btrfs: Add nodiscard mount option.
Add nodiscard mount option to disable discard with remount option.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index e87609a..7254cf5 100644
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -98,9 +98,12 @@
can be avoided. Especially useful when trying to mount a multi-device
setup as root. May be specified multiple times for multiple devices.
+ nodiscard(*)
discard
- Issue frequent commands to let the block device reclaim space freed by
- the filesystem. This is useful for SSD devices, thinly provisioned
+ Disable/enable discard mount option.
+ Discard issues frequent commands to let the block device reclaim space
+ freed by the filesystem.
+ This is useful for SSD devices, thinly provisioned
LUNs and virtual machine images, but may have a significant
performance impact. (The fstrim command is also available to
initiate batch trims from userspace).