* Bug in RAID1 in 2.4
@ 2003-12-20 8:25 Pete Zaitcev
2003-12-21 9:44 ` Neil Brown
0 siblings, 1 reply; 2+ messages in thread
From: Pete Zaitcev @ 2003-12-20 8:25 UTC (permalink / raw)
To: neilb; +Cc: linux-raid, Ingo Molnar, Pete Zaitcev
In drivers/md/raid1.c, raid1_sync_request contains the following:
block_nr = sector_nr;
bsize = 512;
while (!(block_nr & 1) && bsize < PAGE_SIZE
&& (block_nr+2)*(bsize>>9) < (mddev->sb->size *2)) {
block_nr >>= 1;
bsize <<= 1;
}
Suppose that a mirror is 4K in size. The code above produces
reads (and writes) of the following offsets and sizes:
0K[2K], 2K[1K], 3K[0.5K], 3.5K[0.5K]
The above is correct, but it makes the RAID1 completely unuseable
on s390, because I/O with sizes less than 4K is not supported.
I would like the attached patch applied to correct the issue.
-- Pete
--- linux-2.4.23/drivers/md/raid1.c 2003-06-13 07:51:34.000000000 -0700
+++ linux-2.4.23-nip/drivers/md/raid1.c 2003-12-19 23:57:57.000000000 -0800
@@ -1436,7 +1436,7 @@
block_nr = sector_nr;
bsize = 512;
while (!(block_nr & 1) && bsize < PAGE_SIZE
- && (block_nr+2)*(bsize>>9) < (mddev->sb->size *2)) {
+ && (block_nr+2)*(bsize>>9) <= (mddev->sb->size *2)) {
block_nr >>= 1;
bsize <<= 1;
}
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: Bug in RAID1 in 2.4
2003-12-20 8:25 Bug in RAID1 in 2.4 Pete Zaitcev
@ 2003-12-21 9:44 ` Neil Brown
0 siblings, 0 replies; 2+ messages in thread
From: Neil Brown @ 2003-12-21 9:44 UTC (permalink / raw)
To: Pete Zaitcev; +Cc: Marcelo Tosatti, linux-raid, Ingo Molnar
On Saturday December 20, zaitcev@redhat.com wrote:
> In drivers/md/raid1.c, raid1_sync_request contains the following:
>
> block_nr = sector_nr;
> bsize = 512;
> while (!(block_nr & 1) && bsize < PAGE_SIZE
> && (block_nr+2)*(bsize>>9) < (mddev->sb->size *2)) {
> block_nr >>= 1;
> bsize <<= 1;
> }
>
> Suppose that a mirror is 4K in size. The code above produces
> reads (and writes) of the following offsets and sizes:
> 0K[2K], 2K[1K], 3K[0.5K], 3.5K[0.5K]
>
> The above is correct, but it makes the RAID1 completely unuseable
> on s390, because I/O with sizes less than 4K is not supported.
> I would like the attached patch applied to correct the issue.
Yes, I agree. Marcelo, could you please apply this patch.
The '<' test is just to make sure a request of 2*bsize at block_nr
will still fit within the size of the device, so a <= is appropriate.
NeilBrown
--- linux-2.4.23/drivers/md/raid1.c 2003-06-13 07:51:34.000000000 -0700
+++ linux-2.4.23-nip/drivers/md/raid1.c 2003-12-19 23:57:57.000000000 -0800
@@ -1436,7 +1436,7 @@
block_nr = sector_nr;
bsize = 512;
while (!(block_nr & 1) && bsize < PAGE_SIZE
- && (block_nr+2)*(bsize>>9) < (mddev->sb->size *2)) {
+ && (block_nr+2)*(bsize>>9) <= (mddev->sb->size *2)) {
block_nr >>= 1;
bsize <<= 1;
}
^ permalink raw reply [flat|nested] 2+ messages in thread
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2003-12-20 8:25 Bug in RAID1 in 2.4 Pete Zaitcev
2003-12-21 9:44 ` Neil Brown
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