ceph: fix cap_snap and realm split
The cap_snap creation/queueing relies on both the current i_head_snapc
_and_ the i_snap_realm pointers being correct, so that the new cap_snap
can properly reference the old context and the new i_head_snapc can be
updated to reference the new snaprealm's context. To fix this, we:
- move inodes completely to the new (split) realm so that i_snap_realm
is correct, and
- generate the new snapc's _before_ queueing the cap_snaps in
ceph_update_snap_trace().
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 9e836afb..9e6eef1 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -119,6 +119,7 @@
INIT_LIST_HEAD(&realm->children);
INIT_LIST_HEAD(&realm->child_item);
INIT_LIST_HEAD(&realm->empty_item);
+ INIT_LIST_HEAD(&realm->dirty_item);
INIT_LIST_HEAD(&realm->inodes_with_caps);
spin_lock_init(&realm->inodes_with_caps_lock);
__insert_snap_realm(&mdsc->snap_realms, realm);
@@ -604,6 +605,7 @@
struct ceph_snap_realm *realm;
int invalidate = 0;
int err = -ENOMEM;
+ LIST_HEAD(dirty_realms);
dout("update_snap_trace deletion=%d\n", deletion);
more:
@@ -626,24 +628,6 @@
}
}
- if (le64_to_cpu(ri->seq) > realm->seq) {
- dout("update_snap_trace updating %llx %p %lld -> %lld\n",
- realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
- /*
- * if the realm seq has changed, queue a cap_snap for every
- * inode with open caps. we do this _before_ we update
- * the realm info so that we prepare for writeback under the
- * _previous_ snap context.
- *
- * ...unless it's a snap deletion!
- */
- if (!deletion)
- queue_realm_cap_snaps(realm);
- } else {
- dout("update_snap_trace %llx %p seq %lld unchanged\n",
- realm->ino, realm, realm->seq);
- }
-
/* ensure the parent is correct */
err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
if (err < 0)
@@ -651,6 +635,8 @@
invalidate += err;
if (le64_to_cpu(ri->seq) > realm->seq) {
+ dout("update_snap_trace updating %llx %p %lld -> %lld\n",
+ realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
/* update realm parameters, snap lists */
realm->seq = le64_to_cpu(ri->seq);
realm->created = le64_to_cpu(ri->created);
@@ -668,9 +654,17 @@
if (err < 0)
goto fail;
+ /* queue realm for cap_snap creation */
+ list_add(&realm->dirty_item, &dirty_realms);
+
invalidate = 1;
} else if (!realm->cached_context) {
+ dout("update_snap_trace %llx %p seq %lld new\n",
+ realm->ino, realm, realm->seq);
invalidate = 1;
+ } else {
+ dout("update_snap_trace %llx %p seq %lld unchanged\n",
+ realm->ino, realm, realm->seq);
}
dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino,
@@ -683,6 +677,14 @@
if (invalidate)
rebuild_snap_realms(realm);
+ /*
+ * queue cap snaps _after_ we've built the new snap contexts,
+ * so that i_head_snapc can be set appropriately.
+ */
+ list_for_each_entry(realm, &dirty_realms, dirty_item) {
+ queue_realm_cap_snaps(realm);
+ }
+
__cleanup_empty_realms(mdsc);
return 0;
@@ -816,6 +818,7 @@
};
struct inode *inode = ceph_find_inode(sb, vino);
struct ceph_inode_info *ci;
+ struct ceph_snap_realm *oldrealm;
if (!inode)
continue;
@@ -841,18 +844,19 @@
dout(" will move %p to split realm %llx %p\n",
inode, realm->ino, realm);
/*
- * Remove the inode from the realm's inode
- * list, but don't add it to the new realm
- * yet. We don't want the cap_snap to be
- * queued (again) by ceph_update_snap_trace()
- * below. Queue it _now_, under the old context.
+ * Move the inode to the new realm
*/
spin_lock(&realm->inodes_with_caps_lock);
list_del_init(&ci->i_snap_realm_item);
+ list_add(&ci->i_snap_realm_item,
+ &realm->inodes_with_caps);
+ oldrealm = ci->i_snap_realm;
+ ci->i_snap_realm = realm;
spin_unlock(&realm->inodes_with_caps_lock);
spin_unlock(&inode->i_lock);
- ceph_queue_cap_snap(ci);
+ ceph_get_snap_realm(mdsc, realm);
+ ceph_put_snap_realm(mdsc, oldrealm);
iput(inode);
continue;
@@ -880,43 +884,9 @@
ceph_update_snap_trace(mdsc, p, e,
op == CEPH_SNAP_OP_DESTROY);
- if (op == CEPH_SNAP_OP_SPLIT) {
- /*
- * ok, _now_ add the inodes into the new realm.
- */
- for (i = 0; i < num_split_inos; i++) {
- struct ceph_vino vino = {
- .ino = le64_to_cpu(split_inos[i]),
- .snap = CEPH_NOSNAP,
- };
- struct inode *inode = ceph_find_inode(sb, vino);
- struct ceph_inode_info *ci;
-
- if (!inode)
- continue;
- ci = ceph_inode(inode);
- spin_lock(&inode->i_lock);
- if (list_empty(&ci->i_snap_realm_item)) {
- struct ceph_snap_realm *oldrealm =
- ci->i_snap_realm;
-
- dout(" moving %p to split realm %llx %p\n",
- inode, realm->ino, realm);
- spin_lock(&realm->inodes_with_caps_lock);
- list_add(&ci->i_snap_realm_item,
- &realm->inodes_with_caps);
- ci->i_snap_realm = realm;
- spin_unlock(&realm->inodes_with_caps_lock);
- ceph_get_snap_realm(mdsc, realm);
- ceph_put_snap_realm(mdsc, oldrealm);
- }
- spin_unlock(&inode->i_lock);
- iput(inode);
- }
-
+ if (op == CEPH_SNAP_OP_SPLIT)
/* we took a reference when we created the realm, above */
ceph_put_snap_realm(mdsc, realm);
- }
__cleanup_empty_realms(mdsc);