[dm-devel] [PATCH] device-mapper core should use private bioset

[Stefan Bader]

Hi Alasdair,

I found a problem within device-mapper that occurs in low-mem
situations. It was found using a mirror target but I think in theory it
would hit any setup that stacks device-mapper devices (like LVM on top
of multipath).
Since device-mapper core uses the common fs_bioset it is possible that
the filesystem and the first level target successfully get bios but the
lower level target doesn't because there is no more memory and the pool
was drained by upper layers. So the remapping will be stuck forever.
To solve this device-mapper core would have to use its own bioset. The
following patch is against RHEL4-U4 but for head I guess only the stuff
for dm.c (without hunk 1) and probably dm-io.c (if the bioset stuff
there hasn't been replaced by the kernel built-in code, yet).

Regards,
Stefan Bader
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: dm-add-bioset.diff
URL: <http://listman.redhat.com/archives/dm-devel/attachments/20060814/5a37ca6c/attachment.ksh>