From: Tejun H. <tj...@ke...> - 2009-04-14 02:06:55
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Previously, a request was marked FINISHED before ->end() is executed and thus request_wait_answer() can return before it's done. This patch makes request_wait_answer() wait for ->end() to finish before returning. Note that no current ->end() user waits for request completion, so this change doesn't cause any behavior difference. While at it, beef up the comment above ->end() hook and clarify when and where it's called. Signed-off-by: Tejun Heo <tj...@ke...> --- fs/fuse/dev.c | 41 +++++++++++++++++++++++++---------------- fs/fuse/fuse_i.h | 5 ++++- 2 files changed, 29 insertions(+), 17 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 2a17249..2e1c43d 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -278,7 +278,6 @@ __releases(&fc->lock) req->end = NULL; list_del(&req->list); list_del(&req->intr_entry); - req->state = FUSE_REQ_FINISHED; if (req->background) { if (fc->num_background == FUSE_MAX_BACKGROUND) { fc->blocked = 0; @@ -293,10 +292,21 @@ __releases(&fc->lock) fc->active_background--; flush_bg_queue(fc); } + spin_unlock(&fc->lock); - wake_up(&req->waitq); - if (end) + + if (end) { end(fc, req); + smp_wmb(); + } + + /* + * We own this request and wake_up() has enough memory + * barrier, no need to grab spin lock to set state. + */ + req->state = FUSE_REQ_FINISHED; + + wake_up(&req->waitq); fuse_put_request(fc, req); } @@ -372,17 +382,16 @@ __acquires(&fc->lock) return; aborted: - BUG_ON(req->state != FUSE_REQ_FINISHED); - if (req->locked) { - /* This is uninterruptible sleep, because data is - being copied to/from the buffers of req. During - locked state, there mustn't be any filesystem - operation (e.g. page fault), since that could lead - to deadlock */ - spin_unlock(&fc->lock); - wait_event(req->waitq, !req->locked); - spin_lock(&fc->lock); - } + spin_unlock(&fc->lock); + wait_event(req->waitq, req->state == FUSE_REQ_FINISHED); + /* + * This is uninterruptible sleep, because data is being copied + * to/from the buffers of req. During locked state, there + * mustn't be any filesystem operation (e.g. page fault), + * since that could lead to deadlock + */ + wait_event(req->waitq, !req->locked); + spin_lock(&fc->lock); } void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req) @@ -1060,9 +1069,7 @@ __acquires(&fc->lock) req->aborted = 1; req->out.h.error = -ECONNABORTED; - req->state = FUSE_REQ_FINISHED; list_del_init(&req->list); - wake_up(&req->waitq); if (end) { req->end = NULL; __fuse_get_request(req); @@ -1072,6 +1079,8 @@ __acquires(&fc->lock) fuse_put_request(fc, req); spin_lock(&fc->lock); } + req->state = FUSE_REQ_FINISHED; + wake_up(&req->waitq); } } diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index cdab92d..4da979c 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -291,7 +291,10 @@ struct fuse_req { /** Link on fi->writepages */ struct list_head writepages_entry; - /** Request completion callback */ + /** Request completion callback. This function is called from + the kernel context of the FUSE server if the request isn't + being aborted. If the request is being aborted, it's + called from the kernel context of the aborting process. */ void (*end)(struct fuse_conn *, struct fuse_req *); /** Request is stolen from fuse_file->reserved_req */ -- 1.6.0.2 |