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, 8 insertions, 3 deletions

diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 054363f2b207..40e2790b62ce 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -74,6 +74,7 @@ void ubifs_ro_mode(struct ubifs_info *c, int err)
  * @lnum: logical eraseblock number
  * @offs: offset within the logical eraseblock
  * @quiet: print no messages
+ * @chk_crc: indicates whether to always check the CRC
  *
  * This function checks node magic number and CRC checksum. This function also
  * validates node length to prevent UBIFS from becoming crazy when an attacker
@@ -85,7 +86,7 @@ void ubifs_ro_mode(struct ubifs_info *c, int err)
  * or magic.
  */
 int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
-                     int offs, int quiet)
+                     int offs, int quiet, int chk_crc)
 {
         int err = -EINVAL, type, node_len;
         uint32_t crc, node_crc, magic;
@@ -121,6 +122,10 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
                    node_len > c->ranges[type].max_len)
                 goto out_len;
 
+        if (!chk_crc && type == UBIFS_DATA_NODE && !c->always_chk_crc)
+                if (c->no_chk_data_crc)
+                        return 0;
+
         crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
         node_crc = le32_to_cpu(ch->crc);
         if (crc != node_crc) {
@@ -722,7 +727,7 @@ int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
                 goto out;
         }
 
-        err = ubifs_check_node(c, buf, lnum, offs, 0);
+        err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
         if (err) {
                 ubifs_err("expected node type %d", type);
                 return err;
@@ -781,7 +786,7 @@ int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
                 goto out;
         }
 
-        err = ubifs_check_node(c, buf, lnum, offs, 0);
+        err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
         if (err) {
                 ubifs_err("expected node type %d", type);
                 return err;