From: Harshad Shirwadkar harshadshirwadkar@gmail.com
[ Upstream commit 67d25186046145748d5fe4c5019d832215e01c1e ]
s_mb_buddies_generated gets used later in this patch series to determine if the cr 0 and cr 1 optimziations should be performed or not. Currently, s_mb_buddies_generated is protected under a spin_lock. In the allocation path, it is better if we don't depend on the lock and instead read the value atomically. In order to do that, we drop s_bal_lock altogether and we convert the only two protected fields by it s_mb_buddies_generated and s_mb_generation_time to atomic type.
Signed-off-by: Harshad Shirwadkar harshadshirwadkar@gmail.com Reviewed-by: Andreas Dilger adilger@dilger.ca Reviewed-by: Ritesh Harjani ritesh.list@gmail.com Link: https://lore.kernel.org/r/20210401172129.189766-2-harshadshirwadkar@gmail.co... Signed-off-by: Theodore Ts'o tytso@mit.edu Stable-dep-of: 5354b2af3406 ("ext4: allow ext4_get_group_info() to fail") Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ext4/ext4.h | 5 ++--- fs/ext4/mballoc.c | 13 +++++-------- 2 files changed, 7 insertions(+), 11 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 246573a4e8041..5efd48d7c9a79 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1538,9 +1538,8 @@ struct ext4_sb_info { atomic_t s_bal_goals; /* goal hits */ atomic_t s_bal_breaks; /* too long searches */ atomic_t s_bal_2orders; /* 2^order hits */ - spinlock_t s_bal_lock; - unsigned long s_mb_buddies_generated; - unsigned long long s_mb_generation_time; + atomic_t s_mb_buddies_generated; /* number of buddies generated */ + atomic64_t s_mb_generation_time; atomic_t s_mb_lost_chunks; atomic_t s_mb_preallocated; atomic_t s_mb_discarded; diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 708a5fa3c69f6..beee54480562a 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -816,10 +816,8 @@ void ext4_mb_generate_buddy(struct super_block *sb, clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
period = get_cycles() - period; - spin_lock(&sbi->s_bal_lock); - sbi->s_mb_buddies_generated++; - sbi->s_mb_generation_time += period; - spin_unlock(&sbi->s_bal_lock); + atomic_inc(&sbi->s_mb_buddies_generated); + atomic64_add(period, &sbi->s_mb_generation_time); }
/* The buddy information is attached the buddy cache inode @@ -2855,7 +2853,6 @@ int ext4_mb_init(struct super_block *sb) } while (i <= sb->s_blocksize_bits + 1);
spin_lock_init(&sbi->s_md_lock); - spin_lock_init(&sbi->s_bal_lock); sbi->s_mb_free_pending = 0; INIT_LIST_HEAD(&sbi->s_freed_data_list);
@@ -2991,9 +2988,9 @@ int ext4_mb_release(struct super_block *sb) atomic_read(&sbi->s_bal_breaks), atomic_read(&sbi->s_mb_lost_chunks)); ext4_msg(sb, KERN_INFO, - "mballoc: %lu generated and it took %Lu", - sbi->s_mb_buddies_generated, - sbi->s_mb_generation_time); + "mballoc: %u generated and it took %llu", + atomic_read(&sbi->s_mb_buddies_generated), + atomic64_read(&sbi->s_mb_generation_time)); ext4_msg(sb, KERN_INFO, "mballoc: %u preallocated, %u discarded", atomic_read(&sbi->s_mb_preallocated),