[PATCH] md: fix deadlock due to md thread processing delayed requests.

Before completing a 'write' the md superblock might need to be updated.
This is best done by the md_thread.

The current code schedules this up and queues the write request for later
handling by the md_thread.

However some personalities (Raid5/raid6) will deadlock if the md_thread
tries to submit requests to its own array.

So this patch changes things so the processes submitting the request waits
for the superblock to be written and then submits the request itself.

This fixes a recently-created deadlock in raid5/raid6

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown 2005-06-21 17:17:26 -07:00 committed by Linus Torvalds
parent 41158c7eb2
commit 3d310eb7b3
7 changed files with 23 additions and 39 deletions

View file

@ -261,7 +261,7 @@ struct mddev_s
sector_t recovery_cp;
spinlock_t write_lock;
struct bio_list write_list;
wait_queue_head_t sb_wait; /* for waiting on superblock updates */
unsigned int safemode; /* if set, update "clean" superblock
* when no writes pending.