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afs: Fix lock-wait/callback-break double locking 

__afs_break_callback() holds vnode->lock around its call of
afs_lock_may_be_available() - which also takes that lock.

Fix this by not taking the lock in __afs_break_callback().

Also, there's no point checking the granted_locks and pending_locks queues;
it's sufficient to check lock_state, so move that check out of
afs_lock_may_be_available() into __afs_break_callback() to replace the
queue checks.

Fixes: e8d6c55412 ("AFS: implement file locking")
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2019-05-10 23:03:31 +01:00
parent d9052dda8a
commit c7226e407b
2 changed files with 1 additions and 10 deletions
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8
fs/afs/callback.c
View File

@ -218,14 +218,8 @@ void __afs_break_callback(struct afs_vnode *vnode)
vnode->cb_break++;
afs_clear_permits(vnode);
spin_lock(&vnode->lock);
_debug("break callback");
if (list_empty(&vnode->granted_locks) &&
!list_empty(&vnode->pending_locks))
if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
afs_lock_may_be_available(vnode);
spin_unlock(&vnode->lock);
}
}

3
fs/afs/flock.c
View File

@ -41,9 +41,6 @@ void afs_lock_may_be_available(struct afs_vnode *vnode)
{
_enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
if (vnode->lock_state != AFS_VNODE_LOCK_WAITING_FOR_CB)
return;
spin_lock(&vnode->lock);
if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
afs_next_locker(vnode, 0);