ceph: fix dentry rehashing on virtual .snap dir
If a lookup fails on the magic .snap directory, we bind it to a magic
snap directory inode in ceph_lookup_finish(). That code assumes the dentry
is unhashed, but a recent server-side change started returning NULL leases
on lookup failure, causing the .snap dentry to be hashed and NULL by
ceph_fill_trace().
This causes dentry hash chain corruption, or a dies when d_rehash()
includes
BUG_ON(!d_unhashed(entry));
So, avoid processing the NULL dentry lease if it the dentry matches the
snapdir name in ceph_fill_trace(). That allows the lookup completion to
properly bind it to the snapdir inode. BUG there if dentry is hashed to
be sure.
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index aca82d5..26f883c 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -886,6 +886,7 @@
struct inode *in = NULL;
struct ceph_mds_reply_inode *ininfo;
struct ceph_vino vino;
+ struct ceph_client *client = ceph_sb_to_client(sb);
int i = 0;
int err = 0;
@@ -949,7 +950,14 @@
return err;
}
- if (rinfo->head->is_dentry && !req->r_aborted) {
+ /*
+ * ignore null lease/binding on snapdir ENOENT, or else we
+ * will have trouble splicing in the virtual snapdir later
+ */
+ if (rinfo->head->is_dentry && !req->r_aborted &&
+ (rinfo->head->is_target || strncmp(req->r_dentry->d_name.name,
+ client->mount_args->snapdir_name,
+ req->r_dentry->d_name.len))) {
/*
* lookup link rename : null -> possibly existing inode
* mknod symlink mkdir : null -> new inode
