[PATCH 1/2] Add discard/nodiscard mount option for ext3

[Lukas Czerner <lczerner@redhat.com>]

Those mount option has the same meaning as in ext4 file system. It
provide a way to enable/disable file system's trim support. The trim
support is off by default, thus nodiscard option is not actually
necessary.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
---
 fs/ext3/super.c         |   14 +++++++++++++-
 include/linux/ext3_fs.h |    1 +
 2 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 1bee604..6baf7ef 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -662,6 +662,9 @@ static int ext3_show_options(struct seq_file *seq, struct vfsmount *vfs)
 	if (test_opt(sb, DATA_ERR_ABORT))
 		seq_puts(seq, ",data_err=abort");
 
+	if (test_opt(sb, DISCARD))
+		seq_puts(seq, ",discard");
+
 	if (test_opt(sb, NOLOAD))
 		seq_puts(seq, ",norecovery");
 
@@ -811,7 +814,8 @@ enum {
 	Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
 	Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,
 	Opt_noquota, Opt_ignore, Opt_barrier, Opt_err, Opt_resize,
-	Opt_usrquota, Opt_grpquota
+	Opt_usrquota, Opt_grpquota,
+	Opt_discard, Opt_nodiscard,
 };
 
 static const match_table_t tokens = {
@@ -866,6 +870,8 @@ static const match_table_t tokens = {
 	{Opt_usrquota, "usrquota"},
 	{Opt_barrier, "barrier=%u"},
 	{Opt_resize, "resize"},
+	{Opt_discard, "discard"},
+	{Opt_nodiscard, "nodiscard"},
 	{Opt_err, NULL},
 };
 
@@ -1242,6 +1248,12 @@ set_qf_format:
 		case Opt_bh:
 			clear_opt(sbi->s_mount_opt, NOBH);
 			break;
+		case Opt_discard:
+			set_opt(sbi->s_mount_opt, DISCARD);
+			break;
+		case Opt_nodiscard:
+			clear_opt(sbi->s_mount_opt, DISCARD);
+			break;
 		default:
 			ext3_msg(sb, KERN_ERR,
 				"error: unrecognized mount option \"%s\" "
diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
index 5f494b4..f3fdd94 100644
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -406,6 +406,7 @@ struct ext3_inode {
 #define EXT3_MOUNT_GRPQUOTA		0x200000 /* "old" group quota */
 #define EXT3_MOUNT_DATA_ERR_ABORT	0x400000 /* Abort on file data write
 						  * error in ordered mode */
+#define EXT3_MOUNT_DISCARD		0x800000 /* Issue DISCARD requests */
 
 /* Compatibility, for having both ext2_fs.h and ext3_fs.h included at once */
 #ifndef _LINUX_EXT2_FS_H
-- 
1.6.6.1