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- Set cn_lkflags to LK_SHARED in the LOOKUP_SHARED case so that we only

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acquire shared locks on intermediate directories.
 - For the LASTCN, we may have to LK_UPGRADE the parent directory before
   we lookup the last component.
 - Acquire VFS_ROOT and dp locks based on the cn_lkflag.

Sponsored by:	Isilon Systems, Inc.
This commit is contained in:
Jeff Roberson 2005-03-29 10:07:15 +00:00
parent 18b24235a1
commit 99f3c87034
1 changed files with 29 additions and 5 deletions
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34
sys/kern/vfs_lookup.c
View File

@ -360,11 +360,20 @@ lookup(ndp)
cnp->cn_nameiop != LOOKUP))
docache = 0;
rdonly = cnp->cn_flags & RDONLY;
ndp->ni_dvp = NULL;
cnp->cn_flags &= ~ISSYMLINK;
ndp->ni_dvp = NULL;
#ifdef LOOKUP_SHARED
/*
* We use shared locks until we hit the parent of the last cn then
* we adjust based on the requesting flags.
*/
cnp->cn_lkflags = LK_SHARED;
#else
cnp->cn_lkflags = LK_EXCLUSIVE;
#endif
dp = ndp->ni_startdir;
ndp->ni_startdir = NULLVP;
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, td);
vn_lock(dp, cnp->cn_lkflags | LK_RETRY, td);
dirloop:
/*
@ -487,7 +496,7 @@ lookup(ndp)
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
VFS_UNLOCK_GIANT(tvfslocked);
VREF(dp);
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, td);
vn_lock(dp, cnp->cn_lkflags | LK_RETRY, td);
}
}
@ -505,6 +514,20 @@ lookup(ndp)
ndp->ni_dvp = dp;
ndp->ni_vp = NULL;
ASSERT_VOP_LOCKED(dp, "lookup");
/*
* If we have a shared lock we may need to upgrade the lock for the
* last operation.
*/
if (VOP_ISLOCKED(dp, td) == LK_SHARED &&
(cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
vn_lock(dp, LK_UPGRADE|LK_RETRY, td);
/*
* If we're looking up the last component and we need an exclusive
* lock, adjust our lkflags.
*/
if ((cnp->cn_flags & (ISLASTCN|LOCKSHARED|LOCKLEAF)) ==
(ISLASTCN|LOCKLEAF))
cnp->cn_lkflags = LK_EXCLUSIVE;
#ifdef NAMEI_DIAGNOSTIC
vprint("lookup in", dp);
#endif
@ -523,7 +546,7 @@ lookup(ndp)
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
VFS_UNLOCK_GIANT(tvfslocked);
VREF(dp);
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, td);
vn_lock(dp, cnp->cn_lkflags | LK_RETRY, td);
goto unionlookup;
}
@ -604,7 +627,7 @@ lookup(ndp)
continue;
VOP_UNLOCK(dp, 0, td);
tvfslocked = VFS_LOCK_GIANT(mp);
error = VFS_ROOT(mp, LK_EXCLUSIVE, &tdp, td);
error = VFS_ROOT(mp, cnp->cn_lkflags, &tdp, td);
vfs_unbusy(mp, td);
if (error) {
VFS_UNLOCK_GIANT(tvfslocked);
@ -725,6 +748,7 @@ relookup(dvp, vpp, cnp)
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
dp = dvp;
cnp->cn_lkflags = LK_EXCLUSIVE;
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, td);
/*