mm: trim more holes

If prepare_write fails with AOP_TRUNCATED_PAGE, or if commit_write fails, then
we may have failed the write operation despite prepare_write having
instantiated blocks past i_size.  Fix this, and consolidate the trimming into
one place.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 40 insertions, 40 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 0c54fc9b8e3d..73b98c6a3389 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1895,22 +1895,9 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                 }
 
                 status = a_ops->prepare_write(file, page, offset, offset+bytes);
-                if (unlikely(status)) {
-                        loff_t isize = i_size_read(inode);
+                if (unlikely(status))
+                        goto fs_write_aop_error;
 
-                        if (status != AOP_TRUNCATED_PAGE)
-                                unlock_page(page);
-                        page_cache_release(page);
-                        if (status == AOP_TRUNCATED_PAGE)
-                                continue;
-                        /*
-                         * prepare_write() may have instantiated a few blocks
-                         * outside i_size.  Trim these off again.
-                         */
-                        if (pos + bytes > isize)
-                                vmtruncate(inode, isize);
-                        break;
-                }
                 if (likely(nr_segs == 1))
                         copied = filemap_copy_from_user(page, offset,
                                                         buf, bytes);
@@ -1919,40 +1906,53 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                                                 cur_iov, iov_offset, bytes);
                 flush_dcache_page(page);
                 status = a_ops->commit_write(file, page, offset, offset+bytes);
-                if (status == AOP_TRUNCATED_PAGE) {
-                        page_cache_release(page);
-                        continue;
+                if (unlikely(status < 0 || status == AOP_TRUNCATED_PAGE))
+                        goto fs_write_aop_error;
+                if (unlikely(copied != bytes)) {
+                        status = -EFAULT;
+                        goto fs_write_aop_error;
                 }
+                if (unlikely(status > 0)) /* filesystem did partial write */
+                        copied = status;
+
                 if (likely(copied > 0)) {
-                        if (!status)
-                                status = copied;
-
-                        if (status >= 0) {
-                                written += status;
-                                count -= status;
-                                pos += status;
-                                buf += status;
-                                if (unlikely(nr_segs > 1)) {
-                                        filemap_set_next_iovec(&cur_iov,
-                                                        &iov_offset, status);
-                                        if (count)
-                                                buf = cur_iov->iov_base +
-                                                        iov_offset;
-                                } else {
-                                        iov_offset += status;
-                                }
+                        written += copied;
+                        count -= copied;
+                        pos += copied;
+                        buf += copied;
+                        if (unlikely(nr_segs > 1)) {
+                                filemap_set_next_iovec(&cur_iov,
+                                                &iov_offset, copied);
+                                if (count)
+                                        buf = cur_iov->iov_base + iov_offset;
+                        } else {
+                                iov_offset += copied;
                         }
                 }
-                if (unlikely(copied != bytes))
-                        if (status >= 0)
-                                status = -EFAULT;
                 unlock_page(page);
                 mark_page_accessed(page);
                 page_cache_release(page);
-                if (status < 0)
-                        break;
                 balance_dirty_pages_ratelimited(mapping);
                 cond_resched();
+                continue;
+
+fs_write_aop_error:
+                if (status != AOP_TRUNCATED_PAGE)
+                        unlock_page(page);
+                page_cache_release(page);
+
+                /*
+                 * prepare_write() may have instantiated a few blocks
+                 * outside i_size.  Trim these off again. Don't need
+                 * i_size_read because we hold i_mutex.
+                 */
+                if (pos + bytes > inode->i_size)
+                        vmtruncate(inode, inode->i_size);
+                if (status == AOP_TRUNCATED_PAGE)
+                        continue;
+                else
+                        break;
+
         } while (count);
         *ppos = pos;