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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>
This commit is contained in:
Ryusuke Konishi 2010-07-05 14:27:04 +09:00
parent 773bc4f3b6
commit 802d317754
2 changed files with 9 additions and 4 deletions
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7
Documentation/filesystems/nilfs2.txt
View File

@ -77,9 +77,10 @@ norecovery Disable recovery of the filesystem on mount.
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
============

6
fs/nilfs2/super.c
View File

@ -604,7 +604,7 @@ static const struct export_operations nilfs_export_ops = {
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 @@ static match_table_t tokens = {
{Opt_order, "order=%s"},
{Opt_norecovery, "norecovery"},
{Opt_discard, "discard"},
{Opt_nodiscard, "nodiscard"},
{Opt_err, NULL}
};
@ -676,6 +677,9 @@ static int parse_options(char *options, struct super_block *sb)
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);