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| author |   Tejun Heo <tj@kernel.org> | 2017-12-12 08:38:30 -0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2019-01-22 14:39:38 -0700 |
| commit | 7fc5854f8c6efae9e7624970ab49a1eac2faefb1 (patch) | |
| tree | 7c9ac9ab43c0a47dbaefd155da89c8ba7f7923db /mm | |
| parent | block: cover another queue enter recursion via BIO_QUEUE_ENTERED (diff) | |
| download | linux-dev-7fc5854f8c6efae9e7624970ab49a1eac2faefb1.tar.xz linux-dev-7fc5854f8c6efae9e7624970ab49a1eac2faefb1.zip | |
writeback: synchronize sync(2) against cgroup writeback membership switches
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>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/backing-dev.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 8a8bb8796c6c..72e6d0c55cfa 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -689,6 +689,7 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi) INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); bdi->cgwb_congested_tree = RB_ROOT; mutex_init(&bdi->cgwb_release_mutex); + init_rwsem(&bdi->wb_switch_rwsem); ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); if (!ret) { |