diff options
| author | kato <kato@FreeBSD.org> | 1997-04-17 11:24:57 +0000 |
|---|---|---|
| committer | kato <kato@FreeBSD.org> | 1997-04-17 11:24:57 +0000 |
| commit | b38f98ddc9e3efbde3bcae4c57e2c0ba21ca803e (patch) | |
| tree | 1e319e07403b3d688e2e3eacd2962f764fefd2e7 /sys/miscfs | |
| parent | 89de63b34867b051fbafa128e5f7061ddedcea93 (diff) | |
| download | FreeBSD-src-b38f98ddc9e3efbde3bcae4c57e2c0ba21ca803e.zip FreeBSD-src-b38f98ddc9e3efbde3bcae4c57e2c0ba21ca803e.tar.gz | |
Fix `locking against myself' panic by multi nullfs mount of same
directory pair.
Diffstat (limited to 'sys/miscfs')
| -rw-r--r-- | sys/miscfs/nullfs/null_vfsops.c | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/sys/miscfs/nullfs/null_vfsops.c b/sys/miscfs/nullfs/null_vfsops.c index a62b5e8..10791f8 100644 --- a/sys/miscfs/nullfs/null_vfsops.c +++ b/sys/miscfs/nullfs/null_vfsops.c @@ -36,7 +36,7 @@ * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 * * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 - * $Id: null_vfsops.c,v 1.14 1997/02/22 09:40:21 peter Exp $ + * $Id: null_vfsops.c,v 1.15 1997/04/17 11:17:29 kato Exp $ */ /* @@ -92,6 +92,7 @@ nullfs_mount(mp, path, data, ndp, p) struct vnode *nullm_rootvp; struct null_mount *xmp; u_int size; + int isvnunlocked = 0; #ifdef NULLFS_DIAGNOSTIC printf("nullfs_mount(mp = %x)\n", mp); @@ -113,11 +114,26 @@ nullfs_mount(mp, path, data, ndp, p) return (error); /* + * Unlock lower node to avoid deadlock. + * (XXX) VOP_ISLOCKED is needed? + */ + if ((mp->mnt_vnodecovered->v_op == null_vnodeop_p) && + VOP_ISLOCKED(mp->mnt_vnodecovered)) { + VOP_UNLOCK(mp->mnt_vnodecovered, 0, p); + isvnunlocked = 1; + } + /* * Find lower node */ NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF, UIO_USERSPACE, args.target, p); error = namei(ndp); + /* + * Re-lock vnode. + */ + if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered)) + vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, p); + if (error) return (error); @@ -129,6 +145,14 @@ nullfs_mount(mp, path, data, ndp, p) vrele(ndp->ni_dvp); ndp->ni_dvp = NULLVP; + /* + * Check multi null mount to avoid `lock against myself' panic. + */ + if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { + error = EDEADLK; + return (error); + } + xmp = (struct null_mount *) malloc(sizeof(struct null_mount), M_UFSMNT, M_WAITOK); /* XXX */ |
