From 300c7d75f3a5e8edd3e390ccd56b808f3fb14e33 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Mon, 27 Nov 2006 09:55:28 -0500 Subject: [PATCH] [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 --- fs/gfs2/ops_inode.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c index b247f25effb..fd9fee2ceea 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; } -- 2.41.1