Commit 9c08e42d authored by Baokun Li's avatar Baokun Li Committed by Theodore Ts'o
Browse files

ext4: factor out ext4_mb_scan_group() 



Extract ext4_mb_scan_group() to make the code clearer and to
prepare for the later conversion of 'choose group' to 'scan groups'.
No functional changes.

Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarZhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-15-libaokun1@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 5abd85f6

fs/ext4/mballoc.c

+49 −44
Original line number Diff line number Diff line
@@ -2845,12 +2845,56 @@ void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group, 
	}

}



static int ext4_mb_scan_group(struct ext4_allocation_context *ac,

			      ext4_group_t group)

{

	int ret;

	struct super_block *sb = ac->ac_sb;

	enum criteria cr = ac->ac_criteria;



	ext4_mb_might_prefetch(ac, group);



	/* prevent unnecessary buddy loading. */

	if (cr < CR_ANY_FREE && spin_is_locked(ext4_group_lock_ptr(sb, group)))

		return 0;



	/* This now checks without needing the buddy page */

	ret = ext4_mb_good_group_nolock(ac, group, cr);

	if (ret <= 0) {

		if (!ac->ac_first_err)

			ac->ac_first_err = ret;

		return 0;

	}



	ret = ext4_mb_load_buddy(sb, group, ac->ac_e4b);

	if (ret)

		return ret;



	/* skip busy group */

	if (cr >= CR_ANY_FREE)

		ext4_lock_group(sb, group);

	else if (!ext4_try_lock_group(sb, group))

		goto out_unload;



	/* We need to check again after locking the block group. */

	if (unlikely(!ext4_mb_good_group(ac, group, cr)))

		goto out_unlock;



	__ext4_mb_scan_group(ac);



out_unlock:

	ext4_unlock_group(sb, group);

out_unload:

	ext4_mb_unload_buddy(ac->ac_e4b);

	return ret;

}



static noinline_for_stack int

ext4_mb_regular_allocator(struct ext4_allocation_context *ac)

{

	ext4_group_t ngroups, group, i;

	enum criteria new_cr, cr = CR_GOAL_LEN_FAST;

	int err = 0, first_err = 0;

	int err = 0;

	struct ext4_sb_info *sbi;

	struct super_block *sb;

	struct ext4_buddy e4b;
@@ -2912,6 +2956,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) 


	ac->ac_e4b = &e4b;

	ac->ac_prefetch_ios = 0;

	ac->ac_first_err = 0;

repeat:

	for (; cr < EXT4_MB_NUM_CRS && ac->ac_status == AC_STATUS_CONTINUE; cr++) {

		ac->ac_criteria = cr;
@@ -2926,7 +2971,6 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) 


		for (i = 0, new_cr = cr; i < ngroups; i++,

		     ext4_mb_choose_next_group(ac, &new_cr, &group, ngroups)) {

			int ret = 0;



			cond_resched();

			if (new_cr != cr) {
@@ -2934,49 +2978,10 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) 
				goto repeat;

			}



			ext4_mb_might_prefetch(ac, group);



			/* prevent unnecessary buddy loading. */

			if (cr < CR_ANY_FREE &&

			    spin_is_locked(ext4_group_lock_ptr(sb, group)))

				continue;



			/* This now checks without needing the buddy page */

			ret = ext4_mb_good_group_nolock(ac, group, cr);

			if (ret <= 0) {

				if (!first_err)

					first_err = ret;

				continue;

			}



			err = ext4_mb_load_buddy(sb, group, &e4b);

			err = ext4_mb_scan_group(ac, group);

			if (err)

				goto out;



			/* skip busy group */

			if (cr >= CR_ANY_FREE) {

				ext4_lock_group(sb, group);

			} else if (!ext4_try_lock_group(sb, group)) {

				ext4_mb_unload_buddy(&e4b);

				continue;

			}



			/*

			 * We need to check again after locking the

			 * block group

			 */

			ret = ext4_mb_good_group(ac, group, cr);

			if (ret == 0) {

				ext4_unlock_group(sb, group);

				ext4_mb_unload_buddy(&e4b);

				continue;

			}



			__ext4_mb_scan_group(ac);



			ext4_unlock_group(sb, group);

			ext4_mb_unload_buddy(&e4b);



			if (ac->ac_status != AC_STATUS_CONTINUE)

				break;

		}
@@ -3025,8 +3030,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) 
			atomic_inc(&sbi->s_bal_stream_goals);

	}

out:

	if (!err && ac->ac_status != AC_STATUS_FOUND && first_err)

		err = first_err;

	if (!err && ac->ac_status != AC_STATUS_FOUND && ac->ac_first_err)

		err = ac->ac_first_err;



	mb_debug(sb, "Best len %d, origin len %d, ac_status %u, ac_flags 0x%x, cr %d ret %d\n",

		 ac->ac_b_ex.fe_len, ac->ac_o_ex.fe_len, ac->ac_status,

fs/ext4/mballoc.h

+2 −0
Original line number Diff line number Diff line
@@ -196,6 +196,8 @@ struct ext4_allocation_context { 
	unsigned int ac_prefetch_ios;

	unsigned int ac_prefetch_nr;



	int ac_first_err;



	__u32 ac_flags;		/* allocation hints */

	__u32 ac_groups_linear_remaining;

	__u16 ac_groups_scanned;