minix/sys/ufs/lfs/ulfs_dirhash.c

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/* $NetBSD: ulfs_dirhash.c,v 1.7 2013/07/28 01:10:49 dholland Exp $ */
/* from NetBSD: ufs_dirhash.c,v 1.34 2009/10/05 23:48:08 rmind Exp */
/*
* 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.
*
* $FreeBSD: src/sys/ufs/ufs/ufs_dirhash.c,v 1.3.2.8 2004/12/08 11:54:13 dwmalone Exp $
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ulfs_dirhash.c,v 1.7 2013/07/28 01:10:49 dholland Exp $");
/*
* This implements a hash-based lookup scheme for ULFS directories.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/types.h>
#include <sys/hash.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/pool.h>
#include <sys/sysctl.h>
#include <sys/atomic.h>
#include <ufs/lfs/ulfs_inode.h>
#include <ufs/lfs/ulfs_dirhash.h>
#include <ufs/lfs/ulfsmount.h>
#include <ufs/lfs/ulfs_bswap.h>
#include <ufs/lfs/ulfs_extern.h>
#define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1))
#define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1))
#define OFSFMT(ip) ((ip)->i_lfs->um_maxsymlinklen <= 0)
#define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n))
static u_int ulfs_dirhashminblks = 5;
static u_int ulfs_dirhashmaxmem = 2 * 1024 * 1024;
static u_int ulfs_dirhashmem;
static u_int ulfs_dirhashcheck = 0;
static int ulfsdirhash_hash(struct dirhash *dh, const char *name, int namelen);
static void ulfsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff,
int dirblksiz);
static void ulfsdirhash_delslot(struct dirhash *dh, int slot);
static int ulfsdirhash_findslot(struct dirhash *dh, const char *name,
int namelen, doff_t offset);
static doff_t ulfsdirhash_getprev(struct lfs_direct *dp, doff_t offset,
int dirblksiz);
static int ulfsdirhash_recycle(int wanted);
static pool_cache_t ulfsdirhashblk_cache;
static pool_cache_t ulfsdirhash_cache;
#define DIRHASHLIST_LOCK() mutex_enter(&ulfsdirhash_lock)
#define DIRHASHLIST_UNLOCK() mutex_exit(&ulfsdirhash_lock)
#define DIRHASH_LOCK(dh) mutex_enter(&(dh)->dh_lock)
#define DIRHASH_UNLOCK(dh) mutex_exit(&(dh)->dh_lock)
#define DIRHASH_BLKALLOC() \
pool_cache_get(ulfsdirhashblk_cache, PR_NOWAIT)
#define DIRHASH_BLKFREE(ptr) \
pool_cache_put(ulfsdirhashblk_cache, ptr)
/* Dirhash list; recently-used entries are near the tail. */
static TAILQ_HEAD(, dirhash) ulfsdirhash_list;
/* Protects: ulfsdirhash_list, `dh_list' field, ulfs_dirhashmem. */
static kmutex_t ulfsdirhash_lock;
static struct sysctllog *ulfsdirhash_sysctl_log;
/*
* Locking order:
* ulfsdirhash_lock
* dh_lock
*
* The dh_lock mutex should be acquired either via the inode lock, or via
* ulfsdirhash_lock. Only the owner of the inode may free the associated
* dirhash, but anything can steal its memory and set dh_hash to NULL.
*/
/*
* 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
ulfsdirhash_build(struct inode *ip)
{
struct dirhash *dh;
struct buf *bp = NULL;
struct lfs_direct *ep;
struct vnode *vp;
doff_t bmask, pos;
int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
const int needswap = ULFS_IPNEEDSWAP(ip);
int dirblksiz = ip->i_lfs->um_dirblksiz;
/* Check if we can/should use dirhash. */
if (ip->i_dirhash == NULL) {
if (ip->i_size < (ulfs_dirhashminblks * dirblksiz) || OFSFMT(ip))
return (-1);
} else {
/* Hash exists, but sysctls could have changed. */
if (ip->i_size < (ulfs_dirhashminblks * dirblksiz) ||
ulfs_dirhashmem > ulfs_dirhashmaxmem) {
ulfsdirhash_free(ip);
return (-1);
}
/* Check if hash exists and is intact (note: unlocked read). */
if (ip->i_dirhash->dh_hash != NULL)
return (0);
/* Free the old, recycled hash and build a new one. */
ulfsdirhash_free(ip);
}
/* Don't hash removed directories. */
if (ip->i_nlink == 0)
return (-1);
vp = ip->i_vnode;
/* Allocate 50% more entries than this dir size could ever need. */
KASSERT(ip->i_size >= dirblksiz);
nslots = ip->i_size / LFS_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);
while (atomic_add_int_nv(&ulfs_dirhashmem, memreqd) >
ulfs_dirhashmaxmem) {
atomic_add_int(&ulfs_dirhashmem, -memreqd);
if (memreqd > ulfs_dirhashmaxmem / 2)
return (-1);
/* Try to free some space. */
if (ulfsdirhash_recycle(memreqd) != 0)
return (-1);
else
DIRHASHLIST_UNLOCK();
}
/*
* Use non-blocking mallocs so that we will revert to a linear
* lookup on failure rather than potentially blocking forever.
*/
dh = pool_cache_get(ulfsdirhash_cache, PR_NOWAIT);
if (dh == NULL) {
atomic_add_int(&ulfs_dirhashmem, -memreqd);
return (-1);
}
memset(dh, 0, sizeof(*dh));
mutex_init(&dh->dh_lock, MUTEX_DEFAULT, IPL_NONE);
DIRHASH_LOCK(dh);
dh->dh_hashsz = narrays * sizeof(dh->dh_hash[0]);
dh->dh_hash = kmem_zalloc(dh->dh_hashsz, KM_NOSLEEP);
dh->dh_blkfreesz = nblocks * sizeof(dh->dh_blkfree[0]);
dh->dh_blkfree = kmem_zalloc(dh->dh_blkfreesz, KM_NOSLEEP);
if (dh->dh_hash == NULL || dh->dh_blkfree == NULL)
goto fail;
for (i = 0; i < narrays; i++) {
if ((dh->dh_hash[i] = DIRHASH_BLKALLOC()) == NULL)
goto fail;
for (j = 0; j < DH_NBLKOFF; j++)
dh->dh_hash[i][j] = DIRHASH_EMPTY;
}
/* Initialise the hash table and block statistics. */
dh->dh_narrays = narrays;
dh->dh_hlen = nslots;
dh->dh_nblk = nblocks;
dh->dh_dirblks = dirblocks;
for (i = 0; i < dirblocks; i++)
dh->dh_blkfree[i] = dirblksiz / DIRALIGN;
for (i = 0; i < DH_NFSTATS; i++)
dh->dh_firstfree[i] = -1;
dh->dh_firstfree[DH_NFSTATS] = 0;
dh->dh_seqopt = 0;
dh->dh_seqoff = 0;
dh->dh_score = DH_SCOREINIT;
ip->i_dirhash = dh;
bmask = VFSTOULFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
pos = 0;
while (pos < ip->i_size) {
if ((curcpu()->ci_schedstate.spc_flags & SPCF_SHOULDYIELD)
!= 0) {
preempt();
}
/* If necessary, get the next directory block. */
if ((pos & bmask) == 0) {
if (bp != NULL)
brelse(bp, 0);
if (ulfs_blkatoff(vp, (off_t)pos, NULL, &bp, false) != 0)
goto fail;
}
/* Add this entry to the hash. */
ep = (struct lfs_direct *)((char *)bp->b_data + (pos & bmask));
if (ep->d_reclen == 0 || ep->d_reclen >
dirblksiz - (pos & (dirblksiz - 1))) {
/* Corrupted directory. */
brelse(bp, 0);
goto fail;
}
if (ep->d_ino != 0) {
/* Add the entry (simplified ulfsdirhash_add). */
slot = ulfsdirhash_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;
ulfsdirhash_adjfree(dh, pos, -LFS_DIRSIZ(0, ep, needswap),
dirblksiz);
}
pos += ep->d_reclen;
}
if (bp != NULL)
brelse(bp, 0);
DIRHASHLIST_LOCK();
TAILQ_INSERT_TAIL(&ulfsdirhash_list, dh, dh_list);
dh->dh_onlist = 1;
DIRHASH_UNLOCK(dh);
DIRHASHLIST_UNLOCK();
return (0);
fail:
DIRHASH_UNLOCK(dh);
if (dh->dh_hash != NULL) {
for (i = 0; i < narrays; i++)
if (dh->dh_hash[i] != NULL)
DIRHASH_BLKFREE(dh->dh_hash[i]);
kmem_free(dh->dh_hash, dh->dh_hashsz);
}
if (dh->dh_blkfree != NULL)
kmem_free(dh->dh_blkfree, dh->dh_blkfreesz);
mutex_destroy(&dh->dh_lock);
pool_cache_put(ulfsdirhash_cache, dh);
ip->i_dirhash = NULL;
atomic_add_int(&ulfs_dirhashmem, -memreqd);
return (-1);
}
/*
* Free any hash table associated with inode 'ip'.
*/
void
ulfsdirhash_free(struct inode *ip)
{
struct dirhash *dh;
int i, mem;
if ((dh = ip->i_dirhash) == NULL)
return;
if (dh->dh_onlist) {
DIRHASHLIST_LOCK();
if (dh->dh_onlist)
TAILQ_REMOVE(&ulfsdirhash_list, dh, dh_list);
DIRHASHLIST_UNLOCK();
}
/* The dirhash pointed to by 'dh' is exclusively ours now. */
mem = sizeof(*dh);
if (dh->dh_hash != NULL) {
for (i = 0; i < dh->dh_narrays; i++)
DIRHASH_BLKFREE(dh->dh_hash[i]);
kmem_free(dh->dh_hash, dh->dh_hashsz);
kmem_free(dh->dh_blkfree, dh->dh_blkfreesz);
mem += dh->dh_hashsz;
mem += dh->dh_narrays * DH_NBLKOFF * sizeof(**dh->dh_hash);
mem += dh->dh_nblk * sizeof(*dh->dh_blkfree);
}
mutex_destroy(&dh->dh_lock);
pool_cache_put(ulfsdirhash_cache, dh);
ip->i_dirhash = NULL;
atomic_add_int(&ulfs_dirhashmem, -mem);
}
/*
* 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).
*/
int
ulfsdirhash_lookup(struct inode *ip, const char *name, int namelen, doff_t *offp,
struct buf **bpp, doff_t *prevoffp)
{
struct dirhash *dh, *dh_next;
struct lfs_direct *dp;
struct vnode *vp;
struct buf *bp;
doff_t blkoff, bmask, offset, prevoff;
int i, slot;
const int needswap = ULFS_IPNEEDSWAP(ip);
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return (EJUSTRETURN);
/*
* Move this dirhash towards the end of the list if it has a
* score higher than the next entry, and acquire the dh_lock.
* Optimise the case where it's already the last by performing
* an unlocked read of the TAILQ_NEXT pointer.
*
* In both cases, end up holding just dh_lock.
*/
if (TAILQ_NEXT(dh, dh_list) != NULL) {
DIRHASHLIST_LOCK();
DIRHASH_LOCK(dh);
/*
* 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->dh_hash != NULL &&
(dh_next = TAILQ_NEXT(dh, dh_list)) != NULL &&
dh->dh_score >= dh_next->dh_score) {
KASSERT(dh->dh_onlist);
TAILQ_REMOVE(&ulfsdirhash_list, dh, dh_list);
TAILQ_INSERT_AFTER(&ulfsdirhash_list, dh_next, dh,
dh_list);
}
DIRHASHLIST_UNLOCK();
} else {
/* Already the last, though that could change as we wait. */
DIRHASH_LOCK(dh);
}
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return (EJUSTRETURN);
}
/* Update the score. */
if (dh->dh_score < DH_SCOREMAX)
dh->dh_score++;
vp = ip->i_vnode;
bmask = VFSTOULFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
blkoff = -1;
bp = NULL;
restart:
slot = ulfsdirhash_hash(dh, name, namelen);
if (dh->dh_seqopt) {
/*
* Sequential access optimisation. dh_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 == dh->dh_seqoff)
break;
if (offset == dh->dh_seqoff) {
/*
* We found an entry with the expected offset. This
* is probably the entry we want, but if not, the
* code below will turn off seqoff and retry.
*/
slot = i;
} else
dh->dh_seqopt = 0;
}
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("ulfsdirhash_lookup: bad offset in hash array");
if ((offset & ~bmask) != blkoff) {
if (bp != NULL)
brelse(bp, 0);
blkoff = offset & ~bmask;
if (ulfs_blkatoff(vp, (off_t)blkoff,
NULL, &bp, false) != 0) {
DIRHASH_UNLOCK(dh);
return (EJUSTRETURN);
}
}
dp = (struct lfs_direct *)((char *)bp->b_data + (offset & bmask));
if (dp->d_reclen == 0 || dp->d_reclen >
dirblksiz - (offset & (dirblksiz - 1))) {
/* Corrupted directory. */
DIRHASH_UNLOCK(dh);
brelse(bp, 0);
return (EJUSTRETURN);
}
if (dp->d_namlen == namelen &&
memcmp(dp->d_name, name, namelen) == 0) {
/* Found. Get the prev offset if needed. */
if (prevoffp != NULL) {
if (offset & (dirblksiz - 1)) {
prevoff = ulfsdirhash_getprev(dp,
offset, dirblksiz);
if (prevoff == -1) {
brelse(bp, 0);
return (EJUSTRETURN);
}
} else
prevoff = offset;
*prevoffp = prevoff;
}
/* Check for sequential access, and update offset. */
if (dh->dh_seqopt == 0 && dh->dh_seqoff == offset)
dh->dh_seqopt = 1;
dh->dh_seqoff = offset + LFS_DIRSIZ(0, dp, needswap);
DIRHASH_UNLOCK(dh);
*bpp = bp;
*offp = offset;
return (0);
}
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
if (bp != NULL)
brelse(bp, 0);
ulfsdirhash_free(ip);
return (EJUSTRETURN);
}
/*
* When the name doesn't match in the seqopt case, go back
* and search normally.
*/
if (dh->dh_seqopt) {
dh->dh_seqopt = 0;
goto restart;
}
}
DIRHASH_UNLOCK(dh);
if (bp != NULL)
brelse(bp, 0);
return (ENOENT);
}
/*
* 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
ulfsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize)
{
struct lfs_direct *dp;
struct dirhash *dh;
struct buf *bp;
doff_t pos, slotstart;
int dirblock, error, freebytes, i;
const int needswap = ULFS_IPNEEDSWAP(ip);
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return (-1);
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return (-1);
}
/* 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) {
DIRHASH_UNLOCK(dh);
return (-1);
}
KASSERT(dirblock < dh->dh_nblk &&
dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN));
pos = dirblock * dirblksiz;
error = ulfs_blkatoff(ip->i_vnode, (off_t)pos, (void *)&dp, &bp, false);
if (error) {
DIRHASH_UNLOCK(dh);
return (-1);
}
/* Find the first entry with free space. */
for (i = 0; i < dirblksiz; ) {
if (dp->d_reclen == 0) {
DIRHASH_UNLOCK(dh);
brelse(bp, 0);
return (-1);
}
if (dp->d_ino == 0 || dp->d_reclen > LFS_DIRSIZ(0, dp, needswap))
break;
i += dp->d_reclen;
dp = (struct lfs_direct *)((char *)dp + dp->d_reclen);
}
if (i > dirblksiz) {
DIRHASH_UNLOCK(dh);
brelse(bp, 0);
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 -= LFS_DIRSIZ(0, dp, needswap);
if (dp->d_reclen == 0) {
DIRHASH_UNLOCK(dh);
brelse(bp, 0);
return (-1);
}
i += dp->d_reclen;
dp = (struct lfs_direct *)((char *)dp + dp->d_reclen);
}
if (i > dirblksiz) {
DIRHASH_UNLOCK(dh);
brelse(bp, 0);
return (-1);
}
if (freebytes < slotneeded)
panic("ulfsdirhash_findfree: free mismatch");
DIRHASH_UNLOCK(dh);
brelse(bp, 0);
*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
ulfsdirhash_enduseful(struct inode *ip)
{
struct dirhash *dh;
int i;
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return (-1);
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return (-1);
}
if (dh->dh_blkfree[dh->dh_dirblks - 1] != dirblksiz / DIRALIGN) {
DIRHASH_UNLOCK(dh);
return (-1);
}
for (i = dh->dh_dirblks - 1; i >= 0; i--)
if (dh->dh_blkfree[i] != dirblksiz / DIRALIGN)
break;
DIRHASH_UNLOCK(dh);
return ((doff_t)(i + 1) * dirblksiz);
}
/*
* Insert information into the hash about a new directory entry. dirp
* points to a struct lfs_direct containing the entry, and offset specifies
* the offset of this entry.
*/
void
ulfsdirhash_add(struct inode *ip, struct lfs_direct *dirp, doff_t offset)
{
struct dirhash *dh;
int slot;
const int needswap = ULFS_IPNEEDSWAP(ip);
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return;
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
KASSERT(offset < dh->dh_dirblks * dirblksiz);
/*
* 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) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
/* Find a free hash slot (empty or deleted), and add the entry. */
slot = ulfsdirhash_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 the per-block summary info. */
ulfsdirhash_adjfree(dh, offset, -LFS_DIRSIZ(0, dirp, needswap), dirblksiz);
DIRHASH_UNLOCK(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
ulfsdirhash_remove(struct inode *ip, struct lfs_direct *dirp, doff_t offset)
{
struct dirhash *dh;
int slot;
const int needswap = ULFS_IPNEEDSWAP(ip);
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return;
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
KASSERT(offset < dh->dh_dirblks * dirblksiz);
/* Find the entry */
slot = ulfsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset);
/* Remove the hash entry. */
ulfsdirhash_delslot(dh, slot);
/* Update the per-block summary info. */
ulfsdirhash_adjfree(dh, offset, LFS_DIRSIZ(0, dirp, needswap), dirblksiz);
DIRHASH_UNLOCK(dh);
}
/*
* Change the offset associated with a directory entry in the hash. Used
* when compacting directory blocks.
*/
void
ulfsdirhash_move(struct inode *ip, struct lfs_direct *dirp, doff_t oldoff,
doff_t newoff)
{
struct dirhash *dh;
int slot;
if ((dh = ip->i_dirhash) == NULL)
return;
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
KASSERT(oldoff < dh->dh_dirblks * ip->i_lfs->um_dirblksiz &&
newoff < dh->dh_dirblks * ip->i_lfs->um_dirblksiz);
/* Find the entry, and update the offset. */
slot = ulfsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff);
DH_ENTRY(dh, slot) = newoff;
DIRHASH_UNLOCK(dh);
}
/*
* Inform dirhash that the directory has grown by one block that
* begins at offset (i.e. the new length is offset + DIRBLKSIZ).
*/
void
ulfsdirhash_newblk(struct inode *ip, doff_t offset)
{
struct dirhash *dh;
int block;
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return;
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
KASSERT(offset == dh->dh_dirblks * dirblksiz);
block = offset / dirblksiz;
if (block >= dh->dh_nblk) {
/* Out of space; must rebuild. */
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(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;
DIRHASH_UNLOCK(dh);
}
/*
* Inform dirhash that the directory is being truncated.
*/
void
ulfsdirhash_dirtrunc(struct inode *ip, doff_t offset)
{
struct dirhash *dh;
int block, i;
int dirblksiz = ip->i_lfs->um_dirblksiz;
if ((dh = ip->i_dirhash) == NULL)
return;
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
KASSERT(offset <= dh->dh_dirblks * dirblksiz);
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
* ulfsdirhash_build) then free it, and let the caller rebuild
* if necessary.
*/
if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(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("ulfsdirhash_dirtrunc: blocks in use");
for (i = 0; i < DH_NFSTATS; i++)
if (dh->dh_firstfree[i] >= block)
panic("ulfsdirhash_dirtrunc: first free corrupt");
dh->dh_dirblks = block;
DIRHASH_UNLOCK(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, `sbuf' 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
ulfsdirhash_checkblock(struct inode *ip, char *sbuf, doff_t offset)
{
struct dirhash *dh;
struct lfs_direct *dp;
int block, ffslot, i, nfree;
const int needswap = ULFS_IPNEEDSWAP(ip);
int dirblksiz = ip->i_lfs->um_dirblksiz;
if (!ulfs_dirhashcheck)
return;
if ((dh = ip->i_dirhash) == NULL)
return;
DIRHASH_LOCK(dh);
if (dh->dh_hash == NULL) {
DIRHASH_UNLOCK(dh);
ulfsdirhash_free(ip);
return;
}
block = offset / dirblksiz;
if ((offset & (dirblksiz - 1)) != 0 || block >= dh->dh_dirblks)
panic("ulfsdirhash_checkblock: bad offset");
nfree = 0;
for (i = 0; i < dirblksiz; i += dp->d_reclen) {
dp = (struct lfs_direct *)(sbuf + i);
if (dp->d_reclen == 0 || i + dp->d_reclen > dirblksiz)
panic("ulfsdirhash_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
* ulfs code is tolerant of such entries at other
* offsets, and fsck does not fix them.
*/
if (i != 0)
panic("ulfsdirhash_checkblock: bad dir inode");
#endif
nfree += dp->d_reclen;
continue;
}
/* Check that the entry exists (will panic if it doesn't). */
ulfsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i);
nfree += dp->d_reclen - LFS_DIRSIZ(0, dp, needswap);
}
if (i != dirblksiz)
panic("ulfsdirhash_checkblock: bad dir end");
if (dh->dh_blkfree[block] * DIRALIGN != nfree)
panic("ulfsdirhash_checkblock: bad free count");
ffslot = BLKFREE2IDX(nfree / DIRALIGN);
for (i = 0; i <= DH_NFSTATS; i++)
if (dh->dh_firstfree[i] == block && i != ffslot)
panic("ulfsdirhash_checkblock: bad first-free");
if (dh->dh_firstfree[ffslot] == -1)
panic("ulfsdirhash_checkblock: missing first-free entry");
DIRHASH_UNLOCK(dh);
}
/*
* Hash the specified filename into a dirhash slot.
*/
static int
ulfsdirhash_hash(struct dirhash *dh, const 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 = hash32_buf(name, namelen, HASH32_BUF_INIT);
hash = hash32_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 ulfsdirhash_build() where exclusive access can be assumed.
*/
static void
ulfsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff, int dirblksiz)
{
int block, i, nfidx, ofidx;
KASSERT(mutex_owned(&dh->dh_lock));
/* Update the per-block summary info. */
block = offset / dirblksiz;
KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks);
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
ulfsdirhash_findslot(struct dirhash *dh, const char *name, int namelen,
doff_t offset)
{
int slot;
KASSERT(mutex_owned(&dh->dh_lock));
/* Find the entry. */
KASSERT(dh->dh_hused < dh->dh_hlen);
slot = ulfsdirhash_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("ulfsdirhash_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
ulfsdirhash_delslot(struct dirhash *dh, int slot)
{
int i;
KASSERT(mutex_owned(&dh->dh_lock));
/* 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);
}
}
/*
* 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
ulfsdirhash_getprev(struct lfs_direct *dirp, doff_t offset, int dirblksiz)
{
struct lfs_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 lfs_direct *)(blkbuf + i);
if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos)
return (-1); /* Corrupted directory. */
prevoff = blkoff + i;
}
return (prevoff);
}
/*
* Try to free up `wanted' bytes by stealing memory from existing
* dirhashes. Returns zero with list locked if successful.
*/
static int
ulfsdirhash_recycle(int wanted)
{
struct dirhash *dh;
doff_t **hash;
u_int8_t *blkfree;
int i, mem, narrays;
size_t hashsz, blkfreesz;
DIRHASHLIST_LOCK();
while (wanted + ulfs_dirhashmem > ulfs_dirhashmaxmem) {
/* Find a dirhash, and lock it. */
if ((dh = TAILQ_FIRST(&ulfsdirhash_list)) == NULL) {
DIRHASHLIST_UNLOCK();
return (-1);
}
DIRHASH_LOCK(dh);
KASSERT(dh->dh_hash != NULL);
/* Decrement the score; only recycle if it becomes zero. */
if (--dh->dh_score > 0) {
DIRHASH_UNLOCK(dh);
DIRHASHLIST_UNLOCK();
return (-1);
}
/* Remove it from the list and detach its memory. */
TAILQ_REMOVE(&ulfsdirhash_list, dh, dh_list);
dh->dh_onlist = 0;
hash = dh->dh_hash;
hashsz = dh->dh_hashsz;
dh->dh_hash = NULL;
blkfree = dh->dh_blkfree;
blkfreesz = dh->dh_blkfreesz;
dh->dh_blkfree = NULL;
narrays = dh->dh_narrays;
mem = narrays * sizeof(*dh->dh_hash) +
narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
dh->dh_nblk * sizeof(*dh->dh_blkfree);
/* Unlock everything, free the detached memory. */
DIRHASH_UNLOCK(dh);
DIRHASHLIST_UNLOCK();
for (i = 0; i < narrays; i++)
DIRHASH_BLKFREE(hash[i]);
kmem_free(hash, hashsz);
kmem_free(blkfree, blkfreesz);
/* Account for the returned memory, and repeat if necessary. */
DIRHASHLIST_LOCK();
atomic_add_int(&ulfs_dirhashmem, -mem);
}
/* Success. */
return (0);
}
static void
ulfsdirhash_sysctl_init(void)
{
const struct sysctlnode *rnode, *cnode;
sysctl_createv(&ulfsdirhash_sysctl_log, 0, NULL, &rnode,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "vfs", NULL,
NULL, 0, NULL, 0,
CTL_VFS, CTL_EOL);
sysctl_createv(&ulfsdirhash_sysctl_log, 0, &rnode, &rnode,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "ulfs",
SYSCTL_DESCR("ulfs"),
NULL, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(&ulfsdirhash_sysctl_log, 0, &rnode, &rnode,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "dirhash",
SYSCTL_DESCR("dirhash"),
NULL, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(&ulfsdirhash_sysctl_log, 0, &rnode, &cnode,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "minblocks",
SYSCTL_DESCR("minimum hashed directory size in blocks"),
NULL, 0, &ulfs_dirhashminblks, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(&ulfsdirhash_sysctl_log, 0, &rnode, &cnode,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "maxmem",
SYSCTL_DESCR("maximum dirhash memory usage"),
NULL, 0, &ulfs_dirhashmaxmem, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(&ulfsdirhash_sysctl_log, 0, &rnode, &cnode,
CTLFLAG_PERMANENT|CTLFLAG_READONLY,
CTLTYPE_INT, "memused",
SYSCTL_DESCR("current dirhash memory usage"),
NULL, 0, &ulfs_dirhashmem, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(&ulfsdirhash_sysctl_log, 0, &rnode, &cnode,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "docheck",
SYSCTL_DESCR("enable extra sanity checks"),
NULL, 0, &ulfs_dirhashcheck, 0,
CTL_CREATE, CTL_EOL);
}
void
ulfsdirhash_init(void)
{
mutex_init(&ulfsdirhash_lock, MUTEX_DEFAULT, IPL_NONE);
ulfsdirhashblk_cache = pool_cache_init(DH_NBLKOFF * sizeof(daddr_t), 0,
0, 0, "dirhashblk", NULL, IPL_NONE, NULL, NULL, NULL);
ulfsdirhash_cache = pool_cache_init(sizeof(struct dirhash), 0,
0, 0, "dirhash", NULL, IPL_NONE, NULL, NULL, NULL);
TAILQ_INIT(&ulfsdirhash_list);
ulfsdirhash_sysctl_init();
}
void
ulfsdirhash_done(void)
{
KASSERT(TAILQ_EMPTY(&ulfsdirhash_list));
pool_cache_destroy(ulfsdirhashblk_cache);
pool_cache_destroy(ulfsdirhash_cache);
mutex_destroy(&ulfsdirhash_lock);
sysctl_teardown(&ulfsdirhash_sysctl_log);
}