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| author | Tejun Heo <tj@kernel.org> | 2017-12-12 08:38:30 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-21 18:49:01 +0200 |
| commit | 1cfaba5b49a5e9133b28da6d1a459240c1f61993 (patch) | |
| tree | 9de4c7cab310fa95d1b06ac918e7155f3b452495 /include | |
| parent | d5c71a7c533e88a9fcc74fe1b5c25743868fa300 (diff) | |
| download | linux-1cfaba5b49a5e9133b28da6d1a459240c1f61993.tar.gz linux-1cfaba5b49a5e9133b28da6d1a459240c1f61993.tar.bz2 linux-1cfaba5b49a5e9133b28da6d1a459240c1f61993.zip | |
writeback: synchronize sync(2) against cgroup writeback membership switches
commit 7fc5854f8c6efae9e7624970ab49a1eac2faefb1 upstream.
sync_inodes_sb() can race against cgwb (cgroup writeback) membership
switches and fail to writeback some inodes. For example, if an inode
switches to another wb while sync_inodes_sb() is in progress, the new
wb might not be visible to bdi_split_work_to_wbs() at all or the inode
might jump from a wb which hasn't issued writebacks yet to one which
already has.
This patch adds backing_dev_info->wb_switch_rwsem to synchronize cgwb
switch path against sync_inodes_sb() so that sync_inodes_sb() is
guaranteed to see all the target wbs and inodes can't jump wbs to
escape syncing.
v2: Fixed misplaced rwsem init. Spotted by Jiufei.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jiufei Xue <xuejiufei@gmail.com>
Link: http://lkml.kernel.org/r/dc694ae2-f07f-61e1-7097-7c8411cee12d@gmail.com
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/backing-dev-defs.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 4ea779b25a51..34056ec64c7c 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -157,6 +157,7 @@ struct backing_dev_info { struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ struct rb_root cgwb_congested_tree; /* their congested states */ atomic_t usage_cnt; /* counts both cgwbs and cgwb_contested's */ + struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */ #else struct bdi_writeback_congested *wb_congested; #endif |