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Commit 64649a58 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

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: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5fe17237

mm/filemap.c

+40 −40
Original line number Diff line number Diff line
@@ -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;

			written += copied;

			count -= copied;

			pos += copied;

			buf += copied;

			if (unlikely(nr_segs > 1)) {

				filemap_set_next_iovec(&cur_iov,

							&iov_offset, status);

						&iov_offset, copied);

				if (count)

						buf = cur_iov->iov_base +

							iov_offset;

					buf = cur_iov->iov_base + iov_offset;

			} else {

					iov_offset += status;

				}

				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;