CLEANIT | PGO_SYNCIO | PGO_FREE); if (error) goto out; /* * Invalidate short ( < fs_bsize ) buffers. We will always read * full size buffers later. */ mutex_enter(&bufcache_lock); KASSERT(LIST_FIRST(&vp->v_dirtyblkhd) == NULL); for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) { nbp = LIST_NEXT(bp, b_vnbufs); KASSERT((bp->b_cflags & BC_BUSY) == 0); if (bp->b_bcount < fs->fs_bsize) { bp->b_cflags |= BC_BUSY; brelsel(bp, BC_INVAL | BC_VFLUSH); } } mutex_exit(&bufcache_lock); out: if (sbbuf != NULL) { free(copy_fs->fs_csp, M_UFSMNT); free(sbbuf, M_UFSMNT); } if (fs->fs_active != NULL) { free(fs->fs_active, M_DEVBUF); fs->fs_active = NULL; } mutex_enter(&si->si_lock); if (snaplist != NULL) { if (si->si_snapblklist == snaplist) si->si_snapblklist = NULL; free(snaplist, M_UFSMNT); } if (error) { fs->fs_snapinum[snaploc] = 0; } else { /* * As this is the newest list, it is the most inclusive, so * should replace the previous list. */ si->si_snapblklist = ip->i_snapblklist; } si->si_gen++; mutex_exit(&si->si_lock); if (snapshot_locked) mutex_exit(&si->si_snaplock); if (suspended) { vfs_resume(vp->v_mount); #ifdef DEBUG getmicrotime(&endtime); timersub(&endtime, &starttime, &endtime); printf("%s: suspended %ld.%03ld sec, redo %d of %d\n", mp->mnt_stat.f_mntonname, (long)endtime.tv_sec, endtime.tv_usec / 1000, redo, fs->fs_ncg); #endif } if (error) { if (!UFS_WAPBL_BEGIN(mp)) { (void) ffs_truncate(vp, (off_t)0, 0, NOCRED); UFS_WAPBL_END(mp); } } else vref(vp); return (error); } /* * Prepare vnode to become a snapshot. */ static int snapshot_setup(struct mount *mp, struct vnode *vp) { int error, i, len, loc; daddr_t blkno, numblks; struct buf *ibp, *nbp; struct fs *fs = VFSTOUFS(mp)->um_fs; struct lwp *l = curlwp; /* * Check mount, exclusive reference and owner. */ if (vp->v_mount != mp) return EXDEV; if (vp->v_usecount != 1 || vp->v_writecount != 0) return EBUSY; if (kauth_authorize_generic(l->l_cred, KAUTH_GENERIC_ISSUSER, NULL) != 0 && VTOI(vp)->i_uid != kauth_cred_geteuid(l->l_cred)) return EACCES; if (vp->v_size != 0) { error = ffs_truncate(vp, 0, 0, NOCRED); if (error) return error; } /* * Write an empty list of preallocated blocks to the end of * the snapshot to set size to at least that of the filesystem. */ numblks = howmany(fs->fs_size, fs->fs_frag); blkno = 1; blkno = ufs_rw64(blkno, UFS_FSNEEDSWAP(fs)); error = vn_rdwr(UIO_WRITE, vp, (void *)&blkno, sizeof(blkno), lblktosize(fs, (off_t)numblks), UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT, l->l_cred, NULL, NULL); if (error) return error; /* * 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. */ error = UFS_WAPBL_BEGIN(mp); if (error) return error; for (blkno = NDADDR, i = 0; blkno < numblks; blkno += NINDIR(fs)) { error = ffs_balloc(vp, lblktosize(fs, (off_t)blkno), fs->fs_bsize, l->l_cred, B_METAONLY, &ibp); if (error) goto out; if (DOINGSOFTDEP(vp)) bawrite(ibp); else brelse(ibp, 0); if ((++i % 16) == 0) { UFS_WAPBL_END(mp); error = UFS_WAPBL_BEGIN(mp); if (error) return error; } } /* * Allocate copies for the superblock and its summary information. */ error = ffs_balloc(vp, fs->fs_sblockloc, fs->fs_sbsize, l->l_cred, 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 = ffs_balloc(vp, lblktosize(fs, (off_t)(blkno + loc)), fs->fs_bsize, l->l_cred, 0, &nbp); if (error) goto out; bawrite(nbp); } out: UFS_WAPBL_END(mp); return error; } /* * Create a copy of the superblock and its summary information. * It is up to the caller to free copyfs and copy_fs->fs_csp. */ static int snapshot_copyfs(struct mount *mp, struct vnode *vp, void **sbbuf) { int error, i, len, loc, size; void *space; int32_t *lp; struct buf *bp; struct fs *copyfs, *fs = VFSTOUFS(mp)->um_fs; struct lwp *l = curlwp; struct vnode *devvp = VTOI(vp)->i_devvp; /* * Grab a copy of the superblock and its summary information. * We delay writing it until the suspension is released below. */ *sbbuf = malloc(fs->fs_bsize, M_UFSMNT, M_WAITOK); loc = blkoff(fs, fs->fs_sblockloc); if (loc > 0) memset(*sbbuf, 0, loc); copyfs = (struct fs *)((char *)(*sbbuf) + loc); bcopy(fs, copyfs, fs->fs_sbsize); size = fs->fs_bsize < SBLOCKSIZE ? fs->fs_bsize : SBLOCKSIZE; if (fs->fs_sbsize < size) memset((char *)(*sbbuf) + loc + fs->fs_sbsize, 0, size - fs->fs_sbsize); size = blkroundup(fs, fs->fs_cssize); if (fs->fs_contigsumsize > 0) size += fs->fs_ncg * sizeof(int32_t); space = malloc(size, M_UFSMNT, M_WAITOK); copyfs->fs_csp = space; bcopy(fs->fs_csp, copyfs->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, l->l_cred, 0, &bp)) != 0) { brelse(bp, 0); free(copyfs->fs_csp, M_UFSMNT); free(*sbbuf, M_UFSMNT); *sbbuf = NULL; return error; } bcopy(bp->b_data, space, (u_int)len); space = (char *)space + len; brelse(bp, BC_INVAL | BC_NOCACHE); } if (fs->fs_contigsumsize > 0) { copyfs->fs_maxcluster = lp = space; for (i = 0; i < fs->fs_ncg; i++) *lp++ = fs->fs_contigsumsize; } if (mp->mnt_wapbl) copyfs->fs_flags &= ~FS_DOWAPBL; return 0; } /* * 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. * Note that we skip unlinked snapshot files as they will be handled separately. * Calculate the snapshot list size and create a preliminary list. */ static int snapshot_expunge(struct mount *mp, struct vnode *vp, struct fs *copy_fs, daddr_t *snaplistsize, daddr_t **snaplist) { bool has_wapbl = false; int cg, error, len, loc; daddr_t blkno, *blkp; struct fs *fs = VFSTOUFS(mp)->um_fs; struct inode *xp; struct lwp *l = curlwp; struct vattr vat; struct vnode *logvp = NULL, *mvp = NULL, *xvp; *snaplist = NULL; /* * Get the log inode if any. */ if ((fs->fs_flags & FS_DOWAPBL) && fs->fs_journal_location == UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM) { error = VFS_VGET(mp, fs->fs_journallocs[UFS_WAPBL_INFS_INO], &logvp); if (error) goto out; } /* * Allocate a marker vnode. */ if ((mvp = vnalloc(mp)) == NULL) { error = ENOMEM; goto out; } /* * 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 */; error = UFS_WAPBL_BEGIN(mp); if (error) goto out; has_wapbl = true; mutex_enter(&mntvnode_lock); /* * NOTE: not using the TAILQ_FOREACH here since in this loop vgone() * and vclean() can be called indirectly */ for (xvp = TAILQ_FIRST(&mp->mnt_vnodelist); xvp; xvp = vunmark(mvp)) { vmark(mvp, xvp); /* * Make sure this vnode wasn't reclaimed in getnewvnode(). * Start over if it has (it won't be on the list anymore). */ if (xvp->v_mount != mp || vismarker(xvp)) continue; mutex_enter(&xvp->v_interlock); if ((xvp->v_iflag & VI_XLOCK) || xvp->v_usecount == 0 || xvp->v_type == VNON || VTOI(xvp) == NULL || (VTOI(xvp)->i_flags & SF_SNAPSHOT)) { mutex_exit(&xvp->v_interlock); continue; } mutex_exit(&mntvnode_lock); /* * XXXAD should increase vnode ref count to prevent it * disappearing or being recycled. */ mutex_exit(&xvp->v_interlock); #ifdef DEBUG if (snapdebug) vprint("ffs_snapshot: busy vnode", xvp); #endif xp = VTOI(xvp); if (xvp != logvp) { if (VOP_GETATTR(xvp, &vat, l->l_cred) == 0 && vat.va_nlink > 0) { mutex_enter(&mntvnode_lock); continue; } if (ffs_checkfreefile(copy_fs, vp, xp->i_number)) { mutex_enter(&mntvnode_lock); 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_snap(copy_fs, vp, db_get(xp, loc), len, xp->i_number); blkno = db_get(xp, loc); db_assign(xp, loc, 0); } } *snaplistsize += 1; error = expunge(vp, xp, copy_fs, fullacct, BLK_NOCOPY); if (blkno) db_assign(xp, loc, blkno); if (!error) error = ffs_freefile(copy_fs, vp, xp->i_number, xp->i_mode); if (error) { (void)vunmark(mvp); goto out; } mutex_enter(&mntvnode_lock); } mutex_exit(&mntvnode_lock); /* * Create a preliminary list of preallocated snapshot blocks. */ *snaplist = malloc(*snaplistsize * sizeof(daddr_t), M_UFSMNT, M_WAITOK); blkp = &(*snaplist)[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)); out: if (has_wapbl) UFS_WAPBL_END(mp); if (mvp != NULL) vnfree(mvp); if (logvp != NULL) vput(logvp); if (error && *snaplist != NULL) { free(*snaplist, M_UFSMNT); *snaplist = NULL; } return error; } /* * Copy allocation information from all the snapshots in this snapshot and * then expunge them from its view. Also, collect the list of allocated * blocks in i_snapblklist. */ static int snapshot_expunge_snap(struct mount *mp, struct vnode *vp, struct fs *copy_fs, daddr_t snaplistsize) { int error, i; daddr_t numblks, *snaplist = NULL; struct fs *fs = VFSTOUFS(mp)->um_fs; struct inode *ip = VTOI(vp), *xp; struct lwp *l = curlwp; struct snap_info *si = VFSTOUFS(mp)->um_snapinfo; error = UFS_WAPBL_BEGIN(mp); if (error) return error; TAILQ_FOREACH(xp, &si->si_snapshots, i_nextsnap) { if (xp == ip) break; error = expunge(vp, xp, fs, snapacct, BLK_SNAP); if (error) break; if (xp->i_ffs_effnlink != 0) continue; error = ffs_freefile(copy_fs, vp, xp->i_number, xp->i_mode); if (error) break; } if (error) goto out; /* * Allocate space for the full list of preallocated snapshot blocks. */ snaplist = malloc(snaplistsize * sizeof(daddr_t), M_UFSMNT, M_WAITOK); ip->i_snapblklist = &snaplist[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. */ error = expunge(vp, ip, copy_fs, mapacct, BLK_SNAP); if (error) goto out; if (snaplistsize < ip->i_snapblklist - snaplist) panic("ffs_snapshot: list too small"); snaplistsize = ip->i_snapblklist - snaplist; snaplist[0] = snaplistsize; ip->i_snapblklist = &snaplist[0]; /* * Write out the list of allocated blocks to the end of the snapshot. */ numblks = howmany(fs->fs_size, fs->fs_frag); for (i = 0; i < snaplistsize; i++) snaplist[i] = ufs_rw64(snaplist[i], UFS_FSNEEDSWAP(fs)); error = vn_rdwr(UIO_WRITE, vp, (void *)snaplist, snaplistsize * sizeof(daddr_t), lblktosize(fs, (off_t)numblks), UIO_SYSSPACE, IO_NODELOCKED | IO_JOURNALLOCKED | IO_UNIT, l->l_cred, NULL, NULL); for (i = 0; i < snaplistsize; i++) snaplist[i] = ufs_rw64(snaplist[i], UFS_FSNEEDSWAP(fs)); out: UFS_WAPBL_END(mp); if (error && snaplist != NULL) { free(snaplist, M_UFSMNT); ip->i_snapblklist = NULL; } return error; } /* * Write the superblock and its summary information to the snapshot. * Make sure, the first NDADDR blocks get copied to the snapshot. */ static int snapshot_writefs(struct mount *mp, struct vnode *vp, void *sbbuf) { int error, len, loc; void *space; daddr_t blkno; struct buf *bp; struct fs *copyfs, *fs = VFSTOUFS(mp)->um_fs; struct inode *ip = VTOI(vp); struct lwp *l = curlwp; copyfs = (struct fs *)((char *)sbbuf + blkoff(fs, fs->fs_sblockloc)); /* * 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 = copyfs->fs_csp; #ifdef FFS_EI if (UFS_FSNEEDSWAP(fs)) { ffs_sb_swap(copyfs, copyfs); ffs_csum_swap(space, space, fs->fs_cssize); } #endif error = UFS_WAPBL_BEGIN(mp); if (error) return error; for (loc = 0; loc < len; loc++) { error = bread(vp, blkno + loc, fs->fs_bsize, l->l_cred, B_MODIFY, &bp); if (error) { brelse(bp, 0); break; } bcopy(space, bp->b_data, fs->fs_bsize); space = (char *)space + fs->fs_bsize; bawrite(bp); } if (error) goto out; error = bread(vp, lblkno(fs, fs->fs_sblockloc), fs->fs_bsize, l->l_cred, B_MODIFY, &bp); if (error) { brelse(bp, 0); goto out; } else { bcopy(sbbuf, bp->b_data, fs->fs_bsize); bawrite(bp); } /* * Copy the first NDADDR blocks to the snapshot so ffs_copyonwrite() * and ffs_snapblkfree() will always work on indirect blocks. */ for (loc = 0; loc < NDADDR; loc++) { if (db_get(ip, loc) != 0) continue; error = ffs_balloc(vp, lblktosize(fs, (off_t)loc), fs->fs_bsize, l->l_cred, 0, &bp); if (error) break; error = rwfsblk(vp, B_READ, bp->b_data, loc); if (error) { brelse(bp, 0); break; } bawrite(bp); } out: UFS_WAPBL_END(mp); return error; } /* * Copy all cylinder group maps. */ static int cgaccount(struct vnode *vp, int passno, int *redo) { int cg, error; struct buf *nbp; struct fs *fs = VTOI(vp)->i_fs; error = UFS_WAPBL_BEGIN(vp->v_mount); if (error) return error; if (redo != NULL) *redo = 0; if (passno == 1) fs->fs_active = malloc(howmany(fs->fs_ncg, NBBY), M_DEVBUF, M_WAITOK | M_ZERO); for (cg = 0; cg < fs->fs_ncg; cg++) { if (passno == 2 && ACTIVECG_ISSET(fs, cg)) continue; if (redo != NULL) *redo += 1; error = ffs_balloc(vp, lfragtosize(fs, cgtod(fs, cg)), fs->fs_bsize, curlwp->l_cred, 0, &nbp); if (error) break; error = cgaccount1(cg, vp, nbp->b_data, passno); bawrite(nbp); if (error) break; } UFS_WAPBL_END(vp->v_mount); 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 cgaccount1(int cg, struct vnode *vp, void *data, int passno) { struct buf *bp, *ibp; struct inode *ip; struct cg *cgp; struct fs *fs; struct lwp *l = curlwp; daddr_t base, numblks; int error, len, loc, ns, indiroff; ip = VTOI(vp); fs = ip->i_fs; ns = UFS_FSNEEDSWAP(fs); error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)), (int)fs->fs_cgsize, l->l_cred, 0, &bp); if (error) { brelse(bp, 0); return (error); } cgp = (struct cg *)bp->b_data; if (!cg_chkmagic(cgp, ns)) { brelse(bp, 0); return (EIO); } ACTIVECG_SET(fs, cg); bcopy(bp->b_data, data, fs->fs_cgsize); brelse(bp, 0); if (fs->fs_cgsize < fs->fs_bsize) memset((char *)data + fs->fs_cgsize, 0, fs->fs_bsize - fs->fs_cgsize); numblks = howmany(fs->fs_size, fs->fs_frag); len = howmany(fs->fs_fpg, fs->fs_frag); base = cg * fs->fs_fpg / 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, ns), loc)) db_assign(ip, loc, BLK_NOCOPY); else if (db_get(ip, loc) == BLK_NOCOPY) { if (passno == 2) db_assign(ip, loc, 0); else if (passno == 1) panic("ffs_snapshot: lost direct block"); } } } if ((error = ffs_balloc(vp, lblktosize(fs, (off_t)(base + loc)), fs->fs_bsize, l->l_cred, B_METAONLY, &ibp)) != 0) return (error); indiroff = (base + loc - NDADDR) % NINDIR(fs); for ( ; loc < len; loc++, indiroff++) { if (indiroff >= NINDIR(fs)) { bawrite(ibp); if ((error = ffs_balloc(vp, lblktosize(fs, (off_t)(base + loc)), fs->fs_bsize, l->l_cred, B_METAONLY, &ibp)) != 0) return (error); indiroff = 0; } if (ffs_isblock(fs, cg_blksfree(cgp, ns), loc)) idb_assign(ip, ibp->b_data, indiroff, BLK_NOCOPY); else if (idb_get(ip, ibp->b_data, indiroff) == BLK_NOCOPY) { if (passno == 2) idb_assign(ip, ibp->b_data, indiroff, 0); else if (passno == 1) panic("ffs_snapshot: lost indirect block"); } } 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. */ static int expunge(struct vnode *snapvp, struct inode *cancelip, struct fs *fs, acctfunc_t acctfunc, int expungetype) { int i, error, ns; daddr_t lbn, rlbn; daddr_t len, blkno, numblks, blksperindir; struct ufs1_dinode *dip1; struct ufs2_dinode *dip2; struct lwp *l = curlwp; void *bap; struct buf *bp; ns = UFS_FSNEEDSWAP(fs); /* * 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)); error = snapblkaddr(snapvp, lbn, &blkno); if (error) return error; if (blkno != 0) { error = bread(snapvp, lbn, fs->fs_bsize, l->l_cred, B_MODIFY, &bp); } else { error = ffs_balloc(snapvp, lblktosize(fs, (off_t)lbn), fs->fs_bsize, l->l_cred, 0, &bp); if (! error) error = rwfsblk(snapvp, B_READ, bp->b_data, lbn); } if (error) return error; /* * Set a snapshot inode to be a zero length file, regular files * or unlinked snapshots to be completely unallocated. */ if (fs->fs_magic == FS_UFS1_MAGIC) { dip1 = (struct ufs1_dinode *)bp->b_data + ino_to_fsbo(fs, cancelip->i_number); if (expungetype == BLK_NOCOPY || cancelip->i_ffs_effnlink == 0) dip1->di_mode = 0; dip1->di_size = 0; dip1->di_blocks = 0; dip1->di_flags = ufs_rw32(ufs_rw32(dip1->di_flags, ns) & ~SF_SNAPSHOT, ns); bzero(&dip1->di_db[0], (NDADDR + NIADDR) * sizeof(int32_t)); } else { dip2 = (struct ufs2_dinode *)bp->b_data + ino_to_fsbo(fs, cancelip->i_number); if (expungetype == BLK_NOCOPY || cancelip->i_ffs_effnlink == 0) dip2->di_mode = 0; dip2->di_size = 0; dip2->di_blocks = 0; dip2->di_flags = ufs_rw32(ufs_rw32(dip2->di_flags, ns) & ~SF_SNAPSHOT, ns); bzero(&dip2->di_db[0], (NDADDR + NIADDR) * sizeof(int64_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 (fs->fs_magic == FS_UFS1_MAGIC) bap = &cancelip->i_ffs1_db[0]; else bap = &cancelip->i_ffs2_db[0]; if ((error = (*acctfunc)(snapvp, bap, 0, NDADDR, fs, 0, expungetype))) return (error); if (fs->fs_magic == FS_UFS1_MAGIC) bap = &cancelip->i_ffs1_ib[0]; else bap = &cancelip->i_ffs2_ib[0]; if ((error = (*acctfunc)(snapvp, bap, 0, 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(snapvp, ITOV(cancelip), i, ib_get(cancelip, 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(struct vnode *snapvp, struct vnode *cancelvp, int level, daddr_t blkno, daddr_t lbn, daddr_t rlbn, daddr_t remblks, daddr_t blksperindir, struct fs *fs, acctfunc_t acctfunc, int expungetype) { int error, num, i; daddr_t subblksperindir; struct indir indirs[NIADDR + 2]; daddr_t last; void *bap; struct buf *bp; if (blkno == 0) { if (expungetype == BLK_NOCOPY) return (0); panic("indiracct: 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: 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. */ error = ffs_getblk(cancelvp, lbn, fsbtodb(fs, blkno), fs->fs_bsize, false, &bp); if (error) return error; if ((bp->b_oflags & (BO_DONE | BO_DELWRI)) == 0 && (error = rwfsblk(bp->b_vp, B_READ, bp->b_data, fragstoblks(fs, blkno)))) { brelse(bp, 0); 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, (void *)bap, fs->fs_bsize); brelse(bp, 0); error = (*acctfunc)(snapvp, bap, 0, 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(snapvp, cancelvp, level, idb_get(VTOI(snapvp), 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(struct vnode *vp, void *bap, int oldblkp, int lastblkp, struct fs *fs, daddr_t lblkno, int exptype /* BLK_SNAP or BLK_NOCOPY */) { int error; if ((error = snapacct(vp, bap, oldblkp, lastblkp, fs, lblkno, exptype))) return (error); return (mapacct(vp, bap, oldblkp, lastblkp, fs, lblkno, exptype)); } /* * Identify a set of blocks allocated in a snapshot inode. */ static int snapacct(struct vnode *vp, void *bap, int oldblkp, int lastblkp, struct fs *fs, daddr_t lblkno, int expungetype /* BLK_SNAP or BLK_NOCOPY */) { struct inode *ip = VTOI(vp); struct lwp *l = curlwp; daddr_t blkno; daddr_t lbn; struct buf *ibp; int error; for ( ; oldblkp < lastblkp; oldblkp++) { blkno = idb_get(ip, bap, oldblkp); if (blkno == 0 || blkno == BLK_NOCOPY || blkno == BLK_SNAP) continue; lbn = fragstoblks(fs, blkno); if (lbn < NDADDR) { blkno = db_get(ip, lbn); ip->i_flag |= IN_CHANGE | IN_UPDATE; } else { error = ffs_balloc(vp, lblktosize(fs, (off_t)lbn), fs->fs_bsize, l->l_cred, B_METAONLY, &ibp); if (error) return (error); blkno = idb_get(ip, 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 && blkno == BLK_NOCOPY) { if (lbn >= NDADDR) brelse(ibp, 0); } else { if (blkno != 0) panic("snapacct: bad block"); if (lbn < NDADDR) db_assign(ip, lbn, expungetype); else { idb_assign(ip, ibp->b_data, (lbn - NDADDR) % NINDIR(fs), expungetype); bdwrite(ibp); } } } return (0); } /* * Account for a set of blocks allocated in a snapshot inode. */ static int mapacct(struct vnode *vp, void *bap, int oldblkp, int lastblkp, struct fs *fs, daddr_t lblkno, int expungetype) { 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 = idb_get(ip, bap, 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_snap(fs, vp, blkno, fs->fs_bsize, inum); } return (0); } #endif /* defined(FFS_NO_SNAPSHOT) */ /* * 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(struct inode *ip) { struct mount *mp = ip->i_devvp->v_specmountpoint; struct inode *xp; struct fs *fs; struct snap_info *si; int snaploc; si = VFSTOUFS(mp)->um_snapinfo; /* * Find snapshot in incore list. */ mutex_enter(&si->si_lock); TAILQ_FOREACH(xp, &si->si_snapshots, i_nextsnap) if (xp == ip) break; mutex_exit(&si->si_lock); if (xp != NULL) vrele(ITOV(ip)); #ifdef DEBUG else if (snapdebug) printf("ffs_snapgone: lost snapshot vnode %llu\n", (unsigned long long)ip->i_number); #endif /* * Delete snapshot inode from superblock. Keep list dense. */ mutex_enter(&si->si_lock); fs = ip->i_fs; 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; } si->si_gen++; mutex_exit(&si->si_lock); } /* * Prepare a snapshot file for being removed. */ void ffs_snapremove(struct vnode *vp) { struct inode *ip = VTOI(vp), *xp; struct vnode *devvp = ip->i_devvp; struct fs *fs = ip->i_fs; struct mount *mp = devvp->v_specmountpoint; struct buf *ibp; struct snap_info *si; struct lwp *l = curlwp; daddr_t numblks, blkno, dblk; int error, loc, last; si = VFSTOUFS(mp)->um_snapinfo; mutex_enter(&si->si_snaplock); /* * 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) { mutex_enter(&si->si_lock); TAILQ_REMOVE(&si->si_snapshots, ip, i_nextsnap); ip->i_nextsnap.tqe_prev = 0; if (TAILQ_FIRST(&si->si_snapshots) != 0) { /* Roll back the list of preallocated blocks. */ xp = TAILQ_LAST(&si->si_snapshots, inodelst); si->si_snapblklist = xp->i_snapblklist; } else { si->si_snapblklist = 0; si->si_gen++; mutex_exit(&si->si_lock); fscow_disestablish(mp, ffs_copyonwrite, devvp); mutex_enter(&si->si_lock); } si->si_gen++; mutex_exit(&si->si_lock); if (ip->i_snapblklist != NULL) { free(ip->i_snapblklist, M_UFSMNT); ip->i_snapblklist = NULL; } } mutex_exit(&si->si_snaplock); /* * 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 = db_get(ip, blkno); if (dblk == BLK_NOCOPY || dblk == BLK_SNAP) db_assign(ip, blkno, 0); else if ((dblk == blkstofrags(fs, blkno) && ffs_snapblkfree(fs, ip->i_devvp, dblk, fs->fs_bsize, ip->i_number))) { DIP_ADD(ip, blocks, -btodb(fs->fs_bsize)); db_assign(ip, blkno, 0); } } numblks = howmany(ip->i_size, fs->fs_bsize); for (blkno = NDADDR; blkno < numblks; blkno += NINDIR(fs)) { error = ffs_balloc(vp, lblktosize(fs, (off_t)blkno), fs->fs_bsize, l->l_cred, B_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++) { dblk = idb_get(ip, ibp->b_data, loc); if (dblk == BLK_NOCOPY || dblk == BLK_SNAP) idb_assign(ip, ibp->b_data, loc, 0); else if (dblk == blkstofrags(fs, blkno) && ffs_snapblkfree(fs, ip->i_devvp, dblk, fs->fs_bsize, ip->i_number)) { DIP_ADD(ip, blocks, -btodb(fs->fs_bsize)); idb_assign(ip, ibp->b_data, loc, 0); } } bawrite(ibp); } /* * Clear snapshot flag and drop reference. */ ip->i_flags &= ~SF_SNAPSHOT; DIP_ASSIGN(ip, 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(struct fs *fs, struct vnode *devvp, daddr_t bno, long size, ino_t inum) { struct mount *mp = devvp->v_specmountpoint; struct buf *ibp; struct inode *ip; struct vnode *vp = NULL; struct snap_info *si; void *saved_data = NULL; daddr_t lbn; daddr_t blkno; uint32_t gen; int indiroff = 0, snapshot_locked = 0, error = 0, claimedblk = 0; si = VFSTOUFS(mp)->um_snapinfo; lbn = fragstoblks(fs, bno); mutex_enter(&si->si_lock); retry: gen = si->si_gen; TAILQ_FOREACH(ip, &si->si_snapshots, i_nextsnap) { vp = ITOV(ip); if (snapshot_locked == 0) { if (!mutex_tryenter(&si->si_snaplock)) { mutex_exit(&si->si_lock); mutex_enter(&si->si_snaplock); mutex_enter(&si->si_lock); } snapshot_locked = 1; if (gen != si->si_gen) goto retry; } /* * Lookup block being written. */ if (lbn < NDADDR) { blkno = db_get(ip, lbn); } else { mutex_exit(&si->si_lock); error = ffs_balloc(vp, lblktosize(fs, (off_t)lbn), fs->fs_bsize, FSCRED, B_METAONLY, &ibp); if (error) { mutex_enter(&si->si_lock); break; } indiroff = (lbn - NDADDR) % NINDIR(fs); blkno = idb_get(ip, ibp->b_data, indiroff); mutex_enter(&si->si_lock); if (gen != si->si_gen) { brelse(ibp, 0); goto retry; } } /* * 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 < NDADDR) { db_assign(ip, lbn, BLK_NOCOPY); ip->i_flag |= IN_CHANGE | IN_UPDATE; } else { idb_assign(ip, ibp->b_data, indiroff, BLK_NOCOPY); mutex_exit(&si->si_lock); if (ip->i_ffs_effnlink > 0) bwrite(ibp); else bdwrite(ibp); mutex_enter(&si->si_lock); if (gen != si->si_gen) goto retry; } 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) brelse(ibp, 0); 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 %llu lbn %" PRId64 "from inum %llu\n", "Grabonremove: snapino", (unsigned long long)ip->i_number, lbn, (unsigned long long)inum); #endif mutex_exit(&si->si_lock); if (lbn < NDADDR) { db_assign(ip, lbn, bno); } else { idb_assign(ip, ibp->b_data, indiroff, bno); if (ip->i_ffs_effnlink > 0) bwrite(ibp); else bdwrite(ibp); } DIP_ADD(ip, blocks, btodb(size)); ip->i_flag |= IN_CHANGE | IN_UPDATE; if (ip->i_ffs_effnlink > 0 && mp->mnt_wapbl) error = syncsnap(vp); else error = 0; mutex_exit(&si->si_snaplock); return (error == 0); } if (lbn >= NDADDR) brelse(ibp, 0); #ifdef DEBUG if (snapdebug) printf("%s%llu lbn %" PRId64 " %s %llu size %ld\n", "Copyonremove: snapino ", (unsigned long long)ip->i_number, lbn, "for inum", (unsigned long long)inum, size); #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. */ mutex_exit(&si->si_lock); if (saved_data == NULL) { saved_data = malloc(fs->fs_bsize, M_UFSMNT, M_WAITOK); error = rwfsblk(vp, B_READ, saved_data, lbn); if (error) { free(saved_data, M_UFSMNT); saved_data = NULL; mutex_enter(&si->si_lock); break; } } error = wrsnapblk(vp, saved_data, lbn); if (error == 0 && ip->i_ffs_effnlink > 0 && mp->mnt_wapbl) error = syncsnap(vp); mutex_enter(&si->si_lock); if (error) break; if (gen != si->si_gen) goto retry; } mutex_exit(&si->si_lock); if (saved_data) free(saved_data, M_UFSMNT); /* * 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) mutex_exit(&si->si_snaplock); return (error); } /* * Associate snapshot files when mounting. */ void ffs_snapshot_mount(struct mount *mp) { struct vnode *devvp = VFSTOUFS(mp)->um_devvp; struct fs *fs = VFSTOUFS(mp)->um_fs; struct lwp *l = curlwp; struct vnode *vp; struct inode *ip, *xp; struct snap_info *si; daddr_t snaplistsize, *snapblklist; int i, error, ns, snaploc, loc; /* * No persistent snapshots on apple ufs file systems. */ if (UFS_MPISAPPLEUFS(VFSTOUFS(mp))) return; si = VFSTOUFS(mp)->um_snapinfo; ns = UFS_FSNEEDSWAP(fs); /* * 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; mutex_enter(&si->si_lock); for (snaploc = 0; snaploc < FSMAXSNAP; snaploc++) { if (fs->fs_snapinum[snaploc] == 0) break; if ((error = VFS_VGET(mp, fs->fs_snapinum[snaploc], &vp)) != 0) { printf("ffs_snapshot_mount: vget failed %d\n", error); continue; } ip = VTOI(vp); if ((ip->i_flags & SF_SNAPSHOT) == 0) { printf("ffs_snapshot_mount: non-snapshot inode %d\n", 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; } /* * Read the block hints list. Use an empty list on * read errors. */ error = vn_rdwr(UIO_READ, vp, (void *)&snaplistsize, sizeof(snaplistsize), lblktosize(fs, howmany(fs->fs_size, fs->fs_frag)), UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT, l->l_cred, NULL, NULL); if (error) { printf("ffs_snapshot_mount: read_1 failed %d\n", error); snaplistsize = 1; } else snaplistsize = ufs_rw64(snaplistsize, ns); snapblklist = malloc( snaplistsize * sizeof(daddr_t), M_UFSMNT, M_WAITOK); if (error) snapblklist[0] = 1; else { error = vn_rdwr(UIO_READ, vp, (void *)snapblklist, snaplistsize * sizeof(daddr_t), lblktosize(fs, howmany(fs->fs_size, fs->fs_frag)), UIO_SYSSPACE, IO_NODELOCKED|IO_UNIT, l->l_cred, NULL, NULL); for (i = 0; i < snaplistsize; i++) snapblklist[i] = ufs_rw64(snapblklist[i], ns); if (error) { printf("ffs_snapshot_mount: read_2 failed %d\n", error); snapblklist[0] = 1; } } ip->i_snapblklist = &snapblklist[0]; /* * Link it onto the active snapshot list. */ if (ip->i_nextsnap.tqe_prev != 0) panic("ffs_snapshot_mount: %llu already on list", (unsigned long long)ip->i_number); else TAILQ_INSERT_TAIL(&si->si_snapshots, ip, i_nextsnap); vp->v_vflag |= VV_SYSTEM; VOP_UNLOCK(vp, 0); } /* * No usable snapshots found. */ if (vp == NULL) { mutex_exit(&si->si_lock); return; } /* * Attach the block hints list. We always want to * use the list from the newest snapshot. */ xp = TAILQ_LAST(&si->si_snapshots, inodelst); si->si_snapblklist = xp->i_snapblklist; fscow_establish(mp, ffs_copyonwrite, devvp); si->si_gen++; mutex_exit(&si->si_lock); } /* * Disassociate snapshot files when unmounting. */ void ffs_snapshot_unmount(struct mount *mp) { struct vnode *devvp = VFSTOUFS(mp)->um_devvp; struct inode *xp; struct vnode *vp = NULL; struct snap_info *si; si = VFSTOUFS(mp)->um_snapinfo; mutex_enter(&si->si_lock); while ((xp = TAILQ_FIRST(&si->si_snapshots)) != 0) { vp = ITOV(xp); vp->v_vnlock = &vp->v_lock; TAILQ_REMOVE(&si->si_snapshots, xp, i_nextsnap); xp->i_nextsnap.tqe_prev = 0; if (xp->i_snapblklist == si->si_snapblklist) si->si_snapblklist = NULL; FREE(xp->i_snapblklist, M_UFSMNT); if (xp->i_ffs_effnlink > 0) { si->si_gen++; mutex_exit(&si->si_lock); vrele(vp); mutex_enter(&si->si_lock); } } if (vp) fscow_disestablish(mp, ffs_copyonwrite, devvp); si->si_gen++; mutex_exit(&si->si_lock); } /* * Check for need to copy block that is about to be written, * copying the block if necessary. */ static int ffs_copyonwrite(void *v, struct buf *bp, bool data_valid) { struct fs *fs; struct inode *ip; struct vnode *devvp = v, *vp = NULL; struct mount *mp = devvp->v_specmountpoint; struct snap_info *si; void *saved_data = NULL; daddr_t lbn, blkno, *snapblklist; uint32_t gen; int lower, upper, mid, snapshot_locked = 0, error = 0; /* * Check for valid snapshots. */ si = VFSTOUFS(mp)->um_snapinfo; mutex_enter(&si->si_lock); ip = TAILQ_FIRST(&si->si_snapshots); if (ip == NULL) { mutex_exit(&si->si_lock); return 0; } /* * First check to see if it is after the file system or * in the preallocated list. * By doing this check we avoid several potential deadlocks. */ fs = ip->i_fs; lbn = fragstoblks(fs, dbtofsb(fs, bp->b_blkno)); if (bp->b_blkno >= fsbtodb(fs, fs->fs_size)) { mutex_exit(&si->si_lock); return 0; } snapblklist = si->si_snapblklist; upper = si->si_snapblklist[0] - 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) { mutex_exit(&si->si_lock); return 0; } /* * Not in the precomputed list, so check the snapshots. */ if (data_valid && bp->b_bcount == fs->fs_bsize) saved_data = bp->b_data; retry: gen = si->si_gen; TAILQ_FOREACH(ip, &si->si_snapshots, 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 ffs_balloc. */ if (bp->b_vp == vp) continue; /* * Check to see if block needs to be copied. */ if (lbn < NDADDR) { blkno = db_get(ip, lbn); } else { mutex_exit(&si->si_lock); if ((error = snapblkaddr(vp, lbn, &blkno)) != 0) { mutex_enter(&si->si_lock); break; } mutex_enter(&si->si_lock); if (gen != si->si_gen) goto retry; } #ifdef DIAGNOSTIC if (blkno == BLK_SNAP && bp->b_lblkno >= 0) panic("ffs_copyonwrite: bad copy block"); #endif if (blkno != 0) continue; if (curlwp == uvm.pagedaemon_lwp) { error = ENOMEM; break; } if (snapshot_locked == 0) { if (!mutex_tryenter(&si->si_snaplock)) { mutex_exit(&si->si_lock); mutex_enter(&si->si_snaplock); mutex_enter(&si->si_lock); } snapshot_locked = 1; if (gen != si->si_gen) goto retry; /* Check again if block still needs to be copied */ if (lbn < NDADDR) { blkno = db_get(ip, lbn); } else { mutex_exit(&si->si_lock); if ((error = snapblkaddr(vp, lbn, &blkno)) != 0) { mutex_enter(&si->si_lock); break; } mutex_enter(&si->si_lock); if (gen != si->si_gen) goto retry; } 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. */ #ifdef DEBUG if (snapdebug) { printf("Copyonwrite: snapino %llu lbn %" PRId64 " for ", (unsigned long long)ip->i_number, lbn); if (bp->b_vp == devvp) printf("fs metadata"); else printf("inum %llu", (unsigned long long) VTOI(bp->b_vp)->i_number); printf(" lblkno %" PRId64 "\n", bp->b_lblkno); } #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. */ mutex_exit(&si->si_lock); if (saved_data == NULL) { saved_data = malloc(fs->fs_bsize, M_UFSMNT, M_WAITOK); error = rwfsblk(vp, B_READ, saved_data, lbn); if (error) { free(saved_data, M_UFSMNT); saved_data = NULL; mutex_enter(&si->si_lock); break; } } error = wrsnapblk(vp, saved_data, lbn); if (error == 0 && ip->i_ffs_effnlink > 0 && mp->mnt_wapbl) error = syncsnap(vp); mutex_enter(&si->si_lock); if (error) break; if (gen != si->si_gen) goto retry; } /* * 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. */ mutex_exit(&si->si_lock); if (saved_data && saved_data != bp->b_data) free(saved_data, M_UFSMNT); if (snapshot_locked) mutex_exit(&si->si_snaplock); return error; } /* * Read from a snapshot. */ int ffs_snapshot_read(struct vnode *vp, struct uio *uio, int ioflag) { struct inode *ip = VTOI(vp); struct fs *fs = ip->i_fs; struct snap_info *si = VFSTOUFS(vp->v_mount)->um_snapinfo; struct buf *bp; daddr_t lbn, nextlbn; off_t fsbytes, bytesinfile; long size, xfersize, blkoffset; int error; fstrans_start(vp->v_mount, FSTRANS_SHARED); mutex_enter(&si->si_snaplock); fsbytes = lfragtosize(fs, fs->fs_size); for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) { bytesinfile = fsbytes - uio->uio_offset; if (bytesinfile <= 0) break; lbn = lblkno(fs, uio->uio_offset); nextlbn = lbn + 1; size = fs->fs_bsize; blkoffset = blkoff(fs, uio->uio_offset); xfersize = MIN(MIN(fs->fs_bsize - blkoffset, uio->uio_resid), bytesinfile); if (lblktosize(fs, nextlbn + 1) >= fsbytes) { if (lblktosize(fs, lbn) + size > fsbytes) size = fsbytes - lblktosize(fs, lbn); error = bread(vp, lbn, size, NOCRED, 0, &bp); } else { int nextsize = fs->fs_bsize; error = breadn(vp, lbn, size, &nextlbn, &nextsize, 1, NOCRED, 0, &bp); } if (error) break; /* * We should only get non-zero b_resid when an I/O error * has occurred, which should cause us to break above. * However, if the short read did not cause an error, * then we want to ensure that we do not uiomove bad * or uninitialized data. */ size -= bp->b_resid; if (size < blkoffset + xfersize) { xfersize = size - blkoffset; if (xfersize <= 0) break; } error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio); if (error) break; brelse(bp, BC_AGE); } if (bp != NULL) brelse(bp, BC_AGE); mutex_exit(&si->si_snaplock); fstrans_done(vp->v_mount); return error; } /* * Lookup a snapshots data block address. * Simpler than UFS_BALLOC() as we know all metadata is already allocated * and safe even for the pagedaemon where we cannot bread(). */ static int snapblkaddr(struct vnode *vp, daddr_t lbn, daddr_t *res) { struct indir indirs[NIADDR + 2]; struct inode *ip = VTOI(vp); struct fs *fs = ip->i_fs; struct buf *bp; int error, num; KASSERT(lbn >= 0); if (lbn < NDADDR) { *res = db_get(ip, lbn); return 0; } if ((error = ufs_getlbns(vp, lbn, indirs, &num)) != 0) return error; if (curlwp == uvm.pagedaemon_lwp) { mutex_enter(&bufcache_lock); bp = incore(vp, indirs[num-1].in_lbn); if (bp && (bp->b_oflags & (BO_DONE | BO_DELWRI))) { *res = idb_get(ip, bp->b_data, indirs[num-1].in_off); error = 0; } else error = ENOMEM; mutex_exit(&bufcache_lock); return error; } error = bread(vp, indirs[num-1].in_lbn, fs->fs_bsize, NOCRED, 0, &bp); if (error == 0) *res = idb_get(ip, bp->b_data, indirs[num-1].in_off); brelse(bp, 0); return error; } /* * Read or write the specified block of the filesystem vp resides on * from or to the disk bypassing the buffer cache. */ static int rwfsblk(struct vnode *vp, int flags, void *data, daddr_t lbn) { int error; struct inode *ip = VTOI(vp); struct fs *fs = ip->i_fs; struct buf *nbp; nbp = getiobuf(NULL, true); nbp->b_flags = flags; nbp->b_bcount = nbp->b_bufsize = fs->fs_bsize; nbp->b_error = 0; nbp->b_data = data; nbp->b_blkno = nbp->b_rawblkno = fsbtodb(fs, blkstofrags(fs, lbn)); nbp->b_proc = NULL; nbp->b_dev = ip->i_devvp->v_rdev; SET(nbp->b_cflags, BC_BUSY); /* mark buffer busy */ bdev_strategy(nbp); error = biowait(nbp); putiobuf(nbp); return error; } /* * Write all dirty buffers to disk and invalidate them. */ static int syncsnap(struct vnode *vp) { int error; buf_t *bp; struct fs *fs = VTOI(vp)->i_fs; mutex_enter(&bufcache_lock); while ((bp = LIST_FIRST(&vp->v_dirtyblkhd))) { KASSERT((bp->b_cflags & BC_BUSY) == 0); KASSERT(bp->b_bcount == fs->fs_bsize); bp->b_cflags |= BC_BUSY; mutex_exit(&bufcache_lock); error = rwfsblk(vp, B_WRITE, bp->b_data, fragstoblks(fs, dbtofsb(fs, bp->b_blkno))); brelse(bp, BC_INVAL | BC_VFLUSH); if (error) return error; mutex_enter(&bufcache_lock); } mutex_exit(&bufcache_lock); return 0; } /* * Write the specified block to a snapshot. */ static int wrsnapblk(struct vnode *vp, void *data, daddr_t lbn) { struct inode *ip = VTOI(vp); struct fs *fs = ip->i_fs; struct buf *bp; int error; error = ffs_balloc(vp, lblktosize(fs, (off_t)lbn), fs->fs_bsize, FSCRED, (ip->i_ffs_effnlink > 0 ? B_SYNC : 0), &bp); if (error) return error; bcopy(data, bp->b_data, fs->fs_bsize); if (ip->i_ffs_effnlink > 0) error = bwrite(bp); else bawrite(bp); return error; } /* * Get/Put direct block from inode or buffer containing disk addresses. Take * care for fs type (UFS1/UFS2) and byte swapping. These functions should go * into a global include. */ static inline daddr_t db_get(struct inode *ip, int loc) { if (ip->i_ump->um_fstype == UFS1) return ufs_rw32(ip->i_ffs1_db[loc], UFS_IPNEEDSWAP(ip)); else return ufs_rw64(ip->i_ffs2_db[loc], UFS_IPNEEDSWAP(ip)); } static inline void db_assign(struct inode *ip, int loc, daddr_t val) { if (ip->i_ump->um_fstype == UFS1) ip->i_ffs1_db[loc] = ufs_rw32(val, UFS_IPNEEDSWAP(ip)); else ip->i_ffs2_db[loc] = ufs_rw64(val, UFS_IPNEEDSWAP(ip)); } static inline daddr_t ib_get(struct inode *ip, int loc) { if (ip->i_ump->um_fstype == UFS1) return ufs_rw32(ip->i_ffs1_ib[loc], UFS_IPNEEDSWAP(ip)); else return ufs_rw64(ip->i_ffs2_ib[loc], UFS_IPNEEDSWAP(ip)); } static inline void ib_assign(struct inode *ip, int loc, daddr_t val) { if (ip->i_ump->um_fstype == UFS1) ip->i_ffs1_ib[loc] = ufs_rw32(val, UFS_IPNEEDSWAP(ip)); else ip->i_ffs2_ib[loc] = ufs_rw64(val, UFS_IPNEEDSWAP(ip)); } static inline daddr_t idb_get(struct inode *ip, void *bf, int loc) { if (ip->i_ump->um_fstype == UFS1) return ufs_rw32(((int32_t *)(bf))[loc], UFS_IPNEEDSWAP(ip)); else return ufs_rw64(((int64_t *)(bf))[loc], UFS_IPNEEDSWAP(ip)); } static inline void idb_assign(struct inode *ip, void *bf, int loc, daddr_t val) { if (ip->i_ump->um_fstype == UFS1) ((int32_t *)(bf))[loc] = ufs_rw32(val, UFS_IPNEEDSWAP(ip)); else ((int64_t *)(bf))[loc] = ufs_rw64(val, UFS_IPNEEDSWAP(ip)); }