kernel.git/fs/nilfs2/segment.c, branch linux-6.10.y

nilfs2: fix state management in error path of log writing function

2024-09-12T09:12:48Z

commit 6576dd6695f2afca3f4954029ac4a64f82ba60ab upstream. After commit a694291a6211 ("nilfs2: separate wait function from nilfs_segctor_write") was applied, the log writing function nilfs_segctor_do_construct() was able to issue I/O requests continuously even if user data blocks were split into multiple logs across segments, but two potential flaws were introduced in its error handling. First, if nilfs_segctor_begin_construction() fails while creating the second or subsequent logs, the log writing function returns without calling nilfs_segctor_abort_construction(), so the writeback flag set on pages/folios will remain uncleared. This causes page cache operations to hang waiting for the writeback flag. For example, truncate_inode_pages_final(), which is called via nilfs_evict_inode() when an inode is evicted from memory, will hang. Second, the NILFS_I_COLLECTED flag set on normal inodes remain uncleared. As a result, if the next log write involves checkpoint creation, that's fine, but if a partial log write is performed that does not, inodes with NILFS_I_COLLECTED set are erroneously removed from the "sc_dirty_files" list, and their data and b-tree blocks may not be written to the device, corrupting the block mapping. Fix these issues by uniformly calling nilfs_segctor_abort_construction() on failure of each step in the loop in nilfs_segctor_do_construct(), having it clean up logs and segment usages according to progress, and correcting the conditions for calling nilfs_redirty_inodes() to ensure that the NILFS_I_COLLECTED flag is cleared. Link: https://lkml.kernel.org/r/20240814101119.4070-1-konishi.ryusuke@gmail.com Fixes: a694291a6211 ("nilfs2: separate wait function from nilfs_segctor_write") Signed-off-by: Ryusuke Konishi Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro

2024-08-03T07:00:25Z

[ Upstream commit 0f3819e8c483771a59cf9d3190cd68a7a990083c ] According to the C standard 3.4.3p3, the result of signed integer overflow is undefined. The macro nilfs_cnt32_ge(), which compares two sequence numbers, uses signed integer subtraction that can overflow, and therefore the result of the calculation may differ from what is expected due to undefined behavior in different environments. Similar to an earlier change to the jiffies-related comparison macros in commit 5a581b367b5d ("jiffies: Avoid undefined behavior from signed overflow"), avoid this potential issue by changing the definition of the macro to perform the subtraction as unsigned integers, then cast the result to a signed integer for comparison. Link: https://lkml.kernel.org/r/20130727225828.GA11864@linux.vnet.ibm.com Link: https://lkml.kernel.org/r/20240702183512.6390-1-konishi.ryusuke@gmail.com Fixes: 9ff05123e3bf ("nilfs2: segment constructor") Signed-off-by: Ryusuke Konishi Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

nilfs2: fix potential kernel bug due to lack of writeback flag waiting

2024-06-06T02:19:24Z

Destructive writes to a block device on which nilfs2 is mounted can cause a kernel bug in the folio/page writeback start routine or writeback end routine (__folio_start_writeback in the log below): kernel BUG at mm/page-writeback.c:3070! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI ... RIP: 0010:__folio_start_writeback+0xbaa/0x10e0 Code: 25 ff 0f 00 00 0f 84 18 01 00 00 e8 40 ca c6 ff e9 17 f6 ff ff e8 36 ca c6 ff 4c 89 f7 48 c7 c6 80 c0 12 84 e8 e7 b3 0f 00 90 <0f> 0b e8 1f ca c6 ff 4c 89 f7 48 c7 c6 a0 c6 12 84 e8 d0 b3 0f 00 ... Call Trace: nilfs_segctor_do_construct+0x4654/0x69d0 [nilfs2] nilfs_segctor_construct+0x181/0x6b0 [nilfs2] nilfs_segctor_thread+0x548/0x11c0 [nilfs2] kthread+0x2f0/0x390 ret_from_fork+0x4b/0x80 ret_from_fork_asm+0x1a/0x30 This is because when the log writer starts a writeback for segment summary blocks or a super root block that use the backing device's page cache, it does not wait for the ongoing folio/page writeback, resulting in an inconsistent writeback state. Fix this issue by waiting for ongoing writebacks when putting folios/pages on the backing device into writeback state. Link: https://lkml.kernel.org/r/20240530141556.4411-1-konishi.ryusuke@gmail.com Fixes: 9ff05123e3bf ("nilfs2: segment constructor") Signed-off-by: Ryusuke Konishi Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton

nilfs2: fix potential hang in nilfs_detach_log_writer()

2024-05-24T18:55:07Z

Syzbot has reported a potential hang in nilfs_detach_log_writer() called during nilfs2 unmount. Analysis revealed that this is because nilfs_segctor_sync(), which synchronizes with the log writer thread, can be called after nilfs_segctor_destroy() terminates that thread, as shown in the call trace below: nilfs_detach_log_writer nilfs_segctor_destroy nilfs_segctor_kill_thread --> Shut down log writer thread flush_work nilfs_iput_work_func nilfs_dispose_list iput nilfs_evict_inode nilfs_transaction_commit nilfs_construct_segment (if inode needs sync) nilfs_segctor_sync --> Attempt to synchronize with log writer thread *** DEADLOCK *** Fix this issue by changing nilfs_segctor_sync() so that the log writer thread returns normally without synchronizing after it terminates, and by forcing tasks that are already waiting to complete once after the thread terminates. The skipped inode metadata flushout will then be processed together in the subsequent cleanup work in nilfs_segctor_destroy(). Link: https://lkml.kernel.org/r/20240520132621.4054-4-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+e3973c409251e136fdd0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e3973c409251e136fdd0 Tested-by: Ryusuke Konishi Cc: Cc: "Bai, Shuangpeng" Signed-off-by: Andrew Morton

nilfs2: fix unexpected freezing of nilfs_segctor_sync()

2024-05-24T18:55:07Z

A potential and reproducible race issue has been identified where nilfs_segctor_sync() would block even after the log writer thread writes a checkpoint, unless there is an interrupt or other trigger to resume log writing. This turned out to be because, depending on the execution timing of the log writer thread running in parallel, the log writer thread may skip responding to nilfs_segctor_sync(), which causes a call to schedule() waiting for completion within nilfs_segctor_sync() to lose the opportunity to wake up. The reason why waking up the task waiting in nilfs_segctor_sync() may be skipped is that updating the request generation issued using a shared sequence counter and adding an wait queue entry to the request wait queue to the log writer, are not done atomically. There is a possibility that log writing and request completion notification by nilfs_segctor_wakeup() may occur between the two operations, and in that case, the wait queue entry is not yet visible to nilfs_segctor_wakeup() and the wake-up of nilfs_segctor_sync() will be carried over until the next request occurs. Fix this issue by performing these two operations simultaneously within the lock section of sc_state_lock. Also, following the memory barrier guidelines for event waiting loops, move the call to set_current_state() in the same location into the event waiting loop to ensure that a memory barrier is inserted just before the event condition determination. Link: https://lkml.kernel.org/r/20240520132621.4054-3-konishi.ryusuke@gmail.com Fixes: 9ff05123e3bf ("nilfs2: segment constructor") Signed-off-by: Ryusuke Konishi Tested-by: Ryusuke Konishi Cc: Cc: "Bai, Shuangpeng" Signed-off-by: Andrew Morton

nilfs2: fix use-after-free of timer for log writer thread

2024-05-24T18:55:07Z

Patch series "nilfs2: fix log writer related issues". This bug fix series covers three nilfs2 log writer-related issues, including a timer use-after-free issue and potential deadlock issue on unmount, and a potential freeze issue in event synchronization found during their analysis. Details are described in each commit log. This patch (of 3): A use-after-free issue has been reported regarding the timer sc_timer on the nilfs_sc_info structure. The problem is that even though it is used to wake up a sleeping log writer thread, sc_timer is not shut down until the nilfs_sc_info structure is about to be freed, and is used regardless of the thread's lifetime. Fix this issue by limiting the use of sc_timer only while the log writer thread is alive. Link: https://lkml.kernel.org/r/20240520132621.4054-1-konishi.ryusuke@gmail.com Link: https://lkml.kernel.org/r/20240520132621.4054-2-konishi.ryusuke@gmail.com Fixes: fdce895ea5dd ("nilfs2: change sc_timer from a pointer to an embedded one in struct nilfs_sc_info") Signed-off-by: Ryusuke Konishi Reported-by: "Bai, Shuangpeng" Closes: https://groups.google.com/g/syzkaller/c/MK_LYqtt8ko/m/8rgdWeseAwAJ Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton

Merge tag 'pull-bd_inode-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2024-05-21T16:51:42Z

Pull bdev bd_inode updates from Al Viro: "Replacement of bdev->bd_inode with sane(r) set of primitives by me and Yu Kuai" * tag 'pull-bd_inode-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: RIP ->bd_inode dasd_format(): killing the last remaining user of ->bd_inode nilfs_attach_log_writer(): use ->bd_mapping->host instead of ->bd_inode block/bdev.c: use the knowledge of inode/bdev coallocation gfs2: more obvious initializations of mapping->host fs/buffer.c: massage the remaining users of ->bd_inode to ->bd_mapping blk_ioctl_{discard,zeroout}(): we only want ->bd_inode->i_mapping here... grow_dev_folio(): we only want ->bd_inode->i_mapping there use ->bd_mapping instead of ->bd_inode->i_mapping block_device: add a pointer to struct address_space (page cache of bdev) missing helpers: bdev_unhash(), bdev_drop() block: move two helpers into bdev.c block2mtd: prevent direct access of bd_inode dm-vdo: use bdev_nr_bytes(bdev) instead of i_size_read(bdev->bd_inode) blkdev_write_iter(): saner way to get inode and bdev bcachefs: remove dead function bdev_sectors() ext4: remove block_device_ejected() erofs_buf: store address_space instead of inode erofs: switch erofs_bread() to passing offset instead of block number

nilfs2: remove calls to folio_set_error() and folio_clear_error()

2024-05-11T22:51:43Z

Nobody checks this flag on nilfs2 folios, stop setting and clearing it. That lets us simplify nilfs_end_folio_io() slightly. Link: https://lkml.kernel.org/r/20240420025029.2166544-17-willy@infradead.org Link: https://lkml.kernel.org/r/20240430050901.3239-1-konishi.ryusuke@gmail.com Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Ryusuke Konishi Cc: kernel test robot Cc: Peter Zijlstra Cc: Song Liu Signed-off-by: Andrew Morton

nilfs_attach_log_writer(): use ->bd_mapping->host instead of ->bd_inode

2024-05-03T06:36:55Z

I suspect that inode_attach_wb() use is rather unidiomatic, but that's a separate story - in any case, its use is a few times per mount *and* the route by which we access that inode is "the host of address_space a page belongs to". Signed-off-by: Al Viro

nilfs2: localize highmem mapping for checkpoint finalization within cpfile

2024-02-22T23:38:53Z

Move the checkpoint finalization routine to the cpfile side, and make the page mapping local and temporary. And use kmap_local instead of kmap to access the checkpoint entry page when finalizing a checkpoint. In this conversion, some of the information on the checkpoint entry being rewritten is passed through the arguments of the newly added method nilfs_cpfile_finalize_checkpoint(). Link: https://lkml.kernel.org/r/20240122140202.6950-13-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Signed-off-by: Andrew Morton