Hi Jens,

Unless you have specific reason for not doing in __bio_clone(), I agree
with Neil's suggestion.  Please consider the following patch:

--- linux-2.6.12-rc4-orig/fs/bio.c   2005-05-16 10:13:27.000000000 -0500
+++ linux-2.6.12-rc4-patch/fs/bio.c   2005-05-16 10:15:06.000000000 -0500

@@ -255,10 +255,7 @@
        bio->bi_flags |= 1 << BIO_CLONED;
        bio->bi_rw = bio_src->bi_rw;

-       /*
-        * notes -- maybe just leave bi_idx alone. assume identical mapping
-        * for the clone
-        */
+       bio->bi_idx = bio_src->bi_idx;
        bio->bi_vcnt = bio_src->bi_vcnt;
        bio->bi_size = bio_src->bi_size;
        bio_phys_segments(q, bio);



--

Regards,
Mike T.

On Fri, 2005-05-13 at 18:08, Neil Brown wrote:

On Friday May 13, mhtran@us.ibm.com wrote:

quoted

Hi Neil et al,

The scenario:  Having LVM (striped) volumes on top of 2 raid1 devices
The problem:   Corruption in building the scatter gather list for
device driver (see /drivers/block/blk_rq_map_sg() function)

In DM code, a bio sometimes can be split into several
clones and the clones' bi_idx is set accordingly by DM.  MD raid1 also
clones bio but does not adjust bi_idx. The problem can be fixed in
either __bio_clone() or the caller of bio_clone().  I chose to fix
raid1.

Presumably the same fix would be needed in the "write" path and all in
the read-retry path in raid1d?

Why not just put it in __bio_clone, which would be one change instead
of (atleast) 3?

NeilBrown

quoted

--- linux-2.6.12-rc4-orig/drivers/md/raid1.c    2005-05-10 13:35:06.000000000-0500
+++ linux-2.6.12-rc4-patch/drivers/md/raid1.c   2005-05-13 15:41:43.000000000-0500

@@ -577,6 +577,7 @@

                r1_bio->bios[rdisk] = read_bio;

+               read_bio->bi_idx = bio->bi_idx;
                read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
                read_bio->bi_bdev = mirror->rdev->bdev;
                read_bio->bi_end_io = raid1_end_read_request;

--

Regards,
Mike T.

-
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