This patch resolves the offset problem of the flex_bg
option when you use mke2fs tool.
For example, if you type mkfs.ext4 -I256 -O flex_bg -G32 -E test_fs <device>
and look dumpe2fs <device> result you will see an offset problem.
Group 0: (Blocks 0-32767)
Primary superblock at 0, Group descriptors at 1-5
Reserved GDT blocks at 6-1024
Block bitmap at 1025 (+1025), Inode bitmap at 1058 (+1058)
Inode table at 1090-1601 (+1090)
0 free blocks, 8181 free inodes, 2 directories
Free blocks:
Free inodes: 12-8192
Inode bitmap must start at 1025 + 32 = 1057
In all flexbg groups, the block between the last block bitmap and the
first inode
bitmap (metatdata) is not used, which introduced a hole.
This patch corrects it.
You have to apply it on e2fsprogs (mke2fs 1.41-WIP (17-Jun-2008)) master
branch.
Celine Bourde.
On Thu, 03 Jul 2008 10:21:02 +0200
Celine Bourde <[email protected]> wrote:
> This patch resolves the offset problem of the flex_bg
> option when you use mke2fs tool.
>
> For example, if you type mkfs.ext4 -I256 -O flex_bg -G32 -E test_fs <device>
> and look dumpe2fs <device> result you will see an offset problem.
>
> Group 0: (Blocks 0-32767)
> Primary superblock at 0, Group descriptors at 1-5
> Reserved GDT blocks at 6-1024
> Block bitmap at 1025 (+1025), Inode bitmap at 1058 (+1058)
> Inode table at 1090-1601 (+1090)
> 0 free blocks, 8181 free inodes, 2 directories
> Free blocks:
> Free inodes: 12-8192
>
> Inode bitmap must start at 1025 + 32 = 1057
> In all flexbg groups, the block between the last block bitmap and the
> first inode
> bitmap (metatdata) is not used, which introduced a hole.
>
> This patch corrects it.
> You have to apply it on e2fsprogs (mke2fs 1.41-WIP (17-Jun-2008)) master
> branch.
>
> Celine Bourde.
Acked-by: Jose R. Santos <[email protected]>
-JRS
On Thu, Jul 03, 2008 at 10:21:02AM +0200, Celine Bourde wrote:
> This patch resolves the offset problem of the flex_bg
> option when you use mke2fs tool.
Actually, I think the problem is a bigger one. Ext2fs_get_free_blocks()
returns a error code on failure. So the code before the conditional
you modified is totally bogus:
/* Find the first available block */
if (ext2fs_get_free_blocks(fs, start_blk, last_blk, 1, bmap,
&first_free))
return first_free;
if (ext2fs_get_free_blocks(fs, first_free + offset, last_blk, size,
bmap, &first_free))
return first_free;
return first_free;
I think this should be instead:
/* Find the first available block */
if (ext2fs_get_free_blocks(fs, start_blk, last_blk, 1, bmap,
&first_free) == 0)
return first_free;
if (ext2fs_get_free_blocks(fs, first_free + offset, last_blk, size,
bmap, &first_free) == 0)
return first_free;
/*
* Oops, we weren't able to find enough space. We return
* first_free as a best try.
*/
return first_free;
- Ted
On Thu, 3 Jul 2008 06:55:53 -0500
"Jose R. Santos" <[email protected]> wrote:
> On Thu, 03 Jul 2008 10:21:02 +0200
> Celine Bourde <[email protected]> wrote:
>
> > This patch resolves the offset problem of the flex_bg
> > option when you use mke2fs tool.
> >
> > For example, if you type mkfs.ext4 -I256 -O flex_bg -G32 -E test_fs <device>
> > and look dumpe2fs <device> result you will see an offset problem.
> >
> > Group 0: (Blocks 0-32767)
> > Primary superblock at 0, Group descriptors at 1-5
> > Reserved GDT blocks at 6-1024
> > Block bitmap at 1025 (+1025), Inode bitmap at 1058 (+1058)
> > Inode table at 1090-1601 (+1090)
> > 0 free blocks, 8181 free inodes, 2 directories
> > Free blocks:
> > Free inodes: 12-8192
> >
> > Inode bitmap must start at 1025 + 32 = 1057
> > In all flexbg groups, the block between the last block bitmap and the
> > first inode
> > bitmap (metatdata) is not used, which introduced a hole.
> >
> > This patch corrects it.
> > You have to apply it on e2fsprogs (mke2fs 1.41-WIP (17-Jun-2008)) master
> > branch.
> >
> > Celine Bourde.
>
> Acked-by: Jose R. Santos <[email protected]>
Looks like I jumped the gun to fast acknowledging this patch. The
current patch doesn't run the second ext2fs_get_free_blocks() when
doing a search for block bitmap space.
Here is an updated patch.
commit a58058e85240c7834cd863efa35b21688e104047
Author: Jose R. Santos <[email protected]>
Date: Mon Jul 7 14:36:08 2008 -0500
Fix FLEX_BG offset
The offset for both inode bitmaps and inode tables is overshot by one
block causing a hole between the group of bitmaps and inode tables.
Signed-off-by: Jose R. Santos <[email protected]>
diff --git a/lib/ext2fs/alloc_tables.c b/lib/ext2fs/alloc_tables.c
index d87585b..7f6ac77 100644
--- a/lib/ext2fs/alloc_tables.c
+++ b/lib/ext2fs/alloc_tables.c
@@ -46,6 +46,8 @@ static blk_t flexbg_offset(ext2_filsys fs, dgrp_t group, blk_t start_blk,
if (size > fs->super->s_blocks_per_group / 8)
size = fs->super->s_blocks_per_group / 8;
+ if (offset)
+ offset -= 1;
/*
* Dont do a long search if the previous block
* search is still valid.
-JRS
Thanks, applied. (And ignore my earlier e-mail; I was confused about
what the code was trying to do.)
- Ted