From cdc2ce056a3620139056b60ad7f6d355ad13f445 Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Tue, 16 Mar 2010 13:39:28 -0700 Subject: [PATCH] ceph: fix session locking in handle_caps, ceph_check_caps Passing a session pointer to ceph_check_caps() used to mean it would leave the session mutex locked. That wasn't always possible if it wasn't passed CHECK_CAPS_AUTHONLY. If could unlock the passed session and lock a differet session mutex, which was clearly wrong, and also emitted a warning when it a racing CPU retook it and we did an unlock from the wrong context. This was only a problem when there was more than one MDS. First, make ceph_check_caps unconditionally drop the session mutex, so that it is free to lock other sessions as needed. Then adjust the one caller that passes in a session (handle_cap_grant) accordingly. Signed-off-by: Sage Weil --- fs/ceph/caps.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 726c8d4..7828486 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1407,6 +1407,7 @@ static int try_nonblocking_invalidate(struct inode *inode) */ void ceph_check_caps(struct ceph_inode_info *ci, int flags, struct ceph_mds_session *session) + __releases(session->s_mutex) { struct ceph_client *client = ceph_inode_to_client(&ci->vfs_inode); struct ceph_mds_client *mdsc = &client->mdsc; @@ -1414,7 +1415,6 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, struct ceph_cap *cap; int file_wanted, used; int took_snap_rwsem = 0; /* true if mdsc->snap_rwsem held */ - int drop_session_lock = session ? 0 : 1; int issued, implemented, want, retain, revoking, flushing = 0; int mds = -1; /* keep track of how far we've gone through i_caps list to avoid an infinite loop on retry */ @@ -1639,7 +1639,7 @@ ack: if (queue_invalidate) ceph_queue_invalidate(inode); - if (session && drop_session_lock) + if (session) mutex_unlock(&session->s_mutex); if (took_snap_rwsem) up_read(&mdsc->snap_rwsem); @@ -2688,14 +2688,17 @@ void ceph_handle_caps(struct ceph_mds_session *session, case CEPH_CAP_OP_REVOKE: case CEPH_CAP_OP_GRANT: r = handle_cap_grant(inode, h, session, cap, msg->middle); - if (r == 1) + if (r == 1) { ceph_check_caps(ceph_inode(inode), CHECK_CAPS_NODELAY|CHECK_CAPS_AUTHONLY, session); - else if (r == 2) + session = NULL; + } else if (r == 2) { ceph_check_caps(ceph_inode(inode), CHECK_CAPS_NODELAY, session); + session = NULL; + } break; case CEPH_CAP_OP_FLUSH_ACK: @@ -2713,7 +2716,8 @@ void ceph_handle_caps(struct ceph_mds_session *session, } done: - mutex_unlock(&session->s_mutex); + if (session) + mutex_unlock(&session->s_mutex); if (check_caps) ceph_check_caps(ceph_inode(inode), CHECK_CAPS_NODELAY, NULL); -- 2.7.4