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| author | Wu Fengguang <fengguang.wu@intel.com> | 2010-06-06 10:38:15 -0600 |
|---|---|---|
| committer | Wu Fengguang <fengguang.wu@intel.com> | 2011-06-08 08:25:20 +0800 |
| commit | 6e6938b6d3130305a5960c86b1a9b21e58cf6144 (patch) | |
| tree | de5546e8390ce31cd31412d2ef78ce732a42191c /fs/fs-writeback.c | |
| parent | 59c5f46fbe01a00eedf54a23789634438bb80603 (diff) | |
| download | linux-6e6938b6d3130305a5960c86b1a9b21e58cf6144.tar.bz2 | |
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/fs-writeback.c')
| -rw-r--r-- | fs/fs-writeback.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 0f015a0468de..5ed2ce9a28d0 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -36,6 +36,7 @@ struct wb_writeback_work { long nr_pages; struct super_block *sb; enum writeback_sync_modes sync_mode; + unsigned int tagged_writepages:1; unsigned int for_kupdate:1; unsigned int range_cyclic:1; unsigned int for_background:1; @@ -650,6 +651,7 @@ static long wb_writeback(struct bdi_writeback *wb, { struct writeback_control wbc = { .sync_mode = work->sync_mode, + .tagged_writepages = work->tagged_writepages, .older_than_this = NULL, .for_kupdate = work->for_kupdate, .for_background = work->for_background, @@ -657,7 +659,7 @@ static long wb_writeback(struct bdi_writeback *wb, }; unsigned long oldest_jif; long wrote = 0; - long write_chunk; + long write_chunk = MAX_WRITEBACK_PAGES; struct inode *inode; if (wbc.for_kupdate) { @@ -683,9 +685,7 @@ static long wb_writeback(struct bdi_writeback *wb, * (quickly) tag currently dirty pages * (maybe slowly) sync all tagged pages */ - if (wbc.sync_mode == WB_SYNC_NONE) - write_chunk = MAX_WRITEBACK_PAGES; - else + if (wbc.sync_mode == WB_SYNC_ALL || wbc.tagged_writepages) write_chunk = LONG_MAX; wbc.wb_start = jiffies; /* livelock avoidance */ @@ -1188,10 +1188,11 @@ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) { DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { - .sb = sb, - .sync_mode = WB_SYNC_NONE, - .done = &done, - .nr_pages = nr, + .sb = sb, + .sync_mode = WB_SYNC_NONE, + .tagged_writepages = 1, + .done = &done, + .nr_pages = nr, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); |