From: Baokun Li <libaokun1@huawei.com> mainline inclusion from mainline-v6.17-rc1 commit 5abd85f667a19ef7d880ed00c201fc22de6fa707 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/ICN2MB Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Extract ext4_mb_might_prefetch() to make the code clearer and to prepare for the later conversion of 'choose group' to 'scan groups'. No functional changes. Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-14-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.c | 62 +++++++++++++++++++++++++++++------------------ fs/ext4/mballoc.h | 4 +++ 2 files changed, 42 insertions(+), 24 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index cd8a9be56cc7..305c22df3a80 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2782,6 +2782,37 @@ ext4_group_t ext4_mb_prefetch(struct super_block *sb, ext4_group_t group, return group; } +/* + * Batch reads of the block allocation bitmaps to get + * multiple READs in flight; limit prefetching at inexpensive + * CR, otherwise mballoc can spend a lot of time loading + * imperfect groups + */ +static void ext4_mb_might_prefetch(struct ext4_allocation_context *ac, + ext4_group_t group) +{ + struct ext4_sb_info *sbi; + + if (ac->ac_prefetch_grp != group) + return; + + sbi = EXT4_SB(ac->ac_sb); + if (ext4_mb_cr_expensive(ac->ac_criteria) || + ac->ac_prefetch_ios < sbi->s_mb_prefetch_limit) { + unsigned int nr = sbi->s_mb_prefetch; + + if (ext4_has_feature_flex_bg(ac->ac_sb)) { + nr = 1 << sbi->s_log_groups_per_flex; + nr -= group & (nr - 1); + nr = umin(nr, sbi->s_mb_prefetch); + } + + ac->ac_prefetch_nr = nr; + ac->ac_prefetch_grp = ext4_mb_prefetch(ac->ac_sb, group, nr, + &ac->ac_prefetch_ios); + } +} + /* * Prefetching reads the block bitmap into the buffer cache; but we * need to make sure that the buddy bitmap in the page cache has been @@ -2818,10 +2849,9 @@ void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group, static noinline_for_stack int ext4_mb_regular_allocator(struct ext4_allocation_context *ac) { - ext4_group_t prefetch_grp = 0, ngroups, group, i; + ext4_group_t ngroups, group, i; enum criteria new_cr, cr = CR_GOAL_LEN_FAST; int err = 0, first_err = 0; - unsigned int nr = 0, prefetch_ios = 0; struct ext4_sb_info *sbi; struct super_block *sb; struct ext4_buddy e4b; @@ -2882,6 +2912,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) cr = CR_POWER2_ALIGNED; ac->ac_e4b = &e4b; + ac->ac_prefetch_ios = 0; repeat: for (; cr < EXT4_MB_NUM_CRS && ac->ac_status == AC_STATUS_CONTINUE; cr++) { ac->ac_criteria = cr; @@ -2891,8 +2922,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) */ group = ac->ac_g_ex.fe_group; ac->ac_groups_linear_remaining = sbi->s_mb_max_linear_groups; - prefetch_grp = group; - nr = 0; + ac->ac_prefetch_grp = group; + ac->ac_prefetch_nr = 0; for (i = 0, new_cr = cr; i < ngroups; i++, ext4_mb_choose_next_group(ac, &new_cr, &group, ngroups)) { @@ -2904,24 +2935,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) goto repeat; } - /* - * Batch reads of the block allocation bitmaps - * to get multiple READs in flight; limit - * prefetching at inexpensive CR, otherwise mballoc - * can spend a lot of time loading imperfect groups - */ - if ((prefetch_grp == group) && - (ext4_mb_cr_expensive(cr) || - prefetch_ios < sbi->s_mb_prefetch_limit)) { - nr = sbi->s_mb_prefetch; - if (ext4_has_feature_flex_bg(sb)) { - nr = 1 << sbi->s_log_groups_per_flex; - nr -= group & (nr - 1); - nr = min(nr, sbi->s_mb_prefetch); - } - prefetch_grp = ext4_mb_prefetch(sb, group, - nr, &prefetch_ios); - } + ext4_mb_might_prefetch(ac, group); /* prevent unnecessary buddy loading. */ if (cr < CR_ANY_FREE && @@ -3019,8 +3033,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) ac->ac_b_ex.fe_len, ac->ac_o_ex.fe_len, ac->ac_status, ac->ac_flags, cr, err); - if (nr) - ext4_mb_prefetch_fini(sb, prefetch_grp, nr); + if (ac->ac_prefetch_nr) + ext4_mb_prefetch_fini(sb, ac->ac_prefetch_grp, ac->ac_prefetch_nr); return err; } diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h index 587d4dd5746d..b736ee7eb660 100644 --- a/fs/ext4/mballoc.h +++ b/fs/ext4/mballoc.h @@ -192,6 +192,10 @@ struct ext4_allocation_context { */ ext4_grpblk_t ac_orig_goal_len; + ext4_group_t ac_prefetch_grp; + unsigned int ac_prefetch_ios; + unsigned int ac_prefetch_nr; + __u32 ac_flags; /* allocation hints */ __u32 ac_groups_linear_remaining; __u16 ac_groups_scanned; -- 2.39.2