From: Valerie Clement Date: Fri, 15 Feb 2008 18:43:07 +0000 (-0500) Subject: ext4: modify block allocation algorithm for the last group X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=74d3487fc8aa58cec16dff7239dea1ca59bdab0e;p=openwrt%2Fstaging%2Fblogic.git ext4: modify block allocation algorithm for the last group 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 Signed-off-by: Mingming Cao Signed-off-by: "Theodore Ts'o" --- diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index c4d6f19faf37..8a59f7ba30e6 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -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; } diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d3c6f58a9def..34f3eb615fd5 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -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; }