libfuse: Notifying the kernel of deletion.

libfuse part to allow a FUSE file-system to tell the kernel when a
file or directory is deleted. If the specified dentry has the
specified inode number, the kernel will unhash it.

Signed-off-by: John Muir <john@jmuir.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

5 files changed, 59 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 636dddc..3f6133d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-12-07  Miklos Szeredi <miklos@szeredi.hu>
+
+	* Add fuse_lowlevel_notify_delete() which tells the kernel that a
+	file or directory is deleted.  Patch by John Muir
+
 2011-12-06  Miklos Szeredi <miklos@szeredi.hu>
 
 	* Add mmap() and munmap() methods to low level API.  Currently
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 039eb1f..89e941a 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -79,6 +79,7 @@
  *
  * 7.18
  *  - add FUSE_IOCTL_DIR flag
+ *  - add FUSE_NOTIFY_DELETE
  *  - add FUSE_MMAP and FUSE_MUNMAP
  */
 
@@ -322,6 +323,7 @@ enum fuse_notify_code {
 	FUSE_NOTIFY_INVAL_ENTRY = 3,
 	FUSE_NOTIFY_STORE = 4,
 	FUSE_NOTIFY_RETRIEVE = 5,
+	FUSE_NOTIFY_DELETE = 6,
 	FUSE_NOTIFY_CODE_MAX,
 };
 
@@ -667,6 +669,13 @@ struct fuse_notify_inval_entry_out {
 	__u32	padding;
 };
 
+struct fuse_notify_delete_out {
+	__u64	parent;
+	__u64	child;
+	__u32	namelen;
+	__u32	padding;
+};
+
 struct fuse_notify_store_out {
 	__u64	nodeid;
 	__u64	offset;
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 6435937..8ed555e 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1323,6 +1323,22 @@ int fuse_lowlevel_notify_inval_entry(struct fuse_chan *ch, fuse_ino_t parent,
                                      const char *name, size_t namelen);
 
 /**
+ * Notify to invalidate parent attributes and delete the dentry matching
+ * parent/name if the dentry's inode number matches child (otherwise it
+ * will invalidate the matching dentry).
+ *
+ * @param ch the channel through which to send the notification
+ * @param parent inode number
+ * @param child inode number
+ * @param name file name
+ * @param namelen strlen() of file name
+ * @return zero for success, -errno for failure
+ */
+int fuse_lowlevel_notify_delete(struct fuse_chan *ch,
+				fuse_ino_t parent, fuse_ino_t child,
+				const char *name, size_t namelen);
+
+/**
  * Store data to the kernel buffers
  *
  * Synchronously store data in the kernel buffers belonging to the
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index f69b2b1..3bfc993 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2054,6 +2054,34 @@ int fuse_lowlevel_notify_inval_entry(struct fuse_chan *ch, fuse_ino_t parent,
 	return send_notify_iov(f, ch, FUSE_NOTIFY_INVAL_ENTRY, iov, 3);
 }
 
+int fuse_lowlevel_notify_delete(struct fuse_chan *ch,
+				fuse_ino_t parent, fuse_ino_t child,
+				const char *name, size_t namelen)
+{
+	struct fuse_notify_delete_out outarg;
+	struct fuse_ll *f;
+	struct iovec iov[3];
+
+	if (!ch)
+		return -EINVAL;
+
+	f = (struct fuse_ll *)fuse_session_data(fuse_chan_session(ch));
+	if (!f)
+		return -ENODEV;
+
+	outarg.parent = parent;
+	outarg.child = child;
+	outarg.namelen = namelen;
+	outarg.padding = 0;
+
+	iov[1].iov_base = &outarg;
+	iov[1].iov_len = sizeof(outarg);
+	iov[2].iov_base = (void *)name;
+	iov[2].iov_len = namelen + 1;
+
+	return send_notify_iov(f, ch, FUSE_NOTIFY_DELETE, iov, 3);
+}
+
 int fuse_lowlevel_notify_store(struct fuse_chan *ch, fuse_ino_t ino,
 			       off_t offset, struct fuse_bufvec *bufv,
 			       enum fuse_buf_copy_flags flags)
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 1ee1c9d..95bc7d9 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -195,6 +195,7 @@ FUSE_2.9 {
 		fuse_stop_cleanup_thread;
 		fuse_clean_cache;
 		fuse_reply_mmap;
+		fuse_lowlevel_notify_delete;
 
 	local:
 		*;