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GET /api/1.2/patches/2234985/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 2234985,
    "url": "http://patchwork.ozlabs.org/api/1.2/patches/2234985/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/linux-ext4/patch/20260508121539.4174601-10-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": "<20260508121539.4174601-10-libaokun@linux.alibaba.com>",
    "list_archive_url": null,
    "date": "2026-05-08T12:15:31",
    "name": "[RFC,09/17] ext4: add ext4_inode_bitmap_csum_set_fast() for incremental checksum update",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "7aaeab1678834d1e9a3b4cfd85a29d3847612da9",
    "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/20260508121539.4174601-10-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/2234985/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/2234985/checks/",
    "tags": {},
    "related": [],
    "headers": {
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        ],
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        "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 09/17] ext4: add ext4_inode_bitmap_csum_set_fast() for\n incremental checksum update",
        "Date": "Fri,  8 May 2026 20:15:31 +0800",
        "Message-ID": "<20260508121539.4174601-10-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>",
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        "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"
    },
    "content": "Add a helper function ext4_inode_bitmap_csum_set_fast() that uses\ncrc32c_flip_range() to incrementally update the inode bitmap checksum\nafter flipping a single bit at the given offset. This avoids a full\nbitmap CRC rescan, computing the CRC delta in O(log N) time.\n\nSigned-off-by: Baokun Li <libaokun@linux.alibaba.com>\n---\n fs/ext4/bitmap.c | 23 +++++++++++++++++++++++\n fs/ext4/ext4.h   |  3 +++\n 2 files changed, 26 insertions(+)",
    "diff": "diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c\nindex 008acc439301..ea47ca0d7046 100644\n--- a/fs/ext4/bitmap.c\n+++ b/fs/ext4/bitmap.c\n@@ -71,6 +71,29 @@ void ext4_inode_bitmap_csum_set(struct super_block *sb,\n \text4_inode_bitmap_csum_store(sb, gdp, csum);\n }\n \n+/*\n+ * Update inode bitmap checksum for a single flipped bit.\n+ *\n+ * Use crc32c_flip_range() to incrementally update the checksum after\n+ * flipping the bit at @offset, avoiding a full bitmap CRC rescan.\n+ * The csum_seed cancels out in the XOR delta, so it is not needed here.\n+ */\n+void ext4_inode_bitmap_csum_set_fast(struct super_block *sb,\n+\t\t\t\t     struct ext4_group_desc *gdp,\n+\t\t\t\t     ext4_grpblk_t offset)\n+{\n+\t__u32 new_csum, old_csum;\n+\n+\tif (!ext4_has_feature_metadata_csum(sb))\n+\t\treturn;\n+\n+\told_csum = ext4_inode_bitmap_csum_get(sb, gdp);\n+\tnew_csum = crc32c_flip_range(old_csum, EXT4_INODES_PER_GROUP(sb),\n+\t\t\t\t     offset, 1);\n+\n+\text4_inode_bitmap_csum_store(sb, gdp, new_csum);\n+}\n+\n static inline __u32 ext4_block_bitmap_csum_get(struct super_block *sb,\n \t\t\t\t\t       struct ext4_group_desc *gdp)\n {\ndiff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h\nindex c423a9a04047..e6739d5af490 100644\n--- a/fs/ext4/ext4.h\n+++ b/fs/ext4/ext4.h\n@@ -2764,6 +2764,9 @@ extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);\n void ext4_inode_bitmap_csum_set(struct super_block *sb,\n \t\t\t\tstruct ext4_group_desc *gdp,\n \t\t\t\tstruct buffer_head *bh);\n+void ext4_inode_bitmap_csum_set_fast(struct super_block *sb,\n+\t\t\t\t     struct ext4_group_desc *gdp,\n+\t\t\t\t     ext4_grpblk_t offset);\n int ext4_inode_bitmap_csum_verify(struct super_block *sb,\n \t\t\t\t  struct ext4_group_desc *gdp,\n \t\t\t\t  struct buffer_head *bh);\n",
    "prefixes": [
        "RFC",
        "09/17"
    ]
}