kernel.git/fs/ext4/super.c, branch linux-rolling-stable

ext4: move ext4_percpu_param_init() before ext4_mb_init()

2026-03-04T12:20:25Z

[ Upstream commit 270564513489d98b721a1e4a10017978d5213bff ] When running `kvm-xfstests -c ext4/1k -C 1 generic/383` with the `DOUBLE_CHECK` macro defined, the following panic is triggered: ================================================================== EXT4-fs error (device vdc): ext4_validate_block_bitmap:423: comm mount: bg 0: bad block bitmap checksum BUG: unable to handle page fault for address: ff110000fa2cc000 PGD 3e01067 P4D 3e02067 PUD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 2386 Comm: mount Tainted: G W 6.18.0-gba65a4e7120a-dirty #1152 PREEMPT(none) RIP: 0010:percpu_counter_add_batch+0x13/0xa0 Call Trace: ext4_mark_group_bitmap_corrupted+0xcb/0xe0 ext4_validate_block_bitmap+0x2a1/0x2f0 ext4_read_block_bitmap+0x33/0x50 mb_group_bb_bitmap_alloc+0x33/0x80 ext4_mb_add_groupinfo+0x190/0x250 ext4_mb_init_backend+0x87/0x290 ext4_mb_init+0x456/0x640 __ext4_fill_super+0x1072/0x1680 ext4_fill_super+0xd3/0x280 get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x29/0xd0 vfs_cmd_create+0x59/0xe0 __do_sys_fsconfig+0x4f6/0x6b0 do_syscall_64+0x50/0x1f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== This issue can be reproduced using the following commands: mkfs.ext4 -F -q -b 1024 /dev/sda 5G tune2fs -O quota,project /dev/sda mount /dev/sda /tmp/test With DOUBLE_CHECK defined, mb_group_bb_bitmap_alloc() reads and validates the block bitmap. When the validation fails, ext4_mark_group_bitmap_corrupted() attempts to update sbi->s_freeclusters_counter. However, this percpu_counter has not been initialized yet at this point, which leads to the panic described above. Fix this by moving the execution of ext4_percpu_param_init() to occur before ext4_mb_init(), ensuring the per-CPU counters are initialized before they are used. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Link: https://patch.msgid.link/20251209133116.731350-1-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin

ext4: enable block size larger than page size

2025-11-29T03:35:28Z

Since block device (See commit 3c20917120ce ("block/bdev: enable large folio support for large logical block sizes")) and page cache (See commit ab95d23bab220ef8 ("filemap: allocate mapping_min_order folios in the page cache")) has the ability to have a minimum order when allocating folio, and ext4 has supported large folio in commit 7ac67301e82f ("ext4: enable large folio for regular file"), now add support for block_size > PAGE_SIZE in ext4. set_blocksize() -> bdev_validate_blocksize() already validates the block size, so ext4_load_super() does not need to perform additional checks. Here we only need to add the FS_LBS bit to fs_flags. In addition, block sizes larger than the page size are currently supported only when CONFIG_TRANSPARENT_HUGEPAGE is enabled. To make this explicit, a blocksize_gt_pagesize entry has been added under /sys/fs/ext4/feature/, indicating whether bs > ps is supported. This allows mke2fs to check the interface and determine whether a warning should be issued when formatting a filesystem with block size larger than the page size. Suggested-by: Theodore Ts'o Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Pankaj Raghav Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-25-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: add checks for large folio incompatibilities when BS > PS

2025-11-29T03:35:28Z

Supporting a block size greater than the page size (BS > PS) requires support for large folios. However, several features (e.g., encrypt) do not yet support large folios. To prevent conflicts, this patch adds checks at mount time to prohibit these features from being used when BS > PS. Since these features cannot be changed on remount, there is no need to check on remount. This patch adds s_max_folio_order, initialized during mount according to filesystem features and mount options. If s_max_folio_order is 0, large folios are disabled. With this in place, ext4_set_inode_mapping_order() can be simplified by checking s_max_folio_order, avoiding redundant checks. Signed-off-by: Baokun Li Reviewed-by: Jan Kara Reviewed-by: Zhang Yi Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-24-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: support large block size in ext4_calculate_overhead()

2025-11-29T03:35:26Z

ext4_calculate_overhead() used a single page for its bitmap buffer, which worked fine when PAGE_SIZE >= block size. However, with block size greater than page size (BS > PS) support, the bitmap can exceed a single page. To address this, we now use kvmalloc() to allocate memory of the filesystem block size, to properly support BS > PS. Suggested-by: Jan Kara Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-8-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: introduce s_min_folio_order for future BS > PS support

2025-11-29T03:35:26Z

This commit introduces the s_min_folio_order field to the ext4_sb_info structure. This field will store the minimum folio order required by the current filesystem, laying groundwork for future support of block sizes greater than PAGE_SIZE. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Pankaj Raghav Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-7-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: enable DIOREAD_NOLOCK by default for BS > PS as well

2025-11-29T03:35:26Z

The dioread_nolock related processes already support large folio, so dioread_nolock is enabled by default regardless of whether the blocksize is less than, equal to, or greater than PAGE_SIZE. Signed-off-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Message-ID: <20251121090654.631996-6-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o

ext4: clear i_state_flags when alloc inode

2025-11-26T22:06:09Z

i_state_flags used on 32-bit archs, need to clear this flag when alloc inode. Find this issue when umount ext4, sometimes track the inode as orphan accidently, cause ext4 mesg dump. Fixes: acf943e9768e ("ext4: fix checks for orphan inodes") Signed-off-by: Haibo Chen Reviewed-by: Baokun Li Reviewed-by: Zhang Yi Reviewed-by: Jan Kara Message-ID: <20251104-ext4-v1-1-73691a0800f9@nxp.com> Signed-off-by: Theodore Ts'o Cc: stable@kernel.org

ext4: fix string copying in parse_apply_sb_mount_options()

2025-11-26T22:05:39Z

strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce memtostr() and memtostr_pad()") provides additional information in that regard. So if this happens, the following warning is observed: strnlen: detected buffer overflow: 65 byte read of buffer size 64 WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Modules linked in: CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Call Trace: __fortify_panic+0x1f/0x30 lib/string_helpers.c:1039 strnlen include/linux/fortify-string.h:235 [inline] sized_strscpy include/linux/fortify-string.h:309 [inline] parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline] __ext4_fill_super fs/ext4/super.c:5261 [inline] ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706 get_tree_bdev_flags+0x387/0x620 fs/super.c:1636 vfs_get_tree+0x93/0x380 fs/super.c:1814 do_new_mount fs/namespace.c:3553 [inline] path_mount+0x6ae/0x1f70 fs/namespace.c:3880 do_mount fs/namespace.c:3893 [inline] __do_sys_mount fs/namespace.c:4103 [inline] __se_sys_mount fs/namespace.c:4080 [inline] __x64_sys_mount+0x280/0x300 fs/namespace.c:4080 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x76/0x7e Since userspace is expected to provide s_mount_opts field to be at most 63 characters long with the ending byte being NUL-term, use a 64-byte buffer which matches the size of s_mount_opts, so that strscpy_pad() does its job properly. Return with error if the user still managed to provide a non-NUL-term string here. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes: 8ecb790ea8c3 ("ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Reviewed-by: Baokun Li Reviewed-by: Jan Kara Message-ID: <20251101160430.222297-1-pchelkin@ispras.ru> Signed-off-by: Theodore Ts'o

jbd2: store more accurate errno in superblock when possible

2025-11-26T22:05:39Z

When jbd2_journal_abort() is called, the provided error code is stored in the journal superblock. Some existing calls hard-code -EIO even when the actual failure is not I/O related. This patch updates those calls to pass more accurate error codes, allowing the superblock to record the true cause of failure. This helps improve diagnostics and debugging clarity when analyzing journal aborts. Signed-off-by: Wengang Wang Reviewed-by: Zhang Yi Message-ID: <20251031210501.7337-1-wen.gang.wang@oracle.com> Signed-off-by: Theodore Ts'o

ext4: introduce seq counter for the extent status entry

2025-11-06T15:44:39Z

In the iomap_write_iter(), the iomap buffered write frame does not hold any locks between querying the inode extent mapping info and performing page cache writes. As a result, the extent mapping can be changed due to concurrent I/O in flight. Similarly, in the iomap_writepage_map(), the write-back process faces a similar problem: concurrent changes can invalidate the extent mapping before the I/O is submitted. Therefore, both of these processes must recheck the mapping info after acquiring the folio lock. To address this, similar to XFS, we propose introducing an extent sequence number to serve as a validity cookie for the extent. After commit 24b7a2331fcd ("ext4: clairfy the rules for modifying extents"), we can ensure the extent information should always be processed through the extent status tree, and the extent status tree is always uptodate under i_rwsem or invalidate_lock or folio lock, so it's safe to introduce this sequence number. The sequence number will be increased whenever the extent status tree changes, preparing for the buffered write iomap conversion. Besides, this mechanism is also applicable for the moving extents case. In move_extent_per_page(), it also needs to reacquire data_sem and check the mapping info again under the folio lock. Signed-off-by: Zhang Yi Reviewed-by: Jan Kara Message-ID: <20251013015128.499308-3-yi.zhang@huaweicloud.com> Signed-off-by: Theodore Ts'o