[patch to 2.6.10-rc2] ext3_find_goal

[patch to 2.6.10-rc2] ext3_find_goal

[stone_wang]

We found strange blocks layout in our mail server, after careful study,
we got the reason and tried to fix it.

When loading an inode from buffer/disk(ext2/3_read_inode),then allocating the second block(block==1) of the corresponding file: i_next_alloc_block and i_next_alloc_goal are both zero,and in fact are not valid,
but they(i_next_alloc_block/goal) take effect in the former codes. This causes non-contiguous file.

Below patch add a check,and fixes this.

Stone Wang.
2005.01.23

diff -urN linux-2.6.10-rc2/fs/ext2/inode.c linux-2.6.10-rc2-fixed/fs/ext2/inode.c
--- linux-2.6.10-rc2/fs/ext2/inode.c	2005-01-23 03:01:42.000000000 -0500
+++ linux-2.6.10-rc2-fixed/fs/ext2/inode.c	2005-01-23 02:57:41.000000000 -0500
@@ -354,7 +354,7 @@
 {
 	struct ext2_inode_info *ei = EXT2_I(inode);
 	write_lock(&ei->i_meta_lock);
-	if (block == ei->i_next_alloc_block + 1) {
+	if ((block == ei->i_next_alloc_block + 1)&& ei->i_next_alloc_goal) {
 		ei->i_next_alloc_block++;
 		ei->i_next_alloc_goal++;
 	} 
diff -urN linux-2.6.10-rc2/fs/ext3/inode.c linux-2.6.10-rc2-fixed/fs/ext3/inode.c
--- linux-2.6.10-rc2/fs/ext3/inode.c	2005-01-23 03:01:42.000000000 -0500
+++ linux-2.6.10-rc2-fixed/fs/ext3/inode.c	2005-01-23 02:08:58.000000000 -0500
@@ -464,7 +464,7 @@
 {
 	struct ext3_inode_info *ei = EXT3_I(inode);
 	/* Writer: ->i_next_alloc* */
-	if (block == ei->i_next_alloc_block + 1) {
+	if ((block == ei->i_next_alloc_block + 1)&& ei->i_next_alloc_goal) {
 		ei->i_next_alloc_block++;
 		ei->i_next_alloc_goal++;
 	}

Re: [patch to 2.6.10-rc2] ext3_find_goal

[Jeff Garzik]

stone_wang@sohu.com wrote:
> 
> We found strange blocks layout in our mail server, after careful study,
> we got the reason and tried to fix it.
> 
> When loading an inode from buffer/disk(ext2/3_read_inode),then allocating the second block(block==1) of the corresponding file: i_next_alloc_block and i_next_alloc_goal are both zero,and in fact are not valid,
> but they(i_next_alloc_block/goal) take effect in the former codes. This causes non-contiguous file.
> 
> Below patch add a check,and fixes this.

Good catch!