openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

md/raid5: need_this_block: start simplifying the last two conditions. 

Both the last two cases are only relevant if something has failed and
something needs to be written (but not over-written), and if it is OK
to pre-read blocks at this point.  So factor out those tests and
explain them.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2015-02-02 11:49:10 +11:00
parent a79cfe12c6
commit a9d56950f7
1 changed files with 23 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
drivers/md/raid5.c
View File

@ -2930,16 +2930,34 @@ static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
*/
return 1;
/* Sometimes neither read-modify-write nor reconstruct-write
* cycles can work. In those cases we read every block we
* can. Then the parity-update is certain to have enough to
* work with.
* This can only be a problem when we need to write something,
* and some device has failed. If either of those tests
* fail we need look no further.
*/
if (!s->failed || !s->to_write)
return 0;
if (test_bit(R5_Insync, &dev->flags) &&
!test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
/* Pre-reads at not permitted until after short delay
* to gather multiple requests. However if this
* device is no Insync, the block could only be be computed
* and there is no need to delay that.
*/
return 0;
if (
(sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
(!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) &&
(sh->raid_conf->level <= 5 && fdev[0]->towrite &&
!test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
((sh->raid_conf->level == 6 ||
sh->sector >= sh->raid_conf->mddev->recovery_cp)
&& s->failed && s->to_write &&
&&
(s->to_write - s->non_overwrite <
sh->raid_conf->raid_disks - sh->raid_conf->max_degraded) &&
(!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))))
sh->raid_conf->raid_disks - sh->raid_conf->max_degraded)
))
return 1;
return 0;
}