openwrtv3/tools/genext2fs/patches/400-byteswap_fix.patch
John Crispin b6fbe7bd5d tools: genext2fs: add support for blocksize != 1024
This patch series is extracted from
http://ftp.de.debian.org/debian/pool/main/g/genext2fs/genext2fs_1.4.1-4.debian.tar.gz

The patches are used in Debian for quite a long time, so I assume that
this is solid material. At least, my Ubuntu host fsck.ext4 does not bark :-)

The goal is to allow building filesystems with larger blocksizes instead of the
current default of 1k. This should improve performance and lifetime when the
filesystem is stored e.g. on a SD card (on Raspberry Pi/I2SE Duckbill for example)
which uses internal flash memory. Writing to flash memory is slow because writing
the data of one block results in erasing a whole erase block of the flash memory.
Thus it is preferable to align the filesystem block size on a flash device with
the erase blocksize, or at least bring it closer to the later one, to avoid
unnecessary write amplification.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

SVN-Revision: 40921
2014-06-02 12:43:46 +00:00

44 lines
1.8 KiB
Diff

Index: genext2fs/genext2fs.c
===================================================================
--- genext2fs.orig/genext2fs.c 2011-11-29 17:36:06.000000000 +0100
+++ genext2fs/genext2fs.c 2011-11-29 17:37:37.000000000 +0100
@@ -1779,7 +1779,8 @@
assert(nod->i_block[EXT2_DIND_BLOCK] != 0);
for(i = 0; i < BLOCKSIZE/4; i++)
if(nblk > EXT2_IND_BLOCK + BLOCKSIZE/4 + (BLOCKSIZE/4)*i )
- swap_block(get_blk(fs, ((uint32*)get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]))[i]));
+ if (((uint32*)get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]))[i])
+ swap_block(get_blk(fs, ((uint32*)get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]))[i]));
swap_block(get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]));
if(nblk <= EXT2_IND_BLOCK + BLOCKSIZE/4 + BLOCKSIZE/4 * BLOCKSIZE/4)
return;
@@ -1792,7 +1793,8 @@
(BLOCKSIZE/4)*(BLOCKSIZE/4) +
i*(BLOCKSIZE/4)*(BLOCKSIZE/4) +
j*(BLOCKSIZE/4)) )
- swap_block(get_blk(fs,b2[j]));
+ if (b2[j])
+ swap_block(get_blk(fs,b2[j]));
else {
done = 1;
break;
@@ -1825,7 +1827,8 @@
swap_block(get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]));
for(i = 0; i < BLOCKSIZE/4; i++)
if(nblk > EXT2_IND_BLOCK + BLOCKSIZE/4 + (BLOCKSIZE/4)*i )
- swap_block(get_blk(fs, ((uint32*)get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]))[i]));
+ if (((uint32*)get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]))[i])
+ swap_block(get_blk(fs, ((uint32*)get_blk(fs, nod->i_block[EXT2_DIND_BLOCK]))[i]));
if(nblk <= EXT2_IND_BLOCK + BLOCKSIZE/4 + BLOCKSIZE/4 * BLOCKSIZE/4)
return;
/* Adding support for triple indirection */
@@ -1839,7 +1842,8 @@
(BLOCKSIZE/4)*(BLOCKSIZE/4) +
i*(BLOCKSIZE/4)*(BLOCKSIZE/4) +
j*(BLOCKSIZE/4)) )
- swap_block(get_blk(fs,b2[j]));
+ if (b2[j])
+ swap_block(get_blk(fs,b2[j]));
else {
done = 1;
break;