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md: be careful when testing resync_max against curr_resync_completed. 

While it generally shouldn't happen, it is not impossible for
curr_resync_completed to exceed resync_max.
This can particularly happen when reshaping RAID5 - the current
status isn't copied to curr_resync_completed promptly, so when it
is, it can exceed resync_max.
This happens when the reshape is 'frozen', resync_max is set low,
and reshape is re-enabled.

Taking a difference between two unsigned numbers is always dangerous
anyway, so add a test to behave correctly if
   curr_resync_completed > resync_max

Signed-off-by: NeilBrown <neilb@suse.com>
This commit is contained in:
NeilBrown 2015-07-17 12:06:02 +10:00
parent a4a3d26d87
commit c5e19d906a
2 changed files with 4 additions and 2 deletions
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3
drivers/md/md.c
View File

@ -7834,7 +7834,8 @@ void md_do_sync(struct md_thread *thread)
> (max_sectors >> 4)) ||
time_after_eq(jiffies, update_time + UPDATE_FREQUENCY) ||
(j - mddev->curr_resync_completed)*2
>= mddev->resync_max - mddev->curr_resync_completed
>= mddev->resync_max - mddev->curr_resync_completed ||
mddev->curr_resync_completed > mddev->resync_max
)) {
/* time to update curr_resync_completed */
wait_event(mddev->recovery_wait,

3
drivers/md/raid5.c
View File

@ -5542,7 +5542,8 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
sector_nr += reshape_sectors;
retn = reshape_sectors;
finish:
if ((sector_nr - mddev->curr_resync_completed) * 2
if (mddev->curr_resync_completed > mddev->resync_max ||
(sector_nr - mddev->curr_resync_completed) * 2
>= mddev->resync_max - mddev->curr_resync_completed) {
/* Cannot proceed until we've updated the superblock... */
wait_event(conf->wait_for_overlap,