Add ->flock() operation to low and high level interfaces

This fixes problems with emulating flock() with POSIX locking.
Reported by Sebastian Pipping.

As with lock/setlk/getlk most filesystems don't need to implement
this, as the kernel takes care of file locking.  The only reason to
implement locking operations is for network filesystems which want
file locking to work between clients.

1 files changed, 23 insertions, 0 deletions

diff --git a/include/fuse.h b/include/fuse.h
index 7e52719..b05152d 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -548,6 +548,27 @@ struct fuse_operations {
 	 */
 	int (*read_buf) (const char *, struct fuse_bufvec **bufp,
 			 size_t size, off_t off, struct fuse_file_info *);
+	/**
+	 * Perform BSD file locking operation
+	 *
+	 * The op argument will be either LOCK_SH, LOCK_EX or LOCK_UN
+	 *
+	 * Nonblocking requests will be indicated by ORing LOCK_NB to
+	 * the above operations
+	 *
+	 * For more information see the flock(2) manual page.
+	 *
+	 * Additionally fi->owner will be set to a value unique to
+	 * this open file.  This same value will be supplied to
+	 * ->release() when the file is released.
+	 *
+	 * Note: if this method is not implemented, the kernel will still
+	 * allow file locking to work locally.  Hence it is only
+	 * interesting for network filesystems and similar.
+	 *
+	 * Introduced in version 2.9
+	 */
+	int (*flock) (const char *, struct fuse_file_info *, int op);
 };
 
 /** Extra context that may be needed by some filesystems
@@ -813,6 +834,8 @@ int fuse_fs_create(struct fuse_fs *fs, const char *path, mode_t mode,
 		   struct fuse_file_info *fi);
 int fuse_fs_lock(struct fuse_fs *fs, const char *path,
 		 struct fuse_file_info *fi, int cmd, struct flock *lock);
+int fuse_fs_flock(struct fuse_fs *fs, const char *path,
+		  struct fuse_file_info *fi, int op);
 int fuse_fs_chmod(struct fuse_fs *fs, const char *path, mode_t mode);
 int fuse_fs_chown(struct fuse_fs *fs, const char *path, uid_t uid, gid_t gid);
 int fuse_fs_truncate(struct fuse_fs *fs, const char *path, off_t size);