[PATCH 1/2] libext2fs: fix alloc_allocate_group_table() if the flexbg_offset wraps

[PATCH 1/2] libext2fs: fix alloc_allocate_group_table() if the flexbg_offset wraps

[Theodore Ts'o]

If the previous block group's inode table ends at the very end of file
system, wrap around to the beginning of the flex_bg.

This fixes a bug was tickled by:

mke2fs.conf:
	frontload = {
		features = extent,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize,^resize_inode,sparse_super2
		hash_alg = half_md4
		num_backup_sb = 0
		packed_meta_blocks = 1
		inode_ratio = 4194304
		flex_bg_size = 262144
	}

mke2fs -T frontload /tmp/foo.img 2T
resize2fs -M /tmp/foo.img
resize2fs -M /tmp/foo.img

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 lib/ext2fs/alloc_tables.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/ext2fs/alloc_tables.c b/lib/ext2fs/alloc_tables.c
index fec9003..bc99943 100644
--- a/lib/ext2fs/alloc_tables.c
+++ b/lib/ext2fs/alloc_tables.c
@@ -54,8 +54,8 @@ static blk64_t flexbg_offset(ext2_filsys fs, dgrp_t group, blk64_t start_blk,
 	 * Don't do a long search if the previous block
 	 * search is still valid.
 	 */
-	if (start_blk && ext2fs_test_block_bitmap_range2(bmap, start_blk,
-							 elem_size))
+	if (start_blk && start_blk < ext2fs_blocks_count(fs->super) &&
+	    ext2fs_test_block_bitmap_range2(bmap, start_blk, elem_size))
 		return start_blk;
 
 	start_blk = ext2fs_group_first_block2(fs, flexbg_size * flexbg);
-- 
1.9.0

[PATCH 2/2] resize2fs: fix inode table move for the backwards move case

[Theodore Ts'o]

In the case where the new location of the inode table is before the
old inode table, the optimization which tries to optimize zero block
moves breaks.  Fix it.

This fixes a bug that was tickled by the reproduction described in the
previous commit.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 resize/resize2fs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index 0d968fa..c672cdb 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -1869,6 +1869,8 @@ static errcode_t move_itables(ext2_resize_t rfs)
 
 		if (!diff)
 			continue;
+		if (diff < 0)
+			diff = 0;
 
 		retval = io_channel_read_blk64(fs->io, old_blk,
 					       fs->inode_blocks_per_group,
-- 
1.9.0

Re: [PATCH 1/2] libext2fs: fix alloc_allocate_group_table() if the flexbg_offset wraps

[Lukáš Czerner]

On Mon, 28 Apr 2014, Theodore Ts'o wrote:

> Date: Mon, 28 Apr 2014 10:09:38 -0400
> From: Theodore Ts'o <tytso@mit.edu>
> To: Ext4 Developers List <linux-ext4@vger.kernel.org>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Subject: [PATCH 1/2] libext2fs: fix alloc_allocate_group_table() if the
>     flexbg_offset wraps
> 
> If the previous block group's inode table ends at the very end of file
> system, wrap around to the beginning of the flex_bg.
> 
> This fixes a bug was tickled by:
> 
> mke2fs.conf:
> 	frontload = {
> 		features = extent,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize,^resize_inode,sparse_super2
> 		hash_alg = half_md4
> 		num_backup_sb = 0
> 		packed_meta_blocks = 1
> 		inode_ratio = 4194304
> 		flex_bg_size = 262144
> 	}
> 
> mke2fs -T frontload /tmp/foo.img 2T
> resize2fs -M /tmp/foo.img
> resize2fs -M /tmp/foo.img
> 
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
> ---
>  lib/ext2fs/alloc_tables.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/ext2fs/alloc_tables.c b/lib/ext2fs/alloc_tables.c
> index fec9003..bc99943 100644
> --- a/lib/ext2fs/alloc_tables.c
> +++ b/lib/ext2fs/alloc_tables.c
> @@ -54,8 +54,8 @@ static blk64_t flexbg_offset(ext2_filsys fs, dgrp_t group, blk64_t start_blk,
>  	 * Don't do a long search if the previous block
>  	 * search is still valid.
>  	 */
> -	if (start_blk && ext2fs_test_block_bitmap_range2(bmap, start_blk,
> -							 elem_size))
> +	if (start_blk && start_blk < ext2fs_blocks_count(fs->super) &&
> +	    ext2fs_test_block_bitmap_range2(bmap, start_blk, elem_size))
>  		return start_blk;

Not sure about this, but I just wonder whether this would work with
bigalloc file system as well since it is true that we're testing
blocks in this condition but in ext2fs_test_block_bitmap_range2()
we're searching for a free cluster.

-Lukas

>  
>  	start_blk = ext2fs_group_first_block2(fs, flexbg_size * flexbg);
> 

Re: [PATCH 1/2] libext2fs: fix alloc_allocate_group_table() if the flexbg_offset wraps

[Theodore Ts'o]

On Tue, Apr 29, 2014 at 01:02:07PM +0200, Lukáš Czerner wrote:
> 
> Not sure about this, but I just wonder whether this would work with
> bigalloc file system as well since it is true that we're testing
> blocks in this condition but in ext2fs_test_block_bitmap_range2()
> we're searching for a free cluster.

No, we're fine because the bitmap functions takes block numbers as
arguments, not cluster numbers.  (The bitmap functions converts block
numbers to cluster numbers, and there's a special hack for mke2fs so
we don't burn a separate cluster for each allocation bitmap block.)

					- Ted
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