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authorNikolay Borisov2019-07-25 11:27:29 +0300
committerDavid Sterba2019-07-25 17:34:08 +0200
commit6e7ca09b583de4be6c27d9d4b06e8c5dd46a58fa (patch)
treea08365bc6b1370f162158b1518061f689dc924a8 /fs/fuse/file.c
parent373c3b80e459cb57c34381b928588a3794eb5bbd (diff)
btrfs: Fix deadlock caused by missing memory barrier
Commit 06297d8cefca ("btrfs: switch extent_buffer blocking_writers from atomic to int") changed the type of blocking_writers but forgot to adjust relevant code in btrfs_tree_unlock by converting the smp_mb__after_atomic to smp_mb. This opened up the possibility of a deadlock due to re-ordering of setting blocking_writers and checking/waking up the waiter. This particular lockup is explained in a comment above waitqueue_active() function. Fix it by converting the memory barrier to a full smp_mb, accounting for the fact that blocking_writers is a simple integer. Fixes: 06297d8cefca ("btrfs: switch extent_buffer blocking_writers from atomic to int") Tested-by: Johannes Thumshirn <jthumshirn@suse.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/fuse/file.c')
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