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ext4: modify block allocation algorithm for the last group

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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.

Should the modification also be done in ext2/3 code?

Signed-off-by: Valerie Clement <valerie.clement@bull.net>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Valerie Clement 2008-02-15 13:43:07 -05:00 committed by Theodore Ts'o
parent e56eb65906
commit 74d3487fc8
2 changed files with 14 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
fs/ext4/extents.c
View file

@ -148,6 +148,7 @@ static 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 @@ static 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;
}

8
fs/ext4/inode.c
View file

@ -403,6 +403,7 @@ 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 */
@ -420,8 +421,13 @@ 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;
}