tree dcc853af8b188b2eb59be84dac424698e561057b
parent 6a24c71843de1354d3bcc2ce47fd0b3bee936399
author Stefan Bader <Stefan.Bader@de.ibm.com> 1159863341 -0700
committer Linus Torvalds <torvalds@g5.osdl.org> 1159887856 -0700

[PATCH] dm: use private biosets

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 in clone_bio(), and a
private, but still global, bio_set in split_bvec() 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 needs to use a private bio_set for each device.

Signed-off-by: Stefan Bader <Stefan.Bader@de.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>