Commit ed326044 authored by Sage Weil's avatar Sage Weil
Browse files

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: default avatarSage Weil <sage@newdream.net>
parent 4a625be4

fs/ceph/snap.c

+37 −23
Original line number Diff line number Diff line
@@ -548,6 +548,41 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci, 
	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 @@ more: 
		 *

		 * ...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);

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