UBIFS: add bulk-read facility

Some flash media are capable of reading sequentially at faster rates.
UBIFS bulk-read facility is designed to take advantage of that, by
reading in one go consecutive data nodes that are also located
consecutively in the same LEB.

Read speed on Arm platform with OneNAND goes from 17 MiB/s to
19 MiB/s.

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

1 files changed, 31 insertions, 0 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index d87b0cf5f661..b1c57e8ee855 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -401,6 +401,11 @@ static int ubifs_show_options(struct seq_file *s, struct vfsmount *mnt)
 	else if (c->mount_opts.unmount_mode == 1)
 		seq_printf(s, ",norm_unmount");
 
+	if (c->mount_opts.bulk_read == 2)
+		seq_printf(s, ",bulk_read");
+	else if (c->mount_opts.bulk_read == 1)
+		seq_printf(s, ",no_bulk_read");
+
 	return 0;
 }
 
@@ -538,6 +543,18 @@ static int init_constants_early(struct ubifs_info *c)
 	 * calculations when reporting free space.
 	 */
 	c->leb_overhead = c->leb_size % UBIFS_MAX_DATA_NODE_SZ;
+	/* Buffer size for bulk-reads */
+	c->bulk_read_buf_size = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
+	if (c->bulk_read_buf_size > c->leb_size)
+		c->bulk_read_buf_size = c->leb_size;
+	if (c->bulk_read_buf_size > 128 * 1024) {
+		/* Check if we can kmalloc more than 128KiB */
+		void *try = kmalloc(c->bulk_read_buf_size, GFP_KERNEL);
+
+		kfree(try);
+		if (!try)
+			c->bulk_read_buf_size = 128 * 1024;
+	}
 	return 0;
 }
 
@@ -840,17 +857,23 @@ static int check_volume_empty(struct ubifs_info *c)
  *
  * Opt_fast_unmount: do not run a journal commit before un-mounting
  * Opt_norm_unmount: run a journal commit before un-mounting
+ * Opt_bulk_read: enable bulk-reads
+ * Opt_no_bulk_read: disable bulk-reads
  * Opt_err: just end of array marker
  */
 enum {
 	Opt_fast_unmount,
 	Opt_norm_unmount,
+	Opt_bulk_read,
+	Opt_no_bulk_read,
 	Opt_err,
 };
 
 static match_table_t tokens = {
 	{Opt_fast_unmount, "fast_unmount"},
 	{Opt_norm_unmount, "norm_unmount"},
+	{Opt_bulk_read, "bulk_read"},
+	{Opt_no_bulk_read, "no_bulk_read"},
 	{Opt_err, NULL},
 };
 
@@ -888,6 +911,14 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 			c->mount_opts.unmount_mode = 1;
 			c->fast_unmount = 0;
 			break;
+		case Opt_bulk_read:
+			c->mount_opts.bulk_read = 2;
+			c->bulk_read = 1;
+			break;
+		case Opt_no_bulk_read:
+			c->mount_opts.bulk_read = 1;
+			c->bulk_read = 0;
+			break;
 		default:
 			ubifs_err("unrecognized mount option \"%s\" "
 				  "or missing value", p);