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authorSteven Whitehouse <swhiteho@redhat.com>2006-11-27 17:55:28 +0300
committerSteven Whitehouse <swhiteho@redhat.com>2006-11-30 18:36:53 +0300
commit300c7d75f3a5e8edd3e390ccd56b808f3fb14e33 (patch)
tree1cc627b0e6ef37c3e72691cc75c5be5db14cac72 /fs/gfs2/ops_inode.c
parentcb4c03131836a55bf95e1c165409244ac6b4f39f (diff)
downloadlinux-300c7d75f3a5e8edd3e390ccd56b808f3fb14e33.tar.xz
[GFS2] Fix recursive locking in gfs2_permission
Since gfs2_permission may be called either from the VFS (in which case we need to obtain a shared glock) or from GFS2 (in which case we already have a glock) we need to test to see whether or not a lock is required. The original test was buggy due to a potential race. This one should be safe. This fixes Red Hat bugzilla #217129 Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2/ops_inode.c')
-rw-r--r--fs/gfs2/ops_inode.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c
index b247f25effbf..fd9fee2ceeac 100644
--- a/fs/gfs2/ops_inode.c
+++ b/fs/gfs2/ops_inode.c
@@ -835,6 +835,10 @@ static void *gfs2_follow_link(struct dentry *dentry, struct nameidata *nd)
* @mask:
* @nd: passed from Linux VFS, ignored by us
*
+ * This may be called from the VFS directly, or from within GFS2 with the
+ * inode locked, so we look to see if the glock is already locked and only
+ * lock the glock if its not already been done.
+ *
* Returns: errno
*/
@@ -843,15 +847,18 @@ static int gfs2_permission(struct inode *inode, int mask, struct nameidata *nd)
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_holder i_gh;
int error;
+ int unlock = 0;
- if (!test_bit(GIF_INVALID, &ip->i_flags))
- return generic_permission(inode, mask, gfs2_check_acl);
+ if (gfs2_glock_is_locked_by_me(ip->i_gl) == 0) {
+ error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
+ if (error)
+ return error;
+ unlock = 1;
+ }
- error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
- if (!error) {
- error = generic_permission(inode, mask, gfs2_check_acl_locked);
+ error = generic_permission(inode, mask, gfs2_check_acl_locked);
+ if (unlock)
gfs2_glock_dq_uninit(&i_gh);
- }
return error;
}