On 5/18/22 19:44, Vivek Goyal wrote:
On Wed, May 18, 2022 at 01:41:02PM -0400, Vivek Goyal wrote:
On Tue, May 17, 2022 at 03:37:42PM +0530, Dharmendra Singh wrote:
[..]
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index d6ccee961891..bebe4be3f1cb 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -301,6 +301,7 @@ struct fuse_file_lock {
* 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)
+ * FOPEN_FILE_CREATED: the file was actually created
*/
#define FOPEN_DIRECT_IO (1 << 0)
#define FOPEN_KEEP_CACHE (1 << 1)
@@ -308,6 +309,7 @@ struct fuse_file_lock {
#define FOPEN_CACHE_DIR (1 << 3)
#define FOPEN_STREAM (1 << 4)
#define FOPEN_NOFLUSH (1 << 5)
+#define FOPEN_FILE_CREATED (1 << 6)
/**
* INIT request/reply flags
@@ -537,6 +539,7 @@ enum fuse_opcode {
FUSE_SETUPMAPPING = 48,
FUSE_REMOVEMAPPING = 49,
FUSE_SYNCFS = 50,
+ FUSE_CREATE_EXT = 51,
I am wondering if we really have to introduce a new opcode for this. Both
FUSE_CREATE and FUSE_CREATE_EXT prepare and send fuse_create_in{} and
expect fuse_entry_out and fuse_open_out in response. So no new structures
are being added. Only thing FUSE_CREATE_EXT does extra is that it also
reports back whether file was actually created or not.
May be instead of adding an new fuse_opcode, we could simply add a
new flag which we send in fuse_create_in and that reqeusts to report
if file was created or not. This is along the lines of
FUSE_OPEN_KILL_SUIDGID.
So say, a new flag FUSE_OPEN_REPORT_CREATE flag. Which we will set in
fuse_create_in->open_flags. If file server sees this flag is set, it
knows that it needs to set FOPEN_FILE_CREATED flag in response.
To me creating a new flag FUSE_OPEN_REPORT_CREATE seems better instead
of adding a new opcode.
Actually I take that back. If we were to use a flag, then we will have to
do feature negotiation in advance at init time and only then we can set
FUSE_OPEN_REPORT_CREATE. But we are relying on no new feature bit instead
-ENOSYS will be returned if server does not support FUSE_CREATE_EXT.
So adding a new opcode is better.
I guess it might work, if a flag is set and also returned (I would then
call it FUSE_CREATE_EXT) - user space creat would need to set
FOPEN_FILE_CREATED and that new flag. I just doubt that it simplifies
things.
Btw, thanks a lot for your thorough reviews! Much appreciated.
Thanks,
Bernd
