mainline inclusion from mainline-v6.17-rc1 commit e9eec6f33971fbfcdd32fd1c7dd515ff4d2954c0 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... -------------------------------- When ext4 allocates blocks, we used to just go through the block groups one by one to find a good one. But when there are tons of block groups (like hundreds of thousands or even millions) and not many have free space (meaning they're mostly full), it takes a really long time to check them all, and performance gets bad. So, we added the "mb_optimize_scan" mount option (which is on by default now). It keeps track of some group lists, so when we need a free block, we can just grab a likely group from the right list. This saves time and makes block allocation much faster. But when multiple processes or containers are doing similar things, like constantly allocating 8k blocks, they all try to use the same block group in the same list. Even just two processes doing this can cut the IOPS in half. For example, one container might do 300,000 IOPS, but if you run two at the same time, the total is only 150,000. Since we can already look at block groups in a non-linear way, the first and last groups in the same list are basically the same for finding a block right now. Therefore, add an ext4_try_lock_group() helper function to skip the current group when it is locked by another process, thereby avoiding contention with other processes. This helps ext4 make better use of having multiple block groups. Also, to make sure we don't skip all the groups that have free space when allocating blocks, we won't try to skip busy groups anymore when ac_criteria is CR_ANY_FREE. Performance test data follows: Test: Running will-it-scale/fallocate2 on CPU-bound containers. Observation: Average fallocate operations per container per second. |CPU: Kunpeng 920 | P80 | |Memory: 512GB |-------------------------| |960GB SSD (0.5GB/s)| base | patched | |-------------------|-------|-----------------| |mb_optimize_scan=0 | 2667 | 4821 (+80.7%) | |mb_optimize_scan=1 | 2643 | 4784 (+81.0%) | |CPU: AMD 9654 * 2 | P96 | |Memory: 1536GB |-------------------------| |960GB SSD (1GB/s) | base | patched | |-------------------|-------|-----------------| |mb_optimize_scan=0 | 3450 | 15371 (+345%) | |mb_optimize_scan=1 | 3209 | 6101 (+90.0%) | Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-2-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Conflicts: fs/ext4/mballoc.c [Because of already merged-in hulk commit da6eb19e6550 ("ext4: add ext4_try_lock_group() to skip busy groups").] Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index ec2808247f4f..d7a1fcbdcff6 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -899,8 +899,8 @@ static void ext4_mb_choose_next_group_p2_aligned(struct ext4_allocation_context bb_largest_free_order_node) { if (sbi->s_mb_stats) atomic64_inc(&sbi->s_bal_cX_groups_considered[CR_POWER2_ALIGNED]); - if (likely(ext4_mb_good_group(ac, iter->bb_group, CR_POWER2_ALIGNED)) && - !spin_is_locked(ext4_group_lock_ptr(ac->ac_sb, iter->bb_group))) { + if (!spin_is_locked(ext4_group_lock_ptr(ac->ac_sb, iter->bb_group)) && + likely(ext4_mb_good_group(ac, iter->bb_group, CR_POWER2_ALIGNED))) { *group = iter->bb_group; ac->ac_flags |= EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED; read_unlock(&sbi->s_mb_largest_free_orders_locks[i]); @@ -936,8 +936,8 @@ ext4_mb_find_good_group_avg_frag_lists(struct ext4_allocation_context *ac, int o list_for_each_entry(iter, frag_list, bb_avg_fragment_size_node) { if (sbi->s_mb_stats) atomic64_inc(&sbi->s_bal_cX_groups_considered[cr]); - if (likely(ext4_mb_good_group(ac, iter->bb_group, cr)) && - !spin_is_locked(ext4_group_lock_ptr(ac->ac_sb, iter->bb_group))) { + if (!spin_is_locked(ext4_group_lock_ptr(ac->ac_sb, iter->bb_group)) && + likely(ext4_mb_good_group(ac, iter->bb_group, cr))) { grp = iter; break; } @@ -2899,6 +2899,11 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) nr, &prefetch_ios); } + /* 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) { -- 2.39.2

mainline inclusion from mainline-v6.17-rc1 commit 35bfd4b44ef04a10a091a4037a26296e7cd5273a 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... -------------------------------- In ext4_mb_regular_allocator(), after the call to ext4_mb_find_by_goal() fails to achieve the inode goal, allocation continues with the stream allocation global goal. Currently, hits for both are combined in sbi->s_bal_goals, hindering accurate optimization. This commit separates global goal hits into sbi->s_bal_stream_goals. Since stream allocation doesn't use ac->ac_g_ex.fe_start, set fe_start to -1. This prevents stream allocations from being counted in s_bal_goals. Also clear EXT4_MB_HINT_TRY_GOAL to avoid calling ext4_mb_find_by_goal again. After adding `stream_goal_hits`, `/proc/fs/ext4/sdx/mb_stats` will show: mballoc: reqs: 840347 success: 750992 groups_scanned: 1230506 cr_p2_aligned_stats: hits: 21531 groups_considered: 411664 extents_scanned: 21531 useless_loops: 0 bad_suggestions: 6 cr_goal_fast_stats: hits: 111222 groups_considered: 1806728 extents_scanned: 467908 useless_loops: 0 bad_suggestions: 13 cr_best_avail_stats: hits: 36267 groups_considered: 1817631 extents_scanned: 156143 useless_loops: 0 bad_suggestions: 204 cr_goal_slow_stats: hits: 106396 groups_considered: 5671710 extents_scanned: 22540056 useless_loops: 123747 cr_any_free_stats: hits: 138071 groups_considered: 724692 extents_scanned: 23615593 useless_loops: 585 extents_scanned: 46804261 goal_hits: 1307 stream_goal_hits: 236317 len_goal_hits: 155549 2^n_hits: 21531 breaks: 225096 lost: 35062 buddies_generated: 40/40 buddies_time_used: 48004 preallocated: 5962467 discarded: 4847560 Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-3-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 1 + fs/ext4/mballoc.c | 11 +++++++++-- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 885fe1d9a8e9..936dd5d54600 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1626,6 +1626,7 @@ struct ext4_sb_info { atomic_t s_bal_cX_ex_scanned[EXT4_MB_NUM_CRS]; /* total extents scanned */ atomic_t s_bal_groups_scanned; /* number of groups scanned */ atomic_t s_bal_goals; /* goal hits */ + atomic_t s_bal_stream_goals; /* stream allocation global goal hits */ atomic_t s_bal_len_goals; /* len goal hits */ atomic_t s_bal_breaks; /* too long searches */ atomic_t s_bal_2orders; /* 2^order hits */ diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index c33d40acdf16..488a3ef289cc 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2850,8 +2850,9 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) /* TBD: may be hot point */ spin_lock(&sbi->s_md_lock); ac->ac_g_ex.fe_group = sbi->s_mb_last_group; - ac->ac_g_ex.fe_start = sbi->s_mb_last_start; spin_unlock(&sbi->s_md_lock); + ac->ac_g_ex.fe_start = -1; + ac->ac_flags &= ~EXT4_MB_HINT_TRY_GOAL; } /* @@ -2993,8 +2994,12 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) } } - if (sbi->s_mb_stats && ac->ac_status == AC_STATUS_FOUND) + if (sbi->s_mb_stats && ac->ac_status == AC_STATUS_FOUND) { atomic64_inc(&sbi->s_bal_cX_hits[ac->ac_criteria]); + if (ac->ac_flags & EXT4_MB_STREAM_ALLOC && + ac->ac_b_ex.fe_group == ac->ac_g_ex.fe_group) + atomic_inc(&sbi->s_bal_stream_goals); + } out: if (!err && ac->ac_status != AC_STATUS_FOUND && first_err) err = first_err; @@ -3190,6 +3195,8 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset) seq_printf(seq, "\textents_scanned: %u\n", atomic_read(&sbi->s_bal_ex_scanned)); seq_printf(seq, "\t\tgoal_hits: %u\n", atomic_read(&sbi->s_bal_goals)); + seq_printf(seq, "\t\tstream_goal_hits: %u\n", + atomic_read(&sbi->s_bal_stream_goals)); seq_printf(seq, "\t\tlen_goal_hits: %u\n", atomic_read(&sbi->s_bal_len_goals)); seq_printf(seq, "\t\t2^n_hits: %u\n", atomic_read(&sbi->s_bal_2orders)); -- 2.39.2

mainline inclusion from mainline-v6.17-rc1 commit 4b41deb896e3d0417701759194f0765c06258b9c 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... -------------------------------- After we optimized the block group lock, we found another lock contention issue when running will-it-scale/fallocate2 with multiple processes. The fallocate's block allocation and the truncate's block release were fighting over the s_md_lock. The problem is, this lock protects totally different things in those two processes: the list of freed data blocks (s_freed_data_list) when releasing, and where to start looking for new blocks (mb_last_group) when allocating. Now we only need to track s_mb_last_group and no longer need to track s_mb_last_start, so we don't need the s_md_lock lock to ensure that the two are consistent. Since s_mb_last_group is merely a hint and doesn't require strong synchronization, READ_ONCE/WRITE_ONCE is sufficient. Besides, the s_mb_last_group data type only requires ext4_group_t (i.e., unsigned int), rendering unsigned long superfluous. Performance test data follows: Test: Running will-it-scale/fallocate2 on CPU-bound containers. Observation: Average fallocate operations per container per second. |CPU: Kunpeng 920 | P80 | P1 | |Memory: 512GB |------------------------|-------------------------| |960GB SSD (0.5GB/s)| base | patched | base | patched | |-------------------|-------|----------------|--------|----------------| |mb_optimize_scan=0 | 4821 | 9636 (+99.8%) | 314065 | 337597 (+7.4%) | |mb_optimize_scan=1 | 4784 | 4834 (+1.04%) | 316344 | 341440 (+7.9%) | |CPU: AMD 9654 * 2 | P96 | P1 | |Memory: 1536GB |------------------------|-------------------------| |960GB SSD (1GB/s) | base | patched | base | patched | |-------------------|-------|----------------|--------|----------------| |mb_optimize_scan=0 | 15371 | 22341 (+45.3%) | 205851 | 219707 (+6.7%) | |mb_optimize_scan=1 | 6101 | 9177 (+50.4%) | 207373 | 215732 (+4.0%) | Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-5-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 2 +- fs/ext4/mballoc.c | 12 +++--------- 2 files changed, 4 insertions(+), 10 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 081e672d8a95..d8382d116211 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1612,7 +1612,7 @@ struct ext4_sb_info { unsigned int s_mb_group_prealloc; unsigned int s_max_dir_size_kb; /* where last allocation was done - for stream allocation */ - unsigned long s_mb_last_group; + ext4_group_t s_mb_last_group; unsigned int s_mb_prefetch; unsigned int s_mb_prefetch_limit; unsigned int s_mb_best_avail_max_trim_order; diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 5d2b7863cbda..d6c76fb297e3 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2169,11 +2169,8 @@ static void ext4_mb_use_best_found(struct ext4_allocation_context *ac, ac->ac_buddy_page = e4b->bd_buddy_page; get_page(ac->ac_buddy_page); /* store last allocated for subsequent stream allocation */ - if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) { - spin_lock(&sbi->s_md_lock); - sbi->s_mb_last_group = ac->ac_f_ex.fe_group; - spin_unlock(&sbi->s_md_lock); - } + if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) + WRITE_ONCE(sbi->s_mb_last_group, ac->ac_f_ex.fe_group); /* * As we've just preallocated more space than * user requested originally, we store allocated @@ -2846,10 +2843,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) /* if stream allocation is enabled, use global goal */ if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) { - /* TBD: may be hot point */ - spin_lock(&sbi->s_md_lock); - ac->ac_g_ex.fe_group = sbi->s_mb_last_group; - spin_unlock(&sbi->s_md_lock); + ac->ac_g_ex.fe_group = READ_ONCE(sbi->s_mb_last_group); ac->ac_g_ex.fe_start = -1; ac->ac_flags &= ~EXT4_MB_HINT_TRY_GOAL; } -- 2.39.2

mainline inclusion from mainline-v6.17-rc1 commit 4d18a0b98259c2fa62f04ce5f94a7ec6e840f220 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... -------------------------------- Since nobody has used these EXT4_MB_HINT flags for ages, let's remove them. Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-7-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 6 ------ include/trace/events/ext4.h | 3 --- 2 files changed, 9 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 4b6896198101..c752147afc4e 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -196,14 +196,8 @@ enum criteria { /* prefer goal again. length */ #define EXT4_MB_HINT_MERGE 0x0001 -/* blocks already reserved */ -#define EXT4_MB_HINT_RESERVED 0x0002 -/* metadata is being allocated */ -#define EXT4_MB_HINT_METADATA 0x0004 /* first blocks in the file */ #define EXT4_MB_HINT_FIRST 0x0008 -/* search for the best chunk */ -#define EXT4_MB_HINT_BEST 0x0010 /* data is being allocated */ #define EXT4_MB_HINT_DATA 0x0020 /* don't preallocate (for tails) */ diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h index d500568daeb1..2c9fce13d906 100644 --- a/include/trace/events/ext4.h +++ b/include/trace/events/ext4.h @@ -23,10 +23,7 @@ struct partial_cluster; #define show_mballoc_flags(flags) __print_flags(flags, "|", \ { EXT4_MB_HINT_MERGE, "HINT_MERGE" }, \ - { EXT4_MB_HINT_RESERVED, "HINT_RESV" }, \ - { EXT4_MB_HINT_METADATA, "HINT_MDATA" }, \ { EXT4_MB_HINT_FIRST, "HINT_FIRST" }, \ - { EXT4_MB_HINT_BEST, "HINT_BEST" }, \ { EXT4_MB_HINT_DATA, "HINT_DATA" }, \ { EXT4_MB_HINT_NOPREALLOC, "HINT_NOPREALLOC" }, \ { EXT4_MB_HINT_GROUP_ALLOC, "HINT_GRP_ALLOC" }, \ -- 2.39.2

From: Jinke Han <hanjinke.666@bytedance.com> mainline inclusion from mainline-v6.7-rc1 commit ce774e5365e46be73ed055302c6de123a03394ea 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... -------------------------------- When releasing space in jbd, we traverse s_freed_data_list to get the free range belonging to the current commit transaction. In extreme cases, the time spent may not be small, and we have observed cases exceeding 10ms. This patch makes running and commit transactions manage their own free_data_list respectively, eliminating unnecessary traversal. And in the callback phase of the commit transaction, no one will touch it except the jbd thread itself, so s_md_lock is no longer needed. Signed-off-by: Jinke Han <hanjinke.666@bytedance.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://lore.kernel.org/r/20230612124017.14115-1-hanjinke.666@bytedance.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 2 +- fs/ext4/mballoc.c | 18 +++++------------- 2 files changed, 6 insertions(+), 14 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 79d0d55e3a61..ee57bbc9bca5 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1585,7 +1585,7 @@ struct ext4_sb_info { unsigned int *s_mb_maxs; unsigned int s_group_info_size; unsigned int s_mb_free_pending; - struct list_head s_freed_data_list; /* List of blocks to be freed + struct list_head s_freed_data_list[2]; /* List of blocks to be freed after commit completed */ struct list_head s_discard_list; struct work_struct s_discard_work; diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index c39f23c21a5c..82b3d539be7f 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3683,7 +3683,8 @@ int ext4_mb_init(struct super_block *sb) spin_lock_init(&sbi->s_md_lock); sbi->s_mb_free_pending = 0; - INIT_LIST_HEAD(&sbi->s_freed_data_list); + INIT_LIST_HEAD(&sbi->s_freed_data_list[0]); + INIT_LIST_HEAD(&sbi->s_freed_data_list[1]); INIT_LIST_HEAD(&sbi->s_discard_list); INIT_WORK(&sbi->s_discard_work, ext4_discard_work); atomic_set(&sbi->s_retry_alloc_pending, 0); @@ -3945,19 +3946,10 @@ void ext4_process_freed_data(struct super_block *sb, tid_t commit_tid) struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_free_data *entry, *tmp; LIST_HEAD(freed_data_list); - struct list_head *cut_pos = NULL; + struct list_head *s_freed_head = &sbi->s_freed_data_list[commit_tid & 1]; bool wake; - spin_lock(&sbi->s_md_lock); - list_for_each_entry(entry, &sbi->s_freed_data_list, efd_list) { - if (entry->efd_tid != commit_tid) - break; - cut_pos = &entry->efd_list; - } - if (cut_pos) - list_cut_position(&freed_data_list, &sbi->s_freed_data_list, - cut_pos); - spin_unlock(&sbi->s_md_lock); + list_replace_init(s_freed_head, &freed_data_list); list_for_each_entry(entry, &freed_data_list, efd_list) ext4_free_data_in_buddy(sb, entry); @@ -6490,7 +6482,7 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, } spin_lock(&sbi->s_md_lock); - list_add_tail(&new_entry->efd_list, &sbi->s_freed_data_list); + list_add_tail(&new_entry->efd_list, &sbi->s_freed_data_list[new_entry->efd_tid & 1]); sbi->s_mb_free_pending += clusters; spin_unlock(&sbi->s_md_lock); } -- 2.39.2

mainline inclusion from mainline-v6.17-rc1 commit e7f101a8088770e8f3bb089f13652b9b0fd22b06 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... -------------------------------- Attempt to merge ext4_free_data with already inserted free extents prior to adding new ones. This strategy drastically cuts down the number of times locks are held. For example, if prev, new, and next extents are all mergeable, the existing code (before this patch) requires acquiring the s_md_lock three times: prev merge into new and free prev // hold lock next merge into new and free next // hold lock insert new // hold lock After the patch, it only needs to be acquired once: new merge into next and free new // no lock next merge into prev and free next // hold lock Performance test data follows: Test: Running will-it-scale/fallocate2 on CPU-bound containers. Observation: Average fallocate operations per container per second. |CPU: Kunpeng 920 | P80 | P1 | |Memory: 512GB |------------------------|-------------------------| |960GB SSD (0.5GB/s)| base | patched | base | patched | |-------------------|-------|----------------|--------|----------------| |mb_optimize_scan=0 | 20043 | 20097 (+0.2%) | 314331 | 316141 (+0.5%) | |mb_optimize_scan=1 | 7290 | 13318 (+87.4%) | 324226 | 325273 (+0.3%) | |CPU: AMD 9654 * 2 | P96 | P1 | |Memory: 1536GB |------------------------|-------------------------| |960GB SSD (1GB/s) | base | patched | base | patched | |-------------------|-------|----------------|--------|----------------| |mb_optimize_scan=0 | 54999 | 53603 (-2.5%) | 214380 | 214243 (-0.06%)| |mb_optimize_scan=1 | 13497 | 20887 (+54.6%) | 216276 | 213632 (-1.2%) | Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-10-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.c | 113 +++++++++++++++++++++++++++++++--------------- 1 file changed, 76 insertions(+), 37 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index ab05e047c553..f516c7da7ea8 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -6389,28 +6389,63 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, * are contiguous, AND the extents were freed by the same transaction, * AND the blocks are associated with the same group. */ -static void ext4_try_merge_freed_extent(struct ext4_sb_info *sbi, - struct ext4_free_data *entry, - struct ext4_free_data *new_entry, - struct rb_root *entry_rb_root) +static inline bool +ext4_freed_extents_can_be_merged(struct ext4_free_data *entry1, + struct ext4_free_data *entry2) { - if ((entry->efd_tid != new_entry->efd_tid) || - (entry->efd_group != new_entry->efd_group)) - return; - if (entry->efd_start_cluster + entry->efd_count == - new_entry->efd_start_cluster) { - new_entry->efd_start_cluster = entry->efd_start_cluster; - new_entry->efd_count += entry->efd_count; - } else if (new_entry->efd_start_cluster + new_entry->efd_count == - entry->efd_start_cluster) { - new_entry->efd_count += entry->efd_count; - } else - return; + if (entry1->efd_tid != entry2->efd_tid) + return false; + if (entry1->efd_start_cluster + entry1->efd_count != + entry2->efd_start_cluster) + return false; + if (WARN_ON_ONCE(entry1->efd_group != entry2->efd_group)) + return false; + return true; +} + +static inline void +ext4_merge_freed_extents(struct ext4_sb_info *sbi, struct rb_root *root, + struct ext4_free_data *entry1, + struct ext4_free_data *entry2) +{ + entry1->efd_count += entry2->efd_count; spin_lock(&sbi->s_md_lock); - list_del(&entry->efd_list); + list_del(&entry2->efd_list); spin_unlock(&sbi->s_md_lock); - rb_erase(&entry->efd_node, entry_rb_root); - kmem_cache_free(ext4_free_data_cachep, entry); + rb_erase(&entry2->efd_node, root); + kmem_cache_free(ext4_free_data_cachep, entry2); +} + +static inline void +ext4_try_merge_freed_extent_prev(struct ext4_sb_info *sbi, struct rb_root *root, + struct ext4_free_data *entry) +{ + struct ext4_free_data *prev; + struct rb_node *node; + + node = rb_prev(&entry->efd_node); + if (!node) + return; + + prev = rb_entry(node, struct ext4_free_data, efd_node); + if (ext4_freed_extents_can_be_merged(prev, entry)) + ext4_merge_freed_extents(sbi, root, prev, entry); +} + +static inline void +ext4_try_merge_freed_extent_next(struct ext4_sb_info *sbi, struct rb_root *root, + struct ext4_free_data *entry) +{ + struct ext4_free_data *next; + struct rb_node *node; + + node = rb_next(&entry->efd_node); + if (!node) + return; + + next = rb_entry(node, struct ext4_free_data, efd_node); + if (ext4_freed_extents_can_be_merged(entry, next)) + ext4_merge_freed_extents(sbi, root, entry, next); } static noinline_for_stack void @@ -6420,11 +6455,12 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, ext4_group_t group = e4b->bd_group; ext4_grpblk_t cluster; ext4_grpblk_t clusters = new_entry->efd_count; - struct ext4_free_data *entry; + struct ext4_free_data *entry = NULL; struct ext4_group_info *db = e4b->bd_info; struct super_block *sb = e4b->bd_sb; struct ext4_sb_info *sbi = EXT4_SB(sb); - struct rb_node **n = &db->bb_free_root.rb_node, *node; + struct rb_root *root = &db->bb_free_root; + struct rb_node **n = &root->rb_node; struct rb_node *parent = NULL, *new_node; BUG_ON(!ext4_handle_valid(handle)); @@ -6460,27 +6496,30 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, } } - rb_link_node(new_node, parent, n); - rb_insert_color(new_node, &db->bb_free_root); - - /* Now try to see the extent can be merged to left and right */ - node = rb_prev(new_node); - if (node) { - entry = rb_entry(node, struct ext4_free_data, efd_node); - ext4_try_merge_freed_extent(sbi, entry, new_entry, - &(db->bb_free_root)); + atomic_add(clusters, &sbi->s_mb_free_pending); + if (!entry) + goto insert; + + /* Now try to see the extent can be merged to prev and next */ + if (ext4_freed_extents_can_be_merged(new_entry, entry)) { + entry->efd_start_cluster = cluster; + entry->efd_count += new_entry->efd_count; + kmem_cache_free(ext4_free_data_cachep, new_entry); + ext4_try_merge_freed_extent_prev(sbi, root, entry); + return; } - - node = rb_next(new_node); - if (node) { - entry = rb_entry(node, struct ext4_free_data, efd_node); - ext4_try_merge_freed_extent(sbi, entry, new_entry, - &(db->bb_free_root)); + if (ext4_freed_extents_can_be_merged(entry, new_entry)) { + entry->efd_count += new_entry->efd_count; + kmem_cache_free(ext4_free_data_cachep, new_entry); + ext4_try_merge_freed_extent_next(sbi, root, entry); + return; } +insert: + rb_link_node(new_node, parent, n); + rb_insert_color(new_node, root); spin_lock(&sbi->s_md_lock); list_add_tail(&new_entry->efd_list, &sbi->s_freed_data_list[new_entry->efd_tid & 1]); - atomic_add(clusters, &sbi->s_mb_free_pending); spin_unlock(&sbi->s_md_lock); } -- 2.39.2

mainline inclusion from mainline-v6.17-rc1 commit 7d345aa1fac4c2ec9584fbd6f389f2c2368671d5 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... -------------------------------- The grp->bb_largest_free_order is updated regardless of whether mb_optimize_scan is enabled. This can lead to inconsistencies between grp->bb_largest_free_order and the actual s_mb_largest_free_orders list index when mb_optimize_scan is repeatedly enabled and disabled via remount. For example, if mb_optimize_scan is initially enabled, largest free order is 3, and the group is in s_mb_largest_free_orders[3]. Then, mb_optimize_scan is disabled via remount, block allocations occur, updating largest free order to 2. Finally, mb_optimize_scan is re-enabled via remount, more block allocations update largest free order to 1. At this point, the group would be removed from s_mb_largest_free_orders[3] under the protection of s_mb_largest_free_orders_locks[2]. This lock mismatch can lead to list corruption. To fix this, whenever grp->bb_largest_free_order changes, we now always attempt to remove the group from its old order list. However, we only insert the group into the new order list if `mb_optimize_scan` is enabled. This approach helps prevent lock inconsistencies and ensures the data in the order lists remains reliable. Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning") CC: stable@vger.kernel.org Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-12-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.c | 33 ++++++++++++++------------------- 1 file changed, 14 insertions(+), 19 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 1075a658c6c5..dcad2d88df6b 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1155,33 +1155,28 @@ static void mb_set_largest_free_order(struct super_block *sb, struct ext4_group_info *grp) { struct ext4_sb_info *sbi = EXT4_SB(sb); - int i; + int new, old = grp->bb_largest_free_order; - for (i = MB_NUM_ORDERS(sb) - 1; i >= 0; i--) - if (grp->bb_counters[i] > 0) + for (new = MB_NUM_ORDERS(sb) - 1; new >= 0; new--) + if (grp->bb_counters[new] > 0) break; + /* No need to move between order lists? */ - if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || - i == grp->bb_largest_free_order) { - grp->bb_largest_free_order = i; + if (new == old) return; - } - if (grp->bb_largest_free_order >= 0) { - write_lock(&sbi->s_mb_largest_free_orders_locks[ - grp->bb_largest_free_order]); + if (old >= 0 && !list_empty(&grp->bb_largest_free_order_node)) { + write_lock(&sbi->s_mb_largest_free_orders_locks[old]); list_del_init(&grp->bb_largest_free_order_node); - write_unlock(&sbi->s_mb_largest_free_orders_locks[ - grp->bb_largest_free_order]); + write_unlock(&sbi->s_mb_largest_free_orders_locks[old]); } - grp->bb_largest_free_order = i; - if (grp->bb_largest_free_order >= 0 && grp->bb_free) { - write_lock(&sbi->s_mb_largest_free_orders_locks[ - grp->bb_largest_free_order]); + + grp->bb_largest_free_order = new; + if (test_opt2(sb, MB_OPTIMIZE_SCAN) && new >= 0 && grp->bb_free) { + write_lock(&sbi->s_mb_largest_free_orders_locks[new]); list_add_tail(&grp->bb_largest_free_order_node, - &sbi->s_mb_largest_free_orders[grp->bb_largest_free_order]); - write_unlock(&sbi->s_mb_largest_free_orders_locks[ - grp->bb_largest_free_order]); + &sbi->s_mb_largest_free_orders[new]); + write_unlock(&sbi->s_mb_largest_free_orders_locks[new]); } } -- 2.39.2

From: Ojaswin Mujoo <ojaswin@linux.ibm.com> mainline inclusion from mainline-v6.12-rc1 commit ff2beee206d23f49d022650122f81285849033e4 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... -------------------------------- Although we have checks to make sure s_stripe is a multiple of cluster size, in case we accidentally end up with a scenario where this is not the case, use EXT4_NUM_B2C() so that we don't end up with unexpected cases where EXT4_B2C(stripe) becomes 0. Also make the is_stripe_aligned check in regular_allocator a bit more robust while we are at it. This should ideally have no functional change unless we have a bug somewhere causing (stripe % cluster_size != 0) Reviewed-by: Kemeng Shi <shikemeng@huaweicloud.com> Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Link: https://patch.msgid.link/e0c0a3b58a40935a1361f668851d041575861411.1725002410... Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 19c7a3cfae49..f53aa8814e60 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2354,7 +2354,7 @@ int ext4_mb_find_by_goal(struct ext4_allocation_context *ac, ex.fe_logical = 0xDEADFA11; /* debug value */ if (max >= ac->ac_g_ex.fe_len && - ac->ac_g_ex.fe_len == EXT4_B2C(sbi, sbi->s_stripe)) { + ac->ac_g_ex.fe_len == EXT4_NUM_B2C(sbi, sbi->s_stripe)) { ext4_fsblk_t start; start = ext4_grp_offs_to_block(ac->ac_sb, &ex); @@ -2551,7 +2551,7 @@ void ext4_mb_scan_aligned(struct ext4_allocation_context *ac, do_div(a, sbi->s_stripe); i = (a * sbi->s_stripe) - first_group_block; - stripe = EXT4_B2C(sbi, sbi->s_stripe); + stripe = EXT4_NUM_B2C(sbi, sbi->s_stripe); i = EXT4_B2C(sbi, i); while (i < EXT4_CLUSTERS_PER_GROUP(sb)) { if (!mb_test_bit(i, bitmap)) { @@ -2936,9 +2936,11 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) if (cr == CR_POWER2_ALIGNED) ext4_mb_simple_scan_group(ac, &e4b); else { - bool is_stripe_aligned = sbi->s_stripe && + bool is_stripe_aligned = + (sbi->s_stripe >= + sbi->s_cluster_ratio) && !(ac->ac_g_ex.fe_len % - EXT4_B2C(sbi, sbi->s_stripe)); + EXT4_NUM_B2C(sbi, sbi->s_stripe)); if ((cr == CR_GOAL_LEN_FAST || cr == CR_BEST_AVAIL_LEN) && @@ -3720,7 +3722,7 @@ int ext4_mb_init(struct super_block *sb) */ if (sbi->s_stripe > 1) { sbi->s_mb_group_prealloc = roundup( - sbi->s_mb_group_prealloc, EXT4_B2C(sbi, sbi->s_stripe)); + sbi->s_mb_group_prealloc, EXT4_NUM_B2C(sbi, sbi->s_stripe)); } sbi->s_mb_nr_global_goals = umin(num_possible_cpus(), -- 2.39.2

From: Kemeng Shi <shikemeng@huaweicloud.com> mainline inclusion from mainline-v6.8-rc3 commit 97c32dbffce12136c06d9ceb6919850233d3a1c2 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... -------------------------------- Remove unused ext4_allocation_context::ac_groups_considered Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20240105092102.496631-5-shikemeng@huaweicloud.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.h | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h index 99461f0cdc8a..587d4dd5746d 100644 --- a/fs/ext4/mballoc.h +++ b/fs/ext4/mballoc.h @@ -192,7 +192,6 @@ struct ext4_allocation_context { */ ext4_grpblk_t ac_orig_goal_len; - __u32 ac_groups_considered; __u32 ac_flags; /* allocation hints */ __u32 ac_groups_linear_remaining; __u16 ac_groups_scanned; -- 2.39.2

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

mainline inclusion from mainline-v6.17-rc1 commit f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e 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... -------------------------------- While traversing the list, holding a spin_lock prevents load_buddy, making direct use of ext4_try_lock_group impossible. This can lead to a bouncing scenario where spin_is_locked(grp_A) succeeds, but ext4_try_lock_group() fails, forcing the list traversal to repeatedly restart from grp_A. In contrast, linear traversal directly uses ext4_try_lock_group(), avoiding this bouncing. Therefore, we need a lockless, ordered traversal to achieve linear-like efficiency. Therefore, this commit converts both average fragment size lists and largest free order lists into ordered xarrays. In an xarray, the index represents the block group number and the value holds the block group information; a non-empty value indicates the block group's presence. While insertion and deletion complexity remain O(1), lookup complexity changes from O(1) to O(nlogn), which may slightly reduce single-threaded performance. Additionally, xarray insertions might fail, potentially due to memory allocation issues. However, since we have linear traversal as a fallback, this isn't a major problem. Therefore, we've only added a warning message for insertion failures here. A helper function ext4_mb_find_good_group_xarray() is added to find good groups in the specified xarray starting at the specified position start, and when it reaches ngroups-1, it wraps around to 0 and then to start-1. This ensures an ordered traversal within the xarray. Performance test results are as follows: Single-process operations on an empty disk show negligible impact, while multi-process workloads demonstrate a noticeable performance gain. |CPU: Kunpeng 920 | P80 | P1 | |Memory: 512GB |------------------------|-------------------------| |960GB SSD (0.5GB/s)| base | patched | base | patched | |-------------------|-------|----------------|--------|----------------| |mb_optimize_scan=0 | 20097 | 19555 (-2.6%) | 316141 | 315636 (-0.2%) | |mb_optimize_scan=1 | 13318 | 15496 (+16.3%) | 325273 | 323569 (-0.5%) | |CPU: AMD 9654 * 2 | P96 | P1 | |Memory: 1536GB |------------------------|-------------------------| |960GB SSD (1GB/s) | base | patched | base | patched | |-------------------|-------|----------------|--------|----------------| |mb_optimize_scan=0 | 53603 | 53192 (-0.7%) | 214243 | 212678 (-0.7%) | |mb_optimize_scan=1 | 20887 | 37636 (+80.1%) | 213632 | 214189 (+0.2%) | [ Applied spelling fixes per discussion on the ext4-list see thread referened in the Link tag. --tytso] Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-16-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Conflicts: fs/ext4/mballoc-test.c [Context differences because there is no commit 2b81493f8eb6 ("ext4: Add unit test for ext4_mb_mark_diskspace_used").] Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 8 +- fs/ext4/mballoc.c | 254 +++++++++++++++++++++++++--------------------- 2 files changed, 140 insertions(+), 122 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 07e240231fe0..1e30aaf39e0e 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1590,10 +1590,8 @@ struct ext4_sb_info { struct list_head s_discard_list; struct work_struct s_discard_work; atomic_t s_retry_alloc_pending; - struct list_head *s_mb_avg_fragment_size; - rwlock_t *s_mb_avg_fragment_size_locks; - struct list_head *s_mb_largest_free_orders; - rwlock_t *s_mb_largest_free_orders_locks; + struct xarray *s_mb_avg_fragment_size; + struct xarray *s_mb_largest_free_orders; /* tunables */ unsigned long s_stripe; @@ -3431,8 +3429,6 @@ struct ext4_group_info { void *bb_bitmap; #endif struct rw_semaphore alloc_sem; - struct list_head bb_avg_fragment_size_node; - struct list_head bb_largest_free_order_node; ext4_grpblk_t bb_counters[]; /* Nr of free power-of-two-block * regions, index is order. * bb_counters[3] = 5 means diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 8c427927dacc..c894aa014d2e 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -131,25 +131,30 @@ * If "mb_optimize_scan" mount option is set, we maintain in memory group info * structures in two data structures: * - * 1) Array of largest free order lists (sbi->s_mb_largest_free_orders) + * 1) Array of largest free order xarrays (sbi->s_mb_largest_free_orders) * - * Locking: sbi->s_mb_largest_free_orders_locks(array of rw locks) + * Locking: Writers use xa_lock, readers use rcu_read_lock. * - * This is an array of lists where the index in the array represents the + * This is an array of xarrays where the index in the array represents the * largest free order in the buddy bitmap of the participating group infos of - * that list. So, there are exactly MB_NUM_ORDERS(sb) (which means total - * number of buddy bitmap orders possible) number of lists. Group-infos are - * placed in appropriate lists. + * that xarray. So, there are exactly MB_NUM_ORDERS(sb) (which means total + * number of buddy bitmap orders possible) number of xarrays. Group-infos are + * placed in appropriate xarrays. * - * 2) Average fragment size lists (sbi->s_mb_avg_fragment_size) + * 2) Average fragment size xarrays (sbi->s_mb_avg_fragment_size) * - * Locking: sbi->s_mb_avg_fragment_size_locks(array of rw locks) + * Locking: Writers use xa_lock, readers use rcu_read_lock. * - * This is an array of lists where in the i-th list there are groups with + * This is an array of xarrays where in the i-th xarray there are groups with * average fragment size >= 2^i and < 2^(i+1). The average fragment size * is computed as ext4_group_info->bb_free / ext4_group_info->bb_fragments. - * Note that we don't bother with a special list for completely empty groups - * so we only have MB_NUM_ORDERS(sb) lists. + * Note that we don't bother with a special xarray for completely empty + * groups so we only have MB_NUM_ORDERS(sb) xarrays. Group-infos are placed + * in appropriate xarrays. + * + * In xarray, the index is the block group number, the value is the block group + * information, and a non-empty value indicates the block group is present in + * the current xarray. * * When "mb_optimize_scan" mount option is set, mballoc consults the above data * structures to decide the order in which groups are to be traversed for @@ -855,19 +860,73 @@ mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp) if (new == old) return; - if (old >= 0) { - write_lock(&sbi->s_mb_avg_fragment_size_locks[old]); - list_del(&grp->bb_avg_fragment_size_node); - write_unlock(&sbi->s_mb_avg_fragment_size_locks[old]); - } + if (old >= 0) + xa_erase(&sbi->s_mb_avg_fragment_size[old], grp->bb_group); grp->bb_avg_fragment_size_order = new; if (new >= 0) { - write_lock(&sbi->s_mb_avg_fragment_size_locks[new]); - list_add_tail(&grp->bb_avg_fragment_size_node, - &sbi->s_mb_avg_fragment_size[new]); - write_unlock(&sbi->s_mb_avg_fragment_size_locks[new]); + /* + * Cannot use __GFP_NOFAIL because we hold the group lock. + * Although allocation for insertion may fails, it's not fatal + * as we have linear traversal to fall back on. + */ + int err = xa_insert(&sbi->s_mb_avg_fragment_size[new], + grp->bb_group, grp, GFP_ATOMIC); + if (err) + mb_debug(sb, "insert group: %u to s_mb_avg_fragment_size[%d] failed, err %d", + grp->bb_group, new, err); + } +} + +static struct ext4_group_info * +ext4_mb_find_good_group_xarray(struct ext4_allocation_context *ac, + struct xarray *xa, ext4_group_t start) +{ + struct super_block *sb = ac->ac_sb; + struct ext4_sb_info *sbi = EXT4_SB(sb); + enum criteria cr = ac->ac_criteria; + ext4_group_t ngroups = ext4_get_groups_count(sb); + unsigned long group = start; + ext4_group_t end = ngroups; + struct ext4_group_info *grp; + + if (WARN_ON_ONCE(start >= end)) + return NULL; + +wrap_around: + xa_for_each_range(xa, group, grp, start, end - 1) { + if (sbi->s_mb_stats) + atomic64_inc(&sbi->s_bal_cX_groups_considered[cr]); + + if (!spin_is_locked(ext4_group_lock_ptr(sb, group)) && + likely(ext4_mb_good_group(ac, group, cr))) + return grp; + + cond_resched(); } + + if (start) { + end = start; + start = 0; + goto wrap_around; + } + + return NULL; +} + +/* + * Find a suitable group of given order from the largest free orders xarray. + */ +static struct ext4_group_info * +ext4_mb_find_good_group_largest_free_order(struct ext4_allocation_context *ac, + int order, ext4_group_t start) +{ + struct xarray *xa = &EXT4_SB(ac->ac_sb)->s_mb_largest_free_orders[order]; + + if (xa_empty(xa)) + return NULL; + + return ext4_mb_find_good_group_xarray(ac, xa, start); } /* @@ -878,7 +937,7 @@ static void ext4_mb_choose_next_group_p2_aligned(struct ext4_allocation_context enum criteria *new_cr, ext4_group_t *group, ext4_group_t ngroups) { struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); - struct ext4_group_info *iter; + struct ext4_group_info *grp; int i; if (ac->ac_status == AC_STATUS_FOUND) @@ -888,26 +947,12 @@ static void ext4_mb_choose_next_group_p2_aligned(struct ext4_allocation_context atomic_inc(&sbi->s_bal_p2_aligned_bad_suggestions); for (i = ac->ac_2order; i < MB_NUM_ORDERS(ac->ac_sb); i++) { - if (list_empty(&sbi->s_mb_largest_free_orders[i])) - continue; - read_lock(&sbi->s_mb_largest_free_orders_locks[i]); - if (list_empty(&sbi->s_mb_largest_free_orders[i])) { - read_unlock(&sbi->s_mb_largest_free_orders_locks[i]); - continue; - } - list_for_each_entry(iter, &sbi->s_mb_largest_free_orders[i], - bb_largest_free_order_node) { - if (sbi->s_mb_stats) - atomic64_inc(&sbi->s_bal_cX_groups_considered[CR_POWER2_ALIGNED]); - if (!spin_is_locked(ext4_group_lock_ptr(ac->ac_sb, iter->bb_group)) && - likely(ext4_mb_good_group(ac, iter->bb_group, CR_POWER2_ALIGNED))) { - *group = iter->bb_group; - ac->ac_flags |= EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED; - read_unlock(&sbi->s_mb_largest_free_orders_locks[i]); - return; - } + grp = ext4_mb_find_good_group_largest_free_order(ac, i, *group); + if (grp) { + *group = grp->bb_group; + ac->ac_flags |= EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED; + return; } - read_unlock(&sbi->s_mb_largest_free_orders_locks[i]); } /* Increment cr and search again if no group is found */ @@ -915,35 +960,18 @@ static void ext4_mb_choose_next_group_p2_aligned(struct ext4_allocation_context } /* - * Find a suitable group of given order from the average fragments list. + * Find a suitable group of given order from the average fragments xarray. */ static struct ext4_group_info * -ext4_mb_find_good_group_avg_frag_lists(struct ext4_allocation_context *ac, int order) +ext4_mb_find_good_group_avg_frag_xarray(struct ext4_allocation_context *ac, + int order, ext4_group_t start) { - struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); - struct list_head *frag_list = &sbi->s_mb_avg_fragment_size[order]; - rwlock_t *frag_list_lock = &sbi->s_mb_avg_fragment_size_locks[order]; - struct ext4_group_info *grp = NULL, *iter; - enum criteria cr = ac->ac_criteria; + struct xarray *xa = &EXT4_SB(ac->ac_sb)->s_mb_avg_fragment_size[order]; - if (list_empty(frag_list)) - return NULL; - read_lock(frag_list_lock); - if (list_empty(frag_list)) { - read_unlock(frag_list_lock); + if (xa_empty(xa)) return NULL; - } - list_for_each_entry(iter, frag_list, bb_avg_fragment_size_node) { - if (sbi->s_mb_stats) - atomic64_inc(&sbi->s_bal_cX_groups_considered[cr]); - if (!spin_is_locked(ext4_group_lock_ptr(ac->ac_sb, iter->bb_group)) && - likely(ext4_mb_good_group(ac, iter->bb_group, cr))) { - grp = iter; - break; - } - } - read_unlock(frag_list_lock); - return grp; + + return ext4_mb_find_good_group_xarray(ac, xa, start); } /* @@ -964,7 +992,7 @@ static void ext4_mb_choose_next_group_goal_fast(struct ext4_allocation_context * for (i = mb_avg_fragment_size_order(ac->ac_sb, ac->ac_g_ex.fe_len); i < MB_NUM_ORDERS(ac->ac_sb); i++) { - grp = ext4_mb_find_good_group_avg_frag_lists(ac, i); + grp = ext4_mb_find_good_group_avg_frag_xarray(ac, i, *group); if (grp) { *group = grp->bb_group; ac->ac_flags |= EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED; @@ -1060,7 +1088,8 @@ static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context frag_order = mb_avg_fragment_size_order(ac->ac_sb, ac->ac_g_ex.fe_len); - grp = ext4_mb_find_good_group_avg_frag_lists(ac, frag_order); + grp = ext4_mb_find_good_group_avg_frag_xarray(ac, frag_order, + *group); if (grp) { *group = grp->bb_group; ac->ac_flags |= EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED; @@ -1165,18 +1194,25 @@ mb_set_largest_free_order(struct super_block *sb, struct ext4_group_info *grp) if (new == old) return; - if (old >= 0 && !list_empty(&grp->bb_largest_free_order_node)) { - write_lock(&sbi->s_mb_largest_free_orders_locks[old]); - list_del_init(&grp->bb_largest_free_order_node); - write_unlock(&sbi->s_mb_largest_free_orders_locks[old]); + if (old >= 0) { + struct xarray *xa = &sbi->s_mb_largest_free_orders[old]; + + if (!xa_empty(xa) && xa_load(xa, grp->bb_group)) + xa_erase(xa, grp->bb_group); } grp->bb_largest_free_order = new; if (test_opt2(sb, MB_OPTIMIZE_SCAN) && new >= 0 && grp->bb_free) { - write_lock(&sbi->s_mb_largest_free_orders_locks[new]); - list_add_tail(&grp->bb_largest_free_order_node, - &sbi->s_mb_largest_free_orders[new]); - write_unlock(&sbi->s_mb_largest_free_orders_locks[new]); + /* + * Cannot use __GFP_NOFAIL because we hold the group lock. + * Although allocation for insertion may fails, it's not fatal + * as we have linear traversal to fall back on. + */ + int err = xa_insert(&sbi->s_mb_largest_free_orders[new], + grp->bb_group, grp, GFP_ATOMIC); + if (err) + mb_debug(sb, "insert group: %u to s_mb_largest_free_orders[%d] failed, err %d", + grp->bb_group, new, err); } } @@ -3273,6 +3309,7 @@ static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v) unsigned long position = ((unsigned long) v); struct ext4_group_info *grp; unsigned int count; + unsigned long idx; position--; if (position >= MB_NUM_ORDERS(sb)) { @@ -3281,11 +3318,8 @@ static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v) seq_puts(seq, "avg_fragment_size_lists:\n"); count = 0; - read_lock(&sbi->s_mb_avg_fragment_size_locks[position]); - list_for_each_entry(grp, &sbi->s_mb_avg_fragment_size[position], - bb_avg_fragment_size_node) + xa_for_each(&sbi->s_mb_avg_fragment_size[position], idx, grp) count++; - read_unlock(&sbi->s_mb_avg_fragment_size_locks[position]); seq_printf(seq, "\tlist_order_%u_groups: %u\n", (unsigned int)position, count); return 0; @@ -3297,11 +3331,8 @@ static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v) seq_puts(seq, "max_free_order_lists:\n"); } count = 0; - read_lock(&sbi->s_mb_largest_free_orders_locks[position]); - list_for_each_entry(grp, &sbi->s_mb_largest_free_orders[position], - bb_largest_free_order_node) + xa_for_each(&sbi->s_mb_largest_free_orders[position], idx, grp) count++; - read_unlock(&sbi->s_mb_largest_free_orders_locks[position]); seq_printf(seq, "\tlist_order_%u_groups: %u\n", (unsigned int)position, count); @@ -3421,8 +3452,6 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group, INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list); init_rwsem(&meta_group_info[i]->alloc_sem); meta_group_info[i]->bb_free_root = RB_ROOT; - INIT_LIST_HEAD(&meta_group_info[i]->bb_largest_free_order_node); - INIT_LIST_HEAD(&meta_group_info[i]->bb_avg_fragment_size_node); meta_group_info[i]->bb_largest_free_order = -1; /* uninit */ meta_group_info[i]->bb_avg_fragment_size_order = -1; /* uninit */ meta_group_info[i]->bb_group = group; @@ -3631,6 +3660,20 @@ static void ext4_discard_work(struct work_struct *work) ext4_mb_unload_buddy(&e4b); } +static inline void ext4_mb_avg_fragment_size_destroy(struct ext4_sb_info *sbi) +{ + for (int i = 0; i < MB_NUM_ORDERS(sbi->s_sb); i++) + xa_destroy(&sbi->s_mb_avg_fragment_size[i]); + kfree(sbi->s_mb_avg_fragment_size); +} + +static inline void ext4_mb_largest_free_orders_destroy(struct ext4_sb_info *sbi) +{ + for (int i = 0; i < MB_NUM_ORDERS(sbi->s_sb); i++) + xa_destroy(&sbi->s_mb_largest_free_orders[i]); + kfree(sbi->s_mb_largest_free_orders); +} + int ext4_mb_init(struct super_block *sb) { struct ext4_sb_info *sbi = EXT4_SB(sb); @@ -3676,41 +3719,24 @@ int ext4_mb_init(struct super_block *sb) } while (i < MB_NUM_ORDERS(sb)); sbi->s_mb_avg_fragment_size = - kmalloc_array(MB_NUM_ORDERS(sb), sizeof(struct list_head), + kmalloc_array(MB_NUM_ORDERS(sb), sizeof(struct xarray), GFP_KERNEL); if (!sbi->s_mb_avg_fragment_size) { ret = -ENOMEM; goto out; } - sbi->s_mb_avg_fragment_size_locks = - kmalloc_array(MB_NUM_ORDERS(sb), sizeof(rwlock_t), - GFP_KERNEL); - if (!sbi->s_mb_avg_fragment_size_locks) { - ret = -ENOMEM; - goto out; - } - for (i = 0; i < MB_NUM_ORDERS(sb); i++) { - INIT_LIST_HEAD(&sbi->s_mb_avg_fragment_size[i]); - rwlock_init(&sbi->s_mb_avg_fragment_size_locks[i]); - } + for (i = 0; i < MB_NUM_ORDERS(sb); i++) + xa_init(&sbi->s_mb_avg_fragment_size[i]); + sbi->s_mb_largest_free_orders = - kmalloc_array(MB_NUM_ORDERS(sb), sizeof(struct list_head), + kmalloc_array(MB_NUM_ORDERS(sb), sizeof(struct xarray), GFP_KERNEL); if (!sbi->s_mb_largest_free_orders) { ret = -ENOMEM; goto out; } - sbi->s_mb_largest_free_orders_locks = - kmalloc_array(MB_NUM_ORDERS(sb), sizeof(rwlock_t), - GFP_KERNEL); - if (!sbi->s_mb_largest_free_orders_locks) { - ret = -ENOMEM; - goto out; - } - for (i = 0; i < MB_NUM_ORDERS(sb); i++) { - INIT_LIST_HEAD(&sbi->s_mb_largest_free_orders[i]); - rwlock_init(&sbi->s_mb_largest_free_orders_locks[i]); - } + for (i = 0; i < MB_NUM_ORDERS(sb); i++) + xa_init(&sbi->s_mb_largest_free_orders[i]); spin_lock_init(&sbi->s_md_lock); atomic_set(&sbi->s_mb_free_pending, 0); @@ -3795,10 +3821,8 @@ int ext4_mb_init(struct super_block *sb) kfree(sbi->s_mb_last_groups); sbi->s_mb_last_groups = NULL; out: - kfree(sbi->s_mb_avg_fragment_size); - kfree(sbi->s_mb_avg_fragment_size_locks); - kfree(sbi->s_mb_largest_free_orders); - kfree(sbi->s_mb_largest_free_orders_locks); + ext4_mb_avg_fragment_size_destroy(sbi); + ext4_mb_largest_free_orders_destroy(sbi); kfree(sbi->s_mb_offsets); sbi->s_mb_offsets = NULL; kfree(sbi->s_mb_maxs); @@ -3865,10 +3889,8 @@ int ext4_mb_release(struct super_block *sb) kvfree(group_info); rcu_read_unlock(); } - kfree(sbi->s_mb_avg_fragment_size); - kfree(sbi->s_mb_avg_fragment_size_locks); - kfree(sbi->s_mb_largest_free_orders); - kfree(sbi->s_mb_largest_free_orders_locks); + ext4_mb_avg_fragment_size_destroy(sbi); + ext4_mb_largest_free_orders_destroy(sbi); kfree(sbi->s_mb_offsets); kfree(sbi->s_mb_maxs); iput(sbi->s_buddy_cache); -- 2.39.2

From: Kemeng Shi <shikemeng@huaweicloud.com> mainline inclusion from mainline-v6.10-rc1 commit 2caffb6a277bb0f2a482a2eb824d012d5f45f4d0 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... -------------------------------- Use correct criteria name instead stale integer number in comment Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20240424061904.987525-5-shikemeng@huaweicloud.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 9 ++++++--- fs/ext4/mballoc.c | 16 +++++++++------- fs/ext4/mballoc.h | 4 ++-- 3 files changed, 17 insertions(+), 12 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 1e30aaf39e0e..02cd6b7b5dce 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -218,11 +218,14 @@ enum criteria { #define EXT4_MB_USE_RESERVED 0x2000 /* Do strict check for free blocks while retrying block allocation */ #define EXT4_MB_STRICT_CHECK 0x4000 -/* Large fragment size list lookup succeeded at least once for cr = 0 */ +/* Large fragment size list lookup succeeded at least once for + * CR_POWER2_ALIGNED */ #define EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED 0x8000 -/* Avg fragment size rb tree lookup succeeded at least once for cr = 1 */ +/* Avg fragment size rb tree lookup succeeded at least once for + * CR_GOAL_LEN_FAST */ #define EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED 0x00010000 -/* Avg fragment size rb tree lookup succeeded at least once for cr = 1.5 */ +/* Avg fragment size rb tree lookup succeeded at least once for + * CR_BEST_AVAIL_LEN */ #define EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED 0x00020000 struct ext4_allocation_request { diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index ba3b2b4aad6a..65cdb2c0dfc7 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1169,8 +1169,9 @@ static void ext4_mb_choose_next_group(struct ext4_allocation_context *ac, ext4_mb_choose_next_group_best_avail(ac, new_cr, group); } else { /* - * TODO: For CR=2, we can arrange groups in an rb tree sorted by - * bb_free. But until that happens, we should never come here. + * TODO: For CR_GOAL_LEN_SLOW, we can arrange groups in an + * rb tree sorted by bb_free. But until that happens, we should + * never come here. */ WARN_ON(1); } @@ -2745,7 +2746,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac, int ret; /* - * cr=CR_POWER2_ALIGNED/CR_GOAL_LEN_FAST is a very optimistic + * CR_POWER2_ALIGNED/CR_GOAL_LEN_FAST is a very optimistic * search to find large good chunks almost for free. If buddy * data is not ready, then this optimization makes no sense. But * we never skip the first block group in a flex_bg, since this @@ -3526,10 +3527,11 @@ static int ext4_mb_init_backend(struct super_block *sb) } if (sbi->s_mb_prefetch > ext4_get_groups_count(sb)) sbi->s_mb_prefetch = ext4_get_groups_count(sb); - /* now many real IOs to prefetch within a single allocation at cr=0 - * given cr=0 is an CPU-related optimization we shouldn't try to - * load too many groups, at some point we should start to use what - * we've got in memory. + /* + * now many real IOs to prefetch within a single allocation at + * CR_POWER2_ALIGNED. Given CR_POWER2_ALIGNED is an CPU-related + * optimization we shouldn't try to load too many groups, at some point + * we should start to use what we've got in memory. * with an average random access time 5ms, it'd take a second to get * 200 groups (* N with flex_bg), so let's make this limit 4 */ diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h index 5a0cbd512444..336cafd4187d 100644 --- a/fs/ext4/mballoc.h +++ b/fs/ext4/mballoc.h @@ -187,8 +187,8 @@ struct ext4_allocation_context { struct ext4_free_extent ac_f_ex; /* - * goal len can change in CR1.5, so save the original len. This is - * used while adjusting the PA window and for accounting. + * goal len can change in CR_BEST_AVAIL_LEN, so save the original len. + * This is used while adjusting the PA window and for accounting. */ ext4_grpblk_t ac_orig_goal_len; -- 2.39.2

mainline inclusion from mainline-v6.17-rc1 commit 6347558764911f88acac06ab996e162f0c8a212d 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... -------------------------------- This commit converts the `choose group` logic to `scan group` using previously prepared helper functions. This allows us to leverage xarrays for ordered non-linear traversal, thereby mitigating the "bouncing" issue inherent in the `choose group` mechanism. This also decouples linear and non-linear traversals, leading to cleaner and more readable code. Key changes: * ext4_mb_choose_next_group() is refactored to ext4_mb_scan_groups(). * Replaced ext4_mb_good_group() with ext4_mb_scan_group() in non-linear traversals, and related functions now return error codes instead of group info. * Added ext4_mb_scan_groups_linear() for performing linear scans starting from a specific group for a set number of times. * Linear scans now execute up to sbi->s_mb_max_linear_groups times, so ac_groups_linear_remaining is removed as it's no longer used. * ac->ac_criteria is now used directly instead of passing cr around. Also, ac->ac_criteria is incremented directly after groups scan fails for the corresponding criteria. * Since we're now directly scanning groups instead of finding a good group then scanning, the following variables and flags are no longer needed, s_bal_cX_groups_considered is sufficient. s_bal_p2_aligned_bad_suggestions s_bal_goal_fast_bad_suggestions s_bal_best_avail_bad_suggestions EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20250714130327.1830534-17-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/ext4.h | 12 -- fs/ext4/mballoc.c | 292 +++++++++++++++++++++------------------------- fs/ext4/mballoc.h | 1 - 3 files changed, 131 insertions(+), 174 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 02cd6b7b5dce..a1fc8a94d803 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -218,15 +218,6 @@ enum criteria { #define EXT4_MB_USE_RESERVED 0x2000 /* Do strict check for free blocks while retrying block allocation */ #define EXT4_MB_STRICT_CHECK 0x4000 -/* Large fragment size list lookup succeeded at least once for - * CR_POWER2_ALIGNED */ -#define EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED 0x8000 -/* Avg fragment size rb tree lookup succeeded at least once for - * CR_GOAL_LEN_FAST */ -#define EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED 0x00010000 -/* Avg fragment size rb tree lookup succeeded at least once for - * CR_BEST_AVAIL_LEN */ -#define EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED 0x00020000 struct ext4_allocation_request { /* target inode for block we're allocating */ @@ -1626,9 +1617,6 @@ struct ext4_sb_info { atomic_t s_bal_len_goals; /* len goal hits */ atomic_t s_bal_breaks; /* too long searches */ atomic_t s_bal_2orders; /* 2^order hits */ - atomic_t s_bal_p2_aligned_bad_suggestions; - atomic_t s_bal_goal_fast_bad_suggestions; - atomic_t s_bal_best_avail_bad_suggestions; atomic64_t s_bal_cX_groups_considered[EXT4_MB_NUM_CRS]; atomic64_t s_bal_cX_hits[EXT4_MB_NUM_CRS]; atomic64_t s_bal_cX_failed[EXT4_MB_NUM_CRS]; /* cX loop didn't find blocks */ diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 66191ba5d53c..2ab1eb9d0c77 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -424,8 +424,8 @@ static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap, ext4_group_t group); static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac); -static bool ext4_mb_good_group(struct ext4_allocation_context *ac, - ext4_group_t group, enum criteria cr); +static int ext4_mb_scan_group(struct ext4_allocation_context *ac, + ext4_group_t group); static void ext4_mb_put_pa(struct ext4_allocation_context *ac, struct super_block *sb, struct ext4_prealloc_space *pa); @@ -878,9 +878,8 @@ mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp) } } -static struct ext4_group_info * -ext4_mb_find_good_group_xarray(struct ext4_allocation_context *ac, - struct xarray *xa, ext4_group_t start) +static int ext4_mb_scan_groups_xarray(struct ext4_allocation_context *ac, + struct xarray *xa, ext4_group_t start) { struct super_block *sb = ac->ac_sb; struct ext4_sb_info *sbi = EXT4_SB(sb); @@ -891,16 +890,18 @@ ext4_mb_find_good_group_xarray(struct ext4_allocation_context *ac, struct ext4_group_info *grp; if (WARN_ON_ONCE(start >= end)) - return NULL; + return 0; wrap_around: xa_for_each_range(xa, group, grp, start, end - 1) { + int err; + if (sbi->s_mb_stats) atomic64_inc(&sbi->s_bal_cX_groups_considered[cr]); - if (!spin_is_locked(ext4_group_lock_ptr(sb, group)) && - likely(ext4_mb_good_group(ac, group, cr))) - return grp; + err = ext4_mb_scan_group(ac, grp->bb_group); + if (err || ac->ac_status != AC_STATUS_CONTINUE) + return err; cond_resched(); } @@ -911,95 +912,82 @@ ext4_mb_find_good_group_xarray(struct ext4_allocation_context *ac, goto wrap_around; } - return NULL; + return 0; } /* * Find a suitable group of given order from the largest free orders xarray. */ -static struct ext4_group_info * -ext4_mb_find_good_group_largest_free_order(struct ext4_allocation_context *ac, - int order, ext4_group_t start) +static int +ext4_mb_scan_groups_largest_free_order(struct ext4_allocation_context *ac, + int order, ext4_group_t start) { struct xarray *xa = &EXT4_SB(ac->ac_sb)->s_mb_largest_free_orders[order]; if (xa_empty(xa)) - return NULL; + return 0; - return ext4_mb_find_good_group_xarray(ac, xa, start); + return ext4_mb_scan_groups_xarray(ac, xa, start); } /* * Choose next group by traversing largest_free_order lists. Updates *new_cr if * cr level needs an update. */ -static void ext4_mb_choose_next_group_p2_aligned(struct ext4_allocation_context *ac, - enum criteria *new_cr, ext4_group_t *group) +static int ext4_mb_scan_groups_p2_aligned(struct ext4_allocation_context *ac, + ext4_group_t group) { struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); - struct ext4_group_info *grp; int i; - - if (ac->ac_status == AC_STATUS_FOUND) - return; - - if (unlikely(sbi->s_mb_stats && ac->ac_flags & EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED)) - atomic_inc(&sbi->s_bal_p2_aligned_bad_suggestions); + int ret = 0; for (i = ac->ac_2order; i < MB_NUM_ORDERS(ac->ac_sb); i++) { - grp = ext4_mb_find_good_group_largest_free_order(ac, i, *group); - if (grp) { - *group = grp->bb_group; - ac->ac_flags |= EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED; - return; - } + ret = ext4_mb_scan_groups_largest_free_order(ac, i, group); + if (ret || ac->ac_status != AC_STATUS_CONTINUE) + return ret; } + if (sbi->s_mb_stats) + atomic64_inc(&sbi->s_bal_cX_failed[ac->ac_criteria]); + /* Increment cr and search again if no group is found */ - *new_cr = CR_GOAL_LEN_FAST; + ac->ac_criteria = CR_GOAL_LEN_FAST; + return ret; } /* * Find a suitable group of given order from the average fragments xarray. */ -static struct ext4_group_info * -ext4_mb_find_good_group_avg_frag_xarray(struct ext4_allocation_context *ac, - int order, ext4_group_t start) +static int ext4_mb_scan_groups_avg_frag_order(struct ext4_allocation_context *ac, + int order, ext4_group_t start) { struct xarray *xa = &EXT4_SB(ac->ac_sb)->s_mb_avg_fragment_size[order]; if (xa_empty(xa)) - return NULL; + return 0; - return ext4_mb_find_good_group_xarray(ac, xa, start); + return ext4_mb_scan_groups_xarray(ac, xa, start); } /* * Choose next group by traversing average fragment size list of suitable * order. Updates *new_cr if cr level needs an update. */ -static void ext4_mb_choose_next_group_goal_fast(struct ext4_allocation_context *ac, - enum criteria *new_cr, ext4_group_t *group) +static int ext4_mb_scan_groups_goal_fast(struct ext4_allocation_context *ac, + ext4_group_t group) { struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); - struct ext4_group_info *grp = NULL; - int i; - - if (unlikely(ac->ac_flags & EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED)) { - if (sbi->s_mb_stats) - atomic_inc(&sbi->s_bal_goal_fast_bad_suggestions); - } + int i, ret = 0; - for (i = mb_avg_fragment_size_order(ac->ac_sb, ac->ac_g_ex.fe_len); - i < MB_NUM_ORDERS(ac->ac_sb); i++) { - grp = ext4_mb_find_good_group_avg_frag_xarray(ac, i, *group); - if (grp) { - *group = grp->bb_group; - ac->ac_flags |= EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED; - return; - } + i = mb_avg_fragment_size_order(ac->ac_sb, ac->ac_g_ex.fe_len); + for (; i < MB_NUM_ORDERS(ac->ac_sb); i++) { + ret = ext4_mb_scan_groups_avg_frag_order(ac, i, group); + if (ret || ac->ac_status != AC_STATUS_CONTINUE) + return ret; } + if (sbi->s_mb_stats) + atomic64_inc(&sbi->s_bal_cX_failed[ac->ac_criteria]); /* * CR_BEST_AVAIL_LEN works based on the concept that we have * a larger normalized goal len request which can be trimmed to @@ -1009,9 +997,11 @@ static void ext4_mb_choose_next_group_goal_fast(struct ext4_allocation_context * * See function ext4_mb_normalize_request() (EXT4_MB_HINT_DATA). */ if (ac->ac_flags & EXT4_MB_HINT_DATA) - *new_cr = CR_BEST_AVAIL_LEN; + ac->ac_criteria = CR_BEST_AVAIL_LEN; else - *new_cr = CR_GOAL_LEN_SLOW; + ac->ac_criteria = CR_GOAL_LEN_SLOW; + + return ret; } /* @@ -1023,19 +1013,14 @@ static void ext4_mb_choose_next_group_goal_fast(struct ext4_allocation_context * * preallocations. However, we make sure that we don't trim the request too * much and fall to CR_GOAL_LEN_SLOW in that case. */ -static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context *ac, - enum criteria *new_cr, ext4_group_t *group) +static int ext4_mb_scan_groups_best_avail(struct ext4_allocation_context *ac, + ext4_group_t group) { + int ret = 0; struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); - struct ext4_group_info *grp = NULL; int i, order, min_order; unsigned long num_stripe_clusters = 0; - if (unlikely(ac->ac_flags & EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED)) { - if (sbi->s_mb_stats) - atomic_inc(&sbi->s_bal_best_avail_bad_suggestions); - } - /* * mb_avg_fragment_size_order() returns order in a way that makes * retrieving back the length using (1 << order) inaccurate. Hence, use @@ -1088,18 +1073,18 @@ static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context frag_order = mb_avg_fragment_size_order(ac->ac_sb, ac->ac_g_ex.fe_len); - grp = ext4_mb_find_good_group_avg_frag_xarray(ac, frag_order, - *group); - if (grp) { - *group = grp->bb_group; - ac->ac_flags |= EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED; - return; - } + ret = ext4_mb_scan_groups_avg_frag_order(ac, frag_order, group); + if (ret || ac->ac_status != AC_STATUS_CONTINUE) + return ret; } /* Reset goal length to original goal length before falling into CR_GOAL_LEN_SLOW */ ac->ac_g_ex.fe_len = ac->ac_orig_goal_len; - *new_cr = CR_GOAL_LEN_SLOW; + if (sbi->s_mb_stats) + atomic64_inc(&sbi->s_bal_cX_failed[ac->ac_criteria]); + ac->ac_criteria = CR_GOAL_LEN_SLOW; + + return ret; } static inline int should_optimize_scan(struct ext4_allocation_context *ac) @@ -1114,59 +1099,82 @@ static inline int should_optimize_scan(struct ext4_allocation_context *ac) } /* - * Return next linear group for allocation. + * next linear group for allocation. */ -static ext4_group_t -next_linear_group(ext4_group_t group, ext4_group_t ngroups) +static void next_linear_group(ext4_group_t *group, ext4_group_t ngroups) { /* * Artificially restricted ngroups for non-extent * files makes group > ngroups possible on first loop. */ - return group + 1 >= ngroups ? 0 : group + 1; + *group = *group + 1 >= ngroups ? 0 : *group + 1; } -/* - * ext4_mb_choose_next_group: choose next group for allocation. - * - * @ac Allocation Context - * @new_cr This is an output parameter. If the there is no good group - * available at current CR level, this field is updated to indicate - * the new cr level that should be used. - * @group This is an input / output parameter. As an input it indicates the - * next group that the allocator intends to use for allocation. As - * output, this field indicates the next group that should be used as - * determined by the optimization functions. - * @ngroups Total number of groups - */ -static void ext4_mb_choose_next_group(struct ext4_allocation_context *ac, - enum criteria *new_cr, ext4_group_t *group, ext4_group_t ngroups) +static int ext4_mb_scan_groups_linear(struct ext4_allocation_context *ac, + ext4_group_t ngroups, ext4_group_t *start, ext4_group_t count) { - *new_cr = ac->ac_criteria; + int ret, i; + enum criteria cr = ac->ac_criteria; + struct super_block *sb = ac->ac_sb; + struct ext4_sb_info *sbi = EXT4_SB(sb); + ext4_group_t group = *start; - if (!should_optimize_scan(ac)) { - *group = next_linear_group(*group, ngroups); - return; + for (i = 0; i < count; i++, next_linear_group(&group, ngroups)) { + ret = ext4_mb_scan_group(ac, group); + if (ret || ac->ac_status != AC_STATUS_CONTINUE) + return ret; + cond_resched(); } + *start = group; + if (count == ngroups) + ac->ac_criteria++; + + /* Processed all groups and haven't found blocks */ + if (sbi->s_mb_stats && i == ngroups) + atomic64_inc(&sbi->s_bal_cX_failed[cr]); + + return 0; +} + +static int ext4_mb_scan_groups(struct ext4_allocation_context *ac) +{ + int ret = 0; + ext4_group_t start; + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); + ext4_group_t ngroups = ext4_get_groups_count(ac->ac_sb); + + /* non-extent files are limited to low blocks/groups */ + if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS))) + ngroups = sbi->s_blockfile_groups; + + /* searching for the right group start from the goal value specified */ + start = ac->ac_g_ex.fe_group; + ac->ac_prefetch_grp = start; + ac->ac_prefetch_nr = 0; + + if (!should_optimize_scan(ac)) + return ext4_mb_scan_groups_linear(ac, ngroups, &start, ngroups); + /* * Optimized scanning can return non adjacent groups which can cause * seek overhead for rotational disks. So try few linear groups before * trying optimized scan. */ - if (ac->ac_groups_linear_remaining) { - *group = next_linear_group(*group, ngroups); - ac->ac_groups_linear_remaining--; - return; - } + if (sbi->s_mb_max_linear_groups) + ret = ext4_mb_scan_groups_linear(ac, ngroups, &start, + sbi->s_mb_max_linear_groups); + if (ret || ac->ac_status != AC_STATUS_CONTINUE) + return ret; - if (*new_cr == CR_POWER2_ALIGNED) { - ext4_mb_choose_next_group_p2_aligned(ac, new_cr, group); - } else if (*new_cr == CR_GOAL_LEN_FAST) { - ext4_mb_choose_next_group_goal_fast(ac, new_cr, group); - } else if (*new_cr == CR_BEST_AVAIL_LEN) { - ext4_mb_choose_next_group_best_avail(ac, new_cr, group); - } else { + switch (ac->ac_criteria) { + case CR_POWER2_ALIGNED: + return ext4_mb_scan_groups_p2_aligned(ac, start); + case CR_GOAL_LEN_FAST: + return ext4_mb_scan_groups_goal_fast(ac, start); + case CR_BEST_AVAIL_LEN: + return ext4_mb_scan_groups_best_avail(ac, start); + default: /* * TODO: For CR_GOAL_LEN_SLOW, we can arrange groups in an * rb tree sorted by bb_free. But until that happens, we should @@ -1174,6 +1182,8 @@ static void ext4_mb_choose_next_group(struct ext4_allocation_context *ac, */ WARN_ON(1); } + + return 0; } /* @@ -2929,20 +2939,11 @@ static int ext4_mb_scan_group(struct ext4_allocation_context *ac, 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; + ext4_group_t i; int err = 0; - struct ext4_sb_info *sbi; - struct super_block *sb; + struct super_block *sb = ac->ac_sb; + struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_buddy e4b; - int lost; - - sb = ac->ac_sb; - sbi = EXT4_SB(sb); - ngroups = ext4_get_groups_count(sb); - /* non-extent files are limited to low blocks/groups */ - if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS))) - ngroups = sbi->s_blockfile_groups; BUG_ON(ac->ac_status == AC_STATUS_FOUND); @@ -2988,48 +2989,21 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) * start with CR_GOAL_LEN_FAST, unless it is power of 2 * aligned, in which case let's do that faster approach first. */ + ac->ac_criteria = CR_GOAL_LEN_FAST; if (ac->ac_2order) - cr = CR_POWER2_ALIGNED; + ac->ac_criteria = CR_POWER2_ALIGNED; 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; - /* - * searching for the right group start - * from the goal value specified - */ - group = ac->ac_g_ex.fe_group; - ac->ac_groups_linear_remaining = sbi->s_mb_max_linear_groups; - 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)) { - - cond_resched(); - if (new_cr != cr) { - cr = new_cr; - goto repeat; - } - - err = ext4_mb_scan_group(ac, group); - if (err) - goto out; - - if (ac->ac_status != AC_STATUS_CONTINUE) - break; - } - /* Processed all groups and haven't found blocks */ - if (sbi->s_mb_stats && i == ngroups) - atomic64_inc(&sbi->s_bal_cX_failed[cr]); + while (ac->ac_criteria < EXT4_MB_NUM_CRS) { + err = ext4_mb_scan_groups(ac); + if (err) + goto out; - if (i == ngroups && ac->ac_criteria == CR_BEST_AVAIL_LEN) - /* Reset goal length to original goal length before - * falling into CR_GOAL_LEN_SLOW */ - ac->ac_g_ex.fe_len = ac->ac_orig_goal_len; + if (ac->ac_status != AC_STATUS_CONTINUE) + break; } if (ac->ac_b_ex.fe_len > 0 && ac->ac_status != AC_STATUS_FOUND && @@ -3040,6 +3014,8 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) */ ext4_mb_try_best_found(ac, &e4b); if (ac->ac_status != AC_STATUS_FOUND) { + int lost; + /* * Someone more lucky has already allocated it. * The only thing we can do is just take first @@ -3055,7 +3031,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) ac->ac_b_ex.fe_len = 0; ac->ac_status = AC_STATUS_CONTINUE; ac->ac_flags |= EXT4_MB_HINT_FIRST; - cr = CR_ANY_FREE; + ac->ac_criteria = CR_ANY_FREE; goto repeat; } } @@ -3072,7 +3048,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) 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, - ac->ac_flags, cr, err); + ac->ac_flags, ac->ac_criteria, err); if (ac->ac_prefetch_nr) ext4_mb_prefetch_fini(sb, ac->ac_prefetch_grp, ac->ac_prefetch_nr); @@ -3201,8 +3177,6 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset) atomic_read(&sbi->s_bal_cX_ex_scanned[CR_POWER2_ALIGNED])); seq_printf(seq, "\t\tuseless_loops: %llu\n", atomic64_read(&sbi->s_bal_cX_failed[CR_POWER2_ALIGNED])); - seq_printf(seq, "\t\tbad_suggestions: %u\n", - atomic_read(&sbi->s_bal_p2_aligned_bad_suggestions)); /* CR_GOAL_LEN_FAST stats */ seq_puts(seq, "\tcr_goal_fast_stats:\n"); @@ -3215,8 +3189,6 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset) atomic_read(&sbi->s_bal_cX_ex_scanned[CR_GOAL_LEN_FAST])); seq_printf(seq, "\t\tuseless_loops: %llu\n", atomic64_read(&sbi->s_bal_cX_failed[CR_GOAL_LEN_FAST])); - seq_printf(seq, "\t\tbad_suggestions: %u\n", - atomic_read(&sbi->s_bal_goal_fast_bad_suggestions)); /* CR_BEST_AVAIL_LEN stats */ seq_puts(seq, "\tcr_best_avail_stats:\n"); @@ -3230,8 +3202,6 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset) atomic_read(&sbi->s_bal_cX_ex_scanned[CR_BEST_AVAIL_LEN])); seq_printf(seq, "\t\tuseless_loops: %llu\n", atomic64_read(&sbi->s_bal_cX_failed[CR_BEST_AVAIL_LEN])); - seq_printf(seq, "\t\tbad_suggestions: %u\n", - atomic_read(&sbi->s_bal_best_avail_bad_suggestions)); /* CR_GOAL_LEN_SLOW stats */ seq_puts(seq, "\tcr_goal_slow_stats:\n"); diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h index 336cafd4187d..f7aec43503f8 100644 --- a/fs/ext4/mballoc.h +++ b/fs/ext4/mballoc.h @@ -199,7 +199,6 @@ struct ext4_allocation_context { int ac_first_err; __u32 ac_flags; /* allocation hints */ - __u32 ac_groups_linear_remaining; __u16 ac_groups_scanned; __u16 ac_found; __u16 ac_cX_found[EXT4_MB_NUM_CRS]; -- 2.39.2

maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/ICN2MB Reference: https://lore.kernel.org/r/20250825033830.2230202-1-libaokun@huaweicloud.com -------------------------------- In ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called when sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo slab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy() lacks null pointer checking, this leads to a null pointer dereference. ================================================================== EXT4-fs: no memory for groupinfo slab cache BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: Oops: 0002 [#1] SMP PTI CPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none) RIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40 Call Trace: <TASK> xa_destroy+0x61/0x130 ext4_mb_init+0x483/0x540 __ext4_fill_super+0x116d/0x17b0 ext4_fill_super+0xd3/0x280 get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x29/0xd0 do_new_mount+0x197/0x300 __x64_sys_mount+0x116/0x150 do_syscall_64+0x50/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== Therefore, add necessary null check to ext4_mb_avg_fragment_size_destroy() to prevent this issue. The same fix is also applied to ext4_mb_largest_free_orders_destroy(). Reported-by: syzbot+1713b1aa266195b916c2@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1713b1aa266195b916c2 Fixes: f7eaacbb4e54 ("ext4: convert free groups order lists to xarrays") Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Baokun Li <libaokun1@huawei.com> --- fs/ext4/mballoc.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index fd66bdea4d6a..a196903ed109 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3659,16 +3659,26 @@ static void ext4_discard_work(struct work_struct *work) static inline void ext4_mb_avg_fragment_size_destroy(struct ext4_sb_info *sbi) { + if (!sbi->s_mb_avg_fragment_size) + return; + for (int i = 0; i < MB_NUM_ORDERS(sbi->s_sb); i++) xa_destroy(&sbi->s_mb_avg_fragment_size[i]); + kfree(sbi->s_mb_avg_fragment_size); + sbi->s_mb_avg_fragment_size = NULL; } static inline void ext4_mb_largest_free_orders_destroy(struct ext4_sb_info *sbi) { + if (!sbi->s_mb_largest_free_orders) + return; + for (int i = 0; i < MB_NUM_ORDERS(sbi->s_sb); i++) xa_destroy(&sbi->s_mb_largest_free_orders[i]); + kfree(sbi->s_mb_largest_free_orders); + sbi->s_mb_largest_free_orders = NULL; } int ext4_mb_init(struct super_block *sb) -- 2.39.2