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[2003:f6:f734:a100:6f35:4b1e:8395:13ef]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-453769da7f6sm54880745e9.40.2025.06.24.02.37.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jun 2025 02:37:21 -0700 (PDT) From: Johannes Thumshirn To: linux-btrfs@vger.kernel.org Cc: Damien Le Moal , Naohiro Aota , Johannes Thumshirn Subject: [PATCH v2 2/3] btrfs: zoned: get rid of treelog_bg_lock Date: Tue, 24 Jun 2025 11:37:09 +0200 Message-ID: <20250624093710.18685-3-jth@kernel.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250624093710.18685-1-jth@kernel.org> References: <20250624093710.18685-1-jth@kernel.org> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Johannes Thumshirn Lockstat analysis of benchmark workloads shows a very high contention on treelog_bg_lock. But the lock only protects a single field in 'struct btrfs_fs_info', namely 'u64 treelog_bg'. Use READ_ONCE()/WRITE_ONCE() to access 'btrfs_fs_info::treelog_bg'. Signed-off-by: Johannes Thumshirn --- fs/btrfs/disk-io.c | 1 - fs/btrfs/extent-tree.c | 49 ++++++++++-------------------------------- fs/btrfs/fs.h | 1 - fs/btrfs/zoned.c | 2 +- fs/btrfs/zoned.h | 6 ++---- 5 files changed, 14 insertions(+), 45 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 24896322376d..a54218717cb4 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2789,7 +2789,6 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) spin_lock_init(&fs_info->defrag_inodes_lock); spin_lock_init(&fs_info->super_lock); spin_lock_init(&fs_info->unused_bgs_lock); - spin_lock_init(&fs_info->treelog_bg_lock); spin_lock_init(&fs_info->zone_active_bgs_lock); rwlock_init(&fs_info->tree_mod_log_lock); rwlock_init(&fs_info->global_root_lock); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 80ceca89a9ef..39d3984153a2 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3809,22 +3809,6 @@ static int do_allocation_clustered(struct btrfs_block_group *block_group, return find_free_extent_unclustered(block_group, ffe_ctl); } -/* - * Tree-log block group locking - * ============================ - * - * fs_info::treelog_bg_lock protects the fs_info::treelog_bg which - * indicates the starting address of a block group, which is reserved only - * for tree-log metadata. - * - * Lock nesting - * ============ - * - * space_info::lock - * block_group::lock - * fs_info::treelog_bg_lock - */ - /* * Simple allocator for sequential-only block group. It only allows sequential * allocation. No need to play with trees. This function also reserves the @@ -3841,9 +3825,7 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group, u64 num_bytes = ffe_ctl->num_bytes; u64 avail; u64 bytenr = block_group->start; - u64 log_bytenr; int ret = 0; - bool skip = false; ASSERT(btrfs_is_zoned(block_group->fs_info)); @@ -3851,13 +3833,9 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group, * Do not allow non-tree-log blocks in the dedicated tree-log block * group, and vice versa. */ - spin_lock(&fs_info->treelog_bg_lock); - log_bytenr = fs_info->treelog_bg; - if (log_bytenr && ((ffe_ctl->for_treelog && bytenr != log_bytenr) || - (!ffe_ctl->for_treelog && bytenr == log_bytenr))) - skip = true; - spin_unlock(&fs_info->treelog_bg_lock); - if (skip) + if (READ_ONCE(fs_info->treelog_bg) && + ((ffe_ctl->for_treelog && bytenr != READ_ONCE(fs_info->treelog_bg)) || + (!ffe_ctl->for_treelog && bytenr == READ_ONCE(fs_info->treelog_bg)))) return 1; /* @@ -3892,14 +3870,13 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group, spin_lock(&space_info->lock); spin_lock(&block_group->lock); - spin_lock(&fs_info->treelog_bg_lock); if (ret) goto out; ASSERT(!ffe_ctl->for_treelog || - block_group->start == fs_info->treelog_bg || - fs_info->treelog_bg == 0); + block_group->start == READ_ONCE(fs_info->treelog_bg) || + READ_ONCE(fs_info->treelog_bg) == 0); ASSERT(!ffe_ctl->for_data_reloc || block_group->start == READ_ONCE(fs_info->data_reloc_bg) || READ_ONCE(fs_info->data_reloc_bg) == 0); @@ -3915,7 +3892,7 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group, * Do not allow currently using block group to be tree-log dedicated * block group. */ - if (ffe_ctl->for_treelog && !fs_info->treelog_bg && + if (ffe_ctl->for_treelog && READ_ONCE(fs_info->treelog_bg) == 0 && (block_group->used || block_group->reserved)) { ret = 1; goto out; @@ -3946,8 +3923,8 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group, goto out; } - if (ffe_ctl->for_treelog && !fs_info->treelog_bg) - fs_info->treelog_bg = block_group->start; + if (ffe_ctl->for_treelog && READ_ONCE(fs_info->treelog_bg) == 0) + WRITE_ONCE(fs_info->treelog_bg, block_group->start); if (ffe_ctl->for_data_reloc) { if (READ_ONCE(fs_info->data_reloc_bg) == 0) @@ -3985,10 +3962,9 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group, out: if (ret && ffe_ctl->for_treelog) - fs_info->treelog_bg = 0; + WRITE_ONCE(fs_info->treelog_bg, 0); if (ret && ffe_ctl->for_data_reloc) WRITE_ONCE(fs_info->data_reloc_bg, 0); - spin_unlock(&fs_info->treelog_bg_lock); spin_unlock(&block_group->lock); spin_unlock(&space_info->lock); return ret; @@ -4290,11 +4266,8 @@ static int prepare_allocation_clustered(struct btrfs_fs_info *fs_info, static int prepare_allocation_zoned(struct btrfs_fs_info *fs_info, struct find_free_extent_ctl *ffe_ctl) { - if (ffe_ctl->for_treelog) { - spin_lock(&fs_info->treelog_bg_lock); - if (fs_info->treelog_bg) - ffe_ctl->hint_byte = fs_info->treelog_bg; - spin_unlock(&fs_info->treelog_bg_lock); + if (ffe_ctl->for_treelog && READ_ONCE(fs_info->treelog_bg)) { + ffe_ctl->hint_byte = READ_ONCE(fs_info->treelog_bg); } else if (ffe_ctl->for_data_reloc && READ_ONCE(fs_info->data_reloc_bg)) { ffe_ctl->hint_byte = READ_ONCE(fs_info->data_reloc_bg); diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h index 570f4b85096c..a388af40a251 100644 --- a/fs/btrfs/fs.h +++ b/fs/btrfs/fs.h @@ -846,7 +846,6 @@ struct btrfs_fs_info { u64 max_zone_append_size; struct mutex zoned_meta_io_lock; - spinlock_t treelog_bg_lock; u64 treelog_bg; /* Start of the dedicated data relocation block group */ diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c index 421afdb6eb39..98f483def77d 100644 --- a/fs/btrfs/zoned.c +++ b/fs/btrfs/zoned.c @@ -1948,7 +1948,7 @@ static bool check_bg_is_active(struct btrfs_eb_write_context *ctx, if (test_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &block_group->runtime_flags)) return true; - if (fs_info->treelog_bg == block_group->start) { + if (READ_ONCE(fs_info->treelog_bg) == block_group->start) { if (!btrfs_zone_activate(block_group)) { int ret_fin = btrfs_zone_finish_one_bg(fs_info); diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h index 6e11533b8e14..f71026b6c100 100644 --- a/fs/btrfs/zoned.h +++ b/fs/btrfs/zoned.h @@ -387,10 +387,8 @@ static inline void btrfs_clear_treelog_bg(struct btrfs_block_group *bg) if (!btrfs_is_zoned(fs_info)) return; - spin_lock(&fs_info->treelog_bg_lock); - if (fs_info->treelog_bg == bg->start) - fs_info->treelog_bg = 0; - spin_unlock(&fs_info->treelog_bg_lock); + if (READ_ONCE(fs_info->treelog_bg) == bg->start) + WRITE_ONCE(fs_info->treelog_bg, 0); } static inline void btrfs_zoned_data_reloc_lock(struct btrfs_inode *inode) -- 2.49.0