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/*-
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/ufs/ufs/ufs_dirhash.c 219388 2011-03-07 22:36:11Z kib $");
#include "opt_ufs.h"
#ifdef UFS_DIRHASH
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/malloc.h>
#include <sys/fnv_hash.h>
#include <sys/proc.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/refcount.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/eventhandler.h>
#include <sys/time.h>
#include <vm/uma.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/dir.h>
#include <ufs/ufs/dirhash.h>
#include <ufs/ufs/extattr.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>
#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_dirhashreclaimage = 5;
SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_reclaimage, CTLFLAG_RW,
&ufs_dirhashreclaimage, 0,
"max time in seconds of hash inactivity before deletion 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_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;
int error;
error = 0;
ndh = dh = NULL;
vp = ip->i_vnode;
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 shared lock on existing hashes. */
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 (sx_try_upgrade(&dh->dh_lock))
break;
sx_sunlock(&dh->dh_lock);
}
/* 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;
struct vnode *vp;
ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__);
vp = ip->i_vnode;
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;
int dirblocks, i, j, memreqd, nblocks, narrays, nslots, 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)
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 = offset & ~(DIRBLKSIZ - 1); /* 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 = 0;
/* XXX: this 10% may need to be adjusted */
int memwanted = ufs_dirhashmem / 10;
ufs_dirhashlowmemcount++;
DIRHASHLIST_LOCK();
/*
* Delete dirhashes not used for more than ufs_dirhashreclaimage
* seconds. If 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))
continue;
if (time_second - dh->dh_lastused > ufs_dirhashreclaimage)
memfreed += ufsdirhash_destroy(dh);
/* Unlock if we didn't delete the dirhash */
else
ufsdirhash_release(dh);
}
/*
* If not enough memory was freed, keep deleting hashes from the head
* of the dirhash list. The ones closest to the head should be the
* oldest.
*/
if (memfreed < memwanted) {
TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) {
if (!sx_try_xlock(&dh->dh_lock))
continue;
memfreed += ufsdirhash_destroy(dh);
if (memfreed >= memwanted)
break;
}
}
DIRHASHLIST_UNLOCK();
}
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 */