On 3/6/25 14:16, Luis Henriques wrote:
On Thu, Mar 06 2025, Bernd Schubert wrote:
On 3/6/25 12:12, Luis Henriques wrote:
When mounting a user-space filesystem using io_uring, the initialization
of the rings is done separately in the server side. If for some reason
(e.g. a server bug) this step is not performed it will be impossible to
unmount the filesystem if there are already requests waiting.
This issue is easily reproduced with the libfuse passthrough_ll example,
if the queue depth is set to '0' and a request is queued before trying to
unmount the filesystem. When trying to force the unmount, fuse_abort_conn()
will try to wake up all tasks waiting in fc->blocked_waitq, but because the
rings were never initialized, fuse_uring_ready() will never return 'true'.
Fixes: 3393ff964e0f ("fuse: block request allocation until io-uring init is complete")
Signed-off-by: Luis Henriques <luis@xxxxxxxxxx>
---
fs/fuse/dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 7edceecedfa5..2fe565e9b403 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -77,7 +77,7 @@ void fuse_set_initialized(struct fuse_conn *fc)
static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
{
return !fc->initialized || (for_background && fc->blocked) ||
- (fc->io_uring && !fuse_uring_ready(fc));
+ (fc->io_uring && fc->connected && !fuse_uring_ready(fc));
}
static void fuse_drop_waiting(struct fuse_conn *fc)
Oh yes, I had missed that.
Reviewed-by: Bernd Schubert <bschubert@xxxxxxx>
Thanks! And... by the way, Bernd:
I know io_uring support in libfuse isn't ready yet, but I think there's
some error handling missing in your uring branch. In particular, the
return of fuse_uring_start() is never checked, and thus if the rings
initialization fails, the server will not get any error.
I found that out because I blindly tried the patch below, and I was
surprised that the server was started just fine.
Thank you! I will work a bit on splitting the uring branch into
merge-able patches later today, but probably won't finish today (too
many other things to do).
Thanks,
Bernd
