fuse: Turn writeback cache on

Introduce a bit kernel and userspace exchange between each-other on
the init stage and turn writeback on if the userspace want this and
mount option 'allow_wbcache' is present (controlled by fusermount).

Also add each writable file into per-inode write list and call the
generic_file_aio_write to make use of the Linux page cache engine.

Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 60bb2f9f7b74..cf4750e1bb49 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -93,6 +93,9 @@
  *
  * 7.22
  *  - add FUSE_ASYNC_DIO
+ *
+ * 7.23
+ *  - add FUSE_WRITEBACK_CACHE
  */
 
 #ifndef _LINUX_FUSE_H
@@ -128,7 +131,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 22
+#define FUSE_KERNEL_MINOR_VERSION 23
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -219,6 +222,7 @@ struct fuse_file_lock {
  * FUSE_DO_READDIRPLUS: do READDIRPLUS (READDIR+LOOKUP in one)
  * FUSE_READDIRPLUS_AUTO: adaptive readdirplus
  * FUSE_ASYNC_DIO: asynchronous direct I/O submission
+ * FUSE_WRITEBACK_CACHE: use writeback cache for buffered writes
  */
 #define FUSE_ASYNC_READ         (1 << 0)
 #define FUSE_POSIX_LOCKS        (1 << 1)
@@ -236,6 +240,7 @@ struct fuse_file_lock {
 #define FUSE_DO_READDIRPLUS     (1 << 13)
 #define FUSE_READDIRPLUS_AUTO   (1 << 14)
 #define FUSE_ASYNC_DIO          (1 << 15)
+#define FUSE_WRITEBACK_CACHE    (1 << 16)
 
 /**
  * CUSE INIT request/reply flags