Commit 2bf5eb2a authored by Gou Hao's avatar Gou Hao Committed by Theodore Ts'o
Browse files

ext4: improving calculation of 'fe_{len|start}' in mb_find_extent() 



After first execution of mb_find_order_for_block():

'fe_start' is the value of 'block' passed in mb_find_extent().

'fe_len' is the difference between the length of order-chunk and
remainder of the block divided by order-chunk.

And 'next' does not require initialization after above modifications.

Signed-off-by: default avatarGou Hao <gouhao@uniontech.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231113082617.11258-1-gouhao@uniontech.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent c6bfd724

fs/ext4/mballoc.c

+4 −9
Original line number Diff line number Diff line
@@ -1957,8 +1957,7 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b, 
static int mb_find_extent(struct ext4_buddy *e4b, int block,

				int needed, struct ext4_free_extent *ex)

{

	int next = block;

	int max, order;

	int max, order, next;

	void *buddy;



	assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
@@ -1976,16 +1975,12 @@ static int mb_find_extent(struct ext4_buddy *e4b, int block, 


	/* find actual order */

	order = mb_find_order_for_block(e4b, block);

	block = block >> order;



	ex->fe_len = 1 << order;

	ex->fe_start = block << order;

	ex->fe_len = (1 << order) - (block & ((1 << order) - 1));

	ex->fe_start = block;

	ex->fe_group = e4b->bd_group;



	/* calc difference from given start */

	next = next - ex->fe_start;

	ex->fe_len -= next;

	ex->fe_start += next;

	block = block >> order;



	while (needed > ex->fe_len &&

	       mb_find_buddy(e4b, order, &max)) {