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GET /api/1.2/patches/2234992/?format=api
{ "id": 2234992, "url": "http://patchwork.ozlabs.org/api/1.2/patches/2234992/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-ext4/patch/20260508121539.4174601-8-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": "<20260508121539.4174601-8-libaokun@linux.alibaba.com>", "list_archive_url": null, "date": "2026-05-08T12:15:29", "name": "[RFC,07/17] ext4: use fast incremental CRC update in ext4_mb_mark_context()", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "ea62cafac0978b3e70c976692692b9890cbdb836", "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/20260508121539.4174601-8-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/2234992/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2234992/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <SRS0=cB42=DF=vger.kernel.org=linux-ext4+bounces-16370-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=oBslsgyw;\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=1778242566; h=From:To:Subject:Date:Message-ID:MIME-Version;\n\tbh=mOG2NnAGPPdQ3W0BX30E8ncse768vHXAuwsNTrJ5Vfw=;\n\tb=oBslsgyw53QhYZYqDQ8OoZ3q+LS7yS/f7Rs1zDCitQk66DlKQk5flgwsXL2/gkGqSWKw6ZvDTNVnWzvut3jjw1qGN+0Jw0gPdFfPTyd1tShpDW8vMadK4P3VYJFBWa5h5phDthLN54gG6eULOb96EVDPyOPBPpwAJp6j6Qtwzn0=", "X-Alimail-AntiSpam": "\n AC=PASS;BC=-1|-1;BR=01201311R201e4;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_---0X2XQgpZ_1778242564;", "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 07/17] ext4: use fast incremental CRC update in\n ext4_mb_mark_context()", "Date": "Fri, 8 May 2026 20:15:29 +0800", "Message-ID": "<20260508121539.4174601-8-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": "Use ext4_block_bitmap_csum_set_range() in ext4_mb_mark_context() for\nfast incremental block bitmap checksum updates. Instead of re-scanning\nthe entire bitmap after every allocation or free, the incremental update\ncomputes the CRC delta for the modified bit range in O(log N) time.\n\nAdd a fast_crc flag that is set when EXT4_MB_BITMAP_MARKED_CHECK is not\nused. When fast_crc is true, all bits in the range are guaranteed to flip,\nso the incremental CRC via ext4_block_bitmap_csum_set_range() is correct.\nOtherwise, fall back to ext4_block_bitmap_csum_set() for a full CRC\nrecalculation, since idempotent operations (mb_set_bits/mb_clear_bits\nwith EXT4_MB_BITMAP_MARKED_CHECK) may leave some bits unchanged.\n\nFor the BLOCK_UNINIT case, the bitmap was just initialized and there is\nno valid old checksum, so fast_crc is forced to false to ensure a full\nCRC recalculation establishes a correct baseline.\n\nSigned-off-by: Baokun Li <libaokun@linux.alibaba.com>\n---\n fs/ext4/mballoc.c | 22 +++++++++++++++++++++-\n 1 file changed, 21 insertions(+), 1 deletion(-)", "diff": "diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c\nindex ff2023c9f52c..77f6309916d1 100644\n--- a/fs/ext4/mballoc.c\n+++ b/fs/ext4/mballoc.c\n@@ -4095,6 +4095,7 @@ ext4_mb_mark_context(handle_t *handle, struct super_block *sb, bool state,\n \tstruct buffer_head *gdp_bh;\n \tint err;\n \tunsigned int i, already, changed = len;\n+\tbool fast_crc;\n \n \tKUNIT_STATIC_STUB_REDIRECT(ext4_mb_mark_context,\n \t\t\t\t handle, sb, state, group, blkoff, len,\n@@ -4127,12 +4128,28 @@ ext4_mb_mark_context(handle_t *handle, struct super_block *sb, bool state,\n \t\t\tgoto out_err;\n \t}\n \n+\t/*\n+\t * fast_crc: Use incremental CRC update via crc32c_flip_range().\n+\t * This is only valid when all bits in [blkoff, blkoff+len) are\n+\t * guaranteed to be in the opposite state (i.e., every bit will\n+\t * actually flip). When EXT4_MB_BITMAP_MARKED_CHECK is set,\n+\t * mb_set_bits/mb_clear_bits are idempotent, so some bits may not\n+\t * change and incremental CRC would produce incorrect results.\n+\t */\n+\tfast_crc = !(flags & EXT4_MB_BITMAP_MARKED_CHECK);\n+\n \text4_lock_group(sb, group);\n \tif (ext4_has_group_desc_csum(sb) &&\n \t (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {\n \t\tgdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);\n \t\text4_free_group_clusters_set(sb, gdp,\n \t\t\text4_free_clusters_after_init(sb, group, gdp));\n+\t\t/*\n+\t\t * The bitmap was just initialized, so the old checksum\n+\t\t * is invalid for incremental CRC update. Fall back to\n+\t\t * full recalculation.\n+\t\t */\n+\t\tfast_crc = false;\n \t}\n \n \tif (flags & EXT4_MB_BITMAP_MARKED_CHECK) {\n@@ -4154,7 +4171,10 @@ ext4_mb_mark_context(handle_t *handle, struct super_block *sb, bool state,\n \t\t\text4_free_group_clusters(sb, gdp) + changed);\n \t}\n \n-\text4_block_bitmap_csum_set(sb, gdp, bitmap_bh);\n+\tif (fast_crc)\n+\t\text4_block_bitmap_csum_set_range(sb, gdp, blkoff, len);\n+\telse\n+\t\text4_block_bitmap_csum_set(sb, gdp, bitmap_bh);\n \text4_group_desc_csum_set(sb, group, gdp);\n \text4_unlock_group(sb, group);\n \tif (ret_changed)\n", "prefixes": [ "RFC", "07/17" ] }