Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  mm: export generic_pipe_buf_*() to modules
  fuse: support splice() reading from fuse device
  fuse: allow splice to move pages
  mm: export remove_from_page_cache() to modules
  mm: export lru_cache_add_*() to modules
  fuse: support splice() writing to fuse device
  fuse: get page reference for readpages
  fuse: use get_user_pages_fast()
  fuse: remove unneeded variable

1 files changed, 461 insertions, 66 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index e53df5ebb2b8..9424796d6634 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -16,6 +16,9 @@
 #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>
 
 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
 MODULE_ALIAS("devname:fuse");
@@ -499,6 +502,9 @@ struct fuse_copy_state {
         int write;
         struct fuse_req *req;
         const struct iovec *iov;
+        struct pipe_buffer *pipebufs;
+        struct pipe_buffer *currbuf;
+        struct pipe_inode_info *pipe;
         unsigned long nr_segs;
         unsigned long seglen;
         unsigned long addr;
@@ -506,16 +512,16 @@ struct fuse_copy_state {
         void *mapaddr;
         void *buf;
         unsigned len;
+        unsigned move_pages:1;
 };
 
 static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
-                           int write, struct fuse_req *req,
+                           int write,
                            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;
 }
@@ -523,7 +529,18 @@ static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
 /* Unmap and put previous page of userspace buffer */
 static void fuse_copy_finish(struct fuse_copy_state *cs)
 {
-        if (cs->mapaddr) {
+        if (cs->currbuf) {
+                struct pipe_buffer *buf = cs->currbuf;
+
+                if (!cs->write) {
+                        buf->ops->unmap(cs->pipe, buf, cs->mapaddr);
+                } else {
+                        kunmap_atomic(cs->mapaddr, KM_USER0);
+                        buf->len = PAGE_SIZE - cs->len;
+                }
+                cs->currbuf = NULL;
+                cs->mapaddr = NULL;
+        } else if (cs->mapaddr) {
                 kunmap_atomic(cs->mapaddr, KM_USER0);
                 if (cs->write) {
                         flush_dcache_page(cs->pg);
@@ -545,26 +562,61 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
 
         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--;
+        if (cs->pipebufs) {
+                struct pipe_buffer *buf = cs->pipebufs;
+
+                if (!cs->write) {
+                        err = buf->ops->confirm(cs->pipe, buf);
+                        if (err)
+                                return err;
+
+                        BUG_ON(!cs->nr_segs);
+                        cs->currbuf = buf;
+                        cs->mapaddr = buf->ops->map(cs->pipe, buf, 1);
+                        cs->len = buf->len;
+                        cs->buf = cs->mapaddr + buf->offset;
+                        cs->pipebufs++;
+                        cs->nr_segs--;
+                } else {
+                        struct page *page;
+
+                        if (cs->nr_segs == cs->pipe->buffers)
+                                return -EIO;
+
+                        page = alloc_page(GFP_HIGHUSER);
+                        if (!page)
+                                return -ENOMEM;
+
+                        buf->page = page;
+                        buf->offset = 0;
+                        buf->len = 0;
+
+                        cs->currbuf = buf;
+                        cs->mapaddr = kmap_atomic(page, KM_USER0);
+                        cs->buf = cs->mapaddr;
+                        cs->len = PAGE_SIZE;
+                        cs->pipebufs++;
+                        cs->nr_segs++;
+                }
+        } else {
+                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--;
+                }
+                err = get_user_pages_fast(cs->addr, 1, cs->write, &cs->pg);
+                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;
         }
-        down_read(&current->mm->mmap_sem);
-        err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
-                             &cs->pg, NULL);
-        up_read(&current->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);
 }
@@ -586,23 +638,178 @@ static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
         return ncpy;
 }
 
+static int fuse_check_page(struct page *page)
+{
+        if (page_mapcount(page) ||
+            page->mapping != NULL ||
+            page_count(page) != 1 ||
+            (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
+             ~(1 << PG_locked |
+               1 << PG_referenced |
+               1 << PG_uptodate |
+               1 << PG_lru |
+               1 << PG_active |
+               1 << PG_reclaim))) {
+                printk(KERN_WARNING "fuse: trying to steal weird page\n");
+                printk(KERN_WARNING "  page=%p index=%li flags=%08lx, count=%i, mapcount=%i, mapping=%p\n", page, page->index, page->flags, page_count(page), page_mapcount(page), page->mapping);
+                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;
+        struct address_space *mapping;
+        pgoff_t index;
+
+        unlock_request(cs->fc, cs->req);
+        fuse_copy_finish(cs);
+
+        err = buf->ops->confirm(cs->pipe, buf);
+        if (err)
+                return err;
+
+        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 (buf->ops->steal(cs->pipe, buf) != 0)
+                goto out_fallback;
+
+        newpage = buf->page;
+
+        if (WARN_ON(!PageUptodate(newpage)))
+                return -EIO;
+
+        ClearPageMappedToDisk(newpage);
+
+        if (fuse_check_page(newpage) != 0)
+                goto out_fallback_unlock;
+
+        mapping = oldpage->mapping;
+        index = oldpage->index;
+
+        /*
+         * 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;
+
+        remove_from_page_cache(oldpage);
+        page_cache_release(oldpage);
+
+        err = add_to_page_cache_locked(newpage, mapping, index, GFP_KERNEL);
+        if (err) {
+                printk(KERN_WARNING "fuse_try_move_page: failed to add page");
+                goto out_fallback_unlock;
+        }
+        page_cache_get(newpage);
+
+        if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+                lru_cache_add_file(newpage);
+
+        err = 0;
+        spin_lock(&cs->fc->lock);
+        if (cs->req->aborted)
+                err = -ENOENT;
+        else
+                *pagep = newpage;
+        spin_unlock(&cs->fc->lock);
+
+        if (err) {
+                unlock_page(newpage);
+                page_cache_release(newpage);
+                return err;
+        }
+
+        unlock_page(oldpage);
+        page_cache_release(oldpage);
+        cs->len = 0;
+
+        return 0;
+
+out_fallback_unlock:
+        unlock_page(newpage);
+out_fallback:
+        cs->mapaddr = buf->ops->map(cs->pipe, buf, 1);
+        cs->buf = cs->mapaddr + buf->offset;
+
+        err = lock_request(cs->fc, cs->req);
+        if (err)
+                return err;
+
+        return 1;
+}
+
+static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
+                         unsigned offset, unsigned count)
+{
+        struct pipe_buffer *buf;
+
+        if (cs->nr_segs == cs->pipe->buffers)
+                return -EIO;
+
+        unlock_request(cs->fc, cs->req);
+        fuse_copy_finish(cs);
+
+        buf = cs->pipebufs;
+        page_cache_get(page);
+        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 *page,
+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) {
                 void *mapaddr = kmap_atomic(page, KM_USER1);
                 memset(mapaddr, 0, PAGE_SIZE);
                 kunmap_atomic(mapaddr, KM_USER1);
         }
         while (count) {
-                if (!cs->len) {
-                        int err = fuse_copy_fill(cs);
-                        if (err)
-                                return err;
+                if (cs->write && cs->pipebufs && page) {
+                        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, KM_USER1);
@@ -627,8 +834,10 @@ static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
         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);
+                int err;
+
+                err = fuse_copy_page(cs, &req->pages[i], offset, count,
+                                     zeroing);
                 if (err)
                         return err;
 
@@ -705,11 +914,10 @@ __acquires(&fc->lock)
  *
  * 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)
+static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_copy_state *cs,
+                               size_t nbytes, struct fuse_req *req)
 __releases(&fc->lock)
 {
-        struct fuse_copy_state cs;
         struct fuse_in_header ih;
         struct fuse_interrupt_in arg;
         unsigned reqsize = sizeof(ih) + sizeof(arg);
@@ -725,14 +933,13 @@ __releases(&fc->lock)
         arg.unique = req->in.h.unique;
 
         spin_unlock(&fc->lock);
-        if (iov_length(iov, nr_segs) < reqsize)
+        if (nbytes < reqsize)
                 return -EINVAL;
 
-        fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
-        err = fuse_copy_one(&cs, &ih, sizeof(ih));
+        err = fuse_copy_one(cs, &ih, sizeof(ih));
         if (!err)
-                err = fuse_copy_one(&cs, &arg, sizeof(arg));
-        fuse_copy_finish(&cs);
+                err = fuse_copy_one(cs, &arg, sizeof(arg));
+        fuse_copy_finish(cs);
 
         return err ? err : reqsize;
 }
@@ -746,18 +953,13 @@ __releases(&fc->lock)
  * 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)
+static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file,
+                                struct fuse_copy_state *cs, size_t nbytes)
 {
         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);
@@ -777,7 +979,7 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
         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);
+                return fuse_read_interrupt(fc, cs, nbytes, req);
         }
 
         req = list_entry(fc->pending.next, struct fuse_req, list);
@@ -787,7 +989,7 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
         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) {
+        if (nbytes < reqsize) {
                 req->out.h.error = -EIO;
                 /* SETXATTR is special, since it may contain too large data */
                 if (in->h.opcode == FUSE_SETXATTR)
@@ -796,12 +998,12 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
                 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));
+        cs->req = req;
+        err = fuse_copy_one(cs, &in->h, sizeof(in->h));
         if (!err)
-                err = fuse_copy_args(&cs, in->numargs, in->argpages,
+                err = fuse_copy_args(cs, in->numargs, in->argpages,
                                      (struct fuse_arg *) in->args, 0);
-        fuse_copy_finish(&cs);
+        fuse_copy_finish(cs);
         spin_lock(&fc->lock);
         req->locked = 0;
         if (req->aborted) {
@@ -829,6 +1031,110 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
         return err;
 }
 
+static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
+                              unsigned long nr_segs, loff_t pos)
+{
+        struct fuse_copy_state cs;
+        struct file *file = iocb->ki_filp;
+        struct fuse_conn *fc = fuse_get_conn(file);
+        if (!fc)
+                return -EPERM;
+
+        fuse_copy_init(&cs, fc, 1, iov, nr_segs);
+
+        return fuse_dev_do_read(fc, file, &cs, iov_length(iov, nr_segs));
+}
+
+static int fuse_dev_pipe_buf_steal(struct pipe_inode_info *pipe,
+                                   struct pipe_buffer *buf)
+{
+        return 1;
+}
+
+static const struct pipe_buf_operations fuse_dev_pipe_buf_ops = {
+        .can_merge = 0,
+        .map = generic_pipe_buf_map,
+        .unmap = generic_pipe_buf_unmap,
+        .confirm = generic_pipe_buf_confirm,
+        .release = generic_pipe_buf_release,
+        .steal = fuse_dev_pipe_buf_steal,
+        .get = generic_pipe_buf_get,
+};
+
+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 ret;
+        int page_nr = 0;
+        int do_wakeup = 0;
+        struct pipe_buffer *bufs;
+        struct fuse_copy_state cs;
+        struct fuse_conn *fc = fuse_get_conn(in);
+        if (!fc)
+                return -EPERM;
+
+        bufs = kmalloc(pipe->buffers * sizeof (struct pipe_buffer), GFP_KERNEL);
+        if (!bufs)
+                return -ENOMEM;
+
+        fuse_copy_init(&cs, fc, 1, NULL, 0);
+        cs.pipebufs = bufs;
+        cs.pipe = pipe;
+        ret = fuse_dev_do_read(fc, in, &cs, len);
+        if (ret < 0)
+                goto out;
+
+        ret = 0;
+        pipe_lock(pipe);
+
+        if (!pipe->readers) {
+                send_sig(SIGPIPE, current, 0);
+                if (!ret)
+                        ret = -EPIPE;
+                goto out_unlock;
+        }
+
+        if (pipe->nrbufs + cs.nr_segs > pipe->buffers) {
+                ret = -EIO;
+                goto out_unlock;
+        }
+
+        while (page_nr < cs.nr_segs) {
+                int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
+                struct pipe_buffer *buf = pipe->bufs + newbuf;
+
+                buf->page = bufs[page_nr].page;
+                buf->offset = bufs[page_nr].offset;
+                buf->len = bufs[page_nr].len;
+                buf->ops = &fuse_dev_pipe_buf_ops;
+
+                pipe->nrbufs++;
+                page_nr++;
+                ret += buf->len;
+
+                if (pipe->inode)
+                        do_wakeup = 1;
+        }
+
+out_unlock:
+        pipe_unlock(pipe);
+
+        if (do_wakeup) {
+                smp_mb();
+                if (waitqueue_active(&pipe->wait))
+                        wake_up_interruptible(&pipe->wait);
+                kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+        }
+
+out:
+        for (; page_nr < cs.nr_segs; page_nr++)
+                page_cache_release(bufs[page_nr].page);
+
+        kfree(bufs);
+        return ret;
+}
+
 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
                             struct fuse_copy_state *cs)
 {
@@ -988,23 +1294,17 @@ static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
  * 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)
+static ssize_t fuse_dev_do_write(struct fuse_conn *fc,
+                                 struct fuse_copy_state *cs, size_t nbytes)
 {
         int err;
-        size_t 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));
+        err = fuse_copy_one(cs, &oh, sizeof(oh));
         if (err)
                 goto err_finish;
 
@@ -1017,7 +1317,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
          * and error contains notification code.
          */
         if (!oh.unique) {
-                err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), &cs);
+                err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
                 return err ? err : nbytes;
         }
 
@@ -1036,7 +1336,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
 
         if (req->aborted) {
                 spin_unlock(&fc->lock);
-                fuse_copy_finish(&cs);
+                fuse_copy_finish(cs);
                 spin_lock(&fc->lock);
                 request_end(fc, req);
                 return -ENOENT;
@@ -1053,7 +1353,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
                         queue_interrupt(fc, req);
 
                 spin_unlock(&fc->lock);
-                fuse_copy_finish(&cs);
+                fuse_copy_finish(cs);
                 return nbytes;
         }
 
@@ -1061,11 +1361,13 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
         list_move(&req->list, &fc->io);
         req->out.h = oh;
         req->locked = 1;
-        cs.req = req;
+        cs->req = req;
+        if (!req->out.page_replace)
+                cs->move_pages = 0;
         spin_unlock(&fc->lock);
 
-        err = copy_out_args(&cs, &req->out, nbytes);
-        fuse_copy_finish(&cs);
+        err = copy_out_args(cs, &req->out, nbytes);
+        fuse_copy_finish(cs);
 
         spin_lock(&fc->lock);
         req->locked = 0;
@@ -1081,10 +1383,101 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
  err_unlock:
         spin_unlock(&fc->lock);
  err_finish:
-        fuse_copy_finish(&cs);
+        fuse_copy_finish(cs);
         return err;
 }
 
+static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
+                              unsigned long nr_segs, loff_t pos)
+{
+        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, iov, nr_segs);
+
+        return fuse_dev_do_write(fc, &cs, iov_length(iov, nr_segs));
+}
+
+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 nbuf;
+        unsigned idx;
+        struct pipe_buffer *bufs;
+        struct fuse_copy_state cs;
+        struct fuse_conn *fc;
+        size_t rem;
+        ssize_t ret;
+
+        fc = fuse_get_conn(out);
+        if (!fc)
+                return -EPERM;
+
+        bufs = kmalloc(pipe->buffers * sizeof (struct pipe_buffer), GFP_KERNEL);
+        if (!bufs)
+                return -ENOMEM;
+
+        pipe_lock(pipe);
+        nbuf = 0;
+        rem = 0;
+        for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
+                rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len;
+
+        ret = -EINVAL;
+        if (rem < len) {
+                pipe_unlock(pipe);
+                goto out;
+        }
+
+        rem = len;
+        while (rem) {
+                struct pipe_buffer *ibuf;
+                struct pipe_buffer *obuf;
+
+                BUG_ON(nbuf >= pipe->buffers);
+                BUG_ON(!pipe->nrbufs);
+                ibuf = &pipe->bufs[pipe->curbuf];
+                obuf = &bufs[nbuf];
+
+                if (rem >= ibuf->len) {
+                        *obuf = *ibuf;
+                        ibuf->ops = NULL;
+                        pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
+                        pipe->nrbufs--;
+                } else {
+                        ibuf->ops->get(pipe, ibuf);
+                        *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, fc, 0, NULL, nbuf);
+        cs.pipebufs = bufs;
+        cs.pipe = pipe;
+
+        if (flags & SPLICE_F_MOVE)
+                cs.move_pages = 1;
+
+        ret = fuse_dev_do_write(fc, &cs, len);
+
+        for (idx = 0; idx < nbuf; idx++) {
+                struct pipe_buffer *buf = &bufs[idx];
+                buf->ops->release(pipe, buf);
+        }
+out:
+        kfree(bufs);
+        return ret;
+}
+
 static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
 {
         unsigned mask = POLLOUT | POLLWRNORM;
@@ -1226,8 +1619,10 @@ const struct file_operations fuse_dev_operations = {
         .llseek         = no_llseek,
         .read           = do_sync_read,
         .aio_read       = fuse_dev_read,
+        .splice_read    = fuse_dev_splice_read,
         .write          = do_sync_write,
         .aio_write      = fuse_dev_write,
+        .splice_write   = fuse_dev_splice_write,
         .poll           = fuse_dev_poll,
         .release        = fuse_dev_release,
         .fasync         = fuse_dev_fasync,