In WB_SYNC_ALL mode, filesystems are not expected to skip dirty pages on temporal lock contentions or non fatal errors, otherwise sync() will return without actually syncing the skipped pages. Add a check to catch possible redirty_page_for_writepage() callers that violate this expectation. I'd recommend to keep this check in -mm tree for some time and fixup the possible warnings before pushing it to upstream. If some FS triggers this warning and it's non-trivial to fix the FS, we'll have to work out a sync retry scheme for skipped pages. Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> --- fs/fs-writeback.c | 6 ++++++ 1 file changed, 6 insertions(+) --- linux-next.orig/fs/fs-writeback.c 2010-11-10 07:04:43.000000000 +0800 +++ linux-next/fs/fs-writeback.c 2010-11-10 07:11:03.000000000 +0800 @@ -527,6 +527,12 @@ static int writeback_sb_inodes(struct su * buffers. Skip this inode for now. */ redirty_tail(inode); + /* + * There's no logic to retry skipped pages for sync(), + * filesystems are assumed not to skip dirty pages on + * temporal lock contentions or non fatal errors. + */ + WARN_ON_ONCE(wbc->sync_mode == WB_SYNC_ALL); } spin_unlock(&inode_lock); iput(inode); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>