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fuse: block request allocation until io-uring init is complete

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Avoid races and block request allocation until io-uring
queues are ready.

This is a especially important for background requests,
as bg request completion might cause lock order inversion
of the typical queue->lock and then fc->bg_lock

    fuse_request_end
       spin_lock(&fc->bg_lock);
       flush_bg_queue
         fuse_send_one
           fuse_uring_queue_fuse_req
           spin_lock(&queue->lock);

Signed-off-by: Bernd Schubert <bernd@bsbernd.com>
Reviewed-by: Luis Henriques <luis@igalia.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Bernd Schubert 2025-01-20 02:29:09 +01:00 • committed by Miklos Szeredi
parent b6236c8407
commit 3393ff964e
4 changed files with 10 additions and 1 deletions
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3
fs/fuse/dev.c
View file

@ -76,7 +76,8 @@ void fuse_set_initialized(struct fuse_conn *fc)
static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background) static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
{ {
return !fc->initialized || (for_background && fc->blocked); return !fc->initialized || (for_background && fc->blocked) ||
(fc->io_uring && !fuse_uring_ready(fc));
} }
static void fuse_drop_waiting(struct fuse_conn *fc) static void fuse_drop_waiting(struct fuse_conn *fc)

3
fs/fuse/dev_uring.c
View file

@ -957,6 +957,7 @@ static void fuse_uring_do_register(struct fuse_ring_ent *ent,
if (ready) { if (ready) {
WRITE_ONCE(fiq->ops, &fuse_io_uring_ops); WRITE_ONCE(fiq->ops, &fuse_io_uring_ops);
WRITE_ONCE(ring->ready, true); WRITE_ONCE(ring->ready, true);
wake_up_all(&fc->blocked_waitq);
} }
} }
} }
@ -1130,6 +1131,8 @@ int __maybe_unused fuse_uring_cmd(struct io_uring_cmd *cmd,
if (err) { if (err) {
pr_info_once("FUSE_IO_URING_CMD_REGISTER failed err=%d\n", pr_info_once("FUSE_IO_URING_CMD_REGISTER failed err=%d\n",
err); err);
fc->io_uring = 0;
wake_up_all(&fc->blocked_waitq);
return err; return err;
} }
break; break;

3
fs/fuse/fuse_i.h
View file

@ -867,6 +867,9 @@ struct fuse_conn {
/* Use pages instead of pointer for kernel I/O */ /* Use pages instead of pointer for kernel I/O */
unsigned int use_pages_for_kvec_io:1; unsigned int use_pages_for_kvec_io:1;
/* Use io_uring for communication */
unsigned int io_uring;
/** Maximum stack depth for passthrough backing files */ /** Maximum stack depth for passthrough backing files */
int max_stack_depth; int max_stack_depth;

2
fs/fuse/inode.c
View file

@ -1390,6 +1390,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
else else
ok = false; ok = false;
} }
if (flags & FUSE_OVER_IO_URING && fuse_uring_enabled())
fc->io_uring = 1;
} else { } else {
ra_pages = fc->max_read / PAGE_SIZE; ra_pages = fc->max_read / PAGE_SIZE;
fc->no_lock = 1; fc->no_lock = 1;