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GET /api/1.2/patches/2234980/?format=api
{ "id": 2234980, "url": "http://patchwork.ozlabs.org/api/1.2/patches/2234980/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-ext4/patch/20260508121539.4174601-14-libaokun@linux.alibaba.com/", "project": { "id": 8, "url": "http://patchwork.ozlabs.org/api/1.2/projects/8/?format=api", "name": "Linux ext4 filesystem development", "link_name": "linux-ext4", "list_id": "linux-ext4.vger.kernel.org", "list_email": "linux-ext4@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260508121539.4174601-14-libaokun@linux.alibaba.com>", "list_archive_url": null, "date": "2026-05-08T12:15:35", "name": "[RFC,13/17] ext4: use fast incremental CRC update in ext4_mark_inode_used()", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "593dcbe99ccac167f87b5eebe33e427ccb8362c4", "submitter": { "id": 92757, "url": "http://patchwork.ozlabs.org/api/1.2/people/92757/?format=api", "name": "Baokun Li", "email": "libaokun@linux.alibaba.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-ext4/patch/20260508121539.4174601-14-libaokun@linux.alibaba.com/mbox/", "series": [ { "id": 503377, "url": "http://patchwork.ozlabs.org/api/1.2/series/503377/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-ext4/list/?series=503377", "date": "2026-05-08T12:15:22", "name": "ext4/lib-crc: LBS performance part 1 - incremental CRC32c for bitmap checksums", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/503377/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2234980/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2234980/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <SRS0=4Hsi=DF=vger.kernel.org=linux-ext4+bounces-16375-patchwork-incoming=ozlabs.org@ozlabs.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-ext4@vger.kernel.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "patchwork-incoming@ozlabs.org" ], "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com\n header.a=rsa-sha256 header.s=default header.b=sp3I6mtT;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; 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a=rsa-sha256; c=relaxed/relaxed;\n\td=linux.alibaba.com; s=default;\n\tt=1778242570; h=From:To:Subject:Date:Message-ID:MIME-Version;\n\tbh=omI7SRikdqIgyxB0uPduOEBvp2jJZrJt0MRys7JIsEw=;\n\tb=sp3I6mtTrhZdXKTCvWN30d+yFixCGQ+Tq9wI2lWItqIL1PTJ5BsAne3i0Pxfk6/D8C0ICIRDxZzl5+/24/oHeK6bfbeRQRCq0jfOoYtMRIUiJUPYqqZLpadDfjvDMjZUBW7AlHZrK7kX5Ll6k1ewjBdaHmK9HFp4f4a3GDbomKE=", "X-Alimail-AntiSpam": "\n AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033032089153;MF=libaokun@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0X2XQgr2_1778242569;", "From": "Baokun Li <libaokun@linux.alibaba.com>", "To": "linux-ext4@vger.kernel.org", "Cc": "linux-crypto@vger.kernel.org,\n\tebiggers@kernel.org,\n\tardb@kernel.org,\n\ttytso@mit.edu,\n\tadilger.kernel@dilger.ca,\n\tjack@suse.cz,\n\tyi.zhang@huawei.com,\n\tojaswin@linux.ibm.com,\n\tritesh.list@gmail.com,\n\tBaokun Li <libaokun@linux.alibaba.com>", "Subject": "[PATCH RFC 13/17] ext4: use fast incremental CRC update in\n ext4_mark_inode_used()", "Date": "Fri, 8 May 2026 20:15:35 +0800", "Message-ID": "<20260508121539.4174601-14-libaokun@linux.alibaba.com>", "X-Mailer": "git-send-email 2.43.7", "In-Reply-To": "<20260508121539.4174601-1-libaokun@linux.alibaba.com>", "References": "<20260508121539.4174601-1-libaokun@linux.alibaba.com>", "Precedence": "bulk", "X-Mailing-List": "linux-ext4@vger.kernel.org", "List-Id": "<linux-ext4.vger.kernel.org>", "List-Subscribe": "<mailto:linux-ext4+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-ext4+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-Spam-Status": "No, score=-8.7 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tHEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,\n\tSPF_PASS,UNPARSEABLE_RELAY,USER_IN_DEF_DKIM_WL autolearn=disabled\n\tversion=4.0.1", "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org" }, "content": "Move the bitmap modification, GDP update, and checksum update into a\nsingle group lock acquisition in ext4_mark_inode_used(), eliminating the\nrace window where another thread could interleave a full recomputation\nbetween bitmap modification and checksum update.\n\nAdd a fast_crc flag to select between incremental and full CRC update.\nWhen EXT4_BG_INODE_UNINIT is set, the stored checksum in the group\ndescriptor is not a valid CRC of the bitmap -- mkfs leaves it as zero\nfor UNINIT groups, and ext4_read_inode_bitmap() memsets the buffer to\nzero without updating the gdp checksum. So fast_crc is forced to false\nto fall back to ext4_inode_bitmap_csum_set() for a full recalculation\nthat establishes a correct baseline.\n\nFor non-UNINIT groups, ext4_inode_bitmap_csum_set_fast() computes the\nCRC delta for the single flipped bit in O(log N) time.\n\nSigned-off-by: Baokun Li <libaokun@linux.alibaba.com>\n---\n fs/ext4/ialloc.c | 69 ++++++++++++++++++++++++------------------------\n 1 file changed, 35 insertions(+), 34 deletions(-)", "diff": "diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c\nindex 90896b7f8c73..e209e27f827f 100644\n--- a/fs/ext4/ialloc.c\n+++ b/fs/ext4/ialloc.c\n@@ -838,35 +838,37 @@ int ext4_mark_inode_used(struct super_block *sb, int ino, umode_t mode)\n \t\tgoto out;\n \t}\n \n-\text4_set_bit(bit, inode_bitmap_bh->b_data);\n-\n-\tBUFFER_TRACE(inode_bitmap_bh, \"call ext4_handle_dirty_metadata\");\n-\terr = ext4_handle_dirty_metadata(NULL, NULL, inode_bitmap_bh);\n-\tif (err) {\n-\t\text4_std_error(sb, err);\n-\t\tgoto out;\n-\t}\n-\terr = sync_dirty_buffer(inode_bitmap_bh);\n-\tif (err) {\n-\t\text4_std_error(sb, err);\n-\t\tgoto out;\n-\t}\n-\n \t/* We may have to initialize the block bitmap if it isn't already */\n \terr = ext4_might_init_block_bitmap(NULL, sb, group, gdp);\n \tif (err)\n \t\tgoto out;\n \n+\text4_lock_group(sb, group);\n+\t/* Fast commit replay is single-threaded, no need for test_and_set */\n+\text4_set_bit(bit, inode_bitmap_bh->b_data);\n+\n \t/* Update the relevant bg descriptor fields */\n+\text4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1);\n+\tif (S_ISDIR(mode)) {\n+\t\text4_used_dirs_set(sb, gdp, ext4_used_dirs_count(sb, gdp) + 1);\n+\t\tif (sbi->s_log_groups_per_flex) {\n+\t\t\text4_group_t f = ext4_flex_group(sbi, group);\n+\n+\t\t\tatomic_inc(&sbi_array_rcu_deref(sbi, s_flex_groups,\n+\t\t\t\t\t\t\tf)->used_dirs);\n+\t\t}\n+\t}\n+\n \tif (ext4_has_group_desc_csum(sb)) {\n-\t\tint free;\n+\t\tbool fast_crc = true;\n+\t\tint free = EXT4_INODES_PER_GROUP(sb) -\n+\t\t\t\text4_itable_unused_count(sb, gdp);\n \n-\t\text4_lock_group(sb, group); /* while we modify the bg desc */\n-\t\tfree = EXT4_INODES_PER_GROUP(sb) -\n-\t\t\text4_itable_unused_count(sb, gdp);\n \t\tif (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {\n \t\t\tgdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT);\n \t\t\tfree = 0;\n+\t\t\t/* Incremental CRC needs a valid checksum baseline */\n+\t\t\tfast_crc = false;\n \t\t}\n \n \t\t/*\n@@ -877,27 +879,26 @@ int ext4_mark_inode_used(struct super_block *sb, int ino, umode_t mode)\n \t\tif (bit >= free)\n \t\t\text4_itable_unused_set(sb, gdp,\n \t\t\t\t\t(EXT4_INODES_PER_GROUP(sb) - bit - 1));\n-\t} else {\n-\t\text4_lock_group(sb, group);\n+\t\tif (fast_crc)\n+\t\t\text4_inode_bitmap_csum_set_fast(sb, gdp, bit);\n+\t\telse\n+\t\t\text4_inode_bitmap_csum_set(sb, gdp, inode_bitmap_bh);\n+\t\text4_group_desc_csum_set(sb, group, gdp);\n \t}\n \n-\text4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1);\n-\tif (S_ISDIR(mode)) {\n-\t\text4_used_dirs_set(sb, gdp, ext4_used_dirs_count(sb, gdp) + 1);\n-\t\tif (sbi->s_log_groups_per_flex) {\n-\t\t\text4_group_t f = ext4_flex_group(sbi, group);\n+\text4_unlock_group(sb, group);\n \n-\t\t\tatomic_inc(&sbi_array_rcu_deref(sbi, s_flex_groups,\n-\t\t\t\t\t\t\tf)->used_dirs);\n-\t\t}\n+\tBUFFER_TRACE(inode_bitmap_bh, \"call ext4_handle_dirty_metadata\");\n+\terr = ext4_handle_dirty_metadata(NULL, NULL, inode_bitmap_bh);\n+\tif (err) {\n+\t\text4_std_error(sb, err);\n+\t\tgoto out;\n \t}\n-\n-\tif (ext4_has_group_desc_csum(sb)) {\n-\t\text4_inode_bitmap_csum_set(sb, gdp, inode_bitmap_bh);\n-\t\text4_group_desc_csum_set(sb, group, gdp);\n+\terr = sync_dirty_buffer(inode_bitmap_bh);\n+\tif (err) {\n+\t\text4_std_error(sb, err);\n+\t\tgoto out;\n \t}\n-\n-\text4_unlock_group(sb, group);\n \terr = ext4_handle_dirty_metadata(NULL, NULL, group_desc_bh);\n \tsync_dirty_buffer(group_desc_bh);\n out:\n", "prefixes": [ "RFC", "13/17" ] }