Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Wed, 10 Nov 2010 10:35:05 +0800 | From | Wu Fengguang <> | Subject | [PATCH 5/5] writeback: check skipped pages on WB_SYNC_ALL |
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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@intel.com> --- 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);
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