| /* |
| FUSE: Filesystem in Userspace |
| Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu> |
| |
| This program can be distributed under the terms of the GNU GPL. |
| See the file COPYING. |
| */ |
| |
| #include "fuse_i.h" |
| |
| #include <linux/init.h> |
| #include <linux/module.h> |
| #include <linux/poll.h> |
| #include <linux/uio.h> |
| #include <linux/miscdevice.h> |
| #include <linux/pagemap.h> |
| #include <linux/file.h> |
| #include <linux/slab.h> |
| |
| MODULE_ALIAS_MISCDEV(FUSE_MINOR); |
| |
| static kmem_cache_t *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_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, SLAB_KERNEL); |
| 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); |
| } |
| |
| /* |
| * 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); |
| } |
| |
| /* 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); |
| } |
| |
| struct fuse_req *fuse_get_req(struct fuse_conn *fc) |
| { |
| struct fuse_req *req; |
| sigset_t oldset; |
| int err; |
| |
| block_sigs(&oldset); |
| err = wait_event_interruptible(fc->blocked_waitq, !fc->blocked); |
| restore_sigs(&oldset); |
| if (err) |
| return ERR_PTR(-EINTR); |
| |
| req = fuse_request_alloc(); |
| if (!req) |
| return ERR_PTR(-ENOMEM); |
| |
| 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; |
| return req; |
| } |
| |
| void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req) |
| { |
| if (atomic_dec_and_test(&req->count)) { |
| atomic_dec(&fc->num_waiting); |
| fuse_request_free(req); |
| } |
| } |
| |
| void fuse_release_background(struct fuse_conn *fc, struct fuse_req *req) |
| { |
| iput(req->inode); |
| iput(req->inode2); |
| if (req->file) |
| fput(req->file); |
| 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--; |
| spin_unlock(&fc->lock); |
| } |
| |
| /* |
| * 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 |
| * |
| * 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. |
| * |
| * Called with fc->lock, unlocks it |
| */ |
| static void request_end(struct fuse_conn *fc, struct fuse_req *req) |
| { |
| 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); |
| if (end) |
| end(fc, req); |
| else |
| fuse_put_request(fc, 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. |
| * |
| * 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. |
| */ |
| 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); |
| if (req->file) |
| get_file(req->file); |
| } |
| |
| /* Called with fc->lock held. Releases, and then reacquires it. */ |
| static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) |
| { |
| sigset_t oldset; |
| |
| 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; |
| |
| if (!req->interrupted) { |
| req->out.h.error = -EINTR; |
| req->interrupted = 1; |
| } |
| 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); |
| } |
| 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); |
| } |
| |
| 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 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.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; |
| wake_up(&fc->waitq); |
| 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; |
| 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(struct fuse_conn *fc, struct fuse_req *req) |
| { |
| spin_lock(&fc->lock); |
| background_request(fc, req); |
| if (fc->connected) { |
| queue_request(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); |
| } |
| |
| /* |
| * 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. |
| */ |
| static int lock_request(struct fuse_conn *fc, struct fuse_req *req) |
| { |
| int err = 0; |
| if (req) { |
| spin_lock(&fc->lock); |
| if (req->interrupted) |
| err = -ENOENT; |
| else |
| req->locked = 1; |
| spin_unlock(&fc->lock); |
| } |
| return err; |
| } |
| |
| /* |
| * Unlock request. If it was interrupted 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->interrupted) |
| 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; |
| } |
| |
| /* 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)) { |
| 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); |
| } |
| |
| /* |
| * 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 |
| * request_end(). Otherwise add it to the processing list, and set |
| * the 'sent' flag. |
| */ |
| static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *off) |
| { |
| int err; |
| struct fuse_req *req; |
| struct fuse_in *in; |
| struct fuse_copy_state cs; |
| unsigned reqsize; |
| 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 && |
| list_empty(&fc->pending)) |
| goto err_unlock; |
| |
| request_wait(fc); |
| err = -ENODEV; |
| if (!fc->connected) |
| goto err_unlock; |
| err = -ERESTARTSYS; |
| if (list_empty(&fc->pending)) |
| goto err_unlock; |
| |
| 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 (!err && req->interrupted) |
| err = -ENOENT; |
| if (err) { |
| if (!req->interrupted) |
| 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); |
| spin_unlock(&fc->lock); |
| } |
| return reqsize; |
| |
| err_unlock: |
| spin_unlock(&fc->lock); |
| return err; |
| } |
| |
| static ssize_t fuse_dev_read(struct file *file, char __user *buf, |
| size_t nbytes, loff_t *off) |
| { |
| struct iovec iov; |
| iov.iov_len = nbytes; |
| iov.iov_base = buf; |
| return fuse_dev_readv(file, &iov, 1, off); |
| } |
| |
| /* 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) |
| 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_writev(struct file *file, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *off) |
| { |
| 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(file); |
| 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); |
| err = -EINVAL; |
| if (!req) |
| goto err_unlock; |
| |
| if (req->interrupted) { |
| spin_unlock(&fc->lock); |
| fuse_copy_finish(&cs); |
| spin_lock(&fc->lock); |
| request_end(fc, req); |
| return -ENOENT; |
| } |
| 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->interrupted) |
| err = -ENOENT; |
| } else if (!req->interrupted) |
| 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 ssize_t fuse_dev_write(struct file *file, const char __user *buf, |
| size_t nbytes, loff_t *off) |
| { |
| struct iovec iov; |
| iov.iov_len = nbytes; |
| iov.iov_base = (char __user *) buf; |
| return fuse_dev_writev(file, &iov, 1, off); |
| } |
| |
| 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 (!list_empty(&fc->pending)) |
| 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 interrupted 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) |
| { |
| 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->interrupted = 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->interrupted 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; |
| end_io_requests(fc); |
| end_requests(fc, &fc->pending); |
| end_requests(fc, &fc->processing); |
| wake_up_all(&fc->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); |
| fasync_helper(-1, file, 0, &fc->fasync); |
| kobject_put(&fc->kobj); |
| } |
| |
| 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 = fuse_dev_read, |
| .readv = fuse_dev_readv, |
| .write = fuse_dev_write, |
| .writev = fuse_dev_writev, |
| .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, 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); |
| } |