Commit 43bbddc0 authored by Baokun Li's avatar Baokun Li Committed by Theodore Ts'o
Browse files

ext4: add two helper functions extent_logical_end() and pa_logical_end() 



When we use lstart + len to calculate the end of free extent or prealloc
space, it may exceed the maximum value of 4294967295(0xffffffff) supported
by ext4_lblk_t and cause overflow, which may lead to various problems.

Therefore, we add two helper functions, extent_logical_end() and
pa_logical_end(), to limit the type of end to loff_t, and also convert
lstart to loff_t for calculation to avoid overflow.

Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarRitesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230724121059.11834-2-libaokun1@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 6eaae198

fs/ext4/mballoc.c

+3 −6
Original line number Diff line number Diff line
@@ -4432,7 +4432,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac, 


	/* first, let's learn actual file size

	 * given current request is allocated */

	size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);

	size = extent_logical_end(sbi, &ac->ac_o_ex);

	size = size << bsbits;

	if (size < i_size_read(ac->ac_inode))

		size = i_size_read(ac->ac_inode);
@@ -4766,7 +4766,6 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac) 
	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);

	struct ext4_locality_group *lg;

	struct ext4_prealloc_space *tmp_pa = NULL, *cpa = NULL;

	loff_t tmp_pa_end;

	struct rb_node *iter;

	ext4_fsblk_t goal_block;
@@ -4862,9 +4861,7 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac) 
	 * pa can possibly satisfy the request hence check if it overlaps

	 * original logical start and stop searching if it doesn't.

	 */

	tmp_pa_end = (loff_t)tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);



	if (ac->ac_o_ex.fe_logical >= tmp_pa_end) {

	if (ac->ac_o_ex.fe_logical >= pa_logical_end(sbi, tmp_pa)) {

		spin_unlock(&tmp_pa->pa_lock);

		goto try_group_pa;

	}
@@ -5769,7 +5766,7 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac) 


	group_pa_eligible = sbi->s_mb_group_prealloc > 0;

	inode_pa_eligible = true;

	size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);

	size = extent_logical_end(sbi, &ac->ac_o_ex);

	isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)

		>> bsbits;

fs/ext4/mballoc.h

+14 −0
Original line number Diff line number Diff line
@@ -233,6 +233,20 @@ static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb, 
		(fex->fe_start << EXT4_SB(sb)->s_cluster_bits);

}



static inline loff_t extent_logical_end(struct ext4_sb_info *sbi,

					struct ext4_free_extent *fex)

{

	/* Use loff_t to avoid end exceeding ext4_lblk_t max. */

	return (loff_t)fex->fe_logical + EXT4_C2B(sbi, fex->fe_len);

}



static inline loff_t pa_logical_end(struct ext4_sb_info *sbi,

				    struct ext4_prealloc_space *pa)

{

	/* Use loff_t to avoid end exceeding ext4_lblk_t max. */

	return (loff_t)pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len);

}



typedef int (*ext4_mballoc_query_range_fn)(

	struct super_block		*sb,

	ext4_group_t			agno,