Modify the block allocation algorithm for the last group
From: Valerie Clement <[email protected]>
When a directory inode is allocated in the last group and the last group
contains less than s_blocks_per_group blocks, the initial block allocated
for the directory is not always allocated in the same group as the
directory inode, but in one of the first groups of the filesystem (group 1
for example).
Depending on the current process's pid, ext4_find_near() and
ext4_ext_find_goal() can return a block number greater than the maximum
blocks count in the filesystem and in that case the block will be not
allocated in the same group as the inode.
The following patch fixes the problem.
Comments?
Should the modification also be done in ext2/3 code?
Signed-off-by: Valerie Clement <[email protected]>
---
fs/ext4/extents.c | 8 +++++++-
fs/ext4/inode.c | 8 +++++++-
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 5c4af51..1391ded 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -148,6 +148,7 @@ ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
{
struct ext4_inode_info *ei = EXT4_I(inode);
ext4_fsblk_t bg_start;
+ ext4_fsblk_t last_block;
ext4_grpblk_t colour;
int depth;
@@ -169,8 +170,13 @@ ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
/* OK. use inode's group */
bg_start = (ei->i_block_group * EXT4_BLOCKS_PER_GROUP(inode->i_sb)) +
le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_first_data_block);
- colour = (current->pid % 16) *
+ last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
+
+ if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
+ colour = (current->pid % 16) *
(EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
+ else
+ colour = (current->pid % 16) * ((last_block - bg_start) / 16);
return bg_start + colour + block;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 51bf3b5..c4f8ace 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -405,6 +405,7 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
__le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
__le32 *p;
ext4_fsblk_t bg_start;
+ ext4_fsblk_t last_block;
ext4_grpblk_t colour;
/* Try to find previous block */
@@ -422,8 +423,13 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
* into the same cylinder group then.
*/
bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
- colour = (current->pid % 16) *
+ last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
+
+ if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
+ colour = (current->pid % 16) *
(EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
+ else
+ colour = (current->pid % 16) * ((last_block - bg_start) / 16);
return bg_start + colour;
}
On Wed, 2008-02-13 at 17:26 +0100, Valerie Clement wrote:
> Modify the block allocation algorithm for the last group
>
> From: Valerie Clement <[email protected]>
>
> When a directory inode is allocated in the last group and the last group
> contains less than s_blocks_per_group blocks, the initial block allocated
> for the directory is not always allocated in the same group as the
> directory inode, but in one of the first groups of the filesystem (group 1
> for example).
> Depending on the current process's pid, ext4_find_near() and
> ext4_ext_find_goal() can return a block number greater than the maximum
> blocks count in the filesystem and in that case the block will be not
> allocated in the same group as the inode.
>
> The following patch fixes the problem.
>
> Comments?
Looks sane to me.
> Should the modification also be done in ext2/3 code?
>
I think so.
Mingming
> Signed-off-by: Valerie Clement <[email protected]>
> ---
>
> fs/ext4/extents.c | 8 +++++++-
> fs/ext4/inode.c | 8 +++++++-
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 5c4af51..1391ded 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -148,6 +148,7 @@ ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
> {
> struct ext4_inode_info *ei = EXT4_I(inode);
> ext4_fsblk_t bg_start;
> + ext4_fsblk_t last_block;
> ext4_grpblk_t colour;
> int depth;
>
> @@ -169,8 +170,13 @@ ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
> /* OK. use inode's group */
> bg_start = (ei->i_block_group * EXT4_BLOCKS_PER_GROUP(inode->i_sb)) +
> le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_first_data_block);
> - colour = (current->pid % 16) *
> + last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> +
> + if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> + colour = (current->pid % 16) *
> (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> + else
> + colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> return bg_start + colour + block;
> }
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 51bf3b5..c4f8ace 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -405,6 +405,7 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
> __le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
> __le32 *p;
> ext4_fsblk_t bg_start;
> + ext4_fsblk_t last_block;
> ext4_grpblk_t colour;
>
> /* Try to find previous block */
> @@ -422,8 +423,13 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
> * into the same cylinder group then.
> */
> bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
> - colour = (current->pid % 16) *
> + last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> +
> + if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> + colour = (current->pid % 16) *
> (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> + else
> + colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> return bg_start + colour;
> }
>
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Added in patch queue,
Thanks,
On Wed, 2008-02-13 at 17:26 +0100, Valerie Clement wrote:
> Modify the block allocation algorithm for the last group
>
> From: Valerie Clement <[email protected]>
>
> When a directory inode is allocated in the last group and the last group
> contains less than s_blocks_per_group blocks, the initial block allocated
> for the directory is not always allocated in the same group as the
> directory inode, but in one of the first groups of the filesystem (group 1
> for example).
> Depending on the current process's pid, ext4_find_near() and
> ext4_ext_find_goal() can return a block number greater than the maximum
> blocks count in the filesystem and in that case the block will be not
> allocated in the same group as the inode.
>
> The following patch fixes the problem.
>
> Comments?
> Should the modification also be done in ext2/3 code?
>
> Signed-off-by: Valerie Clement <[email protected]>
> ---
>
> fs/ext4/extents.c | 8 +++++++-
> fs/ext4/inode.c | 8 +++++++-
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 5c4af51..1391ded 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -148,6 +148,7 @@ ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
> {
> struct ext4_inode_info *ei = EXT4_I(inode);
> ext4_fsblk_t bg_start;
> + ext4_fsblk_t last_block;
> ext4_grpblk_t colour;
> int depth;
>
> @@ -169,8 +170,13 @@ ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
> /* OK. use inode's group */
> bg_start = (ei->i_block_group * EXT4_BLOCKS_PER_GROUP(inode->i_sb)) +
> le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_first_data_block);
> - colour = (current->pid % 16) *
> + last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> +
> + if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> + colour = (current->pid % 16) *
> (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> + else
> + colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> return bg_start + colour + block;
> }
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 51bf3b5..c4f8ace 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -405,6 +405,7 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
> __le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
> __le32 *p;
> ext4_fsblk_t bg_start;
> + ext4_fsblk_t last_block;
> ext4_grpblk_t colour;
>
> /* Try to find previous block */
> @@ -422,8 +423,13 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
> * into the same cylinder group then.
> */
> bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
> - colour = (current->pid % 16) *
> + last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> +
> + if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> + colour = (current->pid % 16) *
> (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> + else
> + colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> return bg_start + colour;
> }
>
>
>