ext2load: increase read speed

This patch dramatically drops the amount of time u-boot needs to read a
file from an ext2 partition.  On a typical 2 to 5 MB file (kernels and
initrds) it goes from tens of seconds to a couple seconds.

All we are doing here is grouping contiguous blocks into one read.

Boot tested on Globalscale Technologies Dreamplug (Kirkwood ARM SoC)
with three different files.  sha1sums were calculated in Linux
userspace, and then confirmed after ext2load.

Signed-off-by: Jason Cooper <u-boot@lakedaemon.net>
Tested-by: Eric Nelson <eric.nelson@boundarydevices.com>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>

diff --git a/fs/ext2/ext2fs.c b/fs/ext2/ext2fs.c
index f621741e40555f420e996fe127606901b1d8d671..f1fce48a3920d3ed1220005911ac2092a441f248 100644 (file)
--- a/fs/ext2/ext2fs.c
+++ b/fs/ext2/ext2fs.c
@@ -420,7 +420,6 @@ int ext2fs_read_file
                if (blknr < 0) {
                        return (-1);
                }
-               blknr = blknr << log2blocksize;
 
                /* Last block.  */
                if (i == blockcnt - 1) {
@@ -438,6 +437,29 @@ int ext2fs_read_file
                        blockend -= skipfirst;
                }
 
+               /* grab middle blocks in one go */
+               if (i != pos / blocksize && i != blockcnt - 1 && blockcnt > 3) {
+                       int oldblk = blknr;
+                       int blocknxt;
+                       while (i < blockcnt - 1) {
+                               blocknxt = ext2fs_read_block(node, i + 1);
+                               if (blocknxt == (oldblk + 1)) {
+                                       oldblk = blocknxt;
+                                       i++;
+                               } else {
+                                       blocknxt = ext2fs_read_block(node, i);
+                                       break;
+                               }
+                       }
+
+                       if (oldblk == blknr)
+                               blockend = blocksize;
+                       else
+                               blockend = (1 + blocknxt - blknr) * blocksize;
+               }
+
+               blknr = blknr << log2blocksize;
+
                /* If the block number is 0 this block is not stored on disk but
                   is zero filled instead.  */
                if (blknr) {
@@ -450,7 +472,7 @@ int ext2fs_read_file
                } else {
                        memset (buf, 0, blocksize - skipfirst);
                }
-               buf += blocksize - skipfirst;
+               buf += blockend - skipfirst;
        }
        return (len);
 }