From 7c352bdf048811b8128019ffc1e886161e09c11c Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Fri, 9 Sep 2005 13:10:39 -0700 Subject: [PATCH] FUSE: don't allow restarting of system calls This patch removes ability to interrupt and restart operations while there hasn't been any side-effect. The reason: applications. There are some apps it seems that generate signals at a fast rate. This means, that if the operation cannot make enough progress between two signals, it will be restarted for ever. This bug actually manifested itself with 'krusader' trying to open a file for writing under sshfs. Thanks to Eduard Czimbalmos for the report. The problem can be solved just by making open() uninterruptible, because in this case it was the truncate operation that slowed down the progress. But it's better to solve this by simply not allowing interrupts at all (except SIGKILL), because applications don't expect file operations to be interruptible anyway. As an added bonus the code is simplified somewhat. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/dev.c | 73 +++++++++++------------------------------------------------ 1 file changed, 13 insertions(+), 60 deletions(-) (limited to 'fs/fuse/dev.c') diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index e4ada021d087..d4c869c6d01b 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -103,19 +103,8 @@ static struct fuse_req *do_get_request(struct fuse_conn *fc) return req; } +/* This can return NULL, but only in case it's interrupted by a SIGKILL */ struct fuse_req *fuse_get_request(struct fuse_conn *fc) -{ - if (down_interruptible(&fc->outstanding_sem)) - return NULL; - return do_get_request(fc); -} - -/* - * Non-interruptible version of the above function is for operations - * which can't legally return -ERESTART{SYS,NOINTR}. This can still - * return NULL, but only in case the signal is SIGKILL. - */ -struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc) { int intr; sigset_t oldset; @@ -241,43 +230,20 @@ static void background_request(struct fuse_conn *fc, struct fuse_req *req) get_file(req->file); } -static int request_wait_answer_nonint(struct fuse_req *req) -{ - int err; - sigset_t oldset; - block_sigs(&oldset); - err = wait_event_interruptible(req->waitq, req->finished); - restore_sigs(&oldset); - return err; -} - /* Called with fuse_lock held. Releases, and then reacquires it. */ -static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req, - int interruptible) +static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) { - int intr; + sigset_t oldset; spin_unlock(&fuse_lock); - if (interruptible) - intr = wait_event_interruptible(req->waitq, req->finished); - else - intr = request_wait_answer_nonint(req); + block_sigs(&oldset); + wait_event_interruptible(req->waitq, req->finished); + restore_sigs(&oldset); spin_lock(&fuse_lock); - if (intr && interruptible && req->sent) { - /* If request is already in userspace, only allow KILL - signal to interrupt */ - spin_unlock(&fuse_lock); - intr = request_wait_answer_nonint(req); - spin_lock(&fuse_lock); - } - if (!intr) + if (req->finished) return; - if (!interruptible || req->sent) - req->out.h.error = -EINTR; - else - req->out.h.error = -ERESTARTNOINTR; - + req->out.h.error = -EINTR; req->interrupted = 1; if (req->locked) { /* This is uninterruptible sleep, because data is @@ -330,8 +296,10 @@ static void queue_request(struct fuse_conn *fc, struct fuse_req *req) wake_up(&fc->waitq); } -static void request_send_wait(struct fuse_conn *fc, struct fuse_req *req, - int interruptible) +/* + * This can only be interrupted by a SIGKILL + */ +void request_send(struct fuse_conn *fc, struct fuse_req *req) { req->isreply = 1; spin_lock(&fuse_lock); @@ -345,26 +313,11 @@ static void request_send_wait(struct fuse_conn *fc, struct fuse_req *req, after request_end() */ __fuse_get_request(req); - request_wait_answer(fc, req, interruptible); + request_wait_answer(fc, req); } spin_unlock(&fuse_lock); } -void request_send(struct fuse_conn *fc, struct fuse_req *req) -{ - request_send_wait(fc, req, 1); -} - -/* - * Non-interruptible version of the above function is for operations - * which can't legally return -ERESTART{SYS,NOINTR}. This can still - * be interrupted but only with SIGKILL. - */ -void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req) -{ - request_send_wait(fc, req, 0); -} - static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req) { spin_lock(&fuse_lock); -- cgit v1.2.3