diff options
| author | mckusick <mckusick@FreeBSD.org> | 2002-10-22 01:06:44 +0000 |
|---|---|---|
| committer | mckusick <mckusick@FreeBSD.org> | 2002-10-22 01:06:44 +0000 |
| commit | 76a6cc0dc172d9a26b57c6064948c52bb19a87e5 (patch) | |
| tree | fed70d49a972fe3a75ee2a1516cdb0e0e5ebcdb5 /sys/kern | |
| parent | 305e5868f30dc7852e251f3a6500661328b28866 (diff) | |
| download | FreeBSD-src-76a6cc0dc172d9a26b57c6064948c52bb19a87e5.zip FreeBSD-src-76a6cc0dc172d9a26b57c6064948c52bb19a87e5.tar.gz | |
This update removes a race between unmount and lookup. The lookup
locks the mount point directory while waiting for vfs_busy to clear.
Meanwhile the unmount which holds the vfs_busy lock tried to lock
the mount point vnode. The fix is to observe that it is safe for the
unmount to remove the vnode from the mount point without locking it.
The lookup will wait for the unmount to complete, then recheck the
mount point when the vfs_busy lock clears.
Sponsored by: DARPA & NAI Labs.
Diffstat (limited to 'sys/kern')
| -rw-r--r-- | sys/kern/vfs_mount.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index 96a6c4b..d623508 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -1317,11 +1317,8 @@ dounmount(mp, flags, td) crfree(mp->mnt_cred); mtx_lock(&mountlist_mtx); TAILQ_REMOVE(&mountlist, mp, mnt_list); - if ((coveredvp = mp->mnt_vnodecovered) != NULL) { - vn_lock(coveredvp, LK_EXCLUSIVE|LK_RETRY, td); + if ((coveredvp = mp->mnt_vnodecovered) != NULL) coveredvp->v_mountedhere = NULL; - VOP_UNLOCK(coveredvp, 0, td); - } mp->mnt_vfc->vfc_refcount--; if (!TAILQ_EMPTY(&mp->mnt_nvnodelist)) panic("unmount: dangling vnode"); |
