/* $NetBSD: fss.c,v 1.15 2005/04/17 16:28:26 hannken Exp $ */ /*- * Copyright (c) 2003 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Juergen Hannken-Illjes. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * File system snapshot disk driver. * * Block/character interface to the snapshot of a mounted file system. */ #include __KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.15 2005/04/17 16:28:26 hannken Exp $"); #include "fss.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DEBUG #define FSS_STATISTICS #endif #ifdef FSS_STATISTICS struct fss_stat { u_int64_t cow_calls; u_int64_t cow_copied; u_int64_t cow_cache_full; u_int64_t indir_read; u_int64_t indir_write; }; static struct fss_stat fss_stat[NFSS]; #define FSS_STAT_INC(sc, field) \ do { \ fss_stat[sc->sc_unit].field++; \ } while (0) #define FSS_STAT_SET(sc, field, value) \ do { \ fss_stat[sc->sc_unit].field = value; \ } while (0) #define FSS_STAT_ADD(sc, field, value) \ do { \ fss_stat[sc->sc_unit].field += value; \ } while (0) #define FSS_STAT_VAL(sc, field) fss_stat[sc->sc_unit].field #define FSS_STAT_CLEAR(sc) \ do { \ memset(&fss_stat[sc->sc_unit], 0, \ sizeof(struct fss_stat)); \ } while (0) #else /* FSS_STATISTICS */ #define FSS_STAT_INC(sc, field) #define FSS_STAT_SET(sc, field, value) #define FSS_STAT_ADD(sc, field, value) #define FSS_STAT_CLEAR(sc) #endif /* FSS_STATISTICS */ static struct fss_softc fss_softc[NFSS]; void fssattach(int); dev_type_open(fss_open); dev_type_close(fss_close); dev_type_read(fss_read); dev_type_write(fss_write); dev_type_ioctl(fss_ioctl); dev_type_strategy(fss_strategy); dev_type_dump(fss_dump); dev_type_size(fss_size); static int fss_copy_on_write(void *, struct buf *); static inline void fss_error(struct fss_softc *, const char *, ...); static int fss_create_files(struct fss_softc *, struct fss_set *, off_t *, struct proc *); static int fss_create_snapshot(struct fss_softc *, struct fss_set *, struct proc *); static int fss_delete_snapshot(struct fss_softc *, struct proc *); static int fss_softc_alloc(struct fss_softc *); static void fss_softc_free(struct fss_softc *); static void fss_cluster_iodone(struct buf *); static void fss_read_cluster(struct fss_softc *, u_int32_t); static int fss_write_cluster(struct fss_cache *, u_int32_t); static void fss_bs_thread(void *); static int fss_bmap(struct fss_softc *, off_t, int, struct vnode **, daddr_t *, int *); static int fss_bs_io(struct fss_softc *, fss_io_type, u_int32_t, off_t, int, caddr_t); static u_int32_t *fss_bs_indir(struct fss_softc *, u_int32_t); const struct bdevsw fss_bdevsw = { fss_open, fss_close, fss_strategy, fss_ioctl, fss_dump, fss_size, D_DISK }; const struct cdevsw fss_cdevsw = { fss_open, fss_close, fss_read, fss_write, fss_ioctl, nostop, notty, nopoll, nommap, nokqfilter, D_DISK }; void fssattach(int num) { int i; struct fss_softc *sc; for (i = 0; i < NFSS; i++) { sc = &fss_softc[i]; sc->sc_unit = i; sc->sc_bdev = NODEV; simple_lock_init(&sc->sc_slock); bufq_alloc(&sc->sc_bufq, BUFQ_FCFS|BUFQ_SORT_RAWBLOCK); } } int fss_open(dev_t dev, int flags, int mode, struct proc *p) { int s, mflag; struct fss_softc *sc; mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN); if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL) return ENODEV; FSS_LOCK(sc, s); sc->sc_flags |= mflag; FSS_UNLOCK(sc, s); return 0; } int fss_close(dev_t dev, int flags, int mode, struct proc *p) { int s, mflag, error; struct fss_softc *sc; mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN); if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL) return ENODEV; FSS_LOCK(sc, s); if ((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) == mflag) { if ((sc->sc_uflags & FSS_UNCONFIG_ON_CLOSE) != 0 && (sc->sc_flags & FSS_ACTIVE) != 0) { FSS_UNLOCK(sc, s); error = fss_ioctl(dev, FSSIOCCLR, NULL, FWRITE, p); if (error) return error; FSS_LOCK(sc, s); } sc->sc_uflags &= ~FSS_UNCONFIG_ON_CLOSE; } sc->sc_flags &= ~mflag; FSS_UNLOCK(sc, s); return 0; } void fss_strategy(struct buf *bp) { int s; struct fss_softc *sc; sc = FSS_DEV_TO_SOFTC(bp->b_dev); FSS_LOCK(sc, s); if ((bp->b_flags & B_READ) != B_READ || sc == NULL || !FSS_ISVALID(sc)) { FSS_UNLOCK(sc, s); bp->b_error = (sc == NULL ? ENODEV : EROFS); bp->b_flags |= B_ERROR; bp->b_resid = bp->b_bcount; biodone(bp); return; } bp->b_rawblkno = bp->b_blkno; BUFQ_PUT(&sc->sc_bufq, bp); wakeup(&sc->sc_bs_proc); FSS_UNLOCK(sc, s); } int fss_read(dev_t dev, struct uio *uio, int flags) { return physio(fss_strategy, NULL, dev, B_READ, minphys, uio); } int fss_write(dev_t dev, struct uio *uio, int flags) { return physio(fss_strategy, NULL, dev, B_WRITE, minphys, uio); } int fss_ioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p) { int s, error; struct fss_softc *sc; struct fss_set *fss = (struct fss_set *)data; struct fss_get *fsg = (struct fss_get *)data; if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL) return ENODEV; FSS_LOCK(sc, s); while ((sc->sc_flags & FSS_EXCL) == FSS_EXCL) { error = ltsleep(sc, PRIBIO|PCATCH, "fsslock", 0, &sc->sc_slock); if (error) { FSS_UNLOCK(sc, s); return error; } } sc->sc_flags |= FSS_EXCL; FSS_UNLOCK(sc, s); switch (cmd) { case FSSIOCSET: if ((flag & FWRITE) == 0) error = EPERM; else if ((sc->sc_flags & FSS_ACTIVE) != 0) error = EBUSY; else error = fss_create_snapshot(sc, fss, p); break; case FSSIOCCLR: if ((flag & FWRITE) == 0) error = EPERM; else if ((sc->sc_flags & FSS_ACTIVE) == 0) error = ENXIO; else error = fss_delete_snapshot(sc, p); break; case FSSIOCGET: switch (sc->sc_flags & (FSS_PERSISTENT | FSS_ACTIVE)) { case FSS_ACTIVE: memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN); fsg->fsg_csize = FSS_CLSIZE(sc); fsg->fsg_time = sc->sc_time; fsg->fsg_mount_size = sc->sc_clcount; fsg->fsg_bs_size = sc->sc_clnext; error = 0; break; case FSS_PERSISTENT | FSS_ACTIVE: memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN); fsg->fsg_csize = 0; fsg->fsg_time = sc->sc_time; fsg->fsg_mount_size = 0; fsg->fsg_bs_size = 0; error = 0; break; default: error = ENXIO; break; } break; case FSSIOFSET: sc->sc_uflags = *(int *)data; error = 0; break; case FSSIOFGET: *(int *)data = sc->sc_uflags; error = 0; break; default: error = EINVAL; break; } FSS_LOCK(sc, s); sc->sc_flags &= ~FSS_EXCL; FSS_UNLOCK(sc, s); wakeup(sc); return error; } int fss_size(dev_t dev) { return -1; } int fss_dump(dev_t dev, daddr_t blkno, caddr_t va, size_t size) { return EROFS; } /* * An error occurred reading or writing the snapshot or backing store. * If it is the first error log to console. * The caller holds the simplelock. */ static inline void fss_error(struct fss_softc *sc, const char *fmt, ...) { va_list ap; if ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE) { va_start(ap, fmt); printf("fss%d: snapshot invalid: ", sc->sc_unit); vprintf(fmt, ap); printf("\n"); va_end(ap); } if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE) sc->sc_flags |= FSS_ERROR; } /* * Allocate the variable sized parts of the softc and * fork the kernel thread. * * The fields sc_clcount, sc_clshift, sc_cache_size and sc_indir_size * must be initialized. */ static int fss_softc_alloc(struct fss_softc *sc) { int i, len, error; len = (sc->sc_clcount+NBBY-1)/NBBY; sc->sc_copied = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); if (sc->sc_copied == NULL) return(ENOMEM); len = sc->sc_cache_size*sizeof(struct fss_cache); sc->sc_cache = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); if (sc->sc_cache == NULL) return(ENOMEM); len = FSS_CLSIZE(sc); for (i = 0; i < sc->sc_cache_size; i++) { sc->sc_cache[i].fc_type = FSS_CACHE_FREE; sc->sc_cache[i].fc_softc = sc; sc->sc_cache[i].fc_xfercount = 0; sc->sc_cache[i].fc_data = malloc(len, M_TEMP, M_WAITOK|M_CANFAIL); if (sc->sc_cache[i].fc_data == NULL) return(ENOMEM); } len = (sc->sc_indir_size+NBBY-1)/NBBY; sc->sc_indir_valid = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); if (sc->sc_indir_valid == NULL) return(ENOMEM); len = FSS_CLSIZE(sc); sc->sc_indir_data = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); if (sc->sc_indir_data == NULL) return(ENOMEM); if ((error = kthread_create1(fss_bs_thread, sc, &sc->sc_bs_proc, "fssbs%d", sc->sc_unit)) != 0) return error; sc->sc_flags |= FSS_BS_THREAD; return 0; } /* * Free the variable sized parts of the softc. */ static void fss_softc_free(struct fss_softc *sc) { int s, i; if ((sc->sc_flags & FSS_BS_THREAD) != 0) { FSS_LOCK(sc, s); sc->sc_flags &= ~FSS_BS_THREAD; wakeup(&sc->sc_bs_proc); while (sc->sc_bs_proc != NULL) ltsleep(&sc->sc_bs_proc, PRIBIO, "fssthread", 0, &sc->sc_slock); FSS_UNLOCK(sc, s); } if (sc->sc_copied != NULL) free(sc->sc_copied, M_TEMP); sc->sc_copied = NULL; if (sc->sc_cache != NULL) { for (i = 0; i < sc->sc_cache_size; i++) if (sc->sc_cache[i].fc_data != NULL) free(sc->sc_cache[i].fc_data, M_TEMP); free(sc->sc_cache, M_TEMP); } sc->sc_cache = NULL; if (sc->sc_indir_valid != NULL) free(sc->sc_indir_valid, M_TEMP); sc->sc_indir_valid = NULL; if (sc->sc_indir_data != NULL) free(sc->sc_indir_data, M_TEMP); sc->sc_indir_data = NULL; } /* * Check if an unmount is ok. If forced, set this snapshot into ERROR state. */ int fss_umount_hook(struct mount *mp, int forced) { int i, s; for (i = 0; i < NFSS; i++) { FSS_LOCK(&fss_softc[i], s); if ((fss_softc[i].sc_flags & FSS_ACTIVE) != 0 && fss_softc[i].sc_mount == mp) { if (forced) fss_error(&fss_softc[i], "forced unmount"); else { FSS_UNLOCK(&fss_softc[i], s); return EBUSY; } } FSS_UNLOCK(&fss_softc[i], s); } return 0; } /* * A buffer is written to the snapshotted block device. Copy to * backing store if needed. */ static int fss_copy_on_write(void *v, struct buf *bp) { int s; u_int32_t cl, ch, c; struct fss_softc *sc = v; FSS_LOCK(sc, s); if (!FSS_ISVALID(sc)) { FSS_UNLOCK(sc, s); return 0; } FSS_UNLOCK(sc, s); FSS_STAT_INC(sc, cow_calls); cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); for (c = cl; c <= ch; c++) fss_read_cluster(sc, c); return 0; } /* * Lookup and open needed files. * * For file system internal snapshot initializes sc_mntname, sc_mount, * sc_bs_vp and sc_time. * * Otherwise returns dev and size of the underlying block device. * Initializes sc_mntname, sc_mount_vp, sc_bdev, sc_bs_vp and sc_mount */ static int fss_create_files(struct fss_softc *sc, struct fss_set *fss, off_t *bsize, struct proc *p) { int error, bits, fsbsize; struct timespec ts; struct partinfo dpart; struct vattr va; struct nameidata nd; /* * Get the mounted file system. */ NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_mount, p); if ((error = namei(&nd)) != 0) return error; if ((nd.ni_vp->v_flag & VROOT) != VROOT) { vrele(nd.ni_vp); return EINVAL; } sc->sc_mount = nd.ni_vp->v_mount; memcpy(sc->sc_mntname, sc->sc_mount->mnt_stat.f_mntonname, MNAMELEN); vrele(nd.ni_vp); /* * Check for file system internal snapshot. */ NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, p); if ((error = namei(&nd)) != 0) return error; if (nd.ni_vp->v_type == VREG && nd.ni_vp->v_mount == sc->sc_mount) { vrele(nd.ni_vp); sc->sc_flags |= FSS_PERSISTENT; NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, p); if ((error = vn_open(&nd, FREAD, 0)) != 0) return error; sc->sc_bs_vp = nd.ni_vp; fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; bits = sizeof(sc->sc_bs_bshift)*NBBY; for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < bits; sc->sc_bs_bshift++) if (FSS_FSBSIZE(sc) == fsbsize) break; if (sc->sc_bs_bshift >= bits) { VOP_UNLOCK(sc->sc_bs_vp, 0); return EINVAL; } sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; sc->sc_clshift = 0; error = VFS_SNAPSHOT(sc->sc_mount, sc->sc_bs_vp, &ts); TIMESPEC_TO_TIMEVAL(&sc->sc_time, &ts); VOP_UNLOCK(sc->sc_bs_vp, 0); return error; } vrele(nd.ni_vp); /* * Get the block device it is mounted on. */ NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, sc->sc_mount->mnt_stat.f_mntfromname, p); if ((error = namei(&nd)) != 0) return error; if (nd.ni_vp->v_type != VBLK) { vrele(nd.ni_vp); return EINVAL; } error = VOP_IOCTL(nd.ni_vp, DIOCGPART, &dpart, FREAD, p->p_ucred, p); if (error) { vrele(nd.ni_vp); return error; } sc->sc_mount_vp = nd.ni_vp; sc->sc_bdev = nd.ni_vp->v_rdev; *bsize = (off_t)dpart.disklab->d_secsize*dpart.part->p_size; vrele(nd.ni_vp); /* * Get the backing store */ NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, p); if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0) return error; VOP_UNLOCK(nd.ni_vp, 0); sc->sc_bs_vp = nd.ni_vp; if (nd.ni_vp->v_type != VREG && nd.ni_vp->v_type != VCHR) return EINVAL; if (sc->sc_bs_vp->v_type == VREG) { error = VOP_GETATTR(sc->sc_bs_vp, &va, p->p_ucred, p); if (error != 0) return error; sc->sc_bs_size = va.va_size; fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; if (fsbsize & (fsbsize-1)) /* No power of two */ return EINVAL; for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < 32; sc->sc_bs_bshift++) if (FSS_FSBSIZE(sc) == fsbsize) break; if (sc->sc_bs_bshift >= 32) return EINVAL; sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; sc->sc_flags |= FSS_BS_ALLOC; } else { sc->sc_bs_bshift = DEV_BSHIFT; sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; sc->sc_flags &= ~FSS_BS_ALLOC; } /* * As all IO to from/to the backing store goes through * VOP_STRATEGY() clean the buffer cache to prevent * cache incoherencies. */ if ((error = vinvalbuf(sc->sc_bs_vp, V_SAVE, p->p_ucred, p, 0, 0)) != 0) return error; return 0; } /* * Create a snapshot. */ static int fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct proc *p) { int len, error; u_int32_t csize; off_t bsize; /* * Open needed files. */ if ((error = fss_create_files(sc, fss, &bsize, p)) != 0) goto bad; if (sc->sc_flags & FSS_PERSISTENT) { fss_softc_alloc(sc); sc->sc_flags |= FSS_ACTIVE; return 0; } /* * Set cluster size. Must be a power of two and * a multiple of backing store block size. */ if (fss->fss_csize <= 0) csize = MAXPHYS; else csize = fss->fss_csize; if (bsize/csize > FSS_CLUSTER_MAX) csize = bsize/FSS_CLUSTER_MAX+1; for (sc->sc_clshift = sc->sc_bs_bshift; sc->sc_clshift < 32; sc->sc_clshift++) if (FSS_CLSIZE(sc) >= csize) break; if (sc->sc_clshift >= 32) { error = EINVAL; goto bad; } sc->sc_clmask = FSS_CLSIZE(sc)-1; /* * Set number of cache slots. */ if (FSS_CLSIZE(sc) <= 8192) sc->sc_cache_size = 32; else if (FSS_CLSIZE(sc) <= 65536) sc->sc_cache_size = 8; else sc->sc_cache_size = 4; /* * Set number of clusters and size of last cluster. */ sc->sc_clcount = FSS_BTOCL(sc, bsize-1)+1; sc->sc_clresid = FSS_CLOFF(sc, bsize-1)+1; /* * Set size of indirect table. */ len = sc->sc_clcount*sizeof(u_int32_t); sc->sc_indir_size = FSS_BTOCL(sc, len)+1; sc->sc_clnext = sc->sc_indir_size; sc->sc_indir_cur = 0; if ((error = fss_softc_alloc(sc)) != 0) goto bad; /* * Activate the snapshot. */ if ((error = vfs_write_suspend(sc->sc_mount, PUSER|PCATCH, 0)) != 0) goto bad; microtime(&sc->sc_time); if (error == 0) error = vn_cow_establish(sc->sc_mount_vp, fss_copy_on_write, sc); if (error == 0) sc->sc_flags |= FSS_ACTIVE; vfs_write_resume(sc->sc_mount); if (error != 0) goto bad; #ifdef DEBUG printf("fss%d: %s snapshot active\n", sc->sc_unit, sc->sc_mntname); printf("fss%d: %u clusters of %u, %u cache slots, %u indir clusters\n", sc->sc_unit, sc->sc_clcount, FSS_CLSIZE(sc), sc->sc_cache_size, sc->sc_indir_size); #endif return 0; bad: fss_softc_free(sc); if (sc->sc_bs_vp != NULL) { if (sc->sc_flags & FSS_PERSISTENT) vn_close(sc->sc_bs_vp, FREAD, p->p_ucred, p); else vn_close(sc->sc_bs_vp, FREAD|FWRITE, p->p_ucred, p); } sc->sc_bs_vp = NULL; return error; } /* * Delete a snapshot. */ static int fss_delete_snapshot(struct fss_softc *sc, struct proc *p) { int s; if ((sc->sc_flags & FSS_PERSISTENT) == 0) vn_cow_disestablish(sc->sc_mount_vp, fss_copy_on_write, sc); FSS_LOCK(sc, s); sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR); sc->sc_mount = NULL; sc->sc_bdev = NODEV; FSS_UNLOCK(sc, s); fss_softc_free(sc); if (sc->sc_flags & FSS_PERSISTENT) vn_close(sc->sc_bs_vp, FREAD, p->p_ucred, p); else vn_close(sc->sc_bs_vp, FREAD|FWRITE, p->p_ucred, p); sc->sc_bs_vp = NULL; sc->sc_flags &= ~(FSS_PERSISTENT|FSS_BS_ALLOC); FSS_STAT_CLEAR(sc); return 0; } /* * Get the block address and number of contiguous blocks. * If the file contains a hole, try to allocate. * Backing store is locked by caller. */ static int fss_bmap(struct fss_softc *sc, off_t start, int len, struct vnode **vpp, daddr_t *bnp, int *runp) { int l, s, error; struct buf *bp, **bpp; if ((sc->sc_bs_vp->v_mount->mnt_flag & MNT_SOFTDEP) != 0) bpp = &bp; else bpp = NULL; error = VOP_BMAP(sc->sc_bs_vp, FSS_BTOFSB(sc, start), vpp, bnp, runp); if ((error == 0 && *bnp != (daddr_t)-1) || (sc->sc_flags & FSS_BS_ALLOC) == 0) goto out; if (start+len >= sc->sc_bs_size) { error = ENOSPC; goto out; } for (l = 0; l < len; l += FSS_FSBSIZE(sc)) { error = VOP_BALLOC(sc->sc_bs_vp, start+l, FSS_FSBSIZE(sc), sc->sc_bs_proc->p_ucred, 0, bpp); if (error) goto out; if (bpp == NULL) continue; s = splbio(); simple_lock(&bp->b_interlock); if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_start) (*bioops.io_start)(bp); if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) (*bioops.io_complete)(bp); bp->b_flags |= B_INVAL; simple_unlock(&bp->b_interlock); splx(s); brelse(bp); } error = VOP_BMAP(sc->sc_bs_vp, FSS_BTOFSB(sc, start), vpp, bnp, runp); out: if ((sc->sc_flags & FSS_PERSISTENT) == 0 && error == 0 && *bnp == (daddr_t)-1) error = ENOSPC; return error; } /* * A read from the snapshotted block device has completed. */ static void fss_cluster_iodone(struct buf *bp) { int s; struct fss_cache *scp = bp->b_private; FSS_LOCK(scp->fc_softc, s); if (bp->b_flags & B_EINTR) fss_error(scp->fc_softc, "fs read interrupted"); if (bp->b_flags & B_ERROR) fss_error(scp->fc_softc, "fs read error %d", bp->b_error); if (bp->b_vp != NULL) brelvp(bp); if (--scp->fc_xfercount == 0) wakeup(&scp->fc_data); FSS_UNLOCK(scp->fc_softc, s); s = splbio(); pool_put(&bufpool, bp); splx(s); } /* * Read a cluster from the snapshotted block device to the cache. */ static void fss_read_cluster(struct fss_softc *sc, u_int32_t cl) { int s, todo, len; caddr_t addr; daddr_t dblk; struct buf *bp; struct fss_cache *scp, *scl; /* * Get a free cache slot. */ scl = sc->sc_cache+sc->sc_cache_size; FSS_LOCK(sc, s); restart: if (isset(sc->sc_copied, cl) || !FSS_ISVALID(sc)) { FSS_UNLOCK(sc, s); return; } for (scp = sc->sc_cache; scp < scl; scp++) if (scp->fc_type != FSS_CACHE_FREE && scp->fc_cluster == cl) { ltsleep(&scp->fc_type, PRIBIO, "cowwait2", 0, &sc->sc_slock); goto restart; } for (scp = sc->sc_cache; scp < scl; scp++) if (scp->fc_type == FSS_CACHE_FREE) { scp->fc_type = FSS_CACHE_BUSY; scp->fc_cluster = cl; break; } if (scp >= scl) { FSS_STAT_INC(sc, cow_cache_full); ltsleep(&sc->sc_cache, PRIBIO, "cowwait3", 0, &sc->sc_slock); goto restart; } FSS_UNLOCK(sc, s); /* * Start the read. */ FSS_STAT_INC(sc, cow_copied); dblk = btodb(FSS_CLTOB(sc, cl)); addr = scp->fc_data; if (cl == sc->sc_clcount-1) { todo = sc->sc_clresid; memset(addr+todo, 0, FSS_CLSIZE(sc)-todo); } else todo = FSS_CLSIZE(sc); while (todo > 0) { len = todo; if (len > MAXPHYS) len = MAXPHYS; s = splbio(); bp = pool_get(&bufpool, PR_WAITOK); splx(s); BUF_INIT(bp); bp->b_flags = B_READ|B_CALL; bp->b_bcount = len; bp->b_bufsize = bp->b_bcount; bp->b_error = 0; bp->b_data = addr; bp->b_blkno = bp->b_rawblkno = dblk; bp->b_proc = NULL; bp->b_dev = sc->sc_bdev; bp->b_vp = NULLVP; bp->b_private = scp; bp->b_iodone = fss_cluster_iodone; DEV_STRATEGY(bp); FSS_LOCK(sc, s); scp->fc_xfercount++; FSS_UNLOCK(sc, s); dblk += btodb(len); addr += len; todo -= len; } /* * Wait for all read requests to complete. */ FSS_LOCK(sc, s); while (scp->fc_xfercount > 0) ltsleep(&scp->fc_data, PRIBIO, "cowwait", 0, &sc->sc_slock); scp->fc_type = FSS_CACHE_VALID; setbit(sc->sc_copied, scp->fc_cluster); FSS_UNLOCK(sc, s); wakeup(&sc->sc_bs_proc); } /* * Write a cluster from the cache to the backing store. */ static int fss_write_cluster(struct fss_cache *scp, u_int32_t cl) { int s, error, todo, len, nra; daddr_t nbn; caddr_t addr; off_t pos; struct buf *bp; struct vnode *vp; struct fss_softc *sc; error = 0; sc = scp->fc_softc; pos = FSS_CLTOB(sc, cl); addr = scp->fc_data; todo = FSS_CLSIZE(sc); vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY); simple_lock(&sc->sc_bs_vp->v_interlock); error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(pos), round_page(pos+todo), PGO_CLEANIT|PGO_SYNCIO|PGO_FREE); while (error == 0 && todo > 0) { error = fss_bmap(sc, pos, todo, &vp, &nbn, &nra); if (error) break; len = FSS_FSBTOB(sc, nra+1)-FSS_FSBOFF(sc, pos); if (len > todo) len = todo; s = splbio(); bp = pool_get(&bufpool, PR_WAITOK); splx(s); BUF_INIT(bp); bp->b_flags = B_CALL; bp->b_bcount = len; bp->b_bufsize = bp->b_bcount; bp->b_error = 0; bp->b_data = addr; bp->b_blkno = bp->b_rawblkno = nbn+btodb(FSS_FSBOFF(sc, pos)); bp->b_proc = NULL; bp->b_vp = NULLVP; bp->b_private = scp; bp->b_iodone = fss_cluster_iodone; bgetvp(vp, bp); bp->b_vp->v_numoutput++; BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); VOP_STRATEGY(vp, bp); FSS_LOCK(sc, s); scp->fc_xfercount++; FSS_UNLOCK(sc, s); pos += len; addr += len; todo -= len; } /* * Wait for all write requests to complete. */ FSS_LOCK(sc, s); while (scp->fc_xfercount > 0) ltsleep(&scp->fc_data, PRIBIO, "bswwait", 0, &sc->sc_slock); FSS_UNLOCK(sc, s); VOP_UNLOCK(sc->sc_bs_vp, 0); return error; } /* * Read/write clusters from/to backing store. * For persistent snapshots must be called with cl == 0. off is the * offset into the snapshot. */ static int fss_bs_io(struct fss_softc *sc, fss_io_type rw, u_int32_t cl, off_t off, int len, caddr_t data) { int s, error, todo, count, nra; off_t pos; daddr_t nbn; struct buf *bp; struct vnode *vp; todo = len; pos = FSS_CLTOB(sc, cl)+off; error = 0; vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY); simple_lock(&sc->sc_bs_vp->v_interlock); error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(pos), round_page(pos+todo), PGO_CLEANIT|PGO_SYNCIO|PGO_FREE); while (error == 0 && todo > 0) { error = fss_bmap(sc, pos, todo, &vp, &nbn, &nra); if (error) break; count = FSS_FSBTOB(sc, nra+1)-FSS_FSBOFF(sc, pos); if (count > todo) count = todo; if (nbn == (daddr_t)-1) { bzero(data, count); todo -= count; data += count; pos += count; continue; } s = splbio(); bp = pool_get(&bufpool, PR_WAITOK); splx(s); BUF_INIT(bp); bp->b_flags = (rw == FSS_READ ? B_READ : 0); bp->b_bcount = count; bp->b_bufsize = bp->b_bcount; bp->b_error = 0; bp->b_data = data; bp->b_blkno = bp->b_rawblkno = nbn+btodb(FSS_FSBOFF(sc, pos)); bp->b_proc = NULL; bp->b_vp = NULLVP; bgetvp(vp, bp); if ((bp->b_flags & B_READ) == 0) bp->b_vp->v_numoutput++; if ((bp->b_flags & B_READ) == 0 || cl < sc->sc_indir_size) BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); VOP_STRATEGY(vp, bp); error = biowait(bp); if (bp->b_vp != NULL) brelvp(bp); s = splbio(); pool_put(&bufpool, bp); splx(s); if (error) break; todo -= count; data += count; pos += count; } VOP_UNLOCK(sc->sc_bs_vp, 0); return error; } /* * Get a pointer to the indirect slot for this cluster. */ static u_int32_t * fss_bs_indir(struct fss_softc *sc, u_int32_t cl) { u_int32_t icl; int ioff; icl = cl/(FSS_CLSIZE(sc)/sizeof(u_int32_t)); ioff = cl%(FSS_CLSIZE(sc)/sizeof(u_int32_t)); if (sc->sc_indir_cur == icl) return &sc->sc_indir_data[ioff]; if (sc->sc_indir_dirty) { FSS_STAT_INC(sc, indir_write); if (fss_bs_io(sc, FSS_WRITE, sc->sc_indir_cur, 0, FSS_CLSIZE(sc), (caddr_t)sc->sc_indir_data) != 0) return NULL; setbit(sc->sc_indir_valid, sc->sc_indir_cur); } sc->sc_indir_dirty = 0; sc->sc_indir_cur = icl; if (isset(sc->sc_indir_valid, sc->sc_indir_cur)) { FSS_STAT_INC(sc, indir_read); if (fss_bs_io(sc, FSS_READ, sc->sc_indir_cur, 0, FSS_CLSIZE(sc), (caddr_t)sc->sc_indir_data) != 0) return NULL; } else memset(sc->sc_indir_data, 0, FSS_CLSIZE(sc)); return &sc->sc_indir_data[ioff]; } /* * The kernel thread (one for every active snapshot). * * After wakeup it cleans the cache and runs the I/O requests. */ static void fss_bs_thread(void *arg) { int error, len, nfreed, nio, s; long off; caddr_t addr; u_int32_t c, cl, ch, *indirp; struct buf *bp, *nbp; struct fss_softc *sc; struct fss_cache *scp, *scl; sc = arg; scl = sc->sc_cache+sc->sc_cache_size; s = splbio(); nbp = pool_get(&bufpool, PR_WAITOK); splx(s); nfreed = nio = 1; /* Dont sleep the first time */ FSS_LOCK(sc, s); for (;;) { if (nfreed == 0 && nio == 0) ltsleep(&sc->sc_bs_proc, PVM-1, "fssbs", 0, &sc->sc_slock); if ((sc->sc_flags & FSS_BS_THREAD) == 0) { sc->sc_bs_proc = NULL; wakeup(&sc->sc_bs_proc); FSS_UNLOCK(sc, s); s = splbio(); pool_put(&bufpool, nbp); splx(s); #ifdef FSS_STATISTICS if ((sc->sc_flags & FSS_PERSISTENT) == 0) { printf("fss%d: cow called %" PRId64 " times," " copied %" PRId64 " clusters," " cache full %" PRId64 " times\n", sc->sc_unit, FSS_STAT_VAL(sc, cow_calls), FSS_STAT_VAL(sc, cow_copied), FSS_STAT_VAL(sc, cow_cache_full)); printf("fss%d: %" PRId64 " indir reads," " %" PRId64 " indir writes\n", sc->sc_unit, FSS_STAT_VAL(sc, indir_read), FSS_STAT_VAL(sc, indir_write)); } #endif /* FSS_STATISTICS */ kthread_exit(0); } /* * Process I/O requests (persistent) */ if (sc->sc_flags & FSS_PERSISTENT) { nfreed = nio = 0; if ((bp = BUFQ_GET(&sc->sc_bufq)) == NULL) continue; nio++; if (FSS_ISVALID(sc)) { FSS_UNLOCK(sc, s); error = fss_bs_io(sc, FSS_READ, 0, dbtob(bp->b_blkno), bp->b_bcount, bp->b_data); FSS_LOCK(sc, s); } else error = ENXIO; if (error) { bp->b_error = error; bp->b_flags |= B_ERROR; bp->b_resid = bp->b_bcount; } biodone(bp); continue; } /* * Clean the cache */ nfreed = 0; for (scp = sc->sc_cache; scp < scl; scp++) { if (scp->fc_type != FSS_CACHE_VALID) continue; FSS_UNLOCK(sc, s); indirp = fss_bs_indir(sc, scp->fc_cluster); if (indirp != NULL) { error = fss_write_cluster(scp, sc->sc_clnext); } else error = EIO; FSS_LOCK(sc, s); if (error == 0) { *indirp = sc->sc_clnext++; sc->sc_indir_dirty = 1; } else fss_error(sc, "write bs error %d", error); scp->fc_type = FSS_CACHE_FREE; nfreed++; wakeup(&scp->fc_type); } if (nfreed) wakeup(&sc->sc_cache); /* * Process I/O requests */ nio = 0; if ((bp = BUFQ_GET(&sc->sc_bufq)) == NULL) continue; nio++; if (!FSS_ISVALID(sc)) { bp->b_error = ENXIO; bp->b_flags |= B_ERROR; bp->b_resid = bp->b_bcount; biodone(bp); continue; } /* * First read from the snapshotted block device. * XXX Split to only read those parts that have not * been saved to backing store? */ FSS_UNLOCK(sc, s); BUF_INIT(nbp); nbp->b_flags = B_READ; nbp->b_bcount = bp->b_bcount; nbp->b_bufsize = bp->b_bcount; nbp->b_error = 0; nbp->b_data = bp->b_data; nbp->b_blkno = nbp->b_rawblkno = bp->b_blkno; nbp->b_proc = bp->b_proc; nbp->b_dev = sc->sc_bdev; nbp->b_vp = NULLVP; DEV_STRATEGY(nbp); if (biowait(nbp) != 0) { bp->b_resid = bp->b_bcount; bp->b_error = nbp->b_error; bp->b_flags |= B_ERROR; biodone(bp); continue; } cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); off = FSS_CLOFF(sc, dbtob(bp->b_blkno)); ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); bp->b_resid = bp->b_bcount; addr = bp->b_data; FSS_LOCK(sc, s); /* * Replace those parts that have been saved to backing store. */ for (c = cl; c <= ch; c++, off = 0, bp->b_resid -= len, addr += len) { len = FSS_CLSIZE(sc)-off; if (len > bp->b_resid) len = bp->b_resid; if (isclr(sc->sc_copied, c)) continue; FSS_UNLOCK(sc, s); indirp = fss_bs_indir(sc, c); FSS_LOCK(sc, s); if (indirp == NULL || *indirp == 0) { /* * Not on backing store. Either in cache * or hole in the snapshotted block device. */ for (scp = sc->sc_cache; scp < scl; scp++) if (scp->fc_type == FSS_CACHE_VALID && scp->fc_cluster == c) break; if (scp < scl) memcpy(addr, scp->fc_data+off, len); else memset(addr, 0, len); continue; } /* * Read from backing store. */ FSS_UNLOCK(sc, s); if ((error = fss_bs_io(sc, FSS_READ, *indirp, off, len, addr)) != 0) { bp->b_resid = bp->b_bcount; bp->b_error = error; bp->b_flags |= B_ERROR; break; } FSS_LOCK(sc, s); } biodone(bp); } }