libfuse: document deadlock avoidance for fuse_notify_inval_entry()

and fuse_notify_delete()

Reported by Han-Wen Nienhuys

2 files changed, 11 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 4c3d136..b8ccda9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,9 @@
 
 2014-07-15  Miklos Szeredi <miklos@szeredi.hu>
 
+	* libfuse: document deadlock avoidance for
+	fuse_notify_inval_entry() and fuse_notify_delete()
+
 	* fusermount, libfuse: send value as unsigned in "user_id=" and
 	"group_id=" options.  Uids/gids larger than 2147483647 would
 	result in EINVAL when mounting the filesystem.  This also needs a
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 2036717..caf4020 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1335,6 +1335,10 @@ int fuse_lowlevel_notify_inval_inode(struct fuse_chan *ch, fuse_ino_t ino,
  * Notify to invalidate parent attributes and the dentry matching
  * parent/name
  *
+ * To avoid a deadlock don't call this function from a filesystem operation and
+ * don't call it with a lock held that can also be held by a filesystem
+ * operation.
+ *
  * @param ch the channel through which to send the invalidation
  * @param parent inode number
  * @param name file name
@@ -1349,6 +1353,10 @@ int fuse_lowlevel_notify_inval_entry(struct fuse_chan *ch, fuse_ino_t parent,
  * parent/name if the dentry's inode number matches child (otherwise it
  * will invalidate the matching dentry).
  *
+ * To avoid a deadlock don't call this function from a filesystem operation and
+ * don't call it with a lock held that can also be held by a filesystem
+ * operation.
+ *
  * @param ch the channel through which to send the notification
  * @param parent inode number
  * @param child inode number