->s_next_generation is protected by s_next_gen_lock but it usage pattern is very primitive and can be replaced with atomic_ops This significantly improve creation/unlink scenario on SMP systems, for example lat_fs_create_unlink test [1] on x2 E5-2680 (32vcpu) system shows ~20% improvement. | nr_tsk | wo/ patch | w/ patch | |--------+-----------+----------| | 1 | 137 | 140 | | 2 | 224 | 233 | | 4 | 356 | 372 | | 8 | 439 | 519 | | 16 | 443 | 585 | | 32 | 598 | 695 | | 64 | 559 | 707 | | 128 | 385 | 437 | Footnotes: [1]https://github.com/dmonakhov/lmbench/blob/master/src/lat_fs_create_unlink.c Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> --- fs/ext4/ext4.h | 3 +-- fs/ext4/ialloc.c | 4 +--- fs/ext4/ioctl.c | 6 ++---- fs/ext4/super.c | 8 ++++---- 4 files changed, 8 insertions(+), 13 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index e2abe01..6be1aa8 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1392,8 +1392,7 @@ struct ext4_sb_info { int s_first_ino; unsigned int s_inode_readahead_blks; unsigned int s_inode_goal; - spinlock_t s_next_gen_lock; - u32 s_next_generation; + atomic_t s_next_generation; u32 s_hash_seed[4]; int s_def_hash_version; int s_hash_unsigned; /* 3 if hash should be signed, 0 if not */ diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index ee82302..d12dabc 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -1138,9 +1138,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir, inode->i_ino); goto out; } - spin_lock(&sbi->s_next_gen_lock); - inode->i_generation = sbi->s_next_generation++; - spin_unlock(&sbi->s_next_gen_lock); + inode->i_generation = atomic_inc_return(&sbi->s_next_generation); /* Precompute checksum seed for inode metadata */ if (ext4_has_metadata_csum(sb)) { diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index afb66d4..7d8b1a5 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -157,10 +157,8 @@ static long swap_inode_boot_loader(struct super_block *sb, inode->i_ctime = inode_bl->i_ctime = current_time(inode); - spin_lock(&sbi->s_next_gen_lock); - inode->i_generation = sbi->s_next_generation++; - inode_bl->i_generation = sbi->s_next_generation++; - spin_unlock(&sbi->s_next_gen_lock); + inode_bl->i_generation = atomic_add_return(2, &sbi->s_next_generation); + inode->i_generation = inode_bl->i_generation -1; ext4_discard_preallocations(inode); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index b104096..bfc6d2e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3419,7 +3419,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) int err = 0; unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO; ext4_group_t first_not_zeroed; - + u32 igen; + if ((data && !orig_data) || !sbi) goto out_free_base; @@ -3977,9 +3978,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } sbi->s_gdb_count = db_count; - get_random_bytes(&sbi->s_next_generation, sizeof(u32)); - spin_lock_init(&sbi->s_next_gen_lock); - + get_random_bytes(&igen, sizeof(u32)); + atomic_set(&sbi->s_next_generation, igen); setup_timer(&sbi->s_err_report, print_daily_error_info, (unsigned long) sb); -- 1.8.3.1
