dm snapshot: fix invalidation deadlock
authorMilan Broz <mbroz@redhat.com>
Thu, 12 Jul 2007 16:28:00 +0000 (17:28 +0100)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Thu, 12 Jul 2007 22:01:08 +0000 (15:01 -0700)
commitfcac03abd325e4f7a4cc8fe05fea2793b1c8eb75
tree79965ed6b2b03468e629a63fca1c14f795091436
parent596f138eede0c113aa655937c8be85fc15ccd61c
dm snapshot: fix invalidation deadlock

Process persistent exception store metadata IOs in a separate thread.

A snapshot may become invalid while inside generic_make_request().
A synchronous write is then needed to update the metadata while still
inside that function.  Since the introduction of
md-dm-reduce-stack-usage-with-stacked-block-devices.patch this has to
be performed by a separate thread to avoid deadlock.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/md/dm-exception-store.c