diff --git a/sys/ufs/ufs/ufs_dirhash.c b/sys/ufs/ufs/ufs_dirhash.c index 13094b5a1c97..d1e1bed0bde4 100644 --- a/sys/ufs/ufs/ufs_dirhash.c +++ b/sys/ufs/ufs/ufs_dirhash.c @@ -1,1327 +1,1327 @@ /*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2001, 2002 Ian Dowse. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. */ /* * This implements a hash-based lookup scheme for UFS directories. */ #include __FBSDID("$FreeBSD$"); #include "opt_ufs.h" #ifdef UFS_DIRHASH #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 #define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1)) #define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1)) #define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0) #define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n)) static MALLOC_DEFINE(M_DIRHASH, "ufs_dirhash", "UFS directory hash tables"); static int ufs_mindirhashsize = DIRBLKSIZ * 5; SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_minsize, CTLFLAG_RW, &ufs_mindirhashsize, 0, "minimum directory size in bytes for which to use hashed lookup"); static int ufs_dirhashmaxmem = 2 * 1024 * 1024; /* NOTE: initial value. It is tuned in ufsdirhash_init() */ SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem, 0, "maximum allowed dirhash memory usage"); static int ufs_dirhashmem; SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem, 0, "current dirhash memory usage"); static int ufs_dirhashcheck = 0; SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck, 0, "enable extra sanity tests"); static int ufs_dirhashlowmemcount = 0; SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_lowmemcount, CTLFLAG_RD, &ufs_dirhashlowmemcount, 0, "number of times low memory hook called"); static int ufs_dirhashreclaimpercent = 10; static int ufsdirhash_set_reclaimpercent(SYSCTL_HANDLER_ARGS); SYSCTL_PROC(_vfs_ufs, OID_AUTO, dirhash_reclaimpercent, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0, ufsdirhash_set_reclaimpercent, "I", "set percentage of dirhash cache to be removed in low VM events"); static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen); static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff); static void ufsdirhash_delslot(struct dirhash *dh, int slot); static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset); static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset); static int ufsdirhash_recycle(int wanted); static void ufsdirhash_lowmem(void); static void ufsdirhash_free_locked(struct inode *ip); static uma_zone_t ufsdirhash_zone; #define DIRHASHLIST_LOCK() mtx_lock(&ufsdirhash_mtx) #define DIRHASHLIST_UNLOCK() mtx_unlock(&ufsdirhash_mtx) -#define DIRHASH_BLKALLOC_WAITOK() uma_zalloc(ufsdirhash_zone, M_WAITOK) +#define DIRHASH_BLKALLOC() uma_zalloc(ufsdirhash_zone, M_NOWAIT) #define DIRHASH_BLKFREE(ptr) uma_zfree(ufsdirhash_zone, (ptr)) #define DIRHASH_ASSERT_LOCKED(dh) \ sx_assert(&(dh)->dh_lock, SA_LOCKED) /* Dirhash list; recently-used entries are near the tail. */ static TAILQ_HEAD(, dirhash) ufsdirhash_list; /* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */ static struct mtx ufsdirhash_mtx; /* * Locking: * * The relationship between inode and dirhash is protected either by an * exclusive vnode lock or the vnode interlock where a shared vnode lock * may be used. The dirhash_mtx is acquired after the dirhash lock. To * handle teardown races, code wishing to lock the dirhash for an inode * when using a shared vnode lock must obtain a private reference on the * dirhash while holding the vnode interlock. They can drop it once they * have obtained the dirhash lock and verified that the dirhash wasn't * recycled while they waited for the dirhash lock. * * ufsdirhash_build() acquires a shared lock on the dirhash when it is * successful. This lock is released after a call to ufsdirhash_lookup(). * * Functions requiring exclusive access use ufsdirhash_acquire() which may * free a dirhash structure that was recycled by ufsdirhash_recycle(). * * The dirhash lock may be held across io operations. * * WITNESS reports a lock order reversal between the "bufwait" lock * and the "dirhash" lock. However, this specific reversal will not * cause a deadlock. To get a deadlock, one would have to lock a * buffer followed by the dirhash while a second thread locked a * buffer while holding the dirhash lock. The second order can happen * under a shared or exclusive vnode lock for the associated directory * in lookup(). The first order, however, can only happen under an * exclusive vnode lock (e.g. unlink(), rename(), etc.). Thus, for * a thread to be doing a "bufwait" -> "dirhash" order, it has to hold * an exclusive vnode lock. That exclusive vnode lock will prevent * any other threads from doing a "dirhash" -> "bufwait" order. */ static void ufsdirhash_hold(struct dirhash *dh) { refcount_acquire(&dh->dh_refcount); } static void ufsdirhash_drop(struct dirhash *dh) { if (refcount_release(&dh->dh_refcount)) { sx_destroy(&dh->dh_lock); free(dh, M_DIRHASH); } } /* * Release the lock on a dirhash. */ static void ufsdirhash_release(struct dirhash *dh) { sx_unlock(&dh->dh_lock); } /* * Either acquire an existing hash locked shared or create a new hash and * return it exclusively locked. May return NULL if the allocation fails. * * The vnode interlock is used to protect the i_dirhash pointer from * simultaneous access while only a shared vnode lock is held. */ static struct dirhash * ufsdirhash_create(struct inode *ip) { struct dirhash *ndh; struct dirhash *dh; struct vnode *vp; bool excl; ndh = dh = NULL; vp = ip->i_vnode; excl = false; for (;;) { /* Racy check for i_dirhash to prefetch a dirhash structure. */ if (ip->i_dirhash == NULL && ndh == NULL) { ndh = malloc(sizeof *dh, M_DIRHASH, M_NOWAIT | M_ZERO); if (ndh == NULL) return (NULL); refcount_init(&ndh->dh_refcount, 1); /* * The DUPOK is to prevent warnings from the * sx_slock() a few lines down which is safe * since the duplicate lock in that case is * the one for this dirhash we are creating * now which has no external references until * after this function returns. */ sx_init_flags(&ndh->dh_lock, "dirhash", SX_DUPOK); sx_xlock(&ndh->dh_lock); } /* * Check i_dirhash. If it's NULL just try to use a * preallocated structure. If none exists loop and try again. */ VI_LOCK(vp); dh = ip->i_dirhash; if (dh == NULL) { ip->i_dirhash = ndh; VI_UNLOCK(vp); if (ndh == NULL) continue; return (ndh); } ufsdirhash_hold(dh); VI_UNLOCK(vp); /* Acquire a lock on existing hashes. */ if (excl) sx_xlock(&dh->dh_lock); else sx_slock(&dh->dh_lock); /* The hash could've been recycled while we were waiting. */ VI_LOCK(vp); if (ip->i_dirhash != dh) { VI_UNLOCK(vp); ufsdirhash_release(dh); ufsdirhash_drop(dh); continue; } VI_UNLOCK(vp); ufsdirhash_drop(dh); /* If the hash is still valid we've succeeded. */ if (dh->dh_hash != NULL) break; /* * If the hash is NULL it has been recycled. Try to upgrade * so we can recreate it. If we fail the upgrade, drop our * lock and try again. */ if (excl || sx_try_upgrade(&dh->dh_lock)) break; sx_sunlock(&dh->dh_lock); excl = true; } /* Free the preallocated structure if it was not necessary. */ if (ndh) { ufsdirhash_release(ndh); ufsdirhash_drop(ndh); } return (dh); } /* * Acquire an exclusive lock on an existing hash. Requires an exclusive * vnode lock to protect the i_dirhash pointer. hashes that have been * recycled are reclaimed here and NULL is returned. */ static struct dirhash * ufsdirhash_acquire(struct inode *ip) { struct dirhash *dh; ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__); dh = ip->i_dirhash; if (dh == NULL) return (NULL); sx_xlock(&dh->dh_lock); if (dh->dh_hash != NULL) return (dh); ufsdirhash_free_locked(ip); return (NULL); } /* * Acquire exclusively and free the hash pointed to by ip. Works with a * shared or exclusive vnode lock. */ void ufsdirhash_free(struct inode *ip) { struct dirhash *dh; struct vnode *vp; vp = ip->i_vnode; for (;;) { /* Grab a reference on this inode's dirhash if it has one. */ VI_LOCK(vp); dh = ip->i_dirhash; if (dh == NULL) { VI_UNLOCK(vp); return; } ufsdirhash_hold(dh); VI_UNLOCK(vp); /* Exclusively lock the dirhash. */ sx_xlock(&dh->dh_lock); /* If this dirhash still belongs to this inode, then free it. */ VI_LOCK(vp); if (ip->i_dirhash == dh) { VI_UNLOCK(vp); ufsdirhash_drop(dh); break; } VI_UNLOCK(vp); /* * This inode's dirhash has changed while we were * waiting for the dirhash lock, so try again. */ ufsdirhash_release(dh); ufsdirhash_drop(dh); } ufsdirhash_free_locked(ip); } /* * Attempt to build up a hash table for the directory contents in * inode 'ip'. Returns 0 on success, or -1 of the operation failed. */ int ufsdirhash_build(struct inode *ip) { struct dirhash *dh; struct buf *bp = NULL; struct direct *ep; struct vnode *vp; doff_t bmask, pos; u_int dirblocks, i, narrays, nblocks, nslots; int j, memreqd, slot; /* Take care of a decreased sysctl value. */ while (ufs_dirhashmem > ufs_dirhashmaxmem) { if (ufsdirhash_recycle(0) != 0) return (-1); /* Recycled enough memory, so unlock the list. */ DIRHASHLIST_UNLOCK(); } /* Check if we can/should use dirhash. */ if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) || ip->i_effnlink == 0) { if (ip->i_dirhash) ufsdirhash_free(ip); return (-1); } dh = ufsdirhash_create(ip); if (dh == NULL) return (-1); if (dh->dh_hash != NULL) return (0); vp = ip->i_vnode; /* Allocate 50% more entries than this dir size could ever need. */ KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size")); nslots = ip->i_size / DIRECTSIZ(1); nslots = (nslots * 3 + 1) / 2; narrays = howmany(nslots, DH_NBLKOFF); nslots = narrays * DH_NBLKOFF; dirblocks = howmany(ip->i_size, DIRBLKSIZ); nblocks = (dirblocks * 3 + 1) / 2; memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) + narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) + nblocks * sizeof(*dh->dh_blkfree); DIRHASHLIST_LOCK(); if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) { DIRHASHLIST_UNLOCK(); if (memreqd > ufs_dirhashmaxmem / 2) goto fail; /* Try to free some space. */ if (ufsdirhash_recycle(memreqd) != 0) goto fail; /* Enough was freed, and list has been locked. */ } ufs_dirhashmem += memreqd; DIRHASHLIST_UNLOCK(); /* Initialise the hash table and block statistics. */ dh->dh_memreq = memreqd; dh->dh_narrays = narrays; dh->dh_hlen = nslots; dh->dh_nblk = nblocks; dh->dh_dirblks = dirblocks; for (i = 0; i < DH_NFSTATS; i++) dh->dh_firstfree[i] = -1; dh->dh_firstfree[DH_NFSTATS] = 0; dh->dh_hused = 0; dh->dh_seqoff = -1; dh->dh_score = DH_SCOREINIT; dh->dh_lastused = time_second; /* * Use non-blocking mallocs so that we will revert to a linear * lookup on failure rather than potentially blocking forever. */ dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]), M_DIRHASH, M_NOWAIT | M_ZERO); if (dh->dh_hash == NULL) goto fail; dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]), M_DIRHASH, M_NOWAIT); if (dh->dh_blkfree == NULL) goto fail; for (i = 0; i < narrays; i++) { - if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL) + if ((dh->dh_hash[i] = DIRHASH_BLKALLOC()) == NULL) goto fail; for (j = 0; j < DH_NBLKOFF; j++) dh->dh_hash[i][j] = DIRHASH_EMPTY; } for (i = 0; i < dirblocks; i++) dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN; bmask = vp->v_mount->mnt_stat.f_iosize - 1; pos = 0; while (pos < ip->i_size) { /* If necessary, get the next directory block. */ if ((pos & bmask) == 0) { if (bp != NULL) brelse(bp); if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0) goto fail; } /* Add this entry to the hash. */ ep = (struct direct *)((char *)bp->b_data + (pos & bmask)); if (ep->d_reclen == 0 || ep->d_reclen > DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) { /* Corrupted directory. */ brelse(bp); goto fail; } if (ep->d_ino != 0) { /* Add the entry (simplified ufsdirhash_add). */ slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen); while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY) slot = WRAPINCR(slot, dh->dh_hlen); dh->dh_hused++; DH_ENTRY(dh, slot) = pos; ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep)); } pos += ep->d_reclen; } if (bp != NULL) brelse(bp); DIRHASHLIST_LOCK(); TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list); dh->dh_onlist = 1; DIRHASHLIST_UNLOCK(); sx_downgrade(&dh->dh_lock); return (0); fail: ufsdirhash_free_locked(ip); return (-1); } /* * Free any hash table associated with inode 'ip'. */ static void ufsdirhash_free_locked(struct inode *ip) { struct dirhash *dh; struct vnode *vp; int i; DIRHASH_ASSERT_LOCKED(ip->i_dirhash); /* * Clear the pointer in the inode to prevent new threads from * finding the dead structure. */ vp = ip->i_vnode; VI_LOCK(vp); dh = ip->i_dirhash; ip->i_dirhash = NULL; VI_UNLOCK(vp); /* * Remove the hash from the list since we are going to free its * memory. */ DIRHASHLIST_LOCK(); if (dh->dh_onlist) TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); ufs_dirhashmem -= dh->dh_memreq; DIRHASHLIST_UNLOCK(); /* * At this point, any waiters for the lock should hold their * own reference on the dirhash structure. They will drop * that reference once they grab the vnode interlock and see * that ip->i_dirhash is NULL. */ sx_xunlock(&dh->dh_lock); /* * Handle partially recycled as well as fully constructed hashes. */ if (dh->dh_hash != NULL) { for (i = 0; i < dh->dh_narrays; i++) if (dh->dh_hash[i] != NULL) DIRHASH_BLKFREE(dh->dh_hash[i]); free(dh->dh_hash, M_DIRHASH); if (dh->dh_blkfree != NULL) free(dh->dh_blkfree, M_DIRHASH); } /* * Drop the inode's reference to the data structure. */ ufsdirhash_drop(dh); } /* * Find the offset of the specified name within the given inode. * Returns 0 on success, ENOENT if the entry does not exist, or * EJUSTRETURN if the caller should revert to a linear search. * * If successful, the directory offset is stored in *offp, and a * pointer to a struct buf containing the entry is stored in *bpp. If * prevoffp is non-NULL, the offset of the previous entry within * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry * is the first in a block, the start of the block is used). * * Must be called with the hash locked. Returns with the hash unlocked. */ int ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp, struct buf **bpp, doff_t *prevoffp) { struct dirhash *dh, *dh_next; struct direct *dp; struct vnode *vp; struct buf *bp; doff_t blkoff, bmask, offset, prevoff, seqoff; int i, slot; int error; dh = ip->i_dirhash; KASSERT(dh != NULL && dh->dh_hash != NULL, ("ufsdirhash_lookup: Invalid dirhash %p\n", dh)); DIRHASH_ASSERT_LOCKED(dh); /* * Move this dirhash towards the end of the list if it has a * score higher than the next entry, and acquire the dh_lock. */ DIRHASHLIST_LOCK(); if (TAILQ_NEXT(dh, dh_list) != NULL) { /* * If the new score will be greater than that of the next * entry, then move this entry past it. With both mutexes * held, dh_next won't go away, but its dh_score could * change; that's not important since it is just a hint. */ if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL && dh->dh_score >= dh_next->dh_score) { KASSERT(dh->dh_onlist, ("dirhash: not on list")); TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh, dh_list); } } /* Update the score. */ if (dh->dh_score < DH_SCOREMAX) dh->dh_score++; /* Update last used time. */ dh->dh_lastused = time_second; DIRHASHLIST_UNLOCK(); vp = ip->i_vnode; bmask = vp->v_mount->mnt_stat.f_iosize - 1; blkoff = -1; bp = NULL; seqoff = dh->dh_seqoff; restart: slot = ufsdirhash_hash(dh, name, namelen); if (seqoff != -1) { /* * Sequential access optimisation. seqoff contains the * offset of the directory entry immediately following * the last entry that was looked up. Check if this offset * appears in the hash chain for the name we are looking for. */ for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY; i = WRAPINCR(i, dh->dh_hlen)) if (offset == seqoff) break; if (offset == seqoff) { /* * We found an entry with the expected offset. This * is probably the entry we want, but if not, the * code below will retry. */ slot = i; } else seqoff = -1; } for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY; slot = WRAPINCR(slot, dh->dh_hlen)) { if (offset == DIRHASH_DEL) continue; if (offset < 0 || offset >= ip->i_size) panic("ufsdirhash_lookup: bad offset in hash array"); if ((offset & ~bmask) != blkoff) { if (bp != NULL) brelse(bp); blkoff = offset & ~bmask; if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) { error = EJUSTRETURN; goto fail; } } KASSERT(bp != NULL, ("no buffer allocated")); dp = (struct direct *)(bp->b_data + (offset & bmask)); if (dp->d_reclen == 0 || dp->d_reclen > DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) { /* Corrupted directory. */ error = EJUSTRETURN; goto fail; } if (dp->d_namlen == namelen && bcmp(dp->d_name, name, namelen) == 0) { /* Found. Get the prev offset if needed. */ if (prevoffp != NULL) { if (offset & (DIRBLKSIZ - 1)) { prevoff = ufsdirhash_getprev(dp, offset); if (prevoff == -1) { error = EJUSTRETURN; goto fail; } } else prevoff = offset; *prevoffp = prevoff; } /* Update offset. */ dh->dh_seqoff = offset + DIRSIZ(0, dp); *bpp = bp; *offp = offset; ufsdirhash_release(dh); return (0); } /* * When the name doesn't match in the sequential * optimization case, go back and search normally. */ if (seqoff != -1) { seqoff = -1; goto restart; } } error = ENOENT; fail: ufsdirhash_release(dh); if (bp != NULL) brelse(bp); return (error); } /* * Find a directory block with room for 'slotneeded' bytes. Returns * the offset of the directory entry that begins the free space. * This will either be the offset of an existing entry that has free * space at the end, or the offset of an entry with d_ino == 0 at * the start of a DIRBLKSIZ block. * * To use the space, the caller may need to compact existing entries in * the directory. The total number of bytes in all of the entries involved * in the compaction is stored in *slotsize. In other words, all of * the entries that must be compacted are exactly contained in the * region beginning at the returned offset and spanning *slotsize bytes. * * Returns -1 if no space was found, indicating that the directory * must be extended. */ doff_t ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize) { struct direct *dp; struct dirhash *dh; struct buf *bp; doff_t pos, slotstart; int dirblock, error, freebytes, i; dh = ip->i_dirhash; KASSERT(dh != NULL && dh->dh_hash != NULL, ("ufsdirhash_findfree: Invalid dirhash %p\n", dh)); DIRHASH_ASSERT_LOCKED(dh); /* Find a directory block with the desired free space. */ dirblock = -1; for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++) if ((dirblock = dh->dh_firstfree[i]) != -1) break; if (dirblock == -1) return (-1); KASSERT(dirblock < dh->dh_nblk && dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN), ("ufsdirhash_findfree: bad stats")); pos = dirblock * DIRBLKSIZ; error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp); if (error) return (-1); /* Find the first entry with free space. */ for (i = 0; i < DIRBLKSIZ; ) { if (dp->d_reclen == 0) { brelse(bp); return (-1); } if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp)) break; i += dp->d_reclen; dp = (struct direct *)((char *)dp + dp->d_reclen); } if (i > DIRBLKSIZ) { brelse(bp); return (-1); } slotstart = pos + i; /* Find the range of entries needed to get enough space */ freebytes = 0; while (i < DIRBLKSIZ && freebytes < slotneeded) { freebytes += dp->d_reclen; if (dp->d_ino != 0) freebytes -= DIRSIZ(0, dp); if (dp->d_reclen == 0) { brelse(bp); return (-1); } i += dp->d_reclen; dp = (struct direct *)((char *)dp + dp->d_reclen); } if (i > DIRBLKSIZ) { brelse(bp); return (-1); } if (freebytes < slotneeded) panic("ufsdirhash_findfree: free mismatch"); brelse(bp); *slotsize = pos + i - slotstart; return (slotstart); } /* * Return the start of the unused space at the end of a directory, or * -1 if there are no trailing unused blocks. */ doff_t ufsdirhash_enduseful(struct inode *ip) { struct dirhash *dh; int i; dh = ip->i_dirhash; DIRHASH_ASSERT_LOCKED(dh); KASSERT(dh != NULL && dh->dh_hash != NULL, ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh)); if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) return (-1); for (i = dh->dh_dirblks - 1; i >= 0; i--) if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) break; return ((doff_t)(i + 1) * DIRBLKSIZ); } /* * Insert information into the hash about a new directory entry. dirp * points to a struct direct containing the entry, and offset specifies * the offset of this entry. */ void ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset) { struct dirhash *dh; int slot; if ((dh = ufsdirhash_acquire(ip)) == NULL) return; KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, ("ufsdirhash_add: bad offset")); /* * Normal hash usage is < 66%. If the usage gets too high then * remove the hash entirely and let it be rebuilt later. */ if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) { ufsdirhash_free_locked(ip); return; } /* Find a free hash slot (empty or deleted), and add the entry. */ slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen); while (DH_ENTRY(dh, slot) >= 0) slot = WRAPINCR(slot, dh->dh_hlen); if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY) dh->dh_hused++; DH_ENTRY(dh, slot) = offset; /* Update last used time. */ dh->dh_lastused = time_second; /* Update the per-block summary info. */ ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp)); ufsdirhash_release(dh); } /* * Remove the specified directory entry from the hash. The entry to remove * is defined by the name in `dirp', which must exist at the specified * `offset' within the directory. */ void ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset) { struct dirhash *dh; int slot; if ((dh = ufsdirhash_acquire(ip)) == NULL) return; KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, ("ufsdirhash_remove: bad offset")); /* Find the entry */ slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset); /* Remove the hash entry. */ ufsdirhash_delslot(dh, slot); /* Update the per-block summary info. */ ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp)); ufsdirhash_release(dh); } /* * Change the offset associated with a directory entry in the hash. Used * when compacting directory blocks. */ void ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff, doff_t newoff) { struct dirhash *dh; int slot; if ((dh = ufsdirhash_acquire(ip)) == NULL) return; KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ && newoff < dh->dh_dirblks * DIRBLKSIZ, ("ufsdirhash_move: bad offset")); /* Find the entry, and update the offset. */ slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff); DH_ENTRY(dh, slot) = newoff; ufsdirhash_release(dh); } /* * Inform dirhash that the directory has grown by one block that * begins at offset (i.e. the new length is offset + DIRBLKSIZ). */ void ufsdirhash_newblk(struct inode *ip, doff_t offset) { struct dirhash *dh; int block; if ((dh = ufsdirhash_acquire(ip)) == NULL) return; KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ, ("ufsdirhash_newblk: bad offset")); block = offset / DIRBLKSIZ; if (block >= dh->dh_nblk) { /* Out of space; must rebuild. */ ufsdirhash_free_locked(ip); return; } dh->dh_dirblks = block + 1; /* Account for the new free block. */ dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN; if (dh->dh_firstfree[DH_NFSTATS] == -1) dh->dh_firstfree[DH_NFSTATS] = block; ufsdirhash_release(dh); } /* * Inform dirhash that the directory is being truncated. */ void ufsdirhash_dirtrunc(struct inode *ip, doff_t offset) { struct dirhash *dh; int block, i; if ((dh = ufsdirhash_acquire(ip)) == NULL) return; KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ, ("ufsdirhash_dirtrunc: bad offset")); block = howmany(offset, DIRBLKSIZ); /* * If the directory shrinks to less than 1/8 of dh_nblk blocks * (about 20% of its original size due to the 50% extra added in * ufsdirhash_build) then free it, and let the caller rebuild * if necessary. */ if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) { ufsdirhash_free_locked(ip); return; } /* * Remove any `first free' information pertaining to the * truncated blocks. All blocks we're removing should be * completely unused. */ if (dh->dh_firstfree[DH_NFSTATS] >= block) dh->dh_firstfree[DH_NFSTATS] = -1; for (i = block; i < dh->dh_dirblks; i++) if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) panic("ufsdirhash_dirtrunc: blocks in use"); for (i = 0; i < DH_NFSTATS; i++) if (dh->dh_firstfree[i] >= block) panic("ufsdirhash_dirtrunc: first free corrupt"); dh->dh_dirblks = block; ufsdirhash_release(dh); } /* * Debugging function to check that the dirhash information about * a directory block matches its actual contents. Panics if a mismatch * is detected. * * On entry, `buf' should point to the start of an in-core * DIRBLKSIZ-sized directory block, and `offset' should contain the * offset from the start of the directory of that block. */ void ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset) { struct dirhash *dh; struct direct *dp; int block, ffslot, i, nfree; if (!ufs_dirhashcheck) return; if ((dh = ufsdirhash_acquire(ip)) == NULL) return; block = offset / DIRBLKSIZ; if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks) panic("ufsdirhash_checkblock: bad offset"); nfree = 0; for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) { dp = (struct direct *)(buf + i); if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ) panic("ufsdirhash_checkblock: bad dir"); if (dp->d_ino == 0) { #if 0 /* * XXX entries with d_ino == 0 should only occur * at the start of a DIRBLKSIZ block. However the * ufs code is tolerant of such entries at other * offsets, and fsck does not fix them. */ if (i != 0) panic("ufsdirhash_checkblock: bad dir inode"); #endif nfree += dp->d_reclen; continue; } /* Check that the entry exists (will panic if it doesn't). */ ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i); nfree += dp->d_reclen - DIRSIZ(0, dp); } if (i != DIRBLKSIZ) panic("ufsdirhash_checkblock: bad dir end"); if (dh->dh_blkfree[block] * DIRALIGN != nfree) panic("ufsdirhash_checkblock: bad free count"); ffslot = BLKFREE2IDX(nfree / DIRALIGN); for (i = 0; i <= DH_NFSTATS; i++) if (dh->dh_firstfree[i] == block && i != ffslot) panic("ufsdirhash_checkblock: bad first-free"); if (dh->dh_firstfree[ffslot] == -1) panic("ufsdirhash_checkblock: missing first-free entry"); ufsdirhash_release(dh); } /* * Hash the specified filename into a dirhash slot. */ static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen) { u_int32_t hash; /* * We hash the name and then some other bit of data that is * invariant over the dirhash's lifetime. Otherwise names * differing only in the last byte are placed close to one * another in the table, which is bad for linear probing. */ hash = fnv_32_buf(name, namelen, FNV1_32_INIT); hash = fnv_32_buf(&dh, sizeof(dh), hash); return (hash % dh->dh_hlen); } /* * Adjust the number of free bytes in the block containing `offset' * by the value specified by `diff'. * * The caller must ensure we have exclusive access to `dh'; normally * that means that dh_lock should be held, but this is also called * from ufsdirhash_build() where exclusive access can be assumed. */ static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff) { int block, i, nfidx, ofidx; /* Update the per-block summary info. */ block = offset / DIRBLKSIZ; KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks, ("dirhash bad offset")); ofidx = BLKFREE2IDX(dh->dh_blkfree[block]); dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN); nfidx = BLKFREE2IDX(dh->dh_blkfree[block]); /* Update the `first free' list if necessary. */ if (ofidx != nfidx) { /* If removing, scan forward for the next block. */ if (dh->dh_firstfree[ofidx] == block) { for (i = block + 1; i < dh->dh_dirblks; i++) if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx) break; dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1; } /* Make this the new `first free' if necessary */ if (dh->dh_firstfree[nfidx] > block || dh->dh_firstfree[nfidx] == -1) dh->dh_firstfree[nfidx] = block; } } /* * Find the specified name which should have the specified offset. * Returns a slot number, and panics on failure. * * `dh' must be locked on entry and remains so on return. */ static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset) { int slot; DIRHASH_ASSERT_LOCKED(dh); /* Find the entry. */ KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full")); slot = ufsdirhash_hash(dh, name, namelen); while (DH_ENTRY(dh, slot) != offset && DH_ENTRY(dh, slot) != DIRHASH_EMPTY) slot = WRAPINCR(slot, dh->dh_hlen); if (DH_ENTRY(dh, slot) != offset) panic("ufsdirhash_findslot: '%.*s' not found", namelen, name); return (slot); } /* * Remove the entry corresponding to the specified slot from the hash array. * * `dh' must be locked on entry and remains so on return. */ static void ufsdirhash_delslot(struct dirhash *dh, int slot) { int i; DIRHASH_ASSERT_LOCKED(dh); /* Mark the entry as deleted. */ DH_ENTRY(dh, slot) = DIRHASH_DEL; /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */ for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; ) i = WRAPINCR(i, dh->dh_hlen); if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) { i = WRAPDECR(i, dh->dh_hlen); while (DH_ENTRY(dh, i) == DIRHASH_DEL) { DH_ENTRY(dh, i) = DIRHASH_EMPTY; dh->dh_hused--; i = WRAPDECR(i, dh->dh_hlen); } KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen")); } } /* * Given a directory entry and its offset, find the offset of the * previous entry in the same DIRBLKSIZ-sized block. Returns an * offset, or -1 if there is no previous entry in the block or some * other problem occurred. */ static doff_t ufsdirhash_getprev(struct direct *dirp, doff_t offset) { struct direct *dp; char *blkbuf; doff_t blkoff, prevoff; int entrypos, i; blkoff = rounddown2(offset, DIRBLKSIZ); /* offset of start of block */ entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */ blkbuf = (char *)dirp - entrypos; prevoff = blkoff; /* If `offset' is the start of a block, there is no previous entry. */ if (entrypos == 0) return (-1); /* Scan from the start of the block until we get to the entry. */ for (i = 0; i < entrypos; i += dp->d_reclen) { dp = (struct direct *)(blkbuf + i); if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos) return (-1); /* Corrupted directory. */ prevoff = blkoff + i; } return (prevoff); } /* * Delete the given dirhash and reclaim its memory. Assumes that * ufsdirhash_list is locked, and leaves it locked. Also assumes * that dh is locked. Returns the amount of memory freed. */ static int ufsdirhash_destroy(struct dirhash *dh) { doff_t **hash; u_int8_t *blkfree; int i, mem, narrays; KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list")); /* Remove it from the list and detach its memory. */ TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); dh->dh_onlist = 0; hash = dh->dh_hash; dh->dh_hash = NULL; blkfree = dh->dh_blkfree; dh->dh_blkfree = NULL; narrays = dh->dh_narrays; mem = dh->dh_memreq; dh->dh_memreq = 0; /* Unlock dirhash and free the detached memory. */ ufsdirhash_release(dh); for (i = 0; i < narrays; i++) DIRHASH_BLKFREE(hash[i]); free(hash, M_DIRHASH); free(blkfree, M_DIRHASH); /* Account for the returned memory. */ ufs_dirhashmem -= mem; return (mem); } /* * Try to free up `wanted' bytes by stealing memory from existing * dirhashes. Returns zero with list locked if successful. */ static int ufsdirhash_recycle(int wanted) { struct dirhash *dh; DIRHASHLIST_LOCK(); dh = TAILQ_FIRST(&ufsdirhash_list); while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) { /* Decrement the score; only recycle if it becomes zero. */ if (dh == NULL || --dh->dh_score > 0) { DIRHASHLIST_UNLOCK(); return (-1); } /* * If we can't lock it it's in use and we don't want to * recycle it anyway. */ if (!sx_try_xlock(&dh->dh_lock)) { dh = TAILQ_NEXT(dh, dh_list); continue; } ufsdirhash_destroy(dh); /* Repeat if necessary. */ dh = TAILQ_FIRST(&ufsdirhash_list); } /* Success; return with list locked. */ return (0); } /* * Callback that frees some dirhashes when the system is low on virtual memory. */ static void ufsdirhash_lowmem() { struct dirhash *dh, *dh_temp; int memfreed, memwanted; ufs_dirhashlowmemcount++; memfreed = 0; memwanted = ufs_dirhashmem * ufs_dirhashreclaimpercent / 100; DIRHASHLIST_LOCK(); /* * Reclaim up to memwanted from the oldest dirhashes. This will allow * us to make some progress when the system is running out of memory * without compromising the dinamicity of maximum age. If the situation * does not improve lowmem will be eventually retriggered and free some * other entry in the cache. The entries on the head of the list should * be the oldest. If during list traversal we can't get a lock on the * dirhash, it will be skipped. */ TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) { if (sx_try_xlock(&dh->dh_lock)) memfreed += ufsdirhash_destroy(dh); if (memfreed >= memwanted) break; } DIRHASHLIST_UNLOCK(); } static int ufsdirhash_set_reclaimpercent(SYSCTL_HANDLER_ARGS) { int error, v; v = ufs_dirhashreclaimpercent; error = sysctl_handle_int(oidp, &v, v, req); if (error) return (error); if (req->newptr == NULL) return (error); if (v == ufs_dirhashreclaimpercent) return (0); /* Refuse invalid percentages */ if (v < 0 || v > 100) return (EINVAL); ufs_dirhashreclaimpercent = v; return (0); } void ufsdirhash_init() { ufs_dirhashmaxmem = lmax(roundup(hibufspace / 64, PAGE_SIZE), 2 * 1024 * 1024); ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF); TAILQ_INIT(&ufsdirhash_list); /* Register a callback function to handle low memory signals */ EVENTHANDLER_REGISTER(vm_lowmem, ufsdirhash_lowmem, NULL, EVENTHANDLER_PRI_FIRST); } void ufsdirhash_uninit() { KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit")); uma_zdestroy(ufsdirhash_zone); mtx_destroy(&ufsdirhash_mtx); } #endif /* UFS_DIRHASH */