diff options
| author | Kirill Tkhai <ktkhai@virtuozzo.com> | 2018-11-08 12:05:25 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2019-02-13 13:15:13 +0100 |
| commit | 217316a601016d0d2913290070e6338576ae73f6 (patch) | |
| tree | 018240bc0794d5702b9eaca6a7b392bff21eb5fd /fs/fuse/dev.c | |
| parent | 8da6e9183275c837e7d2401b3018ff81f657a19a (diff) | |
| download | linux-217316a601016d0d2913290070e6338576ae73f6.tar.bz2 | |
fuse: Optimize request_end() by not taking fiq->waitq.lock
We take global fiq->waitq.lock every time, when we are in this function,
but interrupted requests are just small subset of all requests. This patch
optimizes request_end() and makes it to take the lock when it's really
needed.
queue_interrupt() needs small change for that. After req is linked to
interrupt list, we do smp_mb() and check for FR_FINISHED again. In case of
FR_FINISHED bit has appeared, we remove req and leave the function:
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse/dev.c')
| -rw-r--r-- | fs/fuse/dev.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 11246e7965e8..74171d568621 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -431,10 +431,16 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req) if (test_and_set_bit(FR_FINISHED, &req->flags)) goto put_request; - - spin_lock(&fiq->waitq.lock); - list_del_init(&req->intr_entry); - spin_unlock(&fiq->waitq.lock); + /* + * test_and_set_bit() implies smp_mb() between bit + * changing and below intr_entry check. Pairs with + * smp_mb() from queue_interrupt(). + */ + if (!list_empty(&req->intr_entry)) { + spin_lock(&fiq->waitq.lock); + list_del_init(&req->intr_entry); + spin_unlock(&fiq->waitq.lock); + } WARN_ON(test_bit(FR_PENDING, &req->flags)); WARN_ON(test_bit(FR_SENT, &req->flags)); if (test_bit(FR_BACKGROUND, &req->flags)) { @@ -473,12 +479,18 @@ put_request: static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req) { spin_lock(&fiq->waitq.lock); - if (test_bit(FR_FINISHED, &req->flags)) { - spin_unlock(&fiq->waitq.lock); - return; - } if (list_empty(&req->intr_entry)) { list_add_tail(&req->intr_entry, &fiq->interrupts); + /* + * Pairs with smp_mb() implied by test_and_set_bit() + * from request_end(). + */ + smp_mb(); + if (test_bit(FR_FINISHED, &req->flags)) { + list_del_init(&req->intr_entry); + spin_unlock(&fiq->waitq.lock); + return; + } wake_up_locked(&fiq->waitq); kill_fasync(&fiq->fasync, SIGIO, POLL_IN); } |