/* FUSE: Filesystem in Userspace Copyright (C) 2001-2006 Miklos Szeredi This program can be distributed under the terms of the GNU GPL. See the file COPYING. */ #include "fuse_i.h" #include #include #include #include #include #include #include #include MODULE_ALIAS_MISCDEV(FUSE_MINOR); static struct kmem_cache *fuse_req_cachep; static struct fuse_conn *fuse_get_conn(struct file *file) { /* * Lockless access is OK, because file->private data is set * once during mount and is valid until the file is released. */ return file->private_data; } 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); } struct fuse_req *fuse_request_alloc(void) { struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_KERNEL); if (req) fuse_request_init(req); return req; } struct fuse_req *fuse_request_alloc_nofs(void) { struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_NOFS); if (req) fuse_request_init(req); return req; } void fuse_request_free(struct fuse_req *req) { kmem_cache_free(fuse_req_cachep, req); } static void block_sigs(sigset_t *oldset) { sigset_t mask; siginitsetinv(&mask, sigmask(SIGKILL)); sigprocmask(SIG_BLOCK, &mask, oldset); } static void restore_sigs(sigset_t *oldset) { sigprocmask(SIG_SETMASK, oldset, NULL); } static void __fuse_get_request(struct fuse_req *req) { atomic_inc(&req->count); } /* Must be called with > 1 refcount */ static void __fuse_put_request(struct fuse_req *req) { BUG_ON(atomic_read(&req->count) < 2); 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; sigset_t oldset; int intr; int err; atomic_inc(&fc->num_waiting); block_sigs(&oldset); intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked); restore_sigs(&oldset); err = -EINTR; if (intr) goto out; err = -ENOTCONN; if (!fc->connected) goto out; req = fuse_request_alloc(); err = -ENOMEM; if (!req) goto out; fuse_req_init_context(req); req->waiting = 1; return req; out: atomic_dec(&fc->num_waiting); return ERR_PTR(err); } /* * 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) { struct fuse_req *req = NULL; struct fuse_file *ff = file->private_data; do { wait_event(fc->reserved_req_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; } /* * Put stolen request back into fuse_file->reserved_req */ static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req) { struct file *file = req->stolen_file; struct fuse_file *ff = file->private_data; spin_lock(&fc->lock); fuse_request_init(req); BUG_ON(ff->reserved_req); ff->reserved_req = req; wake_up_all(&fc->reserved_req_waitq); spin_unlock(&fc->lock); fput(file); } /* * Gets a requests for a file operation, always succeeds * * This is used for sending the FLUSH request, which must get to * userspace, due to POSIX locks which may need to be unlocked. * * 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. */ struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file) { struct fuse_req *req; atomic_inc(&fc->num_waiting); wait_event(fc->blocked_waitq, !fc->blocked); req = fuse_request_alloc(); if (!req) req = get_reserved_req(fc, file); 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_request_free(req); } } static unsigned len_args(unsigned numargs, struct fuse_arg *args) { unsigned nbytes = 0; unsigned i; for (i = 0; i < numargs; i++) nbytes += args[i].size; 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) { 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); 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); } static void flush_bg_queue(struct fuse_conn *fc) { while (fc->active_background < FUSE_MAX_BACKGROUND && !list_empty(&fc->bg_queue)) { struct fuse_req *req; req = list_entry(fc->bg_queue.next, struct fuse_req, list); list_del(&req->list); fc->active_background++; queue_request(fc, req); } } /* * 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 * * Called with fc->lock, unlocks it */ static void request_end(struct fuse_conn *fc, struct fuse_req *req) __releases(fc->lock) { 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); } if (fc->num_background == FUSE_CONGESTION_THRESHOLD && fc->connected) { clear_bdi_congested(&fc->bdi, READ); clear_bdi_congested(&fc->bdi, WRITE); } fc->num_background--; fc->active_background--; flush_bg_queue(fc); } spin_unlock(&fc->lock); wake_up(&req->waitq); if (end) end(fc, req); else fuse_put_request(fc, req); } static void wait_answer_interruptible(struct fuse_conn *fc, struct fuse_req *req) __releases(fc->lock) __acquires(fc->lock) { if (signal_pending(current)) return; spin_unlock(&fc->lock); wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED); spin_lock(&fc->lock); } 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); } static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) __releases(fc->lock) __acquires(fc->lock) { 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; req->interrupted = 1; if (req->state == FUSE_REQ_SENT) queue_interrupt(fc, req); } if (!req->force) { 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; /* Request is not yet in userspace, bail out */ if (req->state == FUSE_REQ_PENDING) { list_del(&req->list); __fuse_put_request(req); req->out.h.error = -EINTR; return; } } /* * Either request is already in userspace, or it was forced. * Wait it out. */ spin_unlock(&fc->lock); wait_event(req->waitq, req->state == FUSE_REQ_FINISHED); spin_lock(&fc->lock); if (!req->aborted) 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); } } void request_send(struct fuse_conn *fc, struct fuse_req *req) { req->isreply = 1; spin_lock(&fc->lock); if (!fc->connected) req->out.h.error = -ENOTCONN; else if (fc->conn_error) req->out.h.error = -ECONNREFUSED; else { queue_request(fc, req); /* acquire extra reference, since request is still needed after request_end() */ __fuse_get_request(req); request_wait_answer(fc, req); } spin_unlock(&fc->lock); } static void request_send_nowait_locked(struct fuse_conn *fc, struct fuse_req *req) { req->background = 1; fc->num_background++; if (fc->num_background == FUSE_MAX_BACKGROUND) fc->blocked = 1; if (fc->num_background == FUSE_CONGESTION_THRESHOLD) { set_bdi_congested(&fc->bdi, READ); set_bdi_congested(&fc->bdi, WRITE); } list_add_tail(&req->list, &fc->bg_queue); flush_bg_queue(fc); } static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req) { spin_lock(&fc->lock); if (fc->connected) { request_send_nowait_locked(fc, req); spin_unlock(&fc->lock); } else { req->out.h.error = -ENOTCONN; request_end(fc, req); } } void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req) { req->isreply = 0; request_send_nowait(fc, req); } void request_send_background(struct fuse_conn *fc, struct fuse_req *req) { req->isreply = 1; request_send_nowait(fc, req); } /* * Called under fc->lock * * fc->connected must have been checked previously */ void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req) { req->isreply = 1; request_send_nowait_locked(fc, 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 * 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->aborted) err = -ENOENT; else req->locked = 1; spin_unlock(&fc->lock); } return err; } /* * Unlock request. If it was aborted during being locked, the * requester thread is currently waiting for it to be unlocked, so * wake it up. */ static void unlock_request(struct fuse_conn *fc, struct fuse_req *req) { if (req) { spin_lock(&fc->lock); req->locked = 0; if (req->aborted) wake_up(&req->waitq); spin_unlock(&fc->lock); } } struct fuse_copy_state { struct fuse_conn *fc; int write; struct fuse_req *req; const struct iovec *iov; unsigned long nr_segs; unsigned long seglen; unsigned long addr; struct page *pg; void *mapaddr; void *buf; unsigned len; }; static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc, int write, struct fuse_req *req, const struct iovec *iov, unsigned long nr_segs) { memset(cs, 0, sizeof(*cs)); cs->fc = fc; cs->write = write; cs->req = req; cs->iov = iov; cs->nr_segs = nr_segs; } /* Unmap and put previous page of userspace buffer */ static void fuse_copy_finish(struct fuse_copy_state *cs) { if (cs->mapaddr) { kunmap_atomic(cs->mapaddr, KM_USER0); if (cs->write) { flush_dcache_page(cs->pg); set_page_dirty_lock(cs->pg); } put_page(cs->pg); cs->mapaddr = NULL; } } /* * Get another pagefull of userspace buffer, and map it to kernel * address space, and lock request */ static int fuse_copy_fill(struct fuse_copy_state *cs) { unsigned long offset; int err; unlock_request(cs->fc, cs->req); fuse_copy_finish(cs); if (!cs->seglen) { BUG_ON(!cs->nr_segs); cs->seglen = cs->iov[0].iov_len; cs->addr = (unsigned long) cs->iov[0].iov_base; cs->iov ++; cs->nr_segs --; } down_read(¤t->mm->mmap_sem); err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0, &cs->pg, NULL); up_read(¤t->mm->mmap_sem); if (err < 0) return err; BUG_ON(err != 1); offset = cs->addr % PAGE_SIZE; cs->mapaddr = kmap_atomic(cs->pg, KM_USER0); cs->buf = cs->mapaddr + offset; cs->len = min(PAGE_SIZE - offset, cs->seglen); cs->seglen -= cs->len; cs->addr += cs->len; return lock_request(cs->fc, cs->req); } /* Do as much copy to/from userspace buffer as we can */ static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size) { unsigned ncpy = min(*size, cs->len); if (val) { if (cs->write) memcpy(cs->buf, *val, ncpy); else memcpy(*val, cs->buf, ncpy); *val += ncpy; } *size -= ncpy; cs->len -= ncpy; cs->buf += ncpy; return ncpy; } /* * Copy a page in the request to/from the userspace buffer. Must be * done atomically */ static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page, unsigned offset, unsigned count, int zeroing) { if (page && zeroing && count < PAGE_SIZE) { void *mapaddr = kmap_atomic(page, KM_USER1); memset(mapaddr, 0, PAGE_SIZE); kunmap_atomic(mapaddr, KM_USER1); } while (count) { int err; if (!cs->len && (err = fuse_copy_fill(cs))) return err; if (page) { void *mapaddr = kmap_atomic(page, KM_USER1); void *buf = mapaddr + offset; offset += fuse_copy_do(cs, &buf, &count); kunmap_atomic(mapaddr, KM_USER1); } else offset += fuse_copy_do(cs, NULL, &count); } if (page && !cs->write) flush_dcache_page(page); return 0; } /* Copy pages in the request to/from userspace buffer */ static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes, int zeroing) { unsigned i; struct fuse_req *req = cs->req; unsigned offset = req->page_offset; unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset); for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) { struct page *page = req->pages[i]; int err = fuse_copy_page(cs, page, offset, count, zeroing); if (err) return err; nbytes -= count; count = min(nbytes, (unsigned) PAGE_SIZE); offset = 0; } return 0; } /* Copy a single argument in the request to/from userspace buffer */ static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size) { while (size) { int err; if (!cs->len && (err = fuse_copy_fill(cs))) return err; fuse_copy_do(cs, &val, &size); } return 0; } /* Copy request arguments to/from userspace buffer */ static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs, unsigned argpages, struct fuse_arg *args, int zeroing) { int err = 0; unsigned i; for (i = 0; !err && i < numargs; i++) { struct fuse_arg *arg = &args[i]; if (i == numargs - 1 && argpages) err = fuse_copy_pages(cs, arg->size, zeroing); else err = fuse_copy_one(cs, arg->value, arg->size); } 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 && !request_pending(fc)) { set_current_state(TASK_INTERRUPTIBLE); if (signal_pending(current)) break; spin_unlock(&fc->lock); schedule(); spin_lock(&fc->lock); } set_current_state(TASK_RUNNING); remove_wait_queue(&fc->waitq, &wait); } /* * 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) __releases(fc->lock) { 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 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. */ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { int err; struct fuse_req *req; struct fuse_in *in; struct fuse_copy_state cs; unsigned reqsize; struct file *file = iocb->ki_filp; struct fuse_conn *fc = fuse_get_conn(file); if (!fc) return -EPERM; restart: spin_lock(&fc->lock); err = -EAGAIN; if ((file->f_flags & O_NONBLOCK) && fc->connected && !request_pending(fc)) goto err_unlock; request_wait(fc); err = -ENODEV; if (!fc->connected) goto err_unlock; err = -ERESTARTSYS; 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); in = &req->in; reqsize = in->h.len; /* If request is too large, reply with an error and restart the read */ if (iov_length(iov, nr_segs) < reqsize) { req->out.h.error = -EIO; /* SETXATTR is special, since it may contain too large data */ if (in->h.opcode == FUSE_SETXATTR) req->out.h.error = -E2BIG; request_end(fc, req); goto restart; } spin_unlock(&fc->lock); fuse_copy_init(&cs, fc, 1, req, iov, nr_segs); err = fuse_copy_one(&cs, &in->h, sizeof(in->h)); if (!err) err = fuse_copy_args(&cs, in->numargs, in->argpages, (struct fuse_arg *) in->args, 0); fuse_copy_finish(&cs); spin_lock(&fc->lock); req->locked = 0; if (req->aborted) { request_end(fc, req); return -ENODEV; } if (err) { req->out.h.error = -EIO; request_end(fc, req); return err; } if (!req->isreply) request_end(fc, req); 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; err_unlock: spin_unlock(&fc->lock); return err; } /* Look up request on processing list by unique ID */ static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique) { struct list_head *entry; list_for_each(entry, &fc->processing) { struct fuse_req *req; req = list_entry(entry, struct fuse_req, list); if (req->in.h.unique == unique || req->intr_unique == unique) return req; } return NULL; } static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out, unsigned nbytes) { unsigned reqsize = sizeof(struct fuse_out_header); if (out->h.error) return nbytes != reqsize ? -EINVAL : 0; reqsize += len_args(out->numargs, out->args); if (reqsize < nbytes || (reqsize > nbytes && !out->argvar)) return -EINVAL; else if (reqsize > nbytes) { struct fuse_arg *lastarg = &out->args[out->numargs-1]; unsigned diffsize = reqsize - nbytes; if (diffsize > lastarg->size) return -EINVAL; lastarg->size -= diffsize; } return fuse_copy_args(cs, out->numargs, out->argpages, out->args, out->page_zeroing); } /* * Write a single reply to a request. First the header is copied from * the write buffer. The request is then searched on the processing * list by the unique ID found in the header. If found, then remove * it from the list and copy the rest of the buffer to the request. * The request is finished by calling request_end() */ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { int err; unsigned nbytes = iov_length(iov, nr_segs); struct fuse_req *req; struct fuse_out_header oh; struct fuse_copy_state cs; struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp); if (!fc) return -EPERM; fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs); if (nbytes < sizeof(struct fuse_out_header)) return -EINVAL; err = fuse_copy_one(&cs, &oh, sizeof(oh)); if (err) goto err_finish; err = -EINVAL; if (!oh.unique || oh.error <= -1000 || oh.error > 0 || oh.len != nbytes) goto err_finish; spin_lock(&fc->lock); err = -ENOENT; if (!fc->connected) goto err_unlock; req = request_find(fc, oh.unique); if (!req) goto err_unlock; 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; cs.req = req; spin_unlock(&fc->lock); err = copy_out_args(&cs, &req->out, nbytes); fuse_copy_finish(&cs); spin_lock(&fc->lock); req->locked = 0; if (!err) { if (req->aborted) err = -ENOENT; } else if (!req->aborted) req->out.h.error = -EIO; request_end(fc, req); return err ? err : nbytes; err_unlock: spin_unlock(&fc->lock); err_finish: fuse_copy_finish(&cs); return err; } static unsigned fuse_dev_poll(struct file *file, poll_table *wait) { unsigned mask = POLLOUT | POLLWRNORM; struct fuse_conn *fc = fuse_get_conn(file); if (!fc) return POLLERR; poll_wait(file, &fc->waitq, wait); spin_lock(&fc->lock); if (!fc->connected) mask = POLLERR; else if (request_pending(fc)) mask |= POLLIN | POLLRDNORM; spin_unlock(&fc->lock); return mask; } /* * Abort all requests on the given list (pending or processing) * * This function releases and reacquires fc->lock */ static void end_requests(struct fuse_conn *fc, struct list_head *head) { while (!list_empty(head)) { struct fuse_req *req; req = list_entry(head->next, struct fuse_req, list); req->out.h.error = -ECONNABORTED; request_end(fc, req); spin_lock(&fc->lock); } } /* * Abort requests under I/O * * 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. * * If the request is asynchronous, then the end function needs to be * called after waiting for the request to be unlocked (if it was * locked). */ static void end_io_requests(struct fuse_conn *fc) __releases(fc->lock) __acquires(fc->lock) { while (!list_empty(&fc->io)) { struct fuse_req *req = list_entry(fc->io.next, struct fuse_req, list); void (*end) (struct fuse_conn *, struct fuse_req *) = req->end; 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; /* The end function will consume this reference */ __fuse_get_request(req); spin_unlock(&fc->lock); wait_event(req->waitq, !req->locked); end(fc, req); spin_lock(&fc->lock); } } } /* * Abort all requests. * * Emergency exit in case of a malicious or accidental deadlock, or * just a hung filesystem. * * The same effect is usually achievable through killing the * filesystem daemon and all users of the filesystem. The exception * is the combination of an asynchronous request and the tricky * deadlock (see Documentation/filesystems/fuse.txt). * * During the aborting, progression of requests from the pending and * processing lists onto the io list, and progression of new requests * 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->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); } static int fuse_dev_release(struct inode *inode, struct file *file) { struct fuse_conn *fc = fuse_get_conn(file); if (fc) { spin_lock(&fc->lock); fc->connected = 0; end_requests(fc, &fc->pending); end_requests(fc, &fc->processing); spin_unlock(&fc->lock); fuse_conn_put(fc); } return 0; } static int fuse_dev_fasync(int fd, struct file *file, int on) { struct fuse_conn *fc = fuse_get_conn(file); if (!fc) return -EPERM; /* No locking - fasync_helper does its own locking */ return fasync_helper(fd, file, on, &fc->fasync); } const struct file_operations fuse_dev_operations = { .owner = THIS_MODULE, .llseek = no_llseek, .read = do_sync_read, .aio_read = fuse_dev_read, .write = do_sync_write, .aio_write = fuse_dev_write, .poll = fuse_dev_poll, .release = fuse_dev_release, .fasync = fuse_dev_fasync, }; static struct miscdevice fuse_miscdevice = { .minor = FUSE_MINOR, .name = "fuse", .fops = &fuse_dev_operations, }; int __init fuse_dev_init(void) { int err = -ENOMEM; fuse_req_cachep = kmem_cache_create("fuse_request", sizeof(struct fuse_req), 0, 0, NULL); if (!fuse_req_cachep) goto out; err = misc_register(&fuse_miscdevice); if (err) goto out_cache_clean; return 0; out_cache_clean: kmem_cache_destroy(fuse_req_cachep); out: return err; } void fuse_dev_cleanup(void) { misc_deregister(&fuse_miscdevice); kmem_cache_destroy(fuse_req_cachep); }