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
============
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 13b0e95..9da1221 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -604,7 +604,7 @@
enum {
Opt_err_cont, Opt_err_panic, Opt_err_ro,
Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
- Opt_discard, Opt_err,
+ Opt_discard, Opt_nodiscard, Opt_err,
};
static match_table_t tokens = {
@@ -617,6 +617,7 @@
{Opt_order, "order=%s"},
{Opt_norecovery, "norecovery"},
{Opt_discard, "discard"},
+ {Opt_nodiscard, "nodiscard"},
{Opt_err, NULL}
};
@@ -676,6 +677,9 @@
case Opt_discard:
nilfs_set_opt(sbi, DISCARD);
break;
+ case Opt_nodiscard:
+ nilfs_clear_opt(sbi, DISCARD);
+ break;
default:
printk(KERN_ERR
"NILFS: Unrecognized mount option \"%s\"\n", p);