UBIFS: add no_chk_data_crc mount option

UBIFS read performance can be improved by skipping the CRC
check when data nodes are read.  This option can be used if
the underlying media is considered to be highly reliable.
Note that CRCs are always checked for metadata.

Read speed on Arm platform with OneNAND goes from 19 MiB/s
to 27 MiB/s with data CRC checking disabled.

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>

1 files changed, 31 insertions, 3 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index b1c57e8..cf078b5 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -406,6 +406,11 @@ static int ubifs_show_options(struct seq_file *s, struct vfsmount *mnt)
 	else if (c->mount_opts.bulk_read == 1)
 		seq_printf(s, ",no_bulk_read");
 
+	if (c->mount_opts.chk_data_crc == 2)
+		seq_printf(s, ",chk_data_crc");
+	else if (c->mount_opts.chk_data_crc == 1)
+		seq_printf(s, ",no_chk_data_crc");
+
 	return 0;
 }
 
@@ -859,6 +864,8 @@ static int check_volume_empty(struct ubifs_info *c)
  * Opt_norm_unmount: run a journal commit before un-mounting
  * Opt_bulk_read: enable bulk-reads
  * Opt_no_bulk_read: disable bulk-reads
+ * Opt_chk_data_crc: check CRCs when reading data nodes
+ * Opt_no_chk_data_crc: do not check CRCs when reading data nodes
  * Opt_err: just end of array marker
  */
 enum {
@@ -866,6 +873,8 @@ enum {
 	Opt_norm_unmount,
 	Opt_bulk_read,
 	Opt_no_bulk_read,
+	Opt_chk_data_crc,
+	Opt_no_chk_data_crc,
 	Opt_err,
 };
 
@@ -874,6 +883,8 @@ static match_table_t tokens = {
 	{Opt_norm_unmount, "norm_unmount"},
 	{Opt_bulk_read, "bulk_read"},
 	{Opt_no_bulk_read, "no_bulk_read"},
+	{Opt_chk_data_crc, "chk_data_crc"},
+	{Opt_no_chk_data_crc, "no_chk_data_crc"},
 	{Opt_err, NULL},
 };
 
@@ -919,6 +930,14 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 			c->mount_opts.bulk_read = 1;
 			c->bulk_read = 0;
 			break;
+		case Opt_chk_data_crc:
+			c->mount_opts.chk_data_crc = 2;
+			c->no_chk_data_crc = 0;
+			break;
+		case Opt_no_chk_data_crc:
+			c->mount_opts.chk_data_crc = 1;
+			c->no_chk_data_crc = 1;
+			break;
 		default:
 			ubifs_err("unrecognized mount option \"%s\" "
 				  "or missing value", p);
@@ -1027,6 +1046,8 @@ static int mount_ubifs(struct ubifs_info *c)
 			goto out_free;
 	}
 
+	c->always_chk_crc = 1;
+
 	err = ubifs_read_superblock(c);
 	if (err)
 		goto out_free;
@@ -1168,6 +1189,8 @@ static int mount_ubifs(struct ubifs_info *c)
 	if (err)
 		goto out_infos;
 
+	c->always_chk_crc = 0;
+
 	ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
 		  c->vi.ubi_num, c->vi.vol_id, c->vi.name);
 	if (mounted_read_only)
@@ -1313,6 +1336,7 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 
 	mutex_lock(&c->umount_mutex);
 	c->remounting_rw = 1;
+	c->always_chk_crc = 1;
 
 	/* Check for enough free space */
 	if (ubifs_calc_available(c, c->min_idx_lebs) <= 0) {
@@ -1381,13 +1405,15 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 		c->bgt = NULL;
 		ubifs_err("cannot spawn \"%s\", error %d",
 			  c->bgt_name, err);
-		return err;
+		goto out;
 	}
 	wake_up_process(c->bgt);
 
 	c->orph_buf = vmalloc(c->leb_size);
-	if (!c->orph_buf)
-		return -ENOMEM;
+	if (!c->orph_buf) {
+		err = -ENOMEM;
+		goto out;
+	}
 
 	/* Check for enough log space */
 	lnum = c->lhead_lnum + 1;
@@ -1414,6 +1440,7 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 	dbg_gen("re-mounted read-write");
 	c->vfs_sb->s_flags &= ~MS_RDONLY;
 	c->remounting_rw = 0;
+	c->always_chk_crc = 0;
 	mutex_unlock(&c->umount_mutex);
 	return 0;
 
@@ -1429,6 +1456,7 @@ out:
 	c->ileb_buf = NULL;
 	ubifs_lpt_free(c, 1);
 	c->remounting_rw = 0;
+	c->always_chk_crc = 0;
 	mutex_unlock(&c->umount_mutex);
 	return err;
 }