From a390ccb316beb8ea594b8695d53926710ca454a3 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Sun, 24 Oct 2021 16:26:07 +0300 Subject: fuse: add FOPEN_NOFLUSH Add flag returned by FUSE_OPEN and FUSE_CREATE requests to avoid flushing data cache on close. Different filesystems implement ->flush() is different ways: - Most disk filesystems do not implement ->flush() at all - Some network filesystem (e.g. nfs) flush local write cache of FMODE_WRITE file and send a "flush" command to server - Some network filesystem (e.g. cifs) flush local write cache of FMODE_WRITE file without sending an additional command to server FUSE flushes local write cache of ANY file, even non FMODE_WRITE and sends a "flush" command to server (if server implements it). The FUSE implementation of ->flush() seems over agressive and arbitrary and does not make a lot of sense when writeback caching is disabled. Instead of deciding on another arbitrary implementation that makes sense, leave the choice of per-file flush behavior in the hands of the server. Link: https://lore.kernel.org/linux-fsdevel/CAJfpegspE8e6aKd47uZtSYX8Y-1e1FWS0VL0DH2Skb9gQP5RJQ@mail.gmail.com/ Suggested-by: Miklos Szeredi Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- include/uapi/linux/fuse.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 36ed092227fa..a1dc3ee1d17c 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -184,6 +184,9 @@ * * 7.34 * - add FUSE_SYNCFS + * + * 7.35 + * - add FOPEN_NOFLUSH */ #ifndef _LINUX_FUSE_H @@ -219,7 +222,7 @@ #define FUSE_KERNEL_VERSION 7 /** Minor version number of this interface */ -#define FUSE_KERNEL_MINOR_VERSION 34 +#define FUSE_KERNEL_MINOR_VERSION 35 /** The node ID of the root inode */ #define FUSE_ROOT_ID 1 @@ -290,12 +293,14 @@ struct fuse_file_lock { * FOPEN_NONSEEKABLE: the file is not seekable * FOPEN_CACHE_DIR: allow caching this directory * FOPEN_STREAM: the file is stream-like (no file position at all) + * FOPEN_NOFLUSH: don't flush data cache on close (unless FUSE_WRITEBACK_CACHE) */ #define FOPEN_DIRECT_IO (1 << 0) #define FOPEN_KEEP_CACHE (1 << 1) #define FOPEN_NONSEEKABLE (1 << 2) #define FOPEN_CACHE_DIR (1 << 3) #define FOPEN_STREAM (1 << 4) +#define FOPEN_NOFLUSH (1 << 5) /** * INIT request/reply flags -- cgit v1.2.3