Merge branch 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block

* 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block:
  [PATCH] splice: fixup writeout path after ->map changes
  [PATCH] splice: offset fixes
  [PATCH] tee: link_pipe() must be careful when dropping one of the pipe locks
  [PATCH] splice: cleanup the SPLICE_F_NONBLOCK handling
  [PATCH] splice: close i_size truncate races on read

1 files changed, 127 insertions, 58 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 8d57e89924a6..22fac87e90b3 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -50,7 +50,8 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
         struct page *page = buf->page;
         struct address_space *mapping = page_mapping(page);
 
-        WARN_ON(!PageLocked(page));
+        lock_page(page);
+
         WARN_ON(!PageUptodate(page));
 
         /*
@@ -65,8 +66,10 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
         if (PagePrivate(page))
                 try_to_release_page(page, mapping_gfp_mask(mapping));
 
-        if (!remove_mapping(mapping, page))
+        if (!remove_mapping(mapping, page)) {
+                unlock_page(page);
                 return 1;
+        }
 
         buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
         return 0;
@@ -145,8 +148,8 @@ static struct pipe_buf_operations page_cache_pipe_buf_ops = {
  * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
  */
 static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
-                            int nr_pages, unsigned long offset,
-                            unsigned long len, unsigned int flags)
+                            int nr_pages, unsigned long len,
+                            unsigned int offset, unsigned int flags)
 {
         int ret, do_wakeup, i;
 
@@ -243,14 +246,16 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                            unsigned int flags)
 {
         struct address_space *mapping = in->f_mapping;
-        unsigned int offset, nr_pages;
+        unsigned int loff, offset, nr_pages;
         struct page *pages[PIPE_BUFFERS];
         struct page *page;
-        pgoff_t index;
+        pgoff_t index, end_index;
+        loff_t isize;
+        size_t bytes;
         int i, error;
 
         index = *ppos >> PAGE_CACHE_SHIFT;
-        offset = *ppos & ~PAGE_CACHE_MASK;
+        loff = offset = *ppos & ~PAGE_CACHE_MASK;
         nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
         if (nr_pages > PIPE_BUFFERS)
@@ -268,6 +273,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
          * Now fill in the holes:
          */
         error = 0;
+        bytes = 0;
         for (i = 0; i < nr_pages; i++, index++) {
 find_page:
                 /*
@@ -276,14 +282,6 @@ find_page:
                 page = find_get_page(mapping, index);
                 if (!page) {
                         /*
-                         * If in nonblock mode then dont block on
-                         * readpage (we've kicked readahead so there
-                         * will be asynchronous progress):
-                         */
-                        if (flags & SPLICE_F_NONBLOCK)
-                                break;
-
-                        /*
                          * page didn't exist, allocate one
                          */
                         page = page_cache_alloc_cold(mapping);
@@ -304,6 +302,13 @@ find_page:
                  * If the page isn't uptodate, we may need to start io on it
                  */
                 if (!PageUptodate(page)) {
+                        /*
+                         * If in nonblock mode then dont block on waiting
+                         * for an in-flight io page
+                         */
+                        if (flags & SPLICE_F_NONBLOCK)
+                                break;
+
                         lock_page(page);
 
                         /*
@@ -336,13 +341,41 @@ readpage:
                                         goto find_page;
                                 break;
                         }
+
+                        /*
+                         * i_size must be checked after ->readpage().
+                         */
+                        isize = i_size_read(mapping->host);
+                        end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+                        if (unlikely(!isize || index > end_index)) {
+                                page_cache_release(page);
+                                break;
+                        }
+
+                        /*
+                         * if this is the last page, see if we need to shrink
+                         * the length and stop
+                         */
+                        if (end_index == index) {
+                                loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
+                                if (bytes + loff > isize) {
+                                        page_cache_release(page);
+                                        break;
+                                }
+                                /*
+                                 * force quit after adding this page
+                                 */
+                                nr_pages = i;
+                        }
                 }
 fill_it:
                 pages[i] = page;
+                bytes += PAGE_CACHE_SIZE - loff;
+                loff = 0;
         }
 
         if (i)
-                return move_to_pipe(pipe, pages, i, offset, len, flags);
+                return move_to_pipe(pipe, pages, i, bytes, offset, flags);
 
         return error;
 }
@@ -369,17 +402,20 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
         while (len) {
                 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
 
-                if (ret <= 0)
+                if (ret < 0)
                         break;
+                else if (!ret) {
+                        if (spliced)
+                                break;
+                        if (flags & SPLICE_F_NONBLOCK) {
+                                ret = -EAGAIN;
+                                break;
+                        }
+                }
 
                 *ppos += ret;
                 len -= ret;
                 spliced += ret;
-
-                if (!(flags & SPLICE_F_NONBLOCK))
-                        continue;
-                ret = -EAGAIN;
-                break;
         }
 
         if (spliced)
@@ -474,14 +510,12 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
         if (sd->flags & SPLICE_F_MOVE) {
                 /*
                  * If steal succeeds, buf->page is now pruned from the vm
-                 * side (LRU and page cache) and we can reuse it.
+                 * side (LRU and page cache) and we can reuse it. The page
+                 * will also be looked on successful return.
                  */
                 if (buf->ops->steal(info, buf))
                         goto find_page;
 
-                /*
-                 * this will also set the page locked
-                 */
                 page = buf->page;
                 if (add_to_page_cache(page, mapping, index, gfp_mask))
                         goto find_page;
@@ -490,15 +524,27 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
                         lru_cache_add(page);
         } else {
 find_page:
-                ret = -ENOMEM;
-                page = find_or_create_page(mapping, index, gfp_mask);
-                if (!page)
-                        goto out_nomem;
+                page = find_lock_page(mapping, index);
+                if (!page) {
+                        ret = -ENOMEM;
+                        page = page_cache_alloc_cold(mapping);
+                        if (unlikely(!page))
+                                goto out_nomem;
+
+                        /*
+                         * This will also lock the page
+                         */
+                        ret = add_to_page_cache_lru(page, mapping, index,
+                                                    gfp_mask);
+                        if (unlikely(ret))
+                                goto out;
+                }
 
                 /*
-                 * If the page is uptodate, it is also locked. If it isn't
-                 * uptodate, we can mark it uptodate if we are filling the
-                 * full page. Otherwise we need to read it in first...
+                 * We get here with the page locked. If the page is also
+                 * uptodate, we don't need to do more. If it isn't, we
+                 * may need to bring it in if we are not going to overwrite
+                 * the full page.
                  */
                 if (!PageUptodate(page)) {
                         if (sd->len < PAGE_CACHE_SIZE) {
@@ -520,10 +566,8 @@ find_page:
                                         ret = -EIO;
                                         goto out;
                                 }
-                        } else {
-                                WARN_ON(!PageLocked(page));
+                        } else
                                 SetPageUptodate(page);
-                        }
                 }
         }
 
@@ -552,10 +596,10 @@ find_page:
         mark_page_accessed(page);
         balance_dirty_pages_ratelimited(mapping);
 out:
-        if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
+        if (!(buf->flags & PIPE_BUF_FLAG_STOLEN))
                 page_cache_release(page);
-                unlock_page(page);
-        }
+
+        unlock_page(page);
 out_nomem:
         buf->ops->unmap(info, buf);
         return ret;
@@ -687,22 +731,26 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
         ssize_t ret;
 
         ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
-
-        /*
-         * If file or inode is SYNC and we actually wrote some data, sync it.
-         */
-        if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host))
-            && ret > 0) {
+        if (ret > 0) {
                 struct inode *inode = mapping->host;
-                int err;
 
-                mutex_lock(&inode->i_mutex);
-                err = generic_osync_inode(mapping->host, mapping,
-                                          OSYNC_METADATA|OSYNC_DATA);
-                mutex_unlock(&inode->i_mutex);
+                *ppos += ret;
+
+                /*
+                 * If file or inode is SYNC and we actually wrote some data,
+                 * sync it.
+                 */
+                if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
+                        int err;
+
+                        mutex_lock(&inode->i_mutex);
+                        err = generic_osync_inode(inode, mapping,
+                                                  OSYNC_METADATA|OSYNC_DATA);
+                        mutex_unlock(&inode->i_mutex);
 
-                if (err)
-                        ret = err;
+                        if (err)
+                                ret = err;
+                }
         }
 
         return ret;
@@ -904,6 +952,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
 {
         struct pipe_inode_info *pipe;
         loff_t offset, *off;
+        long ret;
 
         pipe = in->f_dentry->d_inode->i_pipe;
         if (pipe) {
@@ -918,7 +967,12 @@ static long do_splice(struct file *in, loff_t __user *off_in,
                 } else
                         off = &out->f_pos;
 
-                return do_splice_from(pipe, out, off, len, flags);
+                ret = do_splice_from(pipe, out, off, len, flags);
+
+                if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
+                        ret = -EFAULT;
+
+                return ret;
         }
 
         pipe = out->f_dentry->d_inode->i_pipe;
@@ -934,7 +988,12 @@ static long do_splice(struct file *in, loff_t __user *off_in,
                 } else
                         off = &in->f_pos;
 
-                return do_splice_to(in, off, pipe, len, flags);
+                ret = do_splice_to(in, off, pipe, len, flags);
+
+                if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
+                        ret = -EFAULT;
+
+                return ret;
         }
 
         return -EINVAL;
@@ -979,7 +1038,9 @@ static int link_pipe(struct pipe_inode_info *ipipe,
                      size_t len, unsigned int flags)
 {
         struct pipe_buffer *ibuf, *obuf;
-        int ret = 0, do_wakeup = 0, i;
+        int ret, do_wakeup, i, ipipe_first;
+
+        ret = do_wakeup = ipipe_first = 0;
 
         /*
          * Potential ABBA deadlock, work around it by ordering lock
@@ -987,6 +1048,7 @@ static int link_pipe(struct pipe_inode_info *ipipe,
          * could deadlock (one doing tee from A -> B, the other from B -> A).
          */
         if (ipipe->inode < opipe->inode) {
+                ipipe_first = 1;
                 mutex_lock(&ipipe->inode->i_mutex);
                 mutex_lock(&opipe->inode->i_mutex);
         } else {
@@ -1035,9 +1097,11 @@ static int link_pipe(struct pipe_inode_info *ipipe,
 
                         /*
                          * We have input available, but no output room.
-                         * If we already copied data, return that.
+                         * If we already copied data, return that. If we
+                         * need to drop the opipe lock, it must be ordered
+                         * last to avoid deadlocks.
                          */
-                        if (flags & SPLICE_F_NONBLOCK) {
+                        if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) {
                                 if (!ret)
                                         ret = -EAGAIN;
                                 break;
@@ -1071,7 +1135,12 @@ static int link_pipe(struct pipe_inode_info *ipipe,
                         if (ret)
                                 break;
                 }
-                if (flags & SPLICE_F_NONBLOCK) {
+                /*
+                 * pipe_wait() drops the ipipe mutex. To avoid deadlocks
+                 * with another process, we can only safely do that if
+                 * the ipipe lock is ordered last.
+                 */
+                if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) {
                         if (!ret)
                                 ret = -EAGAIN;
                         break;