dm integrity: implement fair range locks

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dm-integrity locks a range of sectors to prevent concurrent I/O or journal
writeback.  These locks were not fair - so that many small overlapping I/Os
could starve a large I/O indefinitely.

Fix this by making the range locks fair.  The ranges that are waiting are
added to the list "wait_list".  If a new I/O overlaps some of the waiting
I/Os, it is not dispatched, but it is also added to that wait list.
Entries on the wait list are processed in first-in-first-out order, so
that an I/O can't starve indefinitely.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

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Mikulas Patocka 2018-07-03 20:13:27 +02:00 • committed by Mike Snitzer

parent 518748b1a7

commit 724376a04d

1 changed files with 59 additions and 9 deletions

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drivers/md/dm-integrity.c

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