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authorWu Fengguang <fengguang.wu@intel.com>2010-06-06 10:38:15 -0600
committerWu Fengguang <fengguang.wu@intel.com>2011-06-08 08:25:20 +0800
commit6e6938b6d3130305a5960c86b1a9b21e58cf6144 (patch)
treede5546e8390ce31cd31412d2ef78ce732a42191c /include/linux/writeback.h
parent59c5f46fbe01a00eedf54a23789634438bb80603 (diff)
writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage
sync(2) is performed in two stages: the WB_SYNC_NONE sync and the WB_SYNC_ALL sync. Identify the first stage with .tagged_writepages and do livelock prevention for it, too. Jan's commit f446daaea9 ("mm: implement writeback livelock avoidance using page tagging") is a partial fix in that it only fixed the WB_SYNC_ALL phase livelock. Although ext4 is tested to no longer livelock with commit f446daaea9, it may due to some "redirty_tail() after pages_skipped" effect which is by no means a guarantee for _all_ the file systems. Note that writeback_inodes_sb() is called by not only sync(), they are treated the same because the other callers also need livelock prevention. Impact: It changes the order in which pages/inodes are synced to disk. Now in the WB_SYNC_NONE stage, it won't proceed to write the next inode until finished with the current inode. Acked-by: Jan Kara <jack@suse.cz> CC: Dave Chinner <david@fromorbit.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Diffstat (limited to 'include/linux/writeback.h')
-rw-r--r--include/linux/writeback.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 17e7ccc322a5..3f6542ca6198 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -47,6 +47,7 @@ struct writeback_control {
unsigned encountered_congestion:1; /* An output: a queue is full */
unsigned for_kupdate:1; /* A kupdate writeback */
unsigned for_background:1; /* A background writeback */
+ unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
unsigned for_reclaim:1; /* Invoked from the page allocator */
unsigned range_cyclic:1; /* range_start is cyclic */
unsigned more_io:1; /* more io to be dispatched */