Merge tag 'for-usb-linus-2013-05-24' of git://git.kernel.org/pub/scm/linux/kernel...

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / xfs / xfs_aops.c

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 2b2691b7342890e64e957d616dfb1c4aa2efc8c1..41a695048be7b09b87baf4517fd8124b6d7a8ffb 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -725,6 +725,25 @@ xfs_convert_page(
                        (xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
                        i_size_read(inode));
 
+       /*
+        * If the current map does not span the entire page we are about to try
+        * to write, then give up. The only way we can write a page that spans
+        * multiple mappings in a single writeback iteration is via the
+        * xfs_vm_writepage() function. Data integrity writeback requires the
+        * entire page to be written in a single attempt, otherwise the part of
+        * the page we don't write here doesn't get written as part of the data
+        * integrity sync.
+        *
+        * For normal writeback, we also don't attempt to write partial pages
+        * here as it simply means that write_cache_pages() will see it under
+        * writeback and ignore the page until some point in the future, at
+        * which time this will be the only page in the file that needs
+        * writeback.  Hence for more optimal IO patterns, we should always
+        * avoid partial page writeback due to multiple mappings on a page here.
+        */
+       if (!xfs_imap_valid(inode, imap, end_offset))
+               goto fail_unlock_page;
+
        len = 1 << inode->i_blkbits;
        p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
                                        PAGE_CACHE_SIZE);