linux-rng/fs/jbd2, branch master

jbd2: ensure that all ongoing I/O complete before freeing blocks

2025-10-10T17:10:06Z

When releasing file system metadata blocks in jbd2_journal_forget(), if this buffer has not yet been checkpointed, it may have already been written back, currently be in the process of being written back, or has not yet written back. jbd2_journal_forget() calls jbd2_journal_try_remove_checkpoint() to check the buffer's status and add it to the current transaction if it has not been written back. This buffer can only be reallocated after the transaction is committed. jbd2_journal_try_remove_checkpoint() attempts to lock the buffer and check its dirty status while holding the buffer lock. If the buffer has already been written back, everything proceeds normally. However, there are two issues. First, the function returns immediately if the buffer is locked by the write-back process. It does not wait for the write-back to complete. Consequently, until the current transaction is committed and the block is reallocated, there is no guarantee that the I/O will complete. This means that ongoing I/O could write stale metadata to the newly allocated block, potentially corrupting data. Second, the function unlocks the buffer as soon as it detects that the buffer is still dirty. If a concurrent write-back occurs immediately after this unlocking and before clear_buffer_dirty() is called in jbd2_journal_forget(), data corruption can theoretically still occur. Although these two issues are unlikely to occur in practice since the undergoing metadata writeback I/O does not take this long to complete, it's better to explicitly ensure that all ongoing I/O operations are completed. Fixes: 597599268e3b ("jbd2: discard dirty data when forgetting an un-journalled buffer") Cc: stable@kernel.org Suggested-by: Jan Kara Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Message-ID: <20250916093337.3161016-2-yi.zhang@huaweicloud.com> Signed-off-by: Theodore Ts'o

jbd2: increase IO priority of checkpoint

2025-09-25T18:37:07Z

In commit 6a3afb6ac6df ("jbd2: increase the journal IO's priority"), the priority of IOs initiated by jbd2 has been raised, exempting them from WBT throttling. Checkpoint is also a crucial operation of jbd2. While no serious issues have been observed so far, it should still be reasonable to exempt checkpoint from WBT throttling. Signed-off-by: Julian Sun Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Signed-off-by: Theodore Ts'o

jbd2: prevent softlockup in jbd2_log_do_checkpoint()

2025-08-13T18:24:14Z

Both jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list() periodically release j_list_lock after processing a batch of buffers to avoid long hold times on the j_list_lock. However, since both functions contend for j_list_lock, the combined time spent waiting and processing can be significant. jbd2_journal_shrink_checkpoint_list() explicitly calls cond_resched() when need_resched() is true to avoid softlockups during prolonged operations. But jbd2_log_do_checkpoint() only exits its loop when need_resched() is true, relying on potentially sleeping functions like __flush_batch() or wait_on_buffer() to trigger rescheduling. If those functions do not sleep, the kernel may hit a softlockup. watchdog: BUG: soft lockup - CPU#3 stuck for 156s! [kworker/u129:2:373] CPU: 3 PID: 373 Comm: kworker/u129:2 Kdump: loaded Not tainted 6.6.0+ #10 Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.27 06/13/2017 Workqueue: writeback wb_workfn (flush-7:2) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : native_queued_spin_lock_slowpath+0x358/0x418 lr : jbd2_log_do_checkpoint+0x31c/0x438 [jbd2] Call trace: native_queued_spin_lock_slowpath+0x358/0x418 jbd2_log_do_checkpoint+0x31c/0x438 [jbd2] __jbd2_log_wait_for_space+0xfc/0x2f8 [jbd2] add_transaction_credits+0x3bc/0x418 [jbd2] start_this_handle+0xf8/0x560 [jbd2] jbd2__journal_start+0x118/0x228 [jbd2] __ext4_journal_start_sb+0x110/0x188 [ext4] ext4_do_writepages+0x3dc/0x740 [ext4] ext4_writepages+0xa4/0x190 [ext4] do_writepages+0x94/0x228 __writeback_single_inode+0x48/0x318 writeback_sb_inodes+0x204/0x590 __writeback_inodes_wb+0x54/0xf8 wb_writeback+0x2cc/0x3d8 wb_do_writeback+0x2e0/0x2f8 wb_workfn+0x80/0x2a8 process_one_work+0x178/0x3e8 worker_thread+0x234/0x3b8 kthread+0xf0/0x108 ret_from_fork+0x10/0x20 So explicitly call cond_resched() in jbd2_log_do_checkpoint() to avoid softlockup. Cc: stable@kernel.org Signed-off-by: Baokun Li Link: https://patch.msgid.link/20250812063752.912130-1-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37Z

Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

jbd2: remove journal_t argument from jbd2_superblock_csum()

2025-05-20T14:31:12Z

Since jbd2_superblock_csum() no longer uses its journal_t argument, remove it. Signed-off-by: Eric Biggers Reviewed-by: Baokun Li Link: https://patch.msgid.link/20250513053809.699974-5-ebiggers@kernel.org Signed-off-by: Theodore Ts'o

jbd2: remove journal_t argument from jbd2_chksum()

2025-05-20T14:31:12Z

Since jbd2_chksum() no longer uses its journal_t argument, remove it. Signed-off-by: Eric Biggers Reviewed-by: Baokun Li Link: https://patch.msgid.link/20250513053809.699974-4-ebiggers@kernel.org Signed-off-by: Theodore Ts'o

ext4/jbd2: convert jbd2_journal_blocks_per_page() to support large folio

2025-05-20T14:31:12Z

jbd2_journal_blocks_per_page() returns the number of blocks in a single page. Rename it to jbd2_journal_blocks_per_folio() and make it returns the number of blocks in the largest folio, preparing for the calculation of journal credits blocks when allocating blocks within a large folio in the writeback path. Signed-off-by: Zhang Yi Link: https://patch.msgid.link/20250512063319.3539411-5-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

jbd2: fix data-race and null-ptr-deref in jbd2_journal_dirty_metadata()

2025-05-20T14:30:37Z

Since handle->h_transaction may be a NULL pointer, so we should change it to call is_handle_aborted(handle) first before dereferencing it. And the following data-race was reported in my fuzzer: ================================================================== BUG: KCSAN: data-race in jbd2_journal_dirty_metadata / jbd2_journal_dirty_metadata write to 0xffff888011024104 of 4 bytes by task 10881 on cpu 1: jbd2_journal_dirty_metadata+0x2a5/0x770 fs/jbd2/transaction.c:1556 __ext4_handle_dirty_metadata+0xe7/0x4b0 fs/ext4/ext4_jbd2.c:358 ext4_do_update_inode fs/ext4/inode.c:5220 [inline] ext4_mark_iloc_dirty+0x32c/0xd50 fs/ext4/inode.c:5869 __ext4_mark_inode_dirty+0xe1/0x450 fs/ext4/inode.c:6074 ext4_dirty_inode+0x98/0xc0 fs/ext4/inode.c:6103 .... read to 0xffff888011024104 of 4 bytes by task 10880 on cpu 0: jbd2_journal_dirty_metadata+0xf2/0x770 fs/jbd2/transaction.c:1512 __ext4_handle_dirty_metadata+0xe7/0x4b0 fs/ext4/ext4_jbd2.c:358 ext4_do_update_inode fs/ext4/inode.c:5220 [inline] ext4_mark_iloc_dirty+0x32c/0xd50 fs/ext4/inode.c:5869 __ext4_mark_inode_dirty+0xe1/0x450 fs/ext4/inode.c:6074 ext4_dirty_inode+0x98/0xc0 fs/ext4/inode.c:6103 .... value changed: 0x00000000 -> 0x00000001 ================================================================== This issue is caused by missing data-race annotation for jh->b_modified. Therefore, the missing annotation needs to be added. Reported-by: syzbot+de24c3fe3c4091051710@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=de24c3fe3c4091051710 Fixes: 6e06ae88edae ("jbd2: speedup jbd2_journal_dirty_metadata()") Signed-off-by: Jeongjun Park Reviewed-by: Jan Kara Link: https://patch.msgid.link/20250514130855.99010-1-aha310510@gmail.com Signed-off-by: Theodore Ts'o Cc: stable@kernel.org

ext4: rework fast commit commit path

2025-05-09T01:56:17Z

This patch reworks fast commit's commit path to remove locking the journal for the entire duration of a fast commit. Instead, we only lock the journal while marking all the eligible inodes as "committing". This allows handles to make progress in parallel with the fast commit. Signed-off-by: Harshad Shirwadkar Link: https://patch.msgid.link/20250508175908.1004880-5-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o

fs/jbd2: use sleeping version of __find_get_block()

2025-04-22T16:16:08Z

Convert to the new nonatomic flavor to benefit from potential performance benefits and adapt in the future vs migration such that semantics are kept. - jbd2_journal_revoke(): can sleep (has might_sleep() in the beginning) - jbd2_journal_cancel_revoke(): only used from do_get_write_access() and do_get_create_access() which do sleep. So can sleep. - jbd2_clear_buffer_revoked_flags() - only called from journal commit code which sleeps. So can sleep. Suggested-by: Jan Kara Reviewed-by: Jan Kara Signed-off-by: Davidlohr Bueso Link: https://kdevops.org/ext4/v6.15-rc2.html # [0] Link: https://lore.kernel.org/all/aAAEvcrmREWa1SKF@bombadil.infradead.org/ # [1] Link: https://lore.kernel.org/20250418015921.132400-6-dave@stgolabs.net Tested-by: kdevops@lists.linux.dev Reviewed-by: Luis Chamberlain Signed-off-by: Christian Brauner