md/raid1: release pending accounting for an I/O only after write-behind is also finished
When using RAID1 and write-behind, md can deadlock when errors occur. With write-behind, r1bio structs can be accounted by raid1 as queued but not counted as pending. The pending count is dropped when the original bio is returned complete but write-behind for the r1bio may still be active. This breaks the accounting used in some conditions to know when the raid1 md device has reached an idle state. It can result in calls to freeze_array deadlocking. freeze_array will never complete from a negative "unqueued" value being calculated due to a queued count larger than the pending count. To properly account for write-behind, move the call to allow_barrier from call_bio_endio to raid_end_bio_io. When using write-behind, md can call call_bio_endio before all write-behind I/O is complete. Using raid_end_bio_io for the point to call allow_barrier will release the pending count at a point where all I/O for an r1bio, even write-behind, is done. Signed-off-by:David Jeffery <djeffery@redhat.com> Signed-off-by:
Song Liu <songliubraving@fb.com>
parent
3024ba2d
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