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>
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 7c12d61..6d866db 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -48,6 +48,7 @@
int writeable;
int in_fs_metadata;
int missing;
+ int can_discard;
spinlock_t io_lock;
@@ -104,6 +105,7 @@
u64 rw_devices;
u64 missing_devices;
u64 total_rw_bytes;
+ u64 num_can_discard;
struct block_device *latest_bdev;
/* all of the devices in the FS, protected by a mutex