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authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2009-02-02 11:33:49 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-02-03 19:59:08 -0500
commitdcf6a79dda5cc2a2bec183e50d829030c0972aaa (patch)
tree557b2867e7c9df361f50b913936d60d4245cf6f8 /mm
parent5193535517825f9a07967e4868a1103013d0a99d (diff)
write-back: fix nr_to_write counter
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/page-writeback.c21
1 files changed, 15 insertions, 6 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b493db7841dc..dc32dae01e5f 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1051,13 +1051,22 @@ continue_unlock:
1051 } 1051 }
1052 } 1052 }
1053 1053
1054 if (wbc->sync_mode == WB_SYNC_NONE) { 1054 if (nr_to_write > 0)
1055 wbc->nr_to_write--; 1055 nr_to_write--;
1056 if (wbc->nr_to_write <= 0) { 1056 else if (wbc->sync_mode == WB_SYNC_NONE) {
1057 done = 1; 1057 /*
1058 break; 1058 * We stop writing back only if we are not
1059 } 1059 * doing integrity sync. In case of integrity
1060 * sync we have to keep going because someone
1061 * may be concurrently dirtying pages, and we
1062 * might have synced a lot of newly appeared
1063 * dirty pages, but have not synced all of the
1064 * old dirty pages.
1065 */
1066 done = 1;
1067 break;
1060 } 1068 }
1069
1061 if (wbc->nonblocking && bdi_write_congested(bdi)) { 1070 if (wbc->nonblocking && bdi_write_congested(bdi)) {
1062 wbc->encountered_congestion = 1; 1071 wbc->encountered_congestion = 1;
1063 done = 1; 1072 done = 1;