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-rw-r--r--fs/xfs/xfs_aops.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 2b2691b73428..41a695048be7 100644
--- 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);