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Message-Id: <20240102123918.799062-1-yi.zhang@huaweicloud.com> Date: Tue, 2 Jan 2024 20:38:53 +0800 From: Zhang Yi <yi.zhang@...weicloud.com> To: linux-ext4@...r.kernel.org Cc: linux-fsdevel@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz, ritesh.list@...il.com, hch@...radead.org, djwong@...nel.org, willy@...radead.org, yi.zhang@...wei.com, yi.zhang@...weicloud.com, chengzhihao1@...wei.com, yukuai3@...wei.com, wangkefeng.wang@...wei.com Subject: [RFC PATCH v2 00/25] ext4: use iomap for regular file's buffered IO path and enable large foilo From: Zhang Yi <yi.zhang@...wei.com> Hello, This is my second version of the RFC patch series that convert ext4 regular file's buffered IO path to iomap. I've been fixing a lot of bugs in v1 and rebased it on 6.7 and with Christoph's "map multiple blocks per ->map_blocks in iomap writeback" series [1]. This series only support ext4 with the default features and mount options, doesn't support inline_data, bigalloc, dax, fs_verity, fs_crypt and data=journal mode, ext4 would fall back to buffer_head path automatically if you enabled these features/options. Although it has many limitations now, it can satisfy the requirements of common cases and bring a great performance benefit. This series have passed kvm-xfstests tests in auto mode, no obvious issues have been found. I will keep doing stress tests, hope most of the corner cases had been covered. For the convenience of review, I split the implementation into small patches, any comments will be helpful. Changes since v1: - Introduce seq count for iomap buffered write and writeback to protect races from extents changes, e.g. truncate, mwrite. - Always allocate unwritten extents for new blocks, drop dioread_lock mode, and make no distinctions between dioread_lock and dioread_nolock. - Don't add ditry data range to jinode, drop data=ordered mode, and make no distinctions between data=ordered and data=writeback mode. - Postpone updating i_disksize to endio. - Allow splitting extents and use reserved space in endio. - Instead of reimplement a new delayed mapping helper ext4_iomap_da_map_blocks() for buffer write, try to reuse ext4_da_map_blocks(). - Add support for disabling large folio on active inodes. - Support online defragmentation, make file fall back to buffer_head and disable large folio in ext4_move_extents(). - Move ext4_nonda_switch() in advance to prevent deadlock in mwrite. - Add dirty_len and pos trace info to trace_iomap_writepage_map(). - Update patch 1-6 to v2 [2]. Patch 1-6: this is a preparation series, it changes ext4_map_blocks() and ext4_set_iomap() to recognize delayed only extents, I've send it out separately[2] because I've done full tests and suppose this can be reviewed and merged first. Patch 7-8: these are two minor iomap changes, one is don't update i_size in zero_range and the other one is for debug in iomap writeback path that I've discussed whit Christoph [3]. Patch 9-14: this is another preparation series, including some changes for delayed extents. Firstly, it factor out buffer_head from ext4_da_map_blocks(), make it to support adding multi-blocks once a time. Then make unwritten to written extents conversion in endio use to reserved space, reduce the risk of potential data loss. Finally, introduce a sequence counter for extent status tree, which is useful for iomap buffer write and write back. Patch 15-21: Implement buffered IO iomap path for read, write, mmap, zero range, truncate and writeback, replace current buffered_head path. Please look at the following patch for details. Patch 22-25: Convert to iomap for regular file's buffered IO path besides inline_data, bigalloc, dax, fs_verity, fs_crypt, and data=journal mode, and enable large folio. It should be note that buffered iomap path hasn't support Online defrag yet, so we need fall back to buffer_head and disable large folio automatically if user call EXT4_IOC_MOVE_EXT. About Tests: - I've test it through kvm-xfstests in auto mode. - I've done a performance tests below. Fio tests with psync on my machine with Intel Xeon Gold 6240 CPU with 400GB system ram, 200GB ramdisk and 1TB nvme ssd disk. == buffer read == buffer head iomap with large folio type bs IOPS BW(MiB/s) IOPS BW(MiB/s) ---------------------------------------------------- hole 4K 565k 2206 811k 3167 hole 64K 45.1k 2820 78.1k 4879 hole 1M 2744 2744 4890 4891 ramdisk 4K 436k 1703 554k 2163 ramdisk 64K 29.6k 1848 44.0k 2747 ramdisk 1M 1994 1995 2809 2809 nvme 4K 306k 1196 324k 1267 nvme 64K 19.3k 1208 24.3k 1517 nvme 1M 1694 1694 2256 2256 == buffer write == buffer head ext4_iomap type Overwrite Sync Writeback bs IOPS BW IOPS BW ------------------------------------------------------------- cache N N N 4K 395k 1544 415k 1621 cache N N N 64K 30.8k 1928 80.1k 5005 cache N N N 1M 1963 1963 5641 5642 cache Y N N 4K 423k 1652 443k 1730 cache Y N N 64K 33.0k 2063 80.8k 5051 cache Y N N 1M 2103 2103 5588 5589 ramdisk N N Y 4K 362k 1416 307k 1198 ramdisk N N Y 64K 22.4k 1399 64.8k 4050 ramdisk N N Y 1M 1670 1670 4559 4560 ramdisk N Y N 4K 9830 38.4 13.5k 52.8 ramdisk N Y N 64K 5834 365 10.1k 629 ramdisk N Y N 1M 1011 1011 2064 2064 ramdisk Y N Y 4K 397k 1550 409k 1598 ramdisk Y N Y 64K 29.2k 1827 73.6k 4597 ramdisk Y N Y 1M 1837 1837 4985 4985 ramdisk Y Y N 4K 173k 675 182k 710 ramdisk Y Y N 64K 17.7k 1109 33.7k 2105 ramdisk Y Y N 1M 1128 1129 1790 1791 nvme N N Y 4K 298k 1164 290k 1134 nvme N N Y 64K 21.5k 1343 57.4k 3590 nvme N N Y 1M 1308 1308 3664 3664 nvme N Y N 4K 10.7k 41.8 12.0k 46.9 nvme N Y N 64K 5962 373 8598 537 nvme N Y N 1M 676 677 1417 1418 nvme Y N Y 4K 366k 1430 373k 1456 nvme Y N Y 64K 26.7k 1670 56.8k 3547 nvme Y N Y 1M 1745 1746 3586 3586 nvme Y Y N 4K 59.0k 230 61.2k 239 nvme Y Y N 64K 13.0k 813 21.0k 1311 nvme Y Y N 1M 683 683 1368 1369 TODO - Keep on doing stress tests and fixing. - I will rebase and resend my another patch set "ext4: more accurate metadata reservaion for delalloc mount option[4]", it's useful for iomap conversion. After this series, I suppose we could totally drop ext4_nonda_switch() and prevent the risk of data loss caused by extents splitting. - Support for more features and mount options in the future. [1] https://lore.kernel.org/linux-fsdevel/20231207072710.176093-1-hch@lst.de/ [2] https://lore.kernel.org/linux-ext4/20231223110223.3650717-1-yi.zhang@huaweicloud.com/ [3] https://lore.kernel.org/linux-fsdevel/20231207150311.GA18830@lst.de/ [4] https://lore.kernel.org/linux-ext4/20230824092619.1327976-1-yi.zhang@huaweicloud.com/ Thanks, Yi. Zhang Yi (25): ext4: refactor ext4_da_map_blocks() ext4: convert to exclusive lock while inserting delalloc extents ext4: correct the hole length returned by ext4_map_blocks() ext4: add a hole extent entry in cache after punch ext4: make ext4_map_blocks() distinguish delalloc only extent ext4: make ext4_set_iomap() recognize IOMAP_DELALLOC map type iomap: don't increase i_size if it's not a write operation iomap: add pos and dirty_len into trace_iomap_writepage_map ext4: allow inserting delalloc extents with multi-blocks ext4: correct delalloc extent length ext4: also mark extent as delalloc if it's been unwritten ext4: factor out bh handles to ext4_da_get_block_prep() ext4: use reserved metadata blocks when splitting extent in endio ext4: introduce seq counter for extent entry ext4: add a new iomap aops for regular file's buffered IO path ext4: implement buffered read iomap path ext4: implement buffered write iomap path ext4: implement writeback iomap path ext4: implement mmap iomap path ext4: implement zero_range iomap path ext4: writeback partial blocks before zero range ext4: fall back to buffer_head path for defrag ext4: partially enable iomap for regular file's buffered IO path filemap: support disable large folios on active inode ext4: enable large folio for regular file with iomap buffered IO path fs/ext4/ext4.h | 14 +- fs/ext4/ext4_jbd2.c | 6 + fs/ext4/ext4_jbd2.h | 7 + fs/ext4/extents.c | 145 +++++--- fs/ext4/extents_status.c | 39 ++- fs/ext4/extents_status.h | 4 +- fs/ext4/file.c | 19 +- fs/ext4/ialloc.c | 5 + fs/ext4/inode.c | 638 +++++++++++++++++++++++++++++------- fs/ext4/move_extent.c | 35 ++ fs/ext4/page-io.c | 107 ++++++ fs/ext4/super.c | 3 + fs/iomap/buffered-io.c | 7 +- fs/iomap/trace.h | 43 ++- include/linux/pagemap.h | 13 + include/trace/events/ext4.h | 31 +- mm/readahead.c | 6 +- 17 files changed, 921 insertions(+), 201 deletions(-) -- 2.39.2
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