Hi all,
I was going through the function "ext2_find_near" in inode.c and could not
interpret the meaning of the last part of this code :
static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
{
struct ext2_inode_info *ei = EXT2_I(inode);
__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
__le32 *p;
ext2_fsblk_t bg_start;
ext2_fsblk_t colour;
/* Try to find previous block */
for (p = ind->p - 1; p >= start; p--)
if (*p)
return le32_to_cpu(*p);
/* No such thing, so let's try location of indirect block */
if (ind->bh)
return ind->bh->b_blocknr;
/*
* It is going to be refered from inode itself? OK, just put it into
* the same cylinder group then.
*/
bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
/ * what does the code below do?? why its is using pid of
current process?? */
colour = (current->pid % 16) *
(EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
return bg_start + colour;
}
What I understand from it is that it has something to do with reducing
the chances of a concurrent allocation -- supposedly from a different
PID.
Can someone just explain a bit on this, what exactly is happening ?
Thanks,
Rohit Sharma.
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