diff options
author | Steven Whitehouse <swhiteho@redhat.com> | 2006-07-03 10:25:08 -0400 |
---|---|---|
committer | Steven Whitehouse <swhiteho@redhat.com> | 2006-07-03 10:25:08 -0400 |
commit | 0a1340c185734a57fbf4775927966ad4a1347b02 (patch) | |
tree | d9ed8f0dd809a7c542a3356601125ea5b5aaa804 /fs/fuse/dev.c | |
parent | af18ddb8864b096e3ed4732e2d4b21c956dcfe3a (diff) | |
parent | 29454dde27d8e340bb1987bad9aa504af7081eba (diff) |
Merge rsync://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
include/linux/kernel.h
Diffstat (limited to 'fs/fuse/dev.c')
-rw-r--r-- | fs/fuse/dev.c | 418 |
1 files changed, 268 insertions, 150 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 104a62dadb9..1e2006caf15 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -34,6 +34,7 @@ static void fuse_request_init(struct fuse_req *req) { memset(req, 0, sizeof(*req)); INIT_LIST_HEAD(&req->list); + INIT_LIST_HEAD(&req->intr_entry); init_waitqueue_head(&req->waitq); atomic_set(&req->count, 1); } @@ -64,18 +65,6 @@ static void restore_sigs(sigset_t *oldset) sigprocmask(SIG_SETMASK, oldset, NULL); } -/* - * Reset request, so that it can be reused - * - * The caller must be _very_ careful to make sure, that it is holding - * the only reference to req - */ -void fuse_reset_request(struct fuse_req *req) -{ - BUG_ON(atomic_read(&req->count) != 1); - fuse_request_init(req); -} - static void __fuse_get_request(struct fuse_req *req) { atomic_inc(&req->count); @@ -88,6 +77,13 @@ static void __fuse_put_request(struct fuse_req *req) atomic_dec(&req->count); } +static void fuse_req_init_context(struct fuse_req *req) +{ + req->in.h.uid = current->fsuid; + req->in.h.gid = current->fsgid; + req->in.h.pid = current->pid; +} + struct fuse_req *fuse_get_req(struct fuse_conn *fc) { struct fuse_req *req; @@ -103,14 +99,16 @@ struct fuse_req *fuse_get_req(struct fuse_conn *fc) if (intr) goto out; + err = -ENOTCONN; + if (!fc->connected) + goto out; + req = fuse_request_alloc(); err = -ENOMEM; if (!req) goto out; - req->in.h.uid = current->fsuid; - req->in.h.gid = current->fsgid; - req->in.h.pid = current->pid; + fuse_req_init_context(req); req->waiting = 1; return req; @@ -119,142 +117,183 @@ struct fuse_req *fuse_get_req(struct fuse_conn *fc) return ERR_PTR(err); } -void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req) +/* + * Return request in fuse_file->reserved_req. However that may + * currently be in use. If that is the case, wait for it to become + * available. + */ +static struct fuse_req *get_reserved_req(struct fuse_conn *fc, + struct file *file) { - if (atomic_dec_and_test(&req->count)) { - if (req->waiting) - atomic_dec(&fc->num_waiting); - fuse_request_free(req); - } + struct fuse_req *req = NULL; + struct fuse_file *ff = file->private_data; + + do { + wait_event(fc->blocked_waitq, ff->reserved_req); + spin_lock(&fc->lock); + if (ff->reserved_req) { + req = ff->reserved_req; + ff->reserved_req = NULL; + get_file(file); + req->stolen_file = file; + } + spin_unlock(&fc->lock); + } while (!req); + + return req; } /* - * Called with sbput_sem held for read (request_end) or write - * (fuse_put_super). By the time fuse_put_super() is finished, all - * inodes belonging to background requests must be released, so the - * iputs have to be done within the locked region. + * Put stolen request back into fuse_file->reserved_req */ -void fuse_release_background(struct fuse_conn *fc, struct fuse_req *req) +static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req) { - iput(req->inode); - iput(req->inode2); + struct file *file = req->stolen_file; + struct fuse_file *ff = file->private_data; + spin_lock(&fc->lock); - list_del(&req->bg_entry); - if (fc->num_background == FUSE_MAX_BACKGROUND) { - fc->blocked = 0; - wake_up_all(&fc->blocked_waitq); - } - fc->num_background--; + fuse_request_init(req); + BUG_ON(ff->reserved_req); + ff->reserved_req = req; + wake_up(&fc->blocked_waitq); spin_unlock(&fc->lock); + fput(file); } /* - * This function is called when a request is finished. Either a reply - * has arrived or it was interrupted (and not yet sent) or some error - * occurred during communication with userspace, or the device file - * was closed. In case of a background request the reference to the - * stored objects are released. The requester thread is woken up (if - * still waiting), the 'end' callback is called if given, else the - * reference to the request is released + * Gets a requests for a file operation, always succeeds * - * Releasing extra reference for foreground requests must be done - * within the same locked region as setting state to finished. This - * is because fuse_reset_request() may be called after request is - * finished and it must be the sole possessor. If request is - * interrupted and put in the background, it will return with an error - * and hence never be reset and reused. + * This is used for sending the FLUSH request, which must get to + * userspace, due to POSIX locks which may need to be unlocked. * - * Called with fc->lock, unlocks it + * If allocation fails due to OOM, use the reserved request in + * fuse_file. + * + * This is very unlikely to deadlock accidentally, since the + * filesystem should not have it's own file open. If deadlock is + * intentional, it can still be broken by "aborting" the filesystem. */ -static void request_end(struct fuse_conn *fc, struct fuse_req *req) +struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file) { - list_del(&req->list); - req->state = FUSE_REQ_FINISHED; - if (!req->background) { - spin_unlock(&fc->lock); - wake_up(&req->waitq); - fuse_put_request(fc, req); - } else { - void (*end) (struct fuse_conn *, struct fuse_req *) = req->end; - req->end = NULL; - spin_unlock(&fc->lock); - down_read(&fc->sbput_sem); - if (fc->mounted) - fuse_release_background(fc, req); - up_read(&fc->sbput_sem); + struct fuse_req *req; - /* fput must go outside sbput_sem, otherwise it can deadlock */ - if (req->file) - fput(req->file); + atomic_inc(&fc->num_waiting); + wait_event(fc->blocked_waitq, !fc->blocked); + req = fuse_request_alloc(); + if (!req) + req = get_reserved_req(fc, file); - if (end) - end(fc, req); + fuse_req_init_context(req); + req->waiting = 1; + return req; +} + +void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req) +{ + if (atomic_dec_and_test(&req->count)) { + if (req->waiting) + atomic_dec(&fc->num_waiting); + + if (req->stolen_file) + put_reserved_req(fc, req); else - fuse_put_request(fc, req); + fuse_request_free(req); } } /* - * Unfortunately request interruption not just solves the deadlock - * problem, it causes problems too. These stem from the fact, that an - * interrupted request is continued to be processed in userspace, - * while all the locks and object references (inode and file) held - * during the operation are released. - * - * To release the locks is exactly why there's a need to interrupt the - * request, so there's not a lot that can be done about this, except - * introduce additional locking in userspace. - * - * More important is to keep inode and file references until userspace - * has replied, otherwise FORGET and RELEASE could be sent while the - * inode/file is still used by the filesystem. - * - * For this reason the concept of "background" request is introduced. - * An interrupted request is backgrounded if it has been already sent - * to userspace. Backgrounding involves getting an extra reference to - * inode(s) or file used in the request, and adding the request to - * fc->background list. When a reply is received for a background - * request, the object references are released, and the request is - * removed from the list. If the filesystem is unmounted while there - * are still background requests, the list is walked and references - * are released as if a reply was received. + * This function is called when a request is finished. Either a reply + * has arrived or it was aborted (and not yet sent) or some error + * occurred during communication with userspace, or the device file + * was closed. The requester thread is woken up (if still waiting), + * the 'end' callback is called if given, else the reference to the + * request is released * - * There's one more use for a background request. The RELEASE message is - * always sent as background, since it doesn't return an error or - * data. + * Called with fc->lock, unlocks it */ -static void background_request(struct fuse_conn *fc, struct fuse_req *req) -{ - req->background = 1; - list_add(&req->bg_entry, &fc->background); - fc->num_background++; - if (fc->num_background == FUSE_MAX_BACKGROUND) - fc->blocked = 1; - if (req->inode) - req->inode = igrab(req->inode); - if (req->inode2) - req->inode2 = igrab(req->inode2); +static void request_end(struct fuse_conn *fc, struct fuse_req *req) +{ + void (*end) (struct fuse_conn *, struct fuse_req *) = req->end; + 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; + wake_up_all(&fc->blocked_waitq); + } + fc->num_background--; + } + spin_unlock(&fc->lock); + dput(req->dentry); + mntput(req->vfsmount); if (req->file) - get_file(req->file); + fput(req->file); + wake_up(&req->waitq); + if (end) + end(fc, req); + else + fuse_put_request(fc, req); } -/* Called with fc->lock held. Releases, and then reacquires it. */ -static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) +static void wait_answer_interruptible(struct fuse_conn *fc, + struct fuse_req *req) { - sigset_t oldset; + if (signal_pending(current)) + return; spin_unlock(&fc->lock); - block_sigs(&oldset); wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED); - restore_sigs(&oldset); spin_lock(&fc->lock); - if (req->state == FUSE_REQ_FINISHED && !req->interrupted) - return; +} + +static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req) +{ + list_add_tail(&req->intr_entry, &fc->interrupts); + wake_up(&fc->waitq); + kill_fasync(&fc->fasync, SIGIO, POLL_IN); +} + +/* Called with fc->lock held. Releases, and then reacquires it. */ +static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) +{ + if (!fc->no_interrupt) { + /* Any signal may interrupt this */ + wait_answer_interruptible(fc, req); + + if (req->aborted) + goto aborted; + if (req->state == FUSE_REQ_FINISHED) + return; - if (!req->interrupted) { - req->out.h.error = -EINTR; req->interrupted = 1; + if (req->state == FUSE_REQ_SENT) + queue_interrupt(fc, req); + } + + if (req->force) { + spin_unlock(&fc->lock); + wait_event(req->waitq, req->state == FUSE_REQ_FINISHED); + spin_lock(&fc->lock); + } else { + sigset_t oldset; + + /* Only fatal signals may interrupt this */ + block_sigs(&oldset); + wait_answer_interruptible(fc, req); + restore_sigs(&oldset); } + + if (req->aborted) + goto aborted; + if (req->state == FUSE_REQ_FINISHED) + return; + + req->out.h.error = -EINTR; + req->aborted = 1; + + aborted: if (req->locked) { /* This is uninterruptible sleep, because data is being copied to/from the buffers of req. During @@ -268,8 +307,11 @@ static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) if (req->state == FUSE_REQ_PENDING) { list_del(&req->list); __fuse_put_request(req); - } else if (req->state == FUSE_REQ_SENT) - background_request(fc, req); + } else if (req->state == FUSE_REQ_SENT) { + spin_unlock(&fc->lock); + wait_event(req->waitq, req->state == FUSE_REQ_FINISHED); + spin_lock(&fc->lock); + } } static unsigned len_args(unsigned numargs, struct fuse_arg *args) @@ -283,13 +325,19 @@ static unsigned len_args(unsigned numargs, struct fuse_arg *args) return nbytes; } +static u64 fuse_get_unique(struct fuse_conn *fc) + { + fc->reqctr++; + /* zero is special */ + if (fc->reqctr == 0) + fc->reqctr = 1; + + return fc->reqctr; +} + static void queue_request(struct fuse_conn *fc, struct fuse_req *req) { - fc->reqctr++; - /* zero is special */ - if (fc->reqctr == 0) - fc->reqctr = 1; - req->in.h.unique = fc->reqctr; + req->in.h.unique = fuse_get_unique(fc); req->in.h.len = sizeof(struct fuse_in_header) + len_args(req->in.numargs, (struct fuse_arg *) req->in.args); list_add_tail(&req->list, &fc->pending); @@ -302,9 +350,6 @@ static void queue_request(struct fuse_conn *fc, struct fuse_req *req) kill_fasync(&fc->fasync, SIGIO, POLL_IN); } -/* - * This can only be interrupted by a SIGKILL - */ void request_send(struct fuse_conn *fc, struct fuse_req *req) { req->isreply = 1; @@ -327,8 +372,12 @@ void request_send(struct fuse_conn *fc, struct fuse_req *req) static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req) { spin_lock(&fc->lock); - background_request(fc, req); if (fc->connected) { + req->background = 1; + fc->num_background++; + if (fc->num_background == FUSE_MAX_BACKGROUND) + fc->blocked = 1; + queue_request(fc, req); spin_unlock(&fc->lock); } else { @@ -352,14 +401,14 @@ void request_send_background(struct fuse_conn *fc, struct fuse_req *req) /* * Lock the request. Up to the next unlock_request() there mustn't be * anything that could cause a page-fault. If the request was already - * interrupted bail out. + * aborted bail out. */ static int lock_request(struct fuse_conn *fc, struct fuse_req *req) { int err = 0; if (req) { spin_lock(&fc->lock); - if (req->interrupted) + if (req->aborted) err = -ENOENT; else req->locked = 1; @@ -369,7 +418,7 @@ static int lock_request(struct fuse_conn *fc, struct fuse_req *req) } /* - * Unlock request. If it was interrupted during being locked, the + * Unlock request. If it was aborted during being locked, the * requester thread is currently waiting for it to be unlocked, so * wake it up. */ @@ -378,7 +427,7 @@ static void unlock_request(struct fuse_conn *fc, struct fuse_req *req) if (req) { spin_lock(&fc->lock); req->locked = 0; - if (req->interrupted) + if (req->aborted) wake_up(&req->waitq); spin_unlock(&fc->lock); } @@ -557,13 +606,18 @@ static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs, return err; } +static int request_pending(struct fuse_conn *fc) +{ + return !list_empty(&fc->pending) || !list_empty(&fc->interrupts); +} + /* Wait until a request is available on the pending list */ static void request_wait(struct fuse_conn *fc) { DECLARE_WAITQUEUE(wait, current); add_wait_queue_exclusive(&fc->waitq, &wait); - while (fc->connected && list_empty(&fc->pending)) { + while (fc->connected && !request_pending(fc)) { set_current_state(TASK_INTERRUPTIBLE); if (signal_pending(current)) break; @@ -577,11 +631,50 @@ static void request_wait(struct fuse_conn *fc) } /* + * Transfer an interrupt request to userspace + * + * Unlike other requests this is assembled on demand, without a need + * to allocate a separate fuse_req structure. + * + * Called with fc->lock held, releases it + */ +static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req, + const struct iovec *iov, unsigned long nr_segs) +{ + struct fuse_copy_state cs; + struct fuse_in_header ih; + struct fuse_interrupt_in arg; + unsigned reqsize = sizeof(ih) + sizeof(arg); + int err; + + list_del_init(&req->intr_entry); + req->intr_unique = fuse_get_unique(fc); + memset(&ih, 0, sizeof(ih)); + memset(&arg, 0, sizeof(arg)); + ih.len = reqsize; + ih.opcode = FUSE_INTERRUPT; + ih.unique = req->intr_unique; + arg.unique = req->in.h.unique; + + spin_unlock(&fc->lock); + if (iov_length(iov, nr_segs) < reqsize) + return -EINVAL; + + fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs); + err = fuse_copy_one(&cs, &ih, sizeof(ih)); + if (!err) + err = fuse_copy_one(&cs, &arg, sizeof(arg)); + fuse_copy_finish(&cs); + + return err ? err : reqsize; +} + +/* * Read a single request into the userspace filesystem's buffer. This * function waits until a request is available, then removes it from * the pending list and copies request data to userspace buffer. If - * no reply is needed (FORGET) or request has been interrupted or - * there was an error during the copying then it's finished by calling + * no reply is needed (FORGET) or request has been aborted or there + * was an error during the copying then it's finished by calling * request_end(). Otherwise add it to the processing list, and set * the 'sent' flag. */ @@ -601,7 +694,7 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov, spin_lock(&fc->lock); err = -EAGAIN; if ((file->f_flags & O_NONBLOCK) && fc->connected && - list_empty(&fc->pending)) + !request_pending(fc)) goto err_unlock; request_wait(fc); @@ -609,9 +702,15 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov, if (!fc->connected) goto err_unlock; err = -ERESTARTSYS; - if (list_empty(&fc->pending)) + if (!request_pending(fc)) goto err_unlock; + if (!list_empty(&fc->interrupts)) { + req = list_entry(fc->interrupts.next, struct fuse_req, + intr_entry); + return fuse_read_interrupt(fc, req, iov, nr_segs); + } + req = list_entry(fc->pending.next, struct fuse_req, list); req->state = FUSE_REQ_READING; list_move(&req->list, &fc->io); @@ -636,10 +735,10 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov, fuse_copy_finish(&cs); spin_lock(&fc->lock); req->locked = 0; - if (!err && req->interrupted) + if (!err && req->aborted) err = -ENOENT; if (err) { - if (!req->interrupted) + if (!req->aborted) req->out.h.error = -EIO; request_end(fc, req); return err; @@ -649,6 +748,8 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov, else { req->state = FUSE_REQ_SENT; list_move_tail(&req->list, &fc->processing); + if (req->interrupted) + queue_interrupt(fc, req); spin_unlock(&fc->lock); } return reqsize; @@ -675,7 +776,7 @@ static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique) list_for_each(entry, &fc->processing) { struct fuse_req *req; req = list_entry(entry, struct fuse_req, list); - if (req->in.h.unique == unique) + if (req->in.h.unique == unique || req->intr_unique == unique) return req; } return NULL; @@ -741,17 +842,33 @@ static ssize_t fuse_dev_writev(struct file *file, const struct iovec *iov, goto err_unlock; req = request_find(fc, oh.unique); - err = -EINVAL; if (!req) goto err_unlock; - if (req->interrupted) { + if (req->aborted) { spin_unlock(&fc->lock); fuse_copy_finish(&cs); spin_lock(&fc->lock); request_end(fc, req); return -ENOENT; } + /* Is it an interrupt reply? */ + if (req->intr_unique == oh.unique) { + err = -EINVAL; + if (nbytes != sizeof(struct fuse_out_header)) + goto err_unlock; + + if (oh.error == -ENOSYS) + fc->no_interrupt = 1; + else if (oh.error == -EAGAIN) + queue_interrupt(fc, req); + + spin_unlock(&fc->lock); + fuse_copy_finish(&cs); + return nbytes; + } + + req->state = FUSE_REQ_WRITING; list_move(&req->list, &fc->io); req->out.h = oh; req->locked = 1; @@ -764,9 +881,9 @@ static ssize_t fuse_dev_writev(struct file *file, const struct iovec *iov, spin_lock(&fc->lock); req->locked = 0; if (!err) { - if (req->interrupted) + if (req->aborted) err = -ENOENT; - } else if (!req->interrupted) + } else if (!req->aborted) req->out.h.error = -EIO; request_end(fc, req); @@ -800,7 +917,7 @@ static unsigned fuse_dev_poll(struct file *file, poll_table *wait) spin_lock(&fc->lock); if (!fc->connected) mask = POLLERR; - else if (!list_empty(&fc->pending)) + else if (request_pending(fc)) mask |= POLLIN | POLLRDNORM; spin_unlock(&fc->lock); @@ -826,7 +943,7 @@ static void end_requests(struct fuse_conn *fc, struct list_head *head) /* * Abort requests under I/O * - * The requests are set to interrupted and finished, and the request + * The requests are set to aborted and finished, and the request * waiter is woken up. This will make request_wait_answer() wait * until the request is unlocked and then return. * @@ -841,7 +958,7 @@ static void end_io_requests(struct fuse_conn *fc) list_entry(fc->io.next, struct fuse_req, list); void (*end) (struct fuse_conn *, struct fuse_req *) = req->end; - req->interrupted = 1; + req->aborted = 1; req->out.h.error = -ECONNABORTED; req->state = FUSE_REQ_FINISHED; list_del_init(&req->list); @@ -874,19 +991,20 @@ static void end_io_requests(struct fuse_conn *fc) * onto the pending list is prevented by req->connected being false. * * Progression of requests under I/O to the processing list is - * prevented by the req->interrupted flag being true for these - * requests. For this reason requests on the io list must be aborted - * first. + * prevented by the req->aborted flag being true for these requests. + * For this reason requests on the io list must be aborted first. */ void fuse_abort_conn(struct fuse_conn *fc) { spin_lock(&fc->lock); if (fc->connected) { fc->connected = 0; + fc->blocked = 0; end_io_requests(fc); end_requests(fc, &fc->pending); end_requests(fc, &fc->processing); wake_up_all(&fc->waitq); + wake_up_all(&fc->blocked_waitq); kill_fasync(&fc->fasync, SIGIO, POLL_IN); } spin_unlock(&fc->lock); @@ -902,7 +1020,7 @@ static int fuse_dev_release(struct inode *inode, struct file *file) end_requests(fc, &fc->processing); spin_unlock(&fc->lock); fasync_helper(-1, file, 0, &fc->fasync); - kobject_put(&fc->kobj); + fuse_conn_put(fc); } return 0; |