ceph: queue cap snap writeback for realm children on snap update
When a realm is updated, we need to queue writeback on inodes in that
realm _and_ its children. Otherwise, if the inode gets cowed on the
server, we can get a hang later due to out-of-sync cap/snap state.
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 2cb190c..6bdbf3a 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -548,6 +548,41 @@
return 1; /* caller may want to ceph_flush_snaps */
}
+/*
+ * Queue cap_snaps for snap writeback for this realm and its children.
+ * Called under snap_rwsem, so realm topology won't change.
+ */
+static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
+{
+ struct ceph_inode_info *ci;
+ struct inode *lastinode = NULL;
+ struct ceph_snap_realm *child;
+
+ dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino);
+
+ spin_lock(&realm->inodes_with_caps_lock);
+ list_for_each_entry(ci, &realm->inodes_with_caps,
+ i_snap_realm_item) {
+ struct inode *inode = igrab(&ci->vfs_inode);
+ if (!inode)
+ continue;
+ spin_unlock(&realm->inodes_with_caps_lock);
+ if (lastinode)
+ iput(lastinode);
+ lastinode = inode;
+ ceph_queue_cap_snap(ci);
+ spin_lock(&realm->inodes_with_caps_lock);
+ }
+ spin_unlock(&realm->inodes_with_caps_lock);
+ if (lastinode)
+ iput(lastinode);
+
+ dout("queue_realm_cap_snaps %p %llx children\n", realm, realm->ino);
+ list_for_each_entry(child, &realm->children, child_item)
+ queue_realm_cap_snaps(child);
+
+ dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
+}
/*
* Parse and apply a snapblob "snap trace" from the MDS. This specifies
@@ -598,29 +633,8 @@
*
* ...unless it's a snap deletion!
*/
- if (!deletion) {
- struct ceph_inode_info *ci;
- struct inode *lastinode = NULL;
-
- spin_lock(&realm->inodes_with_caps_lock);
- list_for_each_entry(ci, &realm->inodes_with_caps,
- i_snap_realm_item) {
- struct inode *inode = igrab(&ci->vfs_inode);
- if (!inode)
- continue;
- spin_unlock(&realm->inodes_with_caps_lock);
- if (lastinode)
- iput(lastinode);
- lastinode = inode;
- ceph_queue_cap_snap(ci);
- spin_lock(&realm->inodes_with_caps_lock);
- }
- spin_unlock(&realm->inodes_with_caps_lock);
- if (lastinode)
- iput(lastinode);
- dout("update_snap_trace cap_snaps queued\n");
- }
-
+ if (!deletion)
+ queue_realm_cap_snaps(realm);
} else {
dout("update_snap_trace %llx %p seq %lld unchanged\n",
realm->ino, realm, realm->seq);