diff options
| author | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2009-02-02 18:33:49 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-02-17 09:28:49 -0800 |
| commit | 66c85494570396661479ba51e17964b2c82b6f39 (patch) | |
| tree | c8f5b88a053548158c834aaa7a4ddf6e965dc4c0 /mm | |
| parent | fa76ac6cbeb58256cf7de97a75d5d7f838a80b32 (diff) | |
write-back: fix nr_to_write counter
commit dcf6a79dda5cc2a2bec183e50d829030c0972aaa upstream.
Commit 05fe478dd04e02fa230c305ab9b5616669821dd3 introduced some
@wbc->nr_to_write breakage.
It made the following changes:
1. Decrement wbc->nr_to_write instead of nr_to_write
2. Decrement wbc->nr_to_write _only_ if wbc->sync_mode == WB_SYNC_NONE
3. If synced nr_to_write pages, stop only if if wbc->sync_mode ==
WB_SYNC_NONE, otherwise keep going.
However, according to the commit message, the intention was to only make
change 3. Change 1 is a bug. Change 2 does not seem to be necessary,
and it breaks UBIFS expectations, so if needed, it should be done
separately later. And change 2 does not seem to be documented in the
commit message.
This patch does the following:
1. Undo changes 1 and 2
2. Add a comment explaining change 3 (it very useful to have comments
in _code_, not only in the commit).
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page-writeback.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 11400ed468e7..0c4100e1f177 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -981,13 +981,22 @@ continue_unlock: } } - if (wbc->sync_mode == WB_SYNC_NONE) { - wbc->nr_to_write--; - if (wbc->nr_to_write <= 0) { - done = 1; - break; - } + if (nr_to_write > 0) + nr_to_write--; + else if (wbc->sync_mode == WB_SYNC_NONE) { + /* + * We stop writing back only if we are not + * doing integrity sync. In case of integrity + * sync we have to keep going because someone + * may be concurrently dirtying pages, and we + * might have synced a lot of newly appeared + * dirty pages, but have not synced all of the + * old dirty pages. + */ + done = 1; + break; } + if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; done = 1; |