From 73ce8355c243a434524a34c05cc417dd0467996e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi <miklos@szeredi.hu> Date: Tue, 11 Apr 2006 21:14:26 +0200 Subject: [fuse] fix deadlock between fuse_put_super() and request_end() A deadlock was possible, when the last reference to the superblock was held due to a background request containing a file reference. Releasing the file would release the vfsmount which in turn would release the superblock. Since sbput_sem is held during the fput() and fuse_put_super() tries to acquire this same semaphore, a deadlock results. The chosen soltuion is to get rid of sbput_sem, and instead use the spinlock to ensure the referenced inodes/file are released only once. Since the actual release may sleep, defer these outside the locked region, but using local variables instead of the structure members. This is a much more rubust solution. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> --- fs/fuse/fuse_i.h | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 19c7185a754..ee9b8304251 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -255,15 +255,9 @@ struct fuse_conn { /** waitq for blocked connection */ wait_queue_head_t blocked_waitq; - /** RW semaphore for exclusion with fuse_put_super() */ - struct rw_semaphore sbput_sem; - /** The next unique request id */ u64 reqctr; - /** Mount is active */ - unsigned mounted; - /** Connection established, cleared on umount, connection abort and device release */ unsigned connected; @@ -474,11 +468,11 @@ void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req); void request_send_background(struct fuse_conn *fc, struct fuse_req *req); /** - * Release inodes and file associated with background request + * Remove request from the the background list */ -void fuse_release_background(struct fuse_conn *fc, struct fuse_req *req); +void fuse_remove_background(struct fuse_conn *fc, struct fuse_req *req); -/* Abort all requests */ +/** Abort all requests */ void fuse_abort_conn(struct fuse_conn *fc); /** -- cgit v1.2.3-70-g09d2 From 9bc5dddad1294955e70eeb87325ba1505fb5fe2e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi <miklos@szeredi.hu> Date: Tue, 11 Apr 2006 21:16:09 +0200 Subject: [fuse] Fix accounting the number of waiting requests Properly accounting the number of waiting requests was forgotten in "clean up request accounting" patch. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> --- fs/fuse/dev.c | 25 +++++++++++++++++++------ fs/fuse/fuse_i.h | 3 +++ 2 files changed, 22 insertions(+), 6 deletions(-) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index d4efb6223e2..8538b298a6b 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -92,30 +92,39 @@ struct fuse_req *fuse_get_req(struct fuse_conn *fc) { struct fuse_req *req; sigset_t oldset; + int intr; int err; + atomic_inc(&fc->num_waiting); block_sigs(&oldset); - err = wait_event_interruptible(fc->blocked_waitq, !fc->blocked); + intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked); restore_sigs(&oldset); - if (err) - return ERR_PTR(-EINTR); + err = -EINTR; + if (intr) + goto out; req = fuse_request_alloc(); + err = -ENOMEM; if (!req) - return ERR_PTR(-ENOMEM); + goto out; - atomic_inc(&fc->num_waiting); fuse_request_init(req); req->in.h.uid = current->fsuid; req->in.h.gid = current->fsgid; req->in.h.pid = current->pid; + req->waiting = 1; return req; + + out: + atomic_dec(&fc->num_waiting); + return ERR_PTR(err); } void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req) { if (atomic_dec_and_test(&req->count)) { - atomic_dec(&fc->num_waiting); + if (req->waiting) + atomic_dec(&fc->num_waiting); fuse_request_free(req); } } @@ -281,6 +290,10 @@ static void queue_request(struct fuse_conn *fc, struct fuse_req *req) len_args(req->in.numargs, (struct fuse_arg *) req->in.args); list_add_tail(&req->list, &fc->pending); req->state = FUSE_REQ_PENDING; + if (!req->waiting) { + req->waiting = 1; + atomic_inc(&fc->num_waiting); + } wake_up(&fc->waitq); kill_fasync(&fc->fasync, SIGIO, POLL_IN); } diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index ee9b8304251..59661c481d9 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -159,6 +159,9 @@ struct fuse_req { /** Data is being copied to/from the request */ unsigned locked:1; + /** Request is counted as "waiting" */ + unsigned waiting:1; + /** State of the request */ enum fuse_req_state state; -- cgit v1.2.3-70-g09d2