user/sven/linux.git/include/uapi/linux/fuse.h, branch v4.4.193

fuse: Add FOPEN_STREAM to use stream_open()

2019-06-11T10:24:13Z

commit bbd84f33652f852ce5992d65db4d020aba21f882 upstream. Starting from commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX") files opened even via nonseekable_open gate read and write via lock and do not allow them to be run simultaneously. This can create read vs write deadlock if a filesystem is trying to implement a socket-like file which is intended to be simultaneously used for both read and write from filesystem client. See commit 10dce8af3422 ("fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock") for details and e.g. commit 581d21a2d02a ("xenbus: fix deadlock on writes to /proc/xen/xenbus") for a similar deadlock example on /proc/xen/xenbus. To avoid such deadlock it was tempting to adjust fuse_finish_open to use stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags, but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE, and in particular GVFS which actually uses offset in its read and write handlers https://codesearch.debian.net/search?q=-%3Enonseekable+%3D https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481 so if we would do such a change it will break a real user. Add another flag (FOPEN_STREAM) for filesystem servers to indicate that the opened handler is having stream-like semantics; does not use file position and thus the kernel is free to issue simultaneous read and write request on opened file handle. This patch together with stream_open() should be added to stable kernels starting from v3.14+. This will allow to patch OSSPD and other FUSE filesystems that provide stream-like files to return FOPEN_STREAM | FOPEN_NONSEEKABLE in open handler and this way avoid the deadlock on all kernel versions. This should work because fuse_finish_open ignores unknown open flags returned from a filesystem and so passing FOPEN_STREAM to a kernel that is not aware of this flag cannot hurt. In turn the kernel that is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE is sufficient to implement streams without read vs write deadlock. Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Kirill Smelkov Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

fuse: device fd clone

2015-07-01T14:26:08Z

Allow an open fuse device to be "cloned". Userspace can create a clone by: newfd = open("/dev/fuse", O_RDWR) ioctl(newfd, FUSE_DEV_IOC_CLONE, &oldfd); At this point newfd will refer to the same fuse connection as oldfd. Signed-off-by: Miklos Szeredi Reviewed-by: Ashish Samant

fuse: add FUSE_NO_OPEN_SUPPORT flag to INIT

2014-07-22T14:37:43Z

Here some additional changes to set a capability flag so that clients can detect when it's appropriate to return -ENOSYS from open. This amends the following commit introduced in 3.14: 7678ac50615d fuse: support clients that don't implement 'open' However we can only add the flag to 3.15 and later since there was no protocol version update in 3.14. Signed-off-by: Miklos Szeredi Cc: # v3.15+

fuse: add renameat2 support

2014-04-28T14:43:44Z

Support RENAME_EXCHANGE and RENAME_NOREPLACE flags on the userspace ABI. Signed-off-by: Miklos Szeredi

fuse: allow ctime flushing to userspace

2014-04-28T12:19:24Z

The patch extends fuse_setattr_in, and extends the flush procedure (fuse_flush_times()) called on ->write_inode() to send the ctime as well as mtime. Signed-off-by: Maxim Patlasov Signed-off-by: Miklos Szeredi

fuse: fuse: add time_gran to INIT_OUT

2014-04-28T12:19:23Z

Allow userspace fs to specify time granularity. This is needed because with writeback_cache mode the kernel is responsible for generating mtime and ctime, but if the underlying filesystem doesn't support nanosecond granularity then the cache will contain a different value from the one stored on the filesystem resulting in a change of times after a cache flush. Make the default granularity 1s. Signed-off-by: Miklos Szeredi

fuse: Turn writeback cache on

2014-04-02T13:38:50Z

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 Signed-off-by: Miklos Szeredi

fuse: add flag to turn on async direct IO

2013-05-01T12:37:21Z

Without async DIO write requests to a single file were always serialized. With async DIO that's no longer the case. So don't turn on async DIO by default for fear of breaking backward compatibility. Signed-off-by: Miklos Szeredi

fuse: fix type definitions in uapi header

2013-04-17T10:30:40Z

Commit 7e98d53086d18c877cb44e9065219335184024de (Synchronize fuse header with one used in library) added #ifdef __linux__ around defines if it is not set. The kernel build is self-contained and can be built on non-Linux toolchains. After the mentioned commit builds on non-Linux toolchains will try to include stdint.h and fail due to -nostdinc, and then fail with a bunch of undefined type errors. Fix by checking for __KERNEL__ instead of __linux__ and using the standard int types instead of the linux specific ones. Reported-by: Arve Hjønnevåg Reported-by: Colin Cross Signed-off-by: Miklos Szeredi

fuse: allow control of adaptive readdirplus use

2013-02-07T13:25:44Z

For some filesystems (e.g. GlusterFS), the cost of performing a normal readdir and readdirplus are identical. Since adaptively using readdirplus has no benefit for those systems, give users/filesystems the option to control adaptive readdirplus use. v2 of this patch incorporates Miklos's suggestion to simplify the code, as well as improving consistency of macro names and documentation. Signed-off-by: Eric Wong Signed-off-by: Miklos Szeredi