ceph: preallocate flock state without locks held
When the lock_kernel() turns into lock_flocks() and a spinlock, we won't
be able to do allocations with the lock held. Preallocate space without
the lock, and retry if the lock state changes out from underneath us.
Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 3356823..fbfc298 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2365,19 +2365,35 @@
if (recon_state->flock) {
int num_fcntl_locks, num_flock_locks;
+ struct ceph_pagelist_cursor trunc_point;
- lock_kernel();
- ceph_count_locks(inode, &num_fcntl_locks, &num_flock_locks);
- rec.v2.flock_len = (2*sizeof(u32) +
- (num_fcntl_locks+num_flock_locks) *
- sizeof(struct ceph_filelock));
+ ceph_pagelist_set_cursor(pagelist, &trunc_point);
+ do {
+ lock_kernel();
+ ceph_count_locks(inode, &num_fcntl_locks,
+ &num_flock_locks);
+ rec.v2.flock_len = (2*sizeof(u32) +
+ (num_fcntl_locks+num_flock_locks) *
+ sizeof(struct ceph_filelock));
+ unlock_kernel();
- err = ceph_pagelist_append(pagelist, &rec, reclen);
- if (!err)
- err = ceph_encode_locks(inode, pagelist,
- num_fcntl_locks,
- num_flock_locks);
- unlock_kernel();
+ /* pre-alloc pagelist */
+ ceph_pagelist_truncate(pagelist, &trunc_point);
+ err = ceph_pagelist_append(pagelist, &rec, reclen);
+ if (!err)
+ err = ceph_pagelist_reserve(pagelist,
+ rec.v2.flock_len);
+
+ /* encode locks */
+ if (!err) {
+ lock_kernel();
+ err = ceph_encode_locks(inode,
+ pagelist,
+ num_fcntl_locks,
+ num_flock_locks);
+ unlock_kernel();
+ }
+ } while (err == -ENOSPC);
} else {
err = ceph_pagelist_append(pagelist, &rec, reclen);
}