kernel.git/fs/ext4/ext4.h, branch linux-6.5.y

ext4: fix race between writepages and remount

2023-11-28T17:15:16Z

commit 745f17a4166e79315e4b7f33ce89d03e75a76983 upstream. We got a WARNING in ext4_add_complete_io: ================================================================== WARNING: at fs/ext4/page-io.c:231 ext4_put_io_end_defer+0x182/0x250 CPU: 10 PID: 77 Comm: ksoftirqd/10 Tainted: 6.3.0-rc2 #85 RIP: 0010:ext4_put_io_end_defer+0x182/0x250 [ext4] [...] Call Trace: ext4_end_bio+0xa8/0x240 [ext4] bio_endio+0x195/0x310 blk_update_request+0x184/0x770 scsi_end_request+0x2f/0x240 scsi_io_completion+0x75/0x450 scsi_finish_command+0xef/0x160 scsi_complete+0xa3/0x180 blk_complete_reqs+0x60/0x80 blk_done_softirq+0x25/0x40 __do_softirq+0x119/0x4c8 run_ksoftirqd+0x42/0x70 smpboot_thread_fn+0x136/0x3c0 kthread+0x140/0x1a0 ret_from_fork+0x2c/0x50 ================================================================== Above issue may happen as follows: cpu1 cpu2 ----------------------------|---------------------------- mount -o dioread_lock ext4_writepages ext4_do_writepages *if (ext4_should_dioread_nolock(inode))* // rsv_blocks is not assigned here mount -o remount,dioread_nolock ext4_journal_start_with_reserve __ext4_journal_start __ext4_journal_start_sb jbd2__journal_start *if (rsv_blocks)* // h_rsv_handle is not initialized here mpage_map_and_submit_extent mpage_map_one_extent dioread_nolock = ext4_should_dioread_nolock(inode) if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) mpd->io_submit.io_end->handle = handle->h_rsv_handle ext4_set_io_unwritten_flag io_end->flag |= EXT4_IO_END_UNWRITTEN // now io_end->handle is NULL but has EXT4_IO_END_UNWRITTEN flag scsi_finish_command scsi_io_completion scsi_io_completion_action scsi_end_request blk_update_request req_bio_endio bio_endio bio->bi_end_io > ext4_end_bio ext4_put_io_end_defer ext4_add_complete_io // trigger WARN_ON(!io_end->handle && sbi->s_journal); The immediate cause of this problem is that ext4_should_dioread_nolock() function returns inconsistent values in the ext4_do_writepages() and mpage_map_one_extent(). There are four conditions in this function that can be changed at mount time to cause this problem. These four conditions can be divided into two categories: (1) journal_data and EXT4_EXTENTS_FL, which can be changed by ioctl (2) DELALLOC and DIOREAD_NOLOCK, which can be changed by remount The two in the first category have been fixed by commit c8585c6fcaf2 ("ext4: fix races between changing inode journal mode and ext4_writepages") and commit cb85f4d23f79 ("ext4: fix race between writepages and enabling EXT4_EXTENTS_FL") respectively. Two cases in the other category have not yet been fixed, and the above issue is caused by this situation. We refer to the fix for the first category, when applying options during remount, we grab s_writepages_rwsem to avoid racing with writepages ops to trigger this problem. Fixes: 6b523df4fb5a ("ext4: use transaction reservation for extent conversion in ext4_end_io") Cc: stable@vger.kernel.org Signed-off-by: Baokun Li Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230524072538.2883391-1-libaokun1@huawei.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

ext4: add correct group descriptors and reserved GDT blocks to system zone

2023-09-19T10:30:22Z

commit 68228da51c9a436872a4ef4b5a7692e29f7e5bc7 upstream. When setup_system_zone, flex_bg is not initialized so it is always 1. Use a new helper function, ext4_num_base_meta_blocks() which does not depend on sbi->s_log_groups_per_flex being initialized. [ Squashed two patches in the Link URL's below together into a single commit, which is simpler to review/understand. Also fix checkpatch warnings. --TYT ] Cc: stable@kernel.org Signed-off-by: Wang Jianjian Link: https://lore.kernel.org/r/tencent_21AF0D446A9916ED5C51492CC6C9A0A77B05@qq.com Link: https://lore.kernel.org/r/tencent_D744D1450CC169AEA77FCF0A64719909ED05@qq.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2023-06-29T20:18:36Z

Pull ext4 updates from Ted Ts'o: "Various cleanups and bug fixes in ext4's extent status tree, journalling, and block allocator subsystems. Also improve performance for parallel DIO overwrites" * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (55 commits) ext4: avoid updating the superblock on a r/o mount if not needed jbd2: skip reading super block if it has been verified ext4: fix to check return value of freeze_bdev() in ext4_shutdown() ext4: refactoring to use the unified helper ext4_quotas_off() ext4: turn quotas off if mount failed after enabling quotas ext4: update doc about journal superblock description ext4: add journal cycled recording support jbd2: continue to record log between each mount jbd2: remove j_format_version jbd2: factor out journal initialization from journal_get_superblock() jbd2: switch to check format version in superblock directly jbd2: remove unused feature macros ext4: ext4_put_super: Remove redundant checking for 'sbi->s_journal_bdev' ext4: Fix reusing stale buffer heads from last failed mounting ext4: allow concurrent unaligned dio overwrites ext4: clean up mballoc criteria comments ext4: make ext4_zeroout_es() return void ext4: make ext4_es_insert_extent() return void ext4: make ext4_es_insert_delayed_block() return void ext4: make ext4_es_remove_extent() return void ...

ext4: clean up mballoc criteria comments

2023-06-26T23:35:12Z

Line wrap and slightly clarify the comments describing mballoc's cirtiera. Define EXT4_MB_NUM_CRS as part of the enum, so that it will automatically get updated when criteria is added or removed. Also fix a potential unitialized use of 'cr' variable if CONFIG_EXT4_DEBUG is enabled. Signed-off-by: Theodore Ts'o

ext4: Give symbolic names to mballoc criterias

2023-06-26T23:34:56Z

mballoc criterias have historically been called by numbers like CR0, CR1... however this makes it confusing to understand what each criteria is about. Change these criterias from numbers to symbolic names and add relevant comments. While we are at it, also reformat and add some comments to ext4_seq_mb_stats_show() for better readability. Additionally, define CR_FAST which signifies the criteria below which we can make quicker decisions like: * quitting early if (free block < requested len) * avoiding to scan free extents smaller than required len. * avoiding to initialize buddy cache and work with existing cache * limiting prefetches Suggested-by: Jan Kara Signed-off-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/a2dc6ec5aea5e5e68cf8e788c2a964ffead9c8b0.1685449706.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o

ext4: Add allocation criteria 1.5 (CR1_5)

2023-06-26T23:34:56Z

CR1_5 aims to optimize allocations which can't be satisfied in CR1. The fact that we couldn't find a group in CR1 suggests that it would be difficult to find a continuous extent to compleltely satisfy our allocations. So before falling to the slower CR2, in CR1.5 we proactively trim the the preallocations so we can find a group with (free / fragments) big enough. This speeds up our allocation at the cost of slightly reduced preallocation. The patch also adds a new sysfs tunable: * /sys/fs/ext4//mb_cr1_5_max_trim_order This controls how much CR1.5 can trim a request before falling to CR2. For example, for a request of order 7 and max trim order 2, CR1.5 can trim this upto order 5. Suggested-by: Ritesh Harjani (IBM) Signed-off-by: Ojaswin Mujoo Reviewed-by: Ritesh Harjani (IBM) Link: https://lore.kernel.org/r/150fdf65c8e4cc4dba71e020ce0859bcf636a5ff.1685449706.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o

ext4: Add counter to track successful allocation of goal length

2023-06-26T23:34:56Z

Track number of allocations where the length of blocks allocated is equal to the length of goal blocks (post normalization). This metric could be useful if making changes to the allocator logic in the future as it could give us visibility into how often do we trim our requests. PS: ac_b_ex.fe_len might get modified due to preallocation efforts and hence we use ac_f_ex.fe_len instead since we want to compare how much the allocator was able to actually find. Signed-off-by: Ojaswin Mujoo Reviewed-by: Ritesh Harjani (IBM) Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/343620e2be8a237239ea2613a7a866ee8607e973.1685449706.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o

ext4: Add per CR extent scanned counter

2023-06-26T23:34:56Z

This gives better visibility into the number of extents scanned in each particular CR. For example, this information can be used to see how out block group scanning logic is performing when the BG is fragmented. Signed-off-by: Ojaswin Mujoo Reviewed-by: Ritesh Harjani (IBM) Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/55bb6d80f6e22ed2a5a830aa045572bdffc8b1b9.1685449706.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o

ext4: Convert mballoc cr (criteria) to enum

2023-06-26T23:34:56Z

Convert criteria to be an enum so it easier to maintain and update the tracefiles to use enum names. This change also makes it easier to insert new criterias in the future. There is no functional change in this patch. Signed-off-by: Ojaswin Mujoo Reviewed-by: Ritesh Harjani (IBM) Link: https://lore.kernel.org/r/5d82fd467bdf70ea45bdaef810af3b146013946c.1685449706.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o

ext4: Remove unused extern variables declaration

2023-06-26T23:34:56Z

ext4_mb_stats & ext4_mb_max_to_scan are never used. We use sbi->s_mb_stats and sbi->s_mb_max_to_scan instead. Hence kill these extern declarations. Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Ojaswin Mujoo Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/928b3142062172533b6d1b5a94de94700590fef3.1685449706.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o