Brian Behlendorf 65d56083b4 Fix zpool on zvol lock inversion deadlock ...

In all but one case the spa_namespace_lock is taken before the
bdev->bd_mutex lock.  But Linux __blkdev_get() function calls
fops->open() with the bdev->bd_mutex lock held and we must
somehow still safely acquire the spa_namespace_lock.

To avoid a potential lock inversion deadlock we preemptively
try to take the spa_namespace_lock().  Normally it will not
be contended and this is safe because spa_open_common() handles
the case where the caller already holds the spa_namespace_lock.

When it is contended we risk a lock inversion if we were to
block waiting for the lock.  Luckily, the __blkdev_get()
function allows us to return -ERESTARTSYS which will result in
bdev->bd_mutex being dropped, reacquired, and fops->open() being
called again.  This process can be repeated safely until both
locks are acquired.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes #612

2012-12-20 09:57:39 -08:00

..

avl

Add script for builtin module building.

2012-07-26 13:45:09 -07:00

nvpair

Add script for builtin module building.

2012-07-26 13:45:09 -07:00

unicode

Add script for builtin module building.

2012-07-26 13:45:09 -07:00

zcommon

Illumos #1948: zpool list should show more detailed pool info

2012-09-19 13:39:05 -07:00

zfs

Fix zpool on zvol lock inversion deadlock

2012-12-20 09:57:39 -08:00

zpios

Add script for builtin module building.

2012-07-26 13:45:09 -07:00

.gitignore

Add .gitignore files to exclude build products

2010-01-08 11:35:17 -08:00

Makefile.in

Add script for builtin module building.

2012-07-26 13:45:09 -07:00