kernel/git/stable/linux.git/fs/jbd2, branch master

ext4: enable scoped NOFS when starting a handle in nojournal mode

2026-07-23T03:47:06+00:00

The jbd2 layer enables NOFS mode using memalloc_nofs_{save,restore}() while a handle is active. We need to do the same in nojournal mode so that it is safe to remove GFP_NOFS flags while a jbd2 handle is active. This will require that we actually allocate a real handle, but with an h_invalid flag set, so there is a place to put the saved memalloc context. Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger

jbd2: bound shrinker scans by examined checkpoint buffers

2026-07-22T16:36:24+00:00

The jbd2 shrinker currently accounts only checkpoint buffers that it successfully releases against nr_to_scan. Busy buffers therefore do not consume the scan budget. If a checkpoint transaction contains mostly busy buffers, the shrinker can scan its entire checkpoint list while holding journal->j_list_lock. Large checkpoint lists can result in excessive lock hold times and leave other CPUs spinning on j_list_lock, causing soft lockups or RCU stalls. Pass nr_to_scan into journal_shrink_one_cp_list() and decrement it for every buffer examined, including busy buffers. Pass NULL from checkpoint cleanup paths so their existing full-list behavior is preserved. This restores the scan-budget semantics that existed before journal_shrink_one_cp_list() was changed to always scan a complete checkpoint list. Fixes: b98dba273a0e ("jbd2: remove journal_clean_one_cp_list()") Cc: stable@vger.kernel.org Signed-off-by: Max Kellermann Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Link: https://patch.msgid.link/20260713102229.1598812-3-max.kellermann@ionos.com Signed-off-by: Theodore Ts'o

jbd2: check need_resched() when skipping busy checkpoint buffers

2026-07-22T16:36:24+00:00

journal_shrink_one_cp_list() skips busy checkpoint buffers when called with JBD2_SHRINK_BUSY_SKIP. The continue statement on this path also skips the need_resched() check at the end of the loop body. Consequently, when a checkpoint list contains mostly busy buffers, the shrinker can walk the entire list while holding journal->j_list_lock, even when a reschedule has been requested. Large checkpoint lists under memory pressure can therefore cause long lock hold times and leave other CPUs spinning on j_list_lock, resulting in soft lockups or RCU stalls. Route the busy-buffer path through the need_resched() check so that the shrinker can release j_list_lock and reschedule promptly, restoring parity with the clean-buffer path, which already checks need_resched(). This does not change which checkpoint buffers are eligible for removal. Fixes: b98dba273a0e ("jbd2: remove journal_clean_one_cp_list()") Cc: stable@vger.kernel.org Signed-off-by: Max Kellermann Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Link: https://patch.msgid.link/20260713102229.1598812-2-max.kellermann@ionos.com Signed-off-by: Theodore Ts'o

Merge tag 'ext4_for_linus-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2026-06-18T16:42:02+00:00

Pull ext4 updates from Ted Ts'o: - A major rework of the fast commit mechanism to avoid lock contention and deadlocks. We also export snapshot statistics in /proc/fs/ext4/*/fc_info - Performance optimization for directory hash computation by processing input in 4-byte chunks and removing function pointers, along with new KUnit tests for directory hash - Cleanups in JBD2 to remove special slabs and use kmalloc() instead - Various bug fixes, including: - Early validation of donor superblock in EXT4_IOC_MOVE_EXT to avoid cross-fs deadlock - Fix for a kernel BUG in ext4_write_inline_data_end under data=journal - Fix for a NULL dereference in jbd2_journal_dirty_metadata when handle is aborted - Fix for an underflow in JBD2 fast commit block initialization check - Fix for LOGFLUSH shutdown ordering to ensure ordered data writeback - Miscellaneous fixes for error path return values and KUnit assertions * tag 'ext4_for_linus-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT ext4: fix kernel BUG in ext4_write_inline_data_end ext4: fix ERR_PTR(0) in ext4_mkdir() jbd2: remove special jbd2 slabs ext4: remove mention of PageWriteback ext4: improve str2hashbuf by processing 4-byte chunks and removing function pointers ext4: add Kunit coverage for directory hash computation ext4: fast commit: export snapshot stats in fc_info ext4: fast commit: add lock_updates tracepoint ext4: fast commit: avoid i_data_sem by dropping ext4_map_blocks() in snapshots ext4: fast commit: avoid self-deadlock in inode snapshotting ext4: fast commit: avoid waiting for FC_COMMITTING ext4: lockdep: handle i_data_sem subclassing for special inodes ext4: fast commit: snapshot inode state before writing log jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit() ext4: fix fast commit wait/wake bit mapping on 64-bit jbd2: check for aborted handle in jbd2_journal_dirty_metadata() ext4: Use %pe to print PTR_ERR() ext4: fix LOGFLUSH shutdown ordering to allow ordered-mode data writeback ext4: replace KUnit tests for memcmp() with KUNIT_ASSERT_MEMEQ()

Merge tag 'vfs-7.2-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-06-14T22:29:45+00:00

Pull misc vfs updates from Christian Brauner: "Features: - Reduce pipe->mutex contention by pre-allocating pages outside the lock in anon_pipe_write(). anon_pipe_write() called alloc_page() once per page while holding pipe->mutex. The allocation can sleep doing direct reclaim and runs memcg charging, which extends the critical section and stalls any concurrent reader on the same mutex. Now up to 8 pages are pre-allocated before the mutex is taken, leftovers are recycled into the per-pipe tmp_page[] cache before unlock, and any remainder is released after unlock, keeping the allocator out of the critical section on both sides. On a writers x readers sweep with 64KB writes against a 1 MB pipe throughput improves 6-28% and average write latency drops 5-22%; under memory pressure - when the cost of holding the mutex across reclaim is highest - throughput improves 21-48% and latency drops 17-33%. The microbenchmark is added to selftests. - uaccess/sockptr: fix the ignored_trailing logic in copy_struct_to_user() to behave as documented and the usize check in copy_struct_from_sockptr() for user pointers, and add copy_struct_{from,to}_bounce_buffer() and copy_struct_to_sockptr() helpers for upcoming users (IPPROTO_SMBDIRECT, IPPROTO_QUIC). - bpf: add a sleepable bpf_real_inode() kfunc that resolves the real inode backing a dentry via d_real_inode(). On overlayfs the inode attached to the dentry doesn't carry the underlying device information; this is used by the filesystem restriction BPF program that was merged into systemd. - docs: add guidelines for submitting new filesystems, motivated by the maintenance burden abandoned and untestable filesystems impose on VFS developers, blocking infrastructure work like folio conversions and iomap migration. Fixes: - libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo() and drop the now-redundant assignments in callers. This began as a one-line dma-buf fix for a path_noexec() warning; a pseudo filesystem has no reason not to set SB_I_NOEXEC. All init_pseudo() callers were audited: the only visible effect is on dma-buf where SB_I_NOEXEC silences the warning. - Handle set_blocksize() failures in legacy filesystems (bfs, hpfs, qnx4, jfs, befs, affs, isofs, minix, ntfs3, omfs). Mounting a device with a sector size > PAGE_SIZE crashed roughly half of them; the rest had the same missing error handling pattern. Plus a follow-up releasing the superblock buffer_head when setting the minix v3 block size fails. - mount: honour SB_NOUSER in the new mount API. - fs/fcntl: fix a SOFTIRQ-unsafe lock order in fasync signaling by switching the process-group paths of send_sigio() and send_sigurg() from read_lock(&tasklist_lock) to RCU, matching the single-PID path. - vfs: add an FS_USERNS_DELEGATABLE flag and set it for NFS, fixing delegated NFS mounts (fsopen() in a container with the mount performed by a privileged daemon) that broke when non-init s_user_ns was tied to FS_USERNS_MOUNT. - selftests/namespaces: fix a hang in nsid_test where an unreaped grandchild kept the TAP pipe write-end open, a waitpid(-1) race in listns_efault_test, and a false FAIL on kernels without listns() where the tests should SKIP. - filelock: fix the break_lease() stub signature for CONFIG_FILE_LOCKING=n. - init/initramfs_test: wait for the async initramfs unpacking before running; the test and do_populate_rootfs() share the parser state. - fs/coredump: reduce redundant log noise in validate_coredump_safety(). - iomap: pass the correct length to fserror_report_io() in __iomap_write_begin(). - backing-file: fix the backing_file_open() kerneldoc. Cleanups: - initramfs: refactor the cpio hex header parsing to use hex2bin() instead of the hand-rolled simple_strntoul() which is reverted, and extend the initramfs KUnit tests to cover header fields with 0x prefixes. - Replace __get_free_pages() and friends with kmalloc()/kzalloc() across quota, proc, ocfs2/dlm, nilfs2, nfs, nfsd, libfs, jfs, jbd2, isofs, fuse, select, namespace, configfs, binfmt_misc, bfs, and the do_mounts init code - part of the larger work of replacing page allocator calls with kmalloc(). - Use clear_and_wake_up_bit() in unlock_buffer() and journal_end_buffer_io_sync() instead of open-coding the sequence. - Drop unused VFS exports: unexport drop_super_exclusive(), remove start_removing_user_path_at(), and fold __start_removing_path() into start_removing_path(). - fs/read_write: narrow the __kernel_write() export with EXPORT_SYMBOL_FOR_MODULES(). - vfs: uapi: retire octal and hex constants in favor of (1 << n) for the O_ flags. Finding a free bit for a new flag across the architectures was needlessly hard with the mixed bases. - dcache: add extra sanity checks of dead dentries in dentry_free() via a new DENTRY_WARN_ONCE() that also prints d_flags. - iov_iter: use kmemdup_array() in dup_iter() to harden the allocation against multiplication overflow. - fs/pipe: write to ->poll_usage only once. - vfs: remove an always-taken if-branch in find_next_fd(). - dcache: use kmalloc_flex() for struct external_name in __d_alloc(). - namei: use QSTR() instead of QSTR_INIT() in path_pts(). - sync_file_range: delete dead S_ISLNK code. - Comment fixes: retire a stale comment in fget_task_next() and fix assorted spelling mistakes" * tag 'vfs-7.2-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (73 commits) backing-file: fix backing_file_open() kerneldoc parameter iomap: pass the correct len to fserror_report_io in __iomap_write_begin vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS filelock: fix break_lease() stub signature for CONFIG_FILE_LOCKING=n vfs: uapi: retire octal and hex numbers in favor of (1 << n) for O_ flags bpf: add bpf_real_inode() kfunc fs/read_write: Do not export __kernel_write() to the entire world libfs: drop redundant SB_I_NOEXEC/SB_I_NODEV in init_pseudo() callers libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo() mount: honour SB_NOUSER in the new mount API fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling selftests/pipe: add pipe_bench microbenchmark fs/pipe: pre-allocate pages outside pipe->mutex in anon_pipe_write fs: retire stale comment in fget_task_next() fs: fix spelling mistakes in comment bfs: replace get_zeroed_page() with kzalloc() binfmt_misc: replace __get_free_page() with kmalloc() configfs: replace __get_free_pages() with kzalloc() fs/namespace: use __getname() to allocate mntpath buffer fs/select: replace __get_free_page() with kmalloc() ...

jbd2: remove special jbd2 slabs

2026-06-10T14:42:55+00:00

When jbd2 was originally written, kmalloc() would not guarantee memory alignment for the requested objects. Since commit 59bb47985c1d in 2019, kmalloc has guaranteed natural alignment for power-of-two allocations. We can now remove the jbd2 special slabs and just use kmalloc() directly. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Jan Kara Acked-by: Mike Rapoport (Microsoft) Acked-by: Vlastimil Babka (SUSE) Reviewed-by: Tal Zussman Link: https://patch.msgid.link/20260528171413.1088143-1-willy@infradead.org Signed-off-by: Theodore Ts'o

jbd2: Convert jbd2_write_superblock() to bh_submit()

2026-06-04T08:28:08+00:00

Avoid an extra indirect function call and changing the buffer refcount by using bh_submit() instead of submit_bh(). Signed-off-by: Matthew Wilcox (Oracle) Link: https://patch.msgid.link/20260528173150.1093780-18-willy@infradead.org Acked-by: Theodore Ts'o Reviewed-by: Jan Kara Cc: linux-ext4@vger.kernel.org Signed-off-by: Christian Brauner (Amutable)

jbd2: Convert journal commit to bh_submit()

2026-06-04T08:28:08+00:00

Avoid an extra indirect function call by using bh_submit() instead of submit_bh() in journal_submit_commit_record() and jbd2_journal_commit_transaction(). These both use journal_end_buffer_io_sync(), so it's more straightforward to do them both at once. Signed-off-by: Matthew Wilcox (Oracle) Link: https://patch.msgid.link/20260528173150.1093780-17-willy@infradead.org Acked-by: Theodore Ts'o Reviewed-by: Jan Kara Cc: linux-ext4@vger.kernel.org Signed-off-by: Christian Brauner (Amutable)

jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()

2026-06-03T14:24:01+00:00

jbd2_journal_initialize_fast_commit() validates journal capacity by checking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS). Both j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds j_last the subtraction wraps to a large value, bypassing the bounds check. The resulting underflow corrupts j_last, j_fc_first, and j_free, leading to journal abort. Fix by checking num_fc_blks against j_last before the subtraction, returning -EFSCORRUPTED. Fixes: 6866d7b3f2bb ("ext4 / jbd2: add fast commit initialization") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Junrui Luo Fixes: e029c5f27987 ("ext4: make num of fast commit blocks configurable") Reviewed-by: Baokun Li Fixes: e029c5f279872 ("ext4: make num of fast commit blocks configurable") Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Link: https://patch.msgid.link/SYBPR01MB7881663C927DE9D7BBF4D1DFAF062@SYBPR01MB7881.ausprd01.prod.outlook.com Signed-off-by: Theodore Ts'o

jbd2: check for aborted handle in jbd2_journal_dirty_metadata()

2026-06-03T14:08:21+00:00

jbd2_journal_dirty_metadata() unconditionally dereferences handle->h_transaction at function entry to obtain the journal pointer: transaction_t *transaction = handle->h_transaction; journal_t *journal = transaction->t_journal; However, h_transaction may legitimately be NULL for an aborted handle. The is_handle_aborted() helper in include/linux/jbd2.h explicitly treats !h_transaction as one of the aborted states: if (handle->h_aborted || !handle->h_transaction) return 1; Every other entry point in fs/jbd2/transaction.c (jbd2_journal_get_{write,undo,create}_access, jbd2_journal_extend, jbd2_journal_restart, jbd2_journal_stop, etc.) guards against this with an is_handle_aborted() check before any dereference of h_transaction. jbd2_journal_dirty_metadata() was missing this guard. This is reachable from ocfs2's xattr code. ocfs2_xa_set() intentionally falls through to ocfs2_xa_journal_dirty() even after ocfs2_xa_prepare_entry() fails, on the assumption that the buffer needs to be journaled to record any partial modifications (see the comment above the out_dirty label in fs/ocfs2/xattr.c). If the failure was caused by the journal being aborted -- e.g. an underlying I/O error during a sub-operation such as __ocfs2_remove_xattr_range() -- the handle's h_transaction has been cleared by the abort path, and the unconditional deref in jbd2_journal_dirty_metadata() becomes a NULL deref. Reproduced by syzbot with a crafted ocfs2 image where I/O against the loop device backing the mount is sabotaged via LOOP_SET_STATUS64 between two setxattr() calls, causing the second setxattr (which truncates an external xattr value) to abort the journal mid-flight: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000 KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: jbd2_journal_dirty_metadata+0x4a/0xd30 fs/jbd2/transaction.c:1520 Call Trace: ocfs2_journal_dirty+0x130/0x700 fs/ocfs2/journal.c:831 ocfs2_xa_journal_dirty fs/ocfs2/xattr.c:1483 [inline] ocfs2_xa_set+0x15e3/0x2ec0 fs/ocfs2/xattr.c:2294 ocfs2_xattr_block_set+0x3e0/0x33c0 fs/ocfs2/xattr.c:3016 __ocfs2_xattr_set_handle+0x6b3/0xf50 fs/ocfs2/xattr.c:3418 ocfs2_xattr_set+0xf3f/0x13e0 fs/ocfs2/xattr.c:3681 __vfs_setxattr+0x43c/0x480 fs/xattr.c:218 ... Fix by adding the standard is_handle_aborted() guard at the top of jbd2_journal_dirty_metadata() and returning -EROFS, matching the pattern used by every other entry point in this file. ocfs2_journal_dirty() already handles a non-zero return from jbd2_journal_dirty_metadata() correctly. Reported-by: syzbot+98f651460e558a21baae@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=98f651460e558a21baae Tested-by: syzbot+98f651460e558a21baae@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Andreas Dilger Link: https://patch.msgid.link/20260507050605.50081-1-kartikey406@gmail.com Signed-off-by: Theodore Ts'o