diff options
Diffstat (limited to 'fs/fuse/dev.c')
| -rw-r--r-- | fs/fuse/dev.c | 2346 |
1 files changed, 2346 insertions, 0 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c new file mode 100644 index 000000000..8ac91ba05 --- /dev/null +++ b/fs/fuse/dev.c @@ -0,0 +1,2346 @@ +/* + FUSE: Filesystem in Userspace + Copyright (C) 2001-2008 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/sched/signal.h> +#include <linux/uio.h> +#include <linux/miscdevice.h> +#include <linux/pagemap.h> +#include <linux/file.h> +#include <linux/slab.h> +#include <linux/pipe_fs_i.h> +#include <linux/swap.h> +#include <linux/splice.h> +#include <linux/sched.h> + +MODULE_ALIAS_MISCDEV(FUSE_MINOR); +MODULE_ALIAS("devname:fuse"); + +/* Ordinary requests have even IDs, while interrupts IDs are odd */ +#define FUSE_INT_REQ_BIT (1ULL << 0) +#define FUSE_REQ_ID_STEP (1ULL << 1) + +static struct kmem_cache *fuse_req_cachep; + +static struct fuse_dev *fuse_get_dev(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 READ_ONCE(file->private_data); +} + +static void fuse_request_init(struct fuse_mount *fm, struct fuse_req *req) +{ + INIT_LIST_HEAD(&req->list); + INIT_LIST_HEAD(&req->intr_entry); + init_waitqueue_head(&req->waitq); + refcount_set(&req->count, 1); + __set_bit(FR_PENDING, &req->flags); + req->fm = fm; +} + +static struct fuse_req *fuse_request_alloc(struct fuse_mount *fm, gfp_t flags) +{ + struct fuse_req *req = kmem_cache_zalloc(fuse_req_cachep, flags); + if (req) + fuse_request_init(fm, req); + + return req; +} + +static void fuse_request_free(struct fuse_req *req) +{ + kmem_cache_free(fuse_req_cachep, req); +} + +static void __fuse_get_request(struct fuse_req *req) +{ + refcount_inc(&req->count); +} + +/* Must be called with > 1 refcount */ +static void __fuse_put_request(struct fuse_req *req) +{ + refcount_dec(&req->count); +} + +void fuse_set_initialized(struct fuse_conn *fc) +{ + /* Make sure stores before this are seen on another CPU */ + smp_wmb(); + fc->initialized = 1; +} + +static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background) +{ + return !fc->initialized || (for_background && fc->blocked); +} + +static void fuse_drop_waiting(struct fuse_conn *fc) +{ + /* + * lockess check of fc->connected is okay, because atomic_dec_and_test() + * provides a memory barrier mached with the one in fuse_wait_aborted() + * to ensure no wake-up is missed. + */ + if (atomic_dec_and_test(&fc->num_waiting) && + !READ_ONCE(fc->connected)) { + /* wake up aborters */ + wake_up_all(&fc->blocked_waitq); + } +} + +static void fuse_put_request(struct fuse_req *req); + +static struct fuse_req *fuse_get_req(struct fuse_mount *fm, bool for_background) +{ + struct fuse_conn *fc = fm->fc; + struct fuse_req *req; + int err; + atomic_inc(&fc->num_waiting); + + if (fuse_block_alloc(fc, for_background)) { + err = -EINTR; + if (wait_event_killable_exclusive(fc->blocked_waitq, + !fuse_block_alloc(fc, for_background))) + goto out; + } + /* Matches smp_wmb() in fuse_set_initialized() */ + smp_rmb(); + + err = -ENOTCONN; + if (!fc->connected) + goto out; + + err = -ECONNREFUSED; + if (fc->conn_error) + goto out; + + req = fuse_request_alloc(fm, GFP_KERNEL); + err = -ENOMEM; + if (!req) { + if (for_background) + wake_up(&fc->blocked_waitq); + goto out; + } + + req->in.h.uid = from_kuid(fc->user_ns, current_fsuid()); + req->in.h.gid = from_kgid(fc->user_ns, current_fsgid()); + req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns); + + __set_bit(FR_WAITING, &req->flags); + if (for_background) + __set_bit(FR_BACKGROUND, &req->flags); + + if (unlikely(req->in.h.uid == ((uid_t)-1) || + req->in.h.gid == ((gid_t)-1))) { + fuse_put_request(req); + return ERR_PTR(-EOVERFLOW); + } + return req; + + out: + fuse_drop_waiting(fc); + return ERR_PTR(err); +} + +static void fuse_put_request(struct fuse_req *req) +{ + struct fuse_conn *fc = req->fm->fc; + + if (refcount_dec_and_test(&req->count)) { + if (test_bit(FR_BACKGROUND, &req->flags)) { + /* + * We get here in the unlikely case that a background + * request was allocated but not sent + */ + spin_lock(&fc->bg_lock); + if (!fc->blocked) + wake_up(&fc->blocked_waitq); + spin_unlock(&fc->bg_lock); + } + + if (test_bit(FR_WAITING, &req->flags)) { + __clear_bit(FR_WAITING, &req->flags); + fuse_drop_waiting(fc); + } + + fuse_request_free(req); + } +} + +unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args) +{ + unsigned nbytes = 0; + unsigned i; + + for (i = 0; i < numargs; i++) + nbytes += args[i].size; + + return nbytes; +} +EXPORT_SYMBOL_GPL(fuse_len_args); + +u64 fuse_get_unique(struct fuse_iqueue *fiq) +{ + fiq->reqctr += FUSE_REQ_ID_STEP; + return fiq->reqctr; +} +EXPORT_SYMBOL_GPL(fuse_get_unique); + +static unsigned int fuse_req_hash(u64 unique) +{ + return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS); +} + +/** + * A new request is available, wake fiq->waitq + */ +static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq) +__releases(fiq->lock) +{ + wake_up(&fiq->waitq); + kill_fasync(&fiq->fasync, SIGIO, POLL_IN); + spin_unlock(&fiq->lock); +} + +const struct fuse_iqueue_ops fuse_dev_fiq_ops = { + .wake_forget_and_unlock = fuse_dev_wake_and_unlock, + .wake_interrupt_and_unlock = fuse_dev_wake_and_unlock, + .wake_pending_and_unlock = fuse_dev_wake_and_unlock, +}; +EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops); + +static void queue_request_and_unlock(struct fuse_iqueue *fiq, + struct fuse_req *req) +__releases(fiq->lock) +{ + req->in.h.len = sizeof(struct fuse_in_header) + + fuse_len_args(req->args->in_numargs, + (struct fuse_arg *) req->args->in_args); + list_add_tail(&req->list, &fiq->pending); + fiq->ops->wake_pending_and_unlock(fiq); +} + +void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget, + u64 nodeid, u64 nlookup) +{ + struct fuse_iqueue *fiq = &fc->iq; + + forget->forget_one.nodeid = nodeid; + forget->forget_one.nlookup = nlookup; + + spin_lock(&fiq->lock); + if (fiq->connected) { + fiq->forget_list_tail->next = forget; + fiq->forget_list_tail = forget; + fiq->ops->wake_forget_and_unlock(fiq); + } else { + kfree(forget); + spin_unlock(&fiq->lock); + } +} + +static void flush_bg_queue(struct fuse_conn *fc) +{ + struct fuse_iqueue *fiq = &fc->iq; + + while (fc->active_background < fc->max_background && + !list_empty(&fc->bg_queue)) { + struct fuse_req *req; + + req = list_first_entry(&fc->bg_queue, struct fuse_req, list); + list_del(&req->list); + fc->active_background++; + spin_lock(&fiq->lock); + req->in.h.unique = fuse_get_unique(fiq); + queue_request_and_unlock(fiq, 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 + */ +void fuse_request_end(struct fuse_req *req) +{ + struct fuse_mount *fm = req->fm; + struct fuse_conn *fc = fm->fc; + struct fuse_iqueue *fiq = &fc->iq; + + if (test_and_set_bit(FR_FINISHED, &req->flags)) + goto put_request; + + /* + * test_and_set_bit() implies smp_mb() between bit + * changing and below FR_INTERRUPTED check. Pairs with + * smp_mb() from queue_interrupt(). + */ + if (test_bit(FR_INTERRUPTED, &req->flags)) { + spin_lock(&fiq->lock); + list_del_init(&req->intr_entry); + spin_unlock(&fiq->lock); + } + WARN_ON(test_bit(FR_PENDING, &req->flags)); + WARN_ON(test_bit(FR_SENT, &req->flags)); + if (test_bit(FR_BACKGROUND, &req->flags)) { + spin_lock(&fc->bg_lock); + clear_bit(FR_BACKGROUND, &req->flags); + if (fc->num_background == fc->max_background) { + fc->blocked = 0; + wake_up(&fc->blocked_waitq); + } else if (!fc->blocked) { + /* + * Wake up next waiter, if any. It's okay to use + * waitqueue_active(), as we've already synced up + * fc->blocked with waiters with the wake_up() call + * above. + */ + if (waitqueue_active(&fc->blocked_waitq)) + wake_up(&fc->blocked_waitq); + } + + if (fc->num_background == fc->congestion_threshold && fm->sb) { + clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); + clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); + } + fc->num_background--; + fc->active_background--; + flush_bg_queue(fc); + spin_unlock(&fc->bg_lock); + } else { + /* Wake up waiter sleeping in request_wait_answer() */ + wake_up(&req->waitq); + } + + if (test_bit(FR_ASYNC, &req->flags)) + req->args->end(fm, req->args, req->out.h.error); +put_request: + fuse_put_request(req); +} +EXPORT_SYMBOL_GPL(fuse_request_end); + +static int queue_interrupt(struct fuse_req *req) +{ + struct fuse_iqueue *fiq = &req->fm->fc->iq; + + spin_lock(&fiq->lock); + /* Check for we've sent request to interrupt this req */ + if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) { + spin_unlock(&fiq->lock); + return -EINVAL; + } + + if (list_empty(&req->intr_entry)) { + list_add_tail(&req->intr_entry, &fiq->interrupts); + /* + * Pairs with smp_mb() implied by test_and_set_bit() + * from fuse_request_end(). + */ + smp_mb(); + if (test_bit(FR_FINISHED, &req->flags)) { + list_del_init(&req->intr_entry); + spin_unlock(&fiq->lock); + return 0; + } + fiq->ops->wake_interrupt_and_unlock(fiq); + } else { + spin_unlock(&fiq->lock); + } + return 0; +} + +static void request_wait_answer(struct fuse_req *req) +{ + struct fuse_conn *fc = req->fm->fc; + struct fuse_iqueue *fiq = &fc->iq; + int err; + + if (!fc->no_interrupt) { + /* Any signal may interrupt this */ + err = wait_event_interruptible(req->waitq, + test_bit(FR_FINISHED, &req->flags)); + if (!err) + return; + + set_bit(FR_INTERRUPTED, &req->flags); + /* matches barrier in fuse_dev_do_read() */ + smp_mb__after_atomic(); + if (test_bit(FR_SENT, &req->flags)) + queue_interrupt(req); + } + + if (!test_bit(FR_FORCE, &req->flags)) { + /* Only fatal signals may interrupt this */ + err = wait_event_killable(req->waitq, + test_bit(FR_FINISHED, &req->flags)); + if (!err) + return; + + spin_lock(&fiq->lock); + /* Request is not yet in userspace, bail out */ + if (test_bit(FR_PENDING, &req->flags)) { + list_del(&req->list); + spin_unlock(&fiq->lock); + __fuse_put_request(req); + req->out.h.error = -EINTR; + return; + } + spin_unlock(&fiq->lock); + } + + /* + * Either request is already in userspace, or it was forced. + * Wait it out. + */ + wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags)); +} + +static void __fuse_request_send(struct fuse_req *req) +{ + struct fuse_iqueue *fiq = &req->fm->fc->iq; + + BUG_ON(test_bit(FR_BACKGROUND, &req->flags)); + spin_lock(&fiq->lock); + if (!fiq->connected) { + spin_unlock(&fiq->lock); + req->out.h.error = -ENOTCONN; + } else { + req->in.h.unique = fuse_get_unique(fiq); + /* acquire extra reference, since request is still needed + after fuse_request_end() */ + __fuse_get_request(req); + queue_request_and_unlock(fiq, req); + + request_wait_answer(req); + /* Pairs with smp_wmb() in fuse_request_end() */ + smp_rmb(); + } +} + +static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args) +{ + if (fc->minor < 4 && args->opcode == FUSE_STATFS) + args->out_args[0].size = FUSE_COMPAT_STATFS_SIZE; + + if (fc->minor < 9) { + switch (args->opcode) { + case FUSE_LOOKUP: + case FUSE_CREATE: + case FUSE_MKNOD: + case FUSE_MKDIR: + case FUSE_SYMLINK: + case FUSE_LINK: + args->out_args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE; + break; + case FUSE_GETATTR: + case FUSE_SETATTR: + args->out_args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE; + break; + } + } + if (fc->minor < 12) { + switch (args->opcode) { + case FUSE_CREATE: + args->in_args[0].size = sizeof(struct fuse_open_in); + break; + case FUSE_MKNOD: + args->in_args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE; + break; + } + } +} + +static void fuse_force_creds(struct fuse_req *req) +{ + struct fuse_conn *fc = req->fm->fc; + + req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid()); + req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid()); + req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns); +} + +static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args) +{ + req->in.h.opcode = args->opcode; + req->in.h.nodeid = args->nodeid; + req->args = args; + if (args->end) + __set_bit(FR_ASYNC, &req->flags); +} + +ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args) +{ + struct fuse_conn *fc = fm->fc; + struct fuse_req *req; + ssize_t ret; + + if (args->force) { + atomic_inc(&fc->num_waiting); + req = fuse_request_alloc(fm, GFP_KERNEL | __GFP_NOFAIL); + + if (!args->nocreds) + fuse_force_creds(req); + + __set_bit(FR_WAITING, &req->flags); + __set_bit(FR_FORCE, &req->flags); + } else { + WARN_ON(args->nocreds); + req = fuse_get_req(fm, false); + if (IS_ERR(req)) + return PTR_ERR(req); + } + + /* Needs to be done after fuse_get_req() so that fc->minor is valid */ + fuse_adjust_compat(fc, args); + fuse_args_to_req(req, args); + + if (!args->noreply) + __set_bit(FR_ISREPLY, &req->flags); + __fuse_request_send(req); + ret = req->out.h.error; + if (!ret && args->out_argvar) { + BUG_ON(args->out_numargs == 0); + ret = args->out_args[args->out_numargs - 1].size; + } + fuse_put_request(req); + + return ret; +} + +static bool fuse_request_queue_background(struct fuse_req *req) +{ + struct fuse_mount *fm = req->fm; + struct fuse_conn *fc = fm->fc; + bool queued = false; + + WARN_ON(!test_bit(FR_BACKGROUND, &req->flags)); + if (!test_bit(FR_WAITING, &req->flags)) { + __set_bit(FR_WAITING, &req->flags); + atomic_inc(&fc->num_waiting); + } + __set_bit(FR_ISREPLY, &req->flags); + spin_lock(&fc->bg_lock); + if (likely(fc->connected)) { + fc->num_background++; + if (fc->num_background == fc->max_background) + fc->blocked = 1; + if (fc->num_background == fc->congestion_threshold && fm->sb) { + set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); + set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); + } + list_add_tail(&req->list, &fc->bg_queue); + flush_bg_queue(fc); + queued = true; + } + spin_unlock(&fc->bg_lock); + + return queued; +} + +int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args, + gfp_t gfp_flags) +{ + struct fuse_req *req; + + if (args->force) { + WARN_ON(!args->nocreds); + req = fuse_request_alloc(fm, gfp_flags); + if (!req) + return -ENOMEM; + __set_bit(FR_BACKGROUND, &req->flags); + } else { + WARN_ON(args->nocreds); + req = fuse_get_req(fm, true); + if (IS_ERR(req)) + return PTR_ERR(req); + } + + fuse_args_to_req(req, args); + + if (!fuse_request_queue_background(req)) { + fuse_put_request(req); + return -ENOTCONN; + } + + return 0; +} +EXPORT_SYMBOL_GPL(fuse_simple_background); + +static int fuse_simple_notify_reply(struct fuse_mount *fm, + struct fuse_args *args, u64 unique) +{ + struct fuse_req *req; + struct fuse_iqueue *fiq = &fm->fc->iq; + int err = 0; + + req = fuse_get_req(fm, false); + if (IS_ERR(req)) + return PTR_ERR(req); + + __clear_bit(FR_ISREPLY, &req->flags); + req->in.h.unique = unique; + + fuse_args_to_req(req, args); + + spin_lock(&fiq->lock); + if (fiq->connected) { + queue_request_and_unlock(fiq, req); + } else { + err = -ENODEV; + spin_unlock(&fiq->lock); + fuse_put_request(req); + } + + return err; +} + +/* + * 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_req *req) +{ + int err = 0; + if (req) { + spin_lock(&req->waitq.lock); + if (test_bit(FR_ABORTED, &req->flags)) + err = -ENOENT; + else + set_bit(FR_LOCKED, &req->flags); + spin_unlock(&req->waitq.lock); + } + return err; +} + +/* + * Unlock request. If it was aborted while locked, caller is responsible + * for unlocking and ending the request. + */ +static int unlock_request(struct fuse_req *req) +{ + int err = 0; + if (req) { + spin_lock(&req->waitq.lock); + if (test_bit(FR_ABORTED, &req->flags)) + err = -ENOENT; + else + clear_bit(FR_LOCKED, &req->flags); + spin_unlock(&req->waitq.lock); + } + return err; +} + +struct fuse_copy_state { + int write; + struct fuse_req *req; + struct iov_iter *iter; + struct pipe_buffer *pipebufs; + struct pipe_buffer *currbuf; + struct pipe_inode_info *pipe; + unsigned long nr_segs; + struct page *pg; + unsigned len; + unsigned offset; + unsigned move_pages:1; +}; + +static void fuse_copy_init(struct fuse_copy_state *cs, int write, + struct iov_iter *iter) +{ + memset(cs, 0, sizeof(*cs)); + cs->write = write; + cs->iter = iter; +} + +/* Unmap and put previous page of userspace buffer */ +static void fuse_copy_finish(struct fuse_copy_state *cs) +{ + if (cs->currbuf) { + struct pipe_buffer *buf = cs->currbuf; + + if (cs->write) + buf->len = PAGE_SIZE - cs->len; + cs->currbuf = NULL; + } else if (cs->pg) { + if (cs->write) { + flush_dcache_page(cs->pg); + set_page_dirty_lock(cs->pg); + } + put_page(cs->pg); + } + cs->pg = 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) +{ + struct page *page; + int err; + + err = unlock_request(cs->req); + if (err) + return err; + + fuse_copy_finish(cs); + if (cs->pipebufs) { + struct pipe_buffer *buf = cs->pipebufs; + + if (!cs->write) { + err = pipe_buf_confirm(cs->pipe, buf); + if (err) + return err; + + BUG_ON(!cs->nr_segs); + cs->currbuf = buf; + cs->pg = buf->page; + cs->offset = buf->offset; + cs->len = buf->len; + cs->pipebufs++; + cs->nr_segs--; + } else { + if (cs->nr_segs >= cs->pipe->max_usage) + return -EIO; + + page = alloc_page(GFP_HIGHUSER); + if (!page) + return -ENOMEM; + + buf->page = page; + buf->offset = 0; + buf->len = 0; + + cs->currbuf = buf; + cs->pg = page; + cs->offset = 0; + cs->len = PAGE_SIZE; + cs->pipebufs++; + cs->nr_segs++; + } + } else { + size_t off; + err = iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off); + if (err < 0) + return err; + BUG_ON(!err); + cs->len = err; + cs->offset = off; + cs->pg = page; + iov_iter_advance(cs->iter, err); + } + + return lock_request(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) { + void *pgaddr = kmap_atomic(cs->pg); + void *buf = pgaddr + cs->offset; + + if (cs->write) + memcpy(buf, *val, ncpy); + else + memcpy(*val, buf, ncpy); + + kunmap_atomic(pgaddr); + *val += ncpy; + } + *size -= ncpy; + cs->len -= ncpy; + cs->offset += ncpy; + return ncpy; +} + +static int fuse_check_page(struct page *page) +{ + if (page_mapcount(page) || + page->mapping != NULL || + (page->flags & PAGE_FLAGS_CHECK_AT_PREP & + ~(1 << PG_locked | + 1 << PG_referenced | + 1 << PG_uptodate | + 1 << PG_lru | + 1 << PG_active | + 1 << PG_workingset | + 1 << PG_reclaim | + 1 << PG_waiters))) { + dump_page(page, "fuse: trying to steal weird page"); + return 1; + } + return 0; +} + +static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep) +{ + int err; + struct page *oldpage = *pagep; + struct page *newpage; + struct pipe_buffer *buf = cs->pipebufs; + + get_page(oldpage); + err = unlock_request(cs->req); + if (err) + goto out_put_old; + + fuse_copy_finish(cs); + + err = pipe_buf_confirm(cs->pipe, buf); + if (err) + goto out_put_old; + + BUG_ON(!cs->nr_segs); + cs->currbuf = buf; + cs->len = buf->len; + cs->pipebufs++; + cs->nr_segs--; + + if (cs->len != PAGE_SIZE) + goto out_fallback; + + if (!pipe_buf_try_steal(cs->pipe, buf)) + goto out_fallback; + + newpage = buf->page; + + if (!PageUptodate(newpage)) + SetPageUptodate(newpage); + + ClearPageMappedToDisk(newpage); + + if (fuse_check_page(newpage) != 0) + goto out_fallback_unlock; + + /* + * This is a new and locked page, it shouldn't be mapped or + * have any special flags on it + */ + if (WARN_ON(page_mapped(oldpage))) + goto out_fallback_unlock; + if (WARN_ON(page_has_private(oldpage))) + goto out_fallback_unlock; + if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage))) + goto out_fallback_unlock; + if (WARN_ON(PageMlocked(oldpage))) + goto out_fallback_unlock; + + err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL); + if (err) { + unlock_page(newpage); + goto out_put_old; + } + + get_page(newpage); + + if (!(buf->flags & PIPE_BUF_FLAG_LRU)) + lru_cache_add(newpage); + + /* + * Release while we have extra ref on stolen page. Otherwise + * anon_pipe_buf_release() might think the page can be reused. + */ + pipe_buf_release(cs->pipe, buf); + + err = 0; + spin_lock(&cs->req->waitq.lock); + if (test_bit(FR_ABORTED, &cs->req->flags)) + err = -ENOENT; + else + *pagep = newpage; + spin_unlock(&cs->req->waitq.lock); + + if (err) { + unlock_page(newpage); + put_page(newpage); + goto out_put_old; + } + + unlock_page(oldpage); + /* Drop ref for ap->pages[] array */ + put_page(oldpage); + cs->len = 0; + + err = 0; +out_put_old: + /* Drop ref obtained in this function */ + put_page(oldpage); + return err; + +out_fallback_unlock: + unlock_page(newpage); +out_fallback: + cs->pg = buf->page; + cs->offset = buf->offset; + + err = lock_request(cs->req); + if (!err) + err = 1; + + goto out_put_old; +} + +static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page, + unsigned offset, unsigned count) +{ + struct pipe_buffer *buf; + int err; + + if (cs->nr_segs >= cs->pipe->max_usage) + return -EIO; + + get_page(page); + err = unlock_request(cs->req); + if (err) { + put_page(page); + return err; + } + + fuse_copy_finish(cs); + + buf = cs->pipebufs; + buf->page = page; + buf->offset = offset; + buf->len = count; + + cs->pipebufs++; + cs->nr_segs++; + cs->len = 0; + + return 0; +} + +/* + * 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 **pagep, + unsigned offset, unsigned count, int zeroing) +{ + int err; + struct page *page = *pagep; + + if (page && zeroing && count < PAGE_SIZE) + clear_highpage(page); + + while (count) { + if (cs->write && cs->pipebufs && page) { + /* + * Can't control lifetime of pipe buffers, so always + * copy user pages. + */ + if (cs->req->args->user_pages) { + err = fuse_copy_fill(cs); + if (err) + return err; + } else { + return fuse_ref_page(cs, page, offset, count); + } + } else if (!cs->len) { + if (cs->move_pages && page && + offset == 0 && count == PAGE_SIZE) { + err = fuse_try_move_page(cs, pagep); + if (err <= 0) + return err; + } else { + err = fuse_copy_fill(cs); + if (err) + return err; + } + } + if (page) { + void *mapaddr = kmap_atomic(page); + void *buf = mapaddr + offset; + offset += fuse_copy_do(cs, &buf, &count); + kunmap_atomic(mapaddr); + } 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; + struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args); + + + for (i = 0; i < ap->num_pages && (nbytes || zeroing); i++) { + int err; + unsigned int offset = ap->descs[i].offset; + unsigned int count = min(nbytes, ap->descs[i].length); + + err = fuse_copy_page(cs, &ap->pages[i], offset, count, zeroing); + if (err) + return err; + + nbytes -= count; + } + 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) { + if (!cs->len) { + int err = fuse_copy_fill(cs); + if (err) + 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 forget_pending(struct fuse_iqueue *fiq) +{ + return fiq->forget_list_head.next != NULL; +} + +static int request_pending(struct fuse_iqueue *fiq) +{ + return !list_empty(&fiq->pending) || !list_empty(&fiq->interrupts) || + forget_pending(fiq); +} + +/* + * 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 fiq->lock held, releases it + */ +static int fuse_read_interrupt(struct fuse_iqueue *fiq, + struct fuse_copy_state *cs, + size_t nbytes, struct fuse_req *req) +__releases(fiq->lock) +{ + struct fuse_in_header ih; + struct fuse_interrupt_in arg; + unsigned reqsize = sizeof(ih) + sizeof(arg); + int err; + + list_del_init(&req->intr_entry); + memset(&ih, 0, sizeof(ih)); + memset(&arg, 0, sizeof(arg)); + ih.len = reqsize; + ih.opcode = FUSE_INTERRUPT; + ih.unique = (req->in.h.unique | FUSE_INT_REQ_BIT); + arg.unique = req->in.h.unique; + + spin_unlock(&fiq->lock); + if (nbytes < reqsize) + return -EINVAL; + + 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; +} + +struct fuse_forget_link *fuse_dequeue_forget(struct fuse_iqueue *fiq, + unsigned int max, + unsigned int *countp) +{ + struct fuse_forget_link *head = fiq->forget_list_head.next; + struct fuse_forget_link **newhead = &head; + unsigned count; + + for (count = 0; *newhead != NULL && count < max; count++) + newhead = &(*newhead)->next; + + fiq->forget_list_head.next = *newhead; + *newhead = NULL; + if (fiq->forget_list_head.next == NULL) + fiq->forget_list_tail = &fiq->forget_list_head; + + if (countp != NULL) + *countp = count; + + return head; +} +EXPORT_SYMBOL(fuse_dequeue_forget); + +static int fuse_read_single_forget(struct fuse_iqueue *fiq, + struct fuse_copy_state *cs, + size_t nbytes) +__releases(fiq->lock) +{ + int err; + struct fuse_forget_link *forget = fuse_dequeue_forget(fiq, 1, NULL); + struct fuse_forget_in arg = { + .nlookup = forget->forget_one.nlookup, + }; + struct fuse_in_header ih = { + .opcode = FUSE_FORGET, + .nodeid = forget->forget_one.nodeid, + .unique = fuse_get_unique(fiq), + .len = sizeof(ih) + sizeof(arg), + }; + + spin_unlock(&fiq->lock); + kfree(forget); + if (nbytes < ih.len) + return -EINVAL; + + err = fuse_copy_one(cs, &ih, sizeof(ih)); + if (!err) + err = fuse_copy_one(cs, &arg, sizeof(arg)); + fuse_copy_finish(cs); + + if (err) + return err; + + return ih.len; +} + +static int fuse_read_batch_forget(struct fuse_iqueue *fiq, + struct fuse_copy_state *cs, size_t nbytes) +__releases(fiq->lock) +{ + int err; + unsigned max_forgets; + unsigned count; + struct fuse_forget_link *head; + struct fuse_batch_forget_in arg = { .count = 0 }; + struct fuse_in_header ih = { + .opcode = FUSE_BATCH_FORGET, + .unique = fuse_get_unique(fiq), + .len = sizeof(ih) + sizeof(arg), + }; + + if (nbytes < ih.len) { + spin_unlock(&fiq->lock); + return -EINVAL; + } + + max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one); + head = fuse_dequeue_forget(fiq, max_forgets, &count); + spin_unlock(&fiq->lock); + + arg.count = count; + ih.len += count * sizeof(struct fuse_forget_one); + err = fuse_copy_one(cs, &ih, sizeof(ih)); + if (!err) + err = fuse_copy_one(cs, &arg, sizeof(arg)); + + while (head) { + struct fuse_forget_link *forget = head; + + if (!err) { + err = fuse_copy_one(cs, &forget->forget_one, + sizeof(forget->forget_one)); + } + head = forget->next; + kfree(forget); + } + + fuse_copy_finish(cs); + + if (err) + return err; + + return ih.len; +} + +static int fuse_read_forget(struct fuse_conn *fc, struct fuse_iqueue *fiq, + struct fuse_copy_state *cs, + size_t nbytes) +__releases(fiq->lock) +{ + if (fc->minor < 16 || fiq->forget_list_head.next->next == NULL) + return fuse_read_single_forget(fiq, cs, nbytes); + else + return fuse_read_batch_forget(fiq, cs, nbytes); +} + +/* + * 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 + * fuse_request_end(). Otherwise add it to the processing list, and set + * the 'sent' flag. + */ +static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file, + struct fuse_copy_state *cs, size_t nbytes) +{ + ssize_t err; + struct fuse_conn *fc = fud->fc; + struct fuse_iqueue *fiq = &fc->iq; + struct fuse_pqueue *fpq = &fud->pq; + struct fuse_req *req; + struct fuse_args *args; + unsigned reqsize; + unsigned int hash; + + /* + * Require sane minimum read buffer - that has capacity for fixed part + * of any request header + negotiated max_write room for data. + * + * Historically libfuse reserves 4K for fixed header room, but e.g. + * GlusterFS reserves only 80 bytes + * + * = `sizeof(fuse_in_header) + sizeof(fuse_write_in)` + * + * which is the absolute minimum any sane filesystem should be using + * for header room. + */ + if (nbytes < max_t(size_t, FUSE_MIN_READ_BUFFER, + sizeof(struct fuse_in_header) + + sizeof(struct fuse_write_in) + + fc->max_write)) + return -EINVAL; + + restart: + for (;;) { + spin_lock(&fiq->lock); + if (!fiq->connected || request_pending(fiq)) + break; + spin_unlock(&fiq->lock); + + if (file->f_flags & O_NONBLOCK) + return -EAGAIN; + err = wait_event_interruptible_exclusive(fiq->waitq, + !fiq->connected || request_pending(fiq)); + if (err) + return err; + } + + if (!fiq->connected) { + err = fc->aborted ? -ECONNABORTED : -ENODEV; + goto err_unlock; + } + + if (!list_empty(&fiq->interrupts)) { + req = list_entry(fiq->interrupts.next, struct fuse_req, + intr_entry); + return fuse_read_interrupt(fiq, cs, nbytes, req); + } + + if (forget_pending(fiq)) { + if (list_empty(&fiq->pending) || fiq->forget_batch-- > 0) + return fuse_read_forget(fc, fiq, cs, nbytes); + + if (fiq->forget_batch <= -8) + fiq->forget_batch = 16; + } + + req = list_entry(fiq->pending.next, struct fuse_req, list); + clear_bit(FR_PENDING, &req->flags); + list_del_init(&req->list); + spin_unlock(&fiq->lock); + + args = req->args; + reqsize = req->in.h.len; + + /* If request is too large, reply with an error and restart the read */ + if (nbytes < reqsize) { + req->out.h.error = -EIO; + /* SETXATTR is special, since it may contain too large data */ + if (args->opcode == FUSE_SETXATTR) + req->out.h.error = -E2BIG; + fuse_request_end(req); + goto restart; + } + spin_lock(&fpq->lock); + /* + * Must not put request on fpq->io queue after having been shut down by + * fuse_abort_conn() + */ + if (!fpq->connected) { + req->out.h.error = err = -ECONNABORTED; + goto out_end; + + } + list_add(&req->list, &fpq->io); + spin_unlock(&fpq->lock); + cs->req = req; + err = fuse_copy_one(cs, &req->in.h, sizeof(req->in.h)); + if (!err) + err = fuse_copy_args(cs, args->in_numargs, args->in_pages, + (struct fuse_arg *) args->in_args, 0); + fuse_copy_finish(cs); + spin_lock(&fpq->lock); + clear_bit(FR_LOCKED, &req->flags); + if (!fpq->connected) { + err = fc->aborted ? -ECONNABORTED : -ENODEV; + goto out_end; + } + if (err) { + req->out.h.error = -EIO; + goto out_end; + } + if (!test_bit(FR_ISREPLY, &req->flags)) { + err = reqsize; + goto out_end; + } + hash = fuse_req_hash(req->in.h.unique); + list_move_tail(&req->list, &fpq->processing[hash]); + __fuse_get_request(req); + set_bit(FR_SENT, &req->flags); + spin_unlock(&fpq->lock); + /* matches barrier in request_wait_answer() */ + smp_mb__after_atomic(); + if (test_bit(FR_INTERRUPTED, &req->flags)) + queue_interrupt(req); + fuse_put_request(req); + + return reqsize; + +out_end: + if (!test_bit(FR_PRIVATE, &req->flags)) + list_del_init(&req->list); + spin_unlock(&fpq->lock); + fuse_request_end(req); + return err; + + err_unlock: + spin_unlock(&fiq->lock); + return err; +} + +static int fuse_dev_open(struct inode *inode, struct file *file) +{ + /* + * The fuse device's file's private_data is used to hold + * the fuse_conn(ection) when it is mounted, and is used to + * keep track of whether the file has been mounted already. + */ + file->private_data = NULL; + return 0; +} + +static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to) +{ + struct fuse_copy_state cs; + struct file *file = iocb->ki_filp; + struct fuse_dev *fud = fuse_get_dev(file); + + if (!fud) + return -EPERM; + + if (!iter_is_iovec(to)) + return -EINVAL; + + fuse_copy_init(&cs, 1, to); + + return fuse_dev_do_read(fud, file, &cs, iov_iter_count(to)); +} + +static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, unsigned int flags) +{ + int total, ret; + int page_nr = 0; + struct pipe_buffer *bufs; + struct fuse_copy_state cs; + struct fuse_dev *fud = fuse_get_dev(in); + + if (!fud) + return -EPERM; + + bufs = kvmalloc_array(pipe->max_usage, sizeof(struct pipe_buffer), + GFP_KERNEL); + if (!bufs) + return -ENOMEM; + + fuse_copy_init(&cs, 1, NULL); + cs.pipebufs = bufs; + cs.pipe = pipe; + ret = fuse_dev_do_read(fud, in, &cs, len); + if (ret < 0) + goto out; + + if (pipe_occupancy(pipe->head, pipe->tail) + cs.nr_segs > pipe->max_usage) { + ret = -EIO; + goto out; + } + + for (ret = total = 0; page_nr < cs.nr_segs; total += ret) { + /* + * Need to be careful about this. Having buf->ops in module + * code can Oops if the buffer persists after module unload. + */ + bufs[page_nr].ops = &nosteal_pipe_buf_ops; + bufs[page_nr].flags = 0; + ret = add_to_pipe(pipe, &bufs[page_nr++]); + if (unlikely(ret < 0)) + break; + } + if (total) + ret = total; +out: + for (; page_nr < cs.nr_segs; page_nr++) + put_page(bufs[page_nr].page); + + kvfree(bufs); + return ret; +} + +static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size, + struct fuse_copy_state *cs) +{ + struct fuse_notify_poll_wakeup_out outarg; + int err = -EINVAL; + + if (size != sizeof(outarg)) + goto err; + + err = fuse_copy_one(cs, &outarg, sizeof(outarg)); + if (err) + goto err; + + fuse_copy_finish(cs); + return fuse_notify_poll_wakeup(fc, &outarg); + +err: + fuse_copy_finish(cs); + return err; +} + +static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size, + struct fuse_copy_state *cs) +{ + struct fuse_notify_inval_inode_out outarg; + int err = -EINVAL; + + if (size != sizeof(outarg)) + goto err; + + err = fuse_copy_one(cs, &outarg, sizeof(outarg)); + if (err) + goto err; + fuse_copy_finish(cs); + + down_read(&fc->killsb); + err = fuse_reverse_inval_inode(fc, outarg.ino, + outarg.off, outarg.len); + up_read(&fc->killsb); + return err; + +err: + fuse_copy_finish(cs); + return err; +} + +static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size, + struct fuse_copy_state *cs) +{ + struct fuse_notify_inval_entry_out outarg; + int err = -ENOMEM; + char *buf; + struct qstr name; + + buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL); + if (!buf) + goto err; + + err = -EINVAL; + if (size < sizeof(outarg)) + goto err; + + err = fuse_copy_one(cs, &outarg, sizeof(outarg)); + if (err) + goto err; + + err = -ENAMETOOLONG; + if (outarg.namelen > FUSE_NAME_MAX) + goto err; + + err = -EINVAL; + if (size != sizeof(outarg) + outarg.namelen + 1) + goto err; + + name.name = buf; + name.len = outarg.namelen; + err = fuse_copy_one(cs, buf, outarg.namelen + 1); + if (err) + goto err; + fuse_copy_finish(cs); + buf[outarg.namelen] = 0; + + down_read(&fc->killsb); + err = fuse_reverse_inval_entry(fc, outarg.parent, 0, &name); + up_read(&fc->killsb); + kfree(buf); + return err; + +err: + kfree(buf); + fuse_copy_finish(cs); + return err; +} + +static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size, + struct fuse_copy_state *cs) +{ + struct fuse_notify_delete_out outarg; + int err = -ENOMEM; + char *buf; + struct qstr name; + + buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL); + if (!buf) + goto err; + + err = -EINVAL; + if (size < sizeof(outarg)) + goto err; + + err = fuse_copy_one(cs, &outarg, sizeof(outarg)); + if (err) + goto err; + + err = -ENAMETOOLONG; + if (outarg.namelen > FUSE_NAME_MAX) + goto err; + + err = -EINVAL; + if (size != sizeof(outarg) + outarg.namelen + 1) + goto err; + + name.name = buf; + name.len = outarg.namelen; + err = fuse_copy_one(cs, buf, outarg.namelen + 1); + if (err) + goto err; + fuse_copy_finish(cs); + buf[outarg.namelen] = 0; + + down_read(&fc->killsb); + err = fuse_reverse_inval_entry(fc, outarg.parent, outarg.child, &name); + up_read(&fc->killsb); + kfree(buf); + return err; + +err: + kfree(buf); + fuse_copy_finish(cs); + return err; +} + +static int fuse_notify_store(struct fuse_conn *fc, unsigned int size, + struct fuse_copy_state *cs) +{ + struct fuse_notify_store_out outarg; + struct inode *inode; + struct address_space *mapping; + u64 nodeid; + int err; + pgoff_t index; + unsigned int offset; + unsigned int num; + loff_t file_size; + loff_t end; + + err = -EINVAL; + if (size < sizeof(outarg)) + goto out_finish; + + err = fuse_copy_one(cs, &outarg, sizeof(outarg)); + if (err) + goto out_finish; + + err = -EINVAL; + if (size - sizeof(outarg) != outarg.size) + goto out_finish; + + nodeid = outarg.nodeid; + + down_read(&fc->killsb); + + err = -ENOENT; + inode = fuse_ilookup(fc, nodeid, NULL); + if (!inode) + goto out_up_killsb; + + mapping = inode->i_mapping; + index = outarg.offset >> PAGE_SHIFT; + offset = outarg.offset & ~PAGE_MASK; + file_size = i_size_read(inode); + end = outarg.offset + outarg.size; + if (end > file_size) { + file_size = end; + fuse_write_update_size(inode, file_size); + } + + num = outarg.size; + while (num) { + struct page *page; + unsigned int this_num; + + err = -ENOMEM; + page = find_or_create_page(mapping, index, + mapping_gfp_mask(mapping)); + if (!page) + goto out_iput; + + this_num = min_t(unsigned, num, PAGE_SIZE - offset); + err = fuse_copy_page(cs, &page, offset, this_num, 0); + if (!err && offset == 0 && + (this_num == PAGE_SIZE || file_size == end)) + SetPageUptodate(page); + unlock_page(page); + put_page(page); + + if (err) + goto out_iput; + + num -= this_num; + offset = 0; + index++; + } + + err = 0; + +out_iput: + iput(inode); +out_up_killsb: + up_read(&fc->killsb); +out_finish: + fuse_copy_finish(cs); + return err; +} + +struct fuse_retrieve_args { + struct fuse_args_pages ap; + struct fuse_notify_retrieve_in inarg; +}; + +static void fuse_retrieve_end(struct fuse_mount *fm, struct fuse_args *args, + int error) +{ + struct fuse_retrieve_args *ra = + container_of(args, typeof(*ra), ap.args); + + release_pages(ra->ap.pages, ra->ap.num_pages); + kfree(ra); +} + +static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode, + struct fuse_notify_retrieve_out *outarg) +{ + int err; + struct address_space *mapping = inode->i_mapping; + pgoff_t index; + loff_t file_size; + unsigned int num; + unsigned int offset; + size_t total_len = 0; + unsigned int num_pages; + struct fuse_conn *fc = fm->fc; + struct fuse_retrieve_args *ra; + size_t args_size = sizeof(*ra); + struct fuse_args_pages *ap; + struct fuse_args *args; + + offset = outarg->offset & ~PAGE_MASK; + file_size = i_size_read(inode); + + num = min(outarg->size, fc->max_write); + if (outarg->offset > file_size) + num = 0; + else if (outarg->offset + num > file_size) + num = file_size - outarg->offset; + + num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT; + num_pages = min(num_pages, fc->max_pages); + + args_size += num_pages * (sizeof(ap->pages[0]) + sizeof(ap->descs[0])); + + ra = kzalloc(args_size, GFP_KERNEL); + if (!ra) + return -ENOMEM; + + ap = &ra->ap; + ap->pages = (void *) (ra + 1); + ap->descs = (void *) (ap->pages + num_pages); + + args = &ap->args; + args->nodeid = outarg->nodeid; + args->opcode = FUSE_NOTIFY_REPLY; + args->in_numargs = 2; + args->in_pages = true; + args->end = fuse_retrieve_end; + + index = outarg->offset >> PAGE_SHIFT; + + while (num && ap->num_pages < num_pages) { + struct page *page; + unsigned int this_num; + + page = find_get_page(mapping, index); + if (!page) + break; + + this_num = min_t(unsigned, num, PAGE_SIZE - offset); + ap->pages[ap->num_pages] = page; + ap->descs[ap->num_pages].offset = offset; + ap->descs[ap->num_pages].length = this_num; + ap->num_pages++; + + offset = 0; + num -= this_num; + total_len += this_num; + index++; + } + ra->inarg.offset = outarg->offset; + ra->inarg.size = total_len; + args->in_args[0].size = sizeof(ra->inarg); + args->in_args[0].value = &ra->inarg; + args->in_args[1].size = total_len; + + err = fuse_simple_notify_reply(fm, args, outarg->notify_unique); + if (err) + fuse_retrieve_end(fm, args, err); + + return err; +} + +static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size, + struct fuse_copy_state *cs) +{ + struct fuse_notify_retrieve_out outarg; + struct fuse_mount *fm; + struct inode *inode; + u64 nodeid; + int err; + + err = -EINVAL; + if (size != sizeof(outarg)) + goto copy_finish; + + err = fuse_copy_one(cs, &outarg, sizeof(outarg)); + if (err) + goto copy_finish; + + fuse_copy_finish(cs); + + down_read(&fc->killsb); + err = -ENOENT; + nodeid = outarg.nodeid; + + inode = fuse_ilookup(fc, nodeid, &fm); + if (inode) { + err = fuse_retrieve(fm, inode, &outarg); + iput(inode); + } + up_read(&fc->killsb); + + return err; + +copy_finish: + fuse_copy_finish(cs); + return err; +} + +static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code, + unsigned int size, struct fuse_copy_state *cs) +{ + /* Don't try to move pages (yet) */ + cs->move_pages = 0; + + switch (code) { + case FUSE_NOTIFY_POLL: + return fuse_notify_poll(fc, size, cs); + + case FUSE_NOTIFY_INVAL_INODE: + return fuse_notify_inval_inode(fc, size, cs); + + case FUSE_NOTIFY_INVAL_ENTRY: + return fuse_notify_inval_entry(fc, size, cs); + + case FUSE_NOTIFY_STORE: + return fuse_notify_store(fc, size, cs); + + case FUSE_NOTIFY_RETRIEVE: + return fuse_notify_retrieve(fc, size, cs); + + case FUSE_NOTIFY_DELETE: + return fuse_notify_delete(fc, size, cs); + + default: + fuse_copy_finish(cs); + return -EINVAL; + } +} + +/* Look up request on processing list by unique ID */ +static struct fuse_req *request_find(struct fuse_pqueue *fpq, u64 unique) +{ + unsigned int hash = fuse_req_hash(unique); + struct fuse_req *req; + + list_for_each_entry(req, &fpq->processing[hash], list) { + if (req->in.h.unique == unique) + return req; + } + return NULL; +} + +static int copy_out_args(struct fuse_copy_state *cs, struct fuse_args *args, + unsigned nbytes) +{ + unsigned reqsize = sizeof(struct fuse_out_header); + + reqsize += fuse_len_args(args->out_numargs, args->out_args); + + if (reqsize < nbytes || (reqsize > nbytes && !args->out_argvar)) + return -EINVAL; + else if (reqsize > nbytes) { + struct fuse_arg *lastarg = &args->out_args[args->out_numargs-1]; + unsigned diffsize = reqsize - nbytes; + + if (diffsize > lastarg->size) + return -EINVAL; + lastarg->size -= diffsize; + } + return fuse_copy_args(cs, args->out_numargs, args->out_pages, + args->out_args, args->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 fuse_request_end(). + */ +static ssize_t fuse_dev_do_write(struct fuse_dev *fud, + struct fuse_copy_state *cs, size_t nbytes) +{ + int err; + struct fuse_conn *fc = fud->fc; + struct fuse_pqueue *fpq = &fud->pq; + struct fuse_req *req; + struct fuse_out_header oh; + + err = -EINVAL; + if (nbytes < sizeof(struct fuse_out_header)) + goto out; + + err = fuse_copy_one(cs, &oh, sizeof(oh)); + if (err) + goto copy_finish; + + err = -EINVAL; + if (oh.len != nbytes) + goto copy_finish; + + /* + * Zero oh.unique indicates unsolicited notification message + * and error contains notification code. + */ + if (!oh.unique) { + err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs); + goto out; + } + + err = -EINVAL; + if (oh.error <= -512 || oh.error > 0) + goto copy_finish; + + spin_lock(&fpq->lock); + req = NULL; + if (fpq->connected) + req = request_find(fpq, oh.unique & ~FUSE_INT_REQ_BIT); + + err = -ENOENT; + if (!req) { + spin_unlock(&fpq->lock); + goto copy_finish; + } + + /* Is it an interrupt reply ID? */ + if (oh.unique & FUSE_INT_REQ_BIT) { + __fuse_get_request(req); + spin_unlock(&fpq->lock); + + err = 0; + if (nbytes != sizeof(struct fuse_out_header)) + err = -EINVAL; + else if (oh.error == -ENOSYS) + fc->no_interrupt = 1; + else if (oh.error == -EAGAIN) + err = queue_interrupt(req); + + fuse_put_request(req); + + goto copy_finish; + } + + clear_bit(FR_SENT, &req->flags); + list_move(&req->list, &fpq->io); + req->out.h = oh; + set_bit(FR_LOCKED, &req->flags); + spin_unlock(&fpq->lock); + cs->req = req; + if (!req->args->page_replace) + cs->move_pages = 0; + + if (oh.error) + err = nbytes != sizeof(oh) ? -EINVAL : 0; + else + err = copy_out_args(cs, req->args, nbytes); + fuse_copy_finish(cs); + + spin_lock(&fpq->lock); + clear_bit(FR_LOCKED, &req->flags); + if (!fpq->connected) + err = -ENOENT; + else if (err) + req->out.h.error = -EIO; + if (!test_bit(FR_PRIVATE, &req->flags)) + list_del_init(&req->list); + spin_unlock(&fpq->lock); + + fuse_request_end(req); +out: + return err ? err : nbytes; + +copy_finish: + fuse_copy_finish(cs); + goto out; +} + +static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from) +{ + struct fuse_copy_state cs; + struct fuse_dev *fud = fuse_get_dev(iocb->ki_filp); + + if (!fud) + return -EPERM; + + if (!iter_is_iovec(from)) + return -EINVAL; + + fuse_copy_init(&cs, 0, from); + + return fuse_dev_do_write(fud, &cs, iov_iter_count(from)); +} + +static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe, + struct file *out, loff_t *ppos, + size_t len, unsigned int flags) +{ + unsigned int head, tail, mask, count; + unsigned nbuf; + unsigned idx; + struct pipe_buffer *bufs; + struct fuse_copy_state cs; + struct fuse_dev *fud; + size_t rem; + ssize_t ret; + + fud = fuse_get_dev(out); + if (!fud) + return -EPERM; + + pipe_lock(pipe); + + head = pipe->head; + tail = pipe->tail; + mask = pipe->ring_size - 1; + count = head - tail; + + bufs = kvmalloc_array(count, sizeof(struct pipe_buffer), GFP_KERNEL); + if (!bufs) { + pipe_unlock(pipe); + return -ENOMEM; + } + + nbuf = 0; + rem = 0; + for (idx = tail; idx != head && rem < len; idx++) + rem += pipe->bufs[idx & mask].len; + + ret = -EINVAL; + if (rem < len) + goto out_free; + + rem = len; + while (rem) { + struct pipe_buffer *ibuf; + struct pipe_buffer *obuf; + + if (WARN_ON(nbuf >= count || tail == head)) + goto out_free; + + ibuf = &pipe->bufs[tail & mask]; + obuf = &bufs[nbuf]; + + if (rem >= ibuf->len) { + *obuf = *ibuf; + ibuf->ops = NULL; + tail++; + pipe->tail = tail; + } else { + if (!pipe_buf_get(pipe, ibuf)) + goto out_free; + + *obuf = *ibuf; + obuf->flags &= ~PIPE_BUF_FLAG_GIFT; + obuf->len = rem; + ibuf->offset += obuf->len; + ibuf->len -= obuf->len; + } + nbuf++; + rem -= obuf->len; + } + pipe_unlock(pipe); + + fuse_copy_init(&cs, 0, NULL); + cs.pipebufs = bufs; + cs.nr_segs = nbuf; + cs.pipe = pipe; + + if (flags & SPLICE_F_MOVE) + cs.move_pages = 1; + + ret = fuse_dev_do_write(fud, &cs, len); + + pipe_lock(pipe); +out_free: + for (idx = 0; idx < nbuf; idx++) { + struct pipe_buffer *buf = &bufs[idx]; + + if (buf->ops) + pipe_buf_release(pipe, buf); + } + pipe_unlock(pipe); + + kvfree(bufs); + return ret; +} + +static __poll_t fuse_dev_poll(struct file *file, poll_table *wait) +{ + __poll_t mask = EPOLLOUT | EPOLLWRNORM; + struct fuse_iqueue *fiq; + struct fuse_dev *fud = fuse_get_dev(file); + + if (!fud) + return EPOLLERR; + + fiq = &fud->fc->iq; + poll_wait(file, &fiq->waitq, wait); + + spin_lock(&fiq->lock); + if (!fiq->connected) + mask = EPOLLERR; + else if (request_pending(fiq)) + mask |= EPOLLIN | EPOLLRDNORM; + spin_unlock(&fiq->lock); + + return mask; +} + +/* Abort all requests on the given list (pending or processing) */ +static void end_requests(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; + clear_bit(FR_SENT, &req->flags); + list_del_init(&req->list); + fuse_request_end(req); + } +} + +static void end_polls(struct fuse_conn *fc) +{ + struct rb_node *p; + + p = rb_first(&fc->polled_files); + + while (p) { + struct fuse_file *ff; + ff = rb_entry(p, struct fuse_file, polled_node); + wake_up_interruptible_all(&ff->poll_wait); + + p = rb_next(p); + } +} + +/* + * 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.rst). + * + * Aborting requests under I/O goes as follows: 1: Separate out unlocked + * requests, they should be finished off immediately. Locked requests will be + * finished after unlock; see unlock_request(). 2: Finish off the unlocked + * requests. It is possible that some request will finish before we can. This + * is OK, the request will in that case be removed from the list before we touch + * it. + */ +void fuse_abort_conn(struct fuse_conn *fc) +{ + struct fuse_iqueue *fiq = &fc->iq; + + spin_lock(&fc->lock); + if (fc->connected) { + struct fuse_dev *fud; + struct fuse_req *req, *next; + LIST_HEAD(to_end); + unsigned int i; + + /* Background queuing checks fc->connected under bg_lock */ + spin_lock(&fc->bg_lock); + fc->connected = 0; + spin_unlock(&fc->bg_lock); + + fuse_set_initialized(fc); + list_for_each_entry(fud, &fc->devices, entry) { + struct fuse_pqueue *fpq = &fud->pq; + + spin_lock(&fpq->lock); + fpq->connected = 0; + list_for_each_entry_safe(req, next, &fpq->io, list) { + req->out.h.error = -ECONNABORTED; + spin_lock(&req->waitq.lock); + set_bit(FR_ABORTED, &req->flags); + if (!test_bit(FR_LOCKED, &req->flags)) { + set_bit(FR_PRIVATE, &req->flags); + __fuse_get_request(req); + list_move(&req->list, &to_end); + } + spin_unlock(&req->waitq.lock); + } + for (i = 0; i < FUSE_PQ_HASH_SIZE; i++) + list_splice_tail_init(&fpq->processing[i], + &to_end); + spin_unlock(&fpq->lock); + } + spin_lock(&fc->bg_lock); + fc->blocked = 0; + fc->max_background = UINT_MAX; + flush_bg_queue(fc); + spin_unlock(&fc->bg_lock); + + spin_lock(&fiq->lock); + fiq->connected = 0; + list_for_each_entry(req, &fiq->pending, list) + clear_bit(FR_PENDING, &req->flags); + list_splice_tail_init(&fiq->pending, &to_end); + while (forget_pending(fiq)) + kfree(fuse_dequeue_forget(fiq, 1, NULL)); + wake_up_all(&fiq->waitq); + spin_unlock(&fiq->lock); + kill_fasync(&fiq->fasync, SIGIO, POLL_IN); + end_polls(fc); + wake_up_all(&fc->blocked_waitq); + spin_unlock(&fc->lock); + + end_requests(&to_end); + } else { + spin_unlock(&fc->lock); + } +} +EXPORT_SYMBOL_GPL(fuse_abort_conn); + +void fuse_wait_aborted(struct fuse_conn *fc) +{ + /* matches implicit memory barrier in fuse_drop_waiting() */ + smp_mb(); + wait_event(fc->blocked_waitq, atomic_read(&fc->num_waiting) == 0); +} + +int fuse_dev_release(struct inode *inode, struct file *file) +{ + struct fuse_dev *fud = fuse_get_dev(file); + + if (fud) { + struct fuse_conn *fc = fud->fc; + struct fuse_pqueue *fpq = &fud->pq; + LIST_HEAD(to_end); + unsigned int i; + + spin_lock(&fpq->lock); + WARN_ON(!list_empty(&fpq->io)); + for (i = 0; i < FUSE_PQ_HASH_SIZE; i++) + list_splice_init(&fpq->processing[i], &to_end); + spin_unlock(&fpq->lock); + + end_requests(&to_end); + + /* Are we the last open device? */ + if (atomic_dec_and_test(&fc->dev_count)) { + WARN_ON(fc->iq.fasync != NULL); + fuse_abort_conn(fc); + } + fuse_dev_free(fud); + } + return 0; +} +EXPORT_SYMBOL_GPL(fuse_dev_release); + +static int fuse_dev_fasync(int fd, struct file *file, int on) +{ + struct fuse_dev *fud = fuse_get_dev(file); + + if (!fud) + return -EPERM; + + /* No locking - fasync_helper does its own locking */ + return fasync_helper(fd, file, on, &fud->fc->iq.fasync); +} + +static int fuse_device_clone(struct fuse_conn *fc, struct file *new) +{ + struct fuse_dev *fud; + + if (new->private_data) + return -EINVAL; + + fud = fuse_dev_alloc_install(fc); + if (!fud) + return -ENOMEM; + + new->private_data = fud; + atomic_inc(&fc->dev_count); + + return 0; +} + +static long fuse_dev_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + int err = -ENOTTY; + + if (cmd == FUSE_DEV_IOC_CLONE) { + int oldfd; + + err = -EFAULT; + if (!get_user(oldfd, (__u32 __user *) arg)) { + struct file *old = fget(oldfd); + + err = -EINVAL; + if (old) { + struct fuse_dev *fud = NULL; + + /* + * Check against file->f_op because CUSE + * uses the same ioctl handler. + */ + if (old->f_op == file->f_op && + old->f_cred->user_ns == file->f_cred->user_ns) + fud = fuse_get_dev(old); + + if (fud) { + mutex_lock(&fuse_mutex); + err = fuse_device_clone(fud->fc, file); + mutex_unlock(&fuse_mutex); + } + fput(old); + } + } + } + return err; +} + +const struct file_operations fuse_dev_operations = { + .owner = THIS_MODULE, + .open = fuse_dev_open, + .llseek = no_llseek, + .read_iter = fuse_dev_read, + .splice_read = fuse_dev_splice_read, + .write_iter = fuse_dev_write, + .splice_write = fuse_dev_splice_write, + .poll = fuse_dev_poll, + .release = fuse_dev_release, + .fasync = fuse_dev_fasync, + .unlocked_ioctl = fuse_dev_ioctl, + .compat_ioctl = compat_ptr_ioctl, +}; +EXPORT_SYMBOL_GPL(fuse_dev_operations); + +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); +} |