nilfs2: add nodiscard mount option
Nilfs has "discard" mount option which issues discard/TRIM commands to
underlying block device, but it lacks a complementary option and has
no way to disable the feature through remount.
This adds "nodiscard" option to resolve this imbalance.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/Documentation/filesystems/nilfs2.txt b/Documentation/filesystems/nilfs2.txt
index 54f61c0..d5c0cef 100644
--- a/Documentation/filesystems/nilfs2.txt
+++ b/Documentation/filesystems/nilfs2.txt
@@ -77,9 +77,10 @@
This disables every write access on the device for
read-only mounts or snapshots. This option will fail
for r/w mounts on an unclean volume.
-discard Issue discard/TRIM commands to the underlying block
- device when blocks are freed. This is useful for SSD
- devices and sparse/thinly-provisioned LUNs.
+discard This enables/disables the use of discard/TRIM commands.
+nodiscard(*) The discard/TRIM commands are sent to the underlying
+ block device when blocks are freed. This is useful
+ for SSD devices and sparse/thinly-provisioned LUNs.
NILFS2 usage
============