Author: kib
Date: Sat Nov 22 13:11:11 2008
New Revision: 185170
URL: http://svn.freebsd.org/changeset/base/185170
Log:
Busy ufs filesystem around block of code that does ".." lookup. Since
mnt_lock is before lock of any vnode on the mp, it uses LK_NOWAIT. Since
MNTK_UNMOUNT may be transient, pdp lock is dropped when vfs_busy()
failed, and operation is retried after some time. This way, ffs_vget()
is not called on the mp that may be in the process of being destroyed by
unmount.
Check for the VI_DOOMED flag on pdp after its lock is reacquired, to
better detect some situations where directory containing ".."
entry is removed during the lookup.
Reviewed by: tegge, attilio (previous version)
Tested by: pho
MFC after: 1 month
Modified:
head/sys/ufs/ufs/ufs_lookup.c
Modified: head/sys/ufs/ufs/ufs_lookup.c
==============================================================================
--- head/sys/ufs/ufs/ufs_lookup.c Sat Nov 22 12:36:15 2008
(r185169)
+++ head/sys/ufs/ufs/ufs_lookup.c Sat Nov 22 13:11:11 2008
(r185170)
@@ -157,6 +157,8 @@ ufs_lookup(ap)
int nameiop = cnp->cn_nameiop;
ino_t ino;
int ltype;
+ int pdoomed;
+ struct mount *mp;
bp = NULL;
slotoffset = -1;
@@ -578,9 +580,32 @@ found:
pdp = vdp;
if (flags & ISDOTDOT) {
ltype = VOP_ISLOCKED(pdp);
+ mp = pdp->v_mount;
+ for (;;) {
+ error = vfs_busy(mp, MBF_NOWAIT);
+ if (error == 0)
+ break;
+ VOP_UNLOCK(pdp, 0);
+ pause("ufs_dd", 1);
+ vn_lock(pdp, ltype | LK_RETRY);
+ VI_LOCK(pdp);
+ pdoomed = pdp->v_iflag & VI_DOOMED;
+ VI_UNLOCK(pdp);
+ if (pdoomed)
+ return (ENOENT);
+ }
VOP_UNLOCK(pdp, 0); /* race to get the inode */
- error = VFS_VGET(pdp->v_mount, ino, cnp->cn_lkflags, &tdp);
+ error = VFS_VGET(mp, ino, cnp->cn_lkflags, &tdp);
+ vfs_unbusy(mp);
vn_lock(pdp, ltype | LK_RETRY);
+ VI_LOCK(pdp);
+ pdoomed = pdp->v_iflag & VI_DOOMED;
+ VI_UNLOCK(pdp);
+ if (pdoomed) {
+ if (error == 0)
+ vput(tdp);
+ error = ENOENT;
+ }
if (error)
return (error);
*vpp = tdp;
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