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ceph: fix session locking in handle_caps, ceph_check_caps

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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 <sage@newdream.net>
This commit is contained in:
Sage Weil 2010-03-16 13:39:28 -07:00
parent 4ea0043a29
commit cdc2ce056a
1 changed files with 9 additions and 5 deletions
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14
fs/ceph/caps.c
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@ -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);