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authorAmir Goldstein <amir73il@gmail.com>2021-10-24 16:26:07 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2021-10-28 10:20:31 +0200
commita390ccb316beb8ea594b8695d53926710ca454a3 (patch)
tree3df484d4fcff192feeb7b182097e8f4b5fa588ac
parentc6c745b81033a4c1f0e5f3b16398a10f2d000c29 (diff)
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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 <mszeredi@redhat.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/fuse/file.c3
-rw-r--r--include/uapi/linux/fuse.h7
2 files changed, 9 insertions, 1 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 26730e699d68..b7f1a164e18a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -476,6 +476,9 @@ static int fuse_flush(struct file *file, fl_owner_t id)
if (fuse_is_bad(inode))
return -EIO;
+ if (ff->open_flags & FOPEN_NOFLUSH && !fm->fc->writeback_cache)
+ return 0;
+
err = write_inode_now(inode, 1);
if (err)
return err;
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