tree 336234b9d9a144f180bc51738f55fef7f743b725
parent 2ab1ba68aeaecd41c4b34f0eaf1d70a37367fb1a
author Josef Bacik <josef@redhat.com> 1312469547 +0000
committer Chris Mason <chris.mason@oracle.com> 1313543355 -0400

Btrfs: detect wether a device supports discard

We have a problem where if a user specifies discard but doesn't actually support
it we will return EOPNOTSUPP from btrfs_discard_extent.  This is a problem
because this gets called (in a fashion) from the tree log recovery code, which
has a nice little BUG_ON(ret) after it, which causes us to fail the tree log
replay.  So instead detect wether our devices support discard when we're adding
them and then don't issue discards if we know that the device doesn't support
it.  And just for good measure set ret = 0 in btrfs_issue_discard just in case
we still get EOPNOTSUPP so we don't screw anybody up like this again.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>