[PATCH v3 06/19] ext2: Avoid unnecessary inode buffer writeback for sync(2)

[Jan Kara <jack@suse.cz>]

For sync(2) the generic code calls sync_blockdev_nowait() and later
sync_blockdev() to persist all metadata buffers. Thus there's no need
for ext2_write_inode() to do that which speeds up sync(2) writeback.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext2/inode.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index dc7003e21b12..48862e73610c 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1563,7 +1563,11 @@ int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
 	} else for (n = 0; n < EXT2_N_BLOCKS; n++)
 		raw_inode->i_block[n] = ei->i_data[n];
 	mark_buffer_dirty(bh);
-	if (wbc->sync_mode == WB_SYNC_ALL) {
+	/*
+	 * For sync(2) the generic code will call sync_blockdev() to write
+	 * all metadata more efficiently.
+	 */
+	if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) {
 		sync_dirty_buffer(bh);
 		if (buffer_req(bh) && !buffer_uptodate(bh)) {
 			printk ("IO error syncing ext2 inode [%s:%08lx]\n",
-- 
2.51.0