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authorWu Fengguang <fengguang.wu@intel.com>2010-06-06 12:38:15 -0400
committerWu Fengguang <fengguang.wu@intel.com>2011-06-07 20:25:20 -0400
commit6e6938b6d3130305a5960c86b1a9b21e58cf6144 (patch)
treede5546e8390ce31cd31412d2ef78ce732a42191c /fs/ext4/inode.c
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 'fs/ext4/inode.c')
-rw-r--r--fs/ext4/inode.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a5763e3505ba..8558b6c3450a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2741,7 +2741,7 @@ static int write_cache_pages_da(struct address_space *mapping,
2741 index = wbc->range_start >> PAGE_CACHE_SHIFT; 2741 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2742 end = wbc->range_end >> PAGE_CACHE_SHIFT; 2742 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2743 2743
2744 if (wbc->sync_mode == WB_SYNC_ALL) 2744 if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2745 tag = PAGECACHE_TAG_TOWRITE; 2745 tag = PAGECACHE_TAG_TOWRITE;
2746 else 2746 else
2747 tag = PAGECACHE_TAG_DIRTY; 2747 tag = PAGECACHE_TAG_DIRTY;
@@ -2973,7 +2973,7 @@ static int ext4_da_writepages(struct address_space *mapping,
2973 } 2973 }
2974 2974
2975retry: 2975retry:
2976 if (wbc->sync_mode == WB_SYNC_ALL) 2976 if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2977 tag_pages_for_writeback(mapping, index, end); 2977 tag_pages_for_writeback(mapping, index, end);
2978 2978
2979 while (!ret && wbc->nr_to_write > 0) { 2979 while (!ret && wbc->nr_to_write > 0) {