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- cache dp->i_offset in the local 'i_offset' variable for use in loop
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   indexes so directory lookup becomes shared lock safe.  In the modifying
   cases an exclusive lock is held here so the commit routine may
   rely on the state of i_offset.
 - Similarly handle i_diroff by fetching at the start and setting only once
   the operation is complete.  Without the exclusive lock these are only
   considered hints.
 - Assert that an exclusive lock is held when we're preparing for a commit
   routine.
 - Honor the lock type request from lookup instead of always using exclusive
   locking.

Tested by:	pho, kris
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Jeff Roberson authored and Jeff Roberson committed Apr 11, 2008
1 parent 42b1030 commit eb1314a
Showing 1 changed file with 48 additions and 29 deletions.
77 changes: 48 additions & 29 deletions sys/ufs/ufs/ufs_lookup.c
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Expand Up @@ -137,6 +137,8 @@ ufs_lookup(ap)
int entryoffsetinblock; /* offset of ep in bp's buffer */
enum {NONE, COMPACT, FOUND} slotstatus;
doff_t slotoffset; /* offset of area with free space */
doff_t i_diroff; /* cached i_diroff value. */
doff_t i_offset; /* cached i_offset value. */
int slotsize; /* size of area at slotoffset */
int slotfreespace; /* amount of space free in slot */
int slotneeded; /* size of the entry we're seeking */
Expand All @@ -154,6 +156,7 @@ ufs_lookup(ap)
int flags = cnp->cn_flags;
int nameiop = cnp->cn_nameiop;
ino_t saved_ino;
int ltype;

bp = NULL;
slotoffset = -1;
Expand All @@ -173,6 +176,7 @@ ufs_lookup(ap)
* we watch for a place to put the new file in
* case it doesn't already exist.
*/
i_diroff = dp->i_diroff;
slotstatus = FOUND;
slotfreespace = slotsize = slotneeded = 0;
if ((nameiop == CREATE || nameiop == RENAME) &&
Expand Down Expand Up @@ -206,13 +210,13 @@ ufs_lookup(ap)
numdirpasses = 1;
entryoffsetinblock = 0; /* silence compiler warning */
switch (ufsdirhash_lookup(dp, cnp->cn_nameptr, cnp->cn_namelen,
&dp->i_offset, &bp, nameiop == DELETE ? &prevoff : NULL)) {
&i_offset, &bp, nameiop == DELETE ? &prevoff : NULL)) {
case 0:
ep = (struct direct *)((char *)bp->b_data +
(dp->i_offset & bmask));
(i_offset & bmask));
goto foundentry;
case ENOENT:
dp->i_offset = roundup2(dp->i_size, DIRBLKSIZ);
i_offset = roundup2(dp->i_size, DIRBLKSIZ);
goto notfound;
default:
/* Something failed; just do a linear search. */
Expand All @@ -231,33 +235,32 @@ ufs_lookup(ap)
* profiling time and hence has been removed in the interest
* of simplicity.
*/
if (nameiop != LOOKUP || dp->i_diroff == 0 ||
dp->i_diroff >= dp->i_size) {
if (nameiop != LOOKUP || i_diroff == 0 || i_diroff >= dp->i_size) {
entryoffsetinblock = 0;
dp->i_offset = 0;
i_offset = 0;
numdirpasses = 1;
} else {
dp->i_offset = dp->i_diroff;
if ((entryoffsetinblock = dp->i_offset & bmask) &&
(error = UFS_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)))
i_offset = i_diroff;
if ((entryoffsetinblock = i_offset & bmask) &&
(error = UFS_BLKATOFF(vdp, (off_t)i_offset, NULL, &bp)))
return (error);
numdirpasses = 2;
nchstats.ncs_2passes++;
}
prevoff = dp->i_offset;
prevoff = i_offset;
endsearch = roundup2(dp->i_size, DIRBLKSIZ);
enduseful = 0;

searchloop:
while (dp->i_offset < endsearch) {
while (i_offset < endsearch) {
/*
* If necessary, get the next directory block.
*/
if ((dp->i_offset & bmask) == 0) {
if ((i_offset & bmask) == 0) {
if (bp != NULL)
brelse(bp);
error =
UFS_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp);
UFS_BLKATOFF(vdp, (off_t)i_offset, NULL, &bp);
if (error)
return (error);
entryoffsetinblock = 0;
Expand All @@ -284,9 +287,9 @@ ufs_lookup(ap)
(dirchk && ufs_dirbadentry(vdp, ep, entryoffsetinblock))) {
int i;

ufs_dirbad(dp, dp->i_offset, "mangled entry");
ufs_dirbad(dp, i_offset, "mangled entry");
i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1));
dp->i_offset += i;
i_offset += i;
entryoffsetinblock += i;
continue;
}
Expand All @@ -305,15 +308,15 @@ ufs_lookup(ap)
if (size > 0) {
if (size >= slotneeded) {
slotstatus = FOUND;
slotoffset = dp->i_offset;
slotoffset = i_offset;
slotsize = ep->d_reclen;
} else if (slotstatus == NONE) {
slotfreespace += size;
if (slotoffset == -1)
slotoffset = dp->i_offset;
slotoffset = i_offset;
if (slotfreespace >= slotneeded) {
slotstatus = COMPACT;
slotsize = dp->i_offset +
slotsize = i_offset +
ep->d_reclen - slotoffset;
}
}
Expand Down Expand Up @@ -347,7 +350,7 @@ ufs_lookup(ap)
if (vdp->v_mount->mnt_maxsymlinklen > 0 &&
ep->d_type == DT_WHT) {
slotstatus = FOUND;
slotoffset = dp->i_offset;
slotoffset = i_offset;
slotsize = ep->d_reclen;
dp->i_reclen = slotsize;
enduseful = dp->i_size;
Expand All @@ -360,11 +363,11 @@ ufs_lookup(ap)
goto found;
}
}
prevoff = dp->i_offset;
dp->i_offset += ep->d_reclen;
prevoff = i_offset;
i_offset += ep->d_reclen;
entryoffsetinblock += ep->d_reclen;
if (ep->d_ino)
enduseful = dp->i_offset;
enduseful = i_offset;
}
notfound:
/*
Expand All @@ -373,10 +376,11 @@ ufs_lookup(ap)
*/
if (numdirpasses == 2) {
numdirpasses--;
dp->i_offset = 0;
endsearch = dp->i_diroff;
i_offset = 0;
endsearch = i_diroff;
goto searchloop;
}
dp->i_offset = i_offset;
if (bp != NULL)
brelse(bp);
/*
Expand All @@ -389,6 +393,7 @@ ufs_lookup(ap)
(ap->a_cnp->cn_flags & DOWHITEOUT) &&
(ap->a_cnp->cn_flags & ISWHITEOUT))) &&
(flags & ISLASTCN) && dp->i_effnlink != 0) {
ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
/*
* Access for write is interpreted as allowing
* creation of files in the directory.
Expand Down Expand Up @@ -452,9 +457,9 @@ ufs_lookup(ap)
* Check that directory length properly reflects presence
* of this entry.
*/
if (dp->i_offset + DIRSIZ(OFSFMT(vdp), ep) > dp->i_size) {
ufs_dirbad(dp, dp->i_offset, "i_size too small");
dp->i_size = dp->i_offset + DIRSIZ(OFSFMT(vdp), ep);
if (i_offset + DIRSIZ(OFSFMT(vdp), ep) > dp->i_size) {
ufs_dirbad(dp, i_offset, "i_size too small");
dp->i_size = i_offset + DIRSIZ(OFSFMT(vdp), ep);
DIP_SET(dp, i_size, dp->i_size);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
}
Expand All @@ -466,13 +471,15 @@ ufs_lookup(ap)
* in the cache as to where the entry was found.
*/
if ((flags & ISLASTCN) && nameiop == LOOKUP)
dp->i_diroff = dp->i_offset &~ (DIRBLKSIZ - 1);
dp->i_diroff = i_offset &~ (DIRBLKSIZ - 1);

dp->i_offset = i_offset;
/*
* If deleting, and at end of pathname, return
* parameters which can be used to remove file.
*/
if (nameiop == DELETE && (flags & ISLASTCN)) {
ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
/*
* Write access to directory required to delete files.
*/
Expand Down Expand Up @@ -557,16 +564,28 @@ ufs_lookup(ap)
*/
pdp = vdp;
if (flags & ISDOTDOT) {
ltype = VOP_ISLOCKED(pdp);
saved_ino = dp->i_ino;
VOP_UNLOCK(pdp, 0); /* race to get the inode */
error = VFS_VGET(pdp->v_mount, saved_ino,
cnp->cn_lkflags, &tdp);
vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY);
vn_lock(pdp, ltype | LK_RETRY);
if (error)
return (error);
*vpp = tdp;
} else if (dp->i_number == dp->i_ino) {
VREF(vdp); /* we want ourself, ie "." */
/*
* When we lookup "." we still can be asked to lock it
* differently.
*/
ltype = cnp->cn_lkflags & LK_TYPE_MASK;
if (ltype != VOP_ISLOCKED(vdp)) {
if (ltype == LK_EXCLUSIVE)
vn_lock(vdp, LK_UPGRADE | LK_RETRY);
else /* if (ltype == LK_SHARED) */
vn_lock(vdp, LK_DOWNGRADE | LK_RETRY);
}
*vpp = vdp;
} else {
error = VFS_VGET(pdp->v_mount, dp->i_ino,
Expand Down

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