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btrfs: Add nodiscard mount option.

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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>
This commit is contained in:
Qu Wenruo 2014-01-06 09:58:27 +08:00 committed by Chris Mason
parent fc0ca9af18
commit e07a2ade44
2 changed files with 10 additions and 3 deletions
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7
Documentation/filesystems/btrfs.txt
View File

@ -98,9 +98,12 @@ Options with (*) are default options and will not show in the mount options.
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).

6
fs/btrfs/super.c
View File

@ -323,7 +323,7 @@ enum {
Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
Opt_check_integrity, Opt_check_integrity_including_extent_data,
Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
Opt_commit_interval, Opt_barrier, Opt_nodefrag,
Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
Opt_err,
};
@ -351,6 +351,7 @@ static match_table_t tokens = {
{Opt_flushoncommit, "flushoncommit"},
{Opt_ratio, "metadata_ratio=%d"},
{Opt_discard, "discard"},
{Opt_nodiscard, "nodiscard"},
{Opt_space_cache, "space_cache"},
{Opt_clear_cache, "clear_cache"},
{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
@ -575,6 +576,9 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
case Opt_discard:
btrfs_set_opt(info->mount_opt, DISCARD);
break;
case Opt_nodiscard:
btrfs_clear_opt(info->mount_opt, DISCARD);
break;
case Opt_space_cache:
btrfs_set_opt(info->mount_opt, SPACE_CACHE);
break;