kernel/linux.git/fs/ext4/mmp.c, branch linux-7.1.y

ext4: use super write guard in write_mmp_block()

2025-11-05T21:52:15+00:00

Link: https://patch.msgid.link/20251104-work-guards-v1-5-5108ac78a171@kernel.org Acked-by: Theodore Ts'o Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

ext4: replace min/max nesting with clamp()

2025-09-25T18:35:21+00:00

The clamp() macro explicitly expresses the intent of constraining a value within bounds.Therefore, replacing max(min(a,b),c) with clamp(val, lo, hi) can improve code readability. Signed-off-by: Xichao Zhao Signed-off-by: Theodore Ts'o

ext4: remove sbi argument from ext4_chksum()

2025-05-20T14:31:12+00:00

Since ext4_chksum() no longer uses its sbi argument, remove it. Signed-off-by: Eric Biggers Reviewed-by: Baokun Li Link: https://patch.msgid.link/20250513053809.699974-2-ebiggers@kernel.org Signed-off-by: Theodore Ts'o

ext4: remove redundant function ext4_has_metadata_csum

2025-03-17T15:19:41+00:00

Since commit f2b4fa19647e ("ext4: switch to using the crc32c library"), ext4_has_metadata_csum() is just an alias for ext4_has_feature_metadata_csum(). ext4_has_feature_metadata_csum() is generated by EXT4_FEATURE_RO_COMPAT_FUNCS and uses the regular naming convention for checking a single ext4 feature. Therefore, remove ext4_has_metadata_csum() and update all its callers to use ext4_has_feature_metadata_csum() directly. Signed-off-by: Eric Biggers Reviewed-by: Darrick J. Wong Link: https://patch.msgid.link/20250207031335.42637-1-ebiggers@kernel.org Signed-off-by: Theodore Ts'o

ext4: add ext4_emergency_state() helper function

2025-03-13T14:16:34+00:00

Since both SHUTDOWN and EMERGENCY_RO are emergency states of the ext4 file system, and they are checked in similar locations, we have added a helper function, ext4_emergency_state(), to determine whether the current file system is in one of these two emergency states. Then, replace calls to ext4_forced_shutdown() with ext4_emergency_state() in those functions that could potentially trigger write operations. Signed-off-by: Baokun Li Reviewed-by: Jan Kara Reviewed-by: Zhang Yi Link: https://patch.msgid.link/20250122114130.229709-4-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o

ext4: fix race in buffer_head read fault injection

2024-11-13T04:54:14+00:00

When I enabled ext4 debug for fault injection testing, I encountered the following warning: EXT4-fs error (device sda): ext4_read_inode_bitmap:201: comm fsstress: Cannot read inode bitmap - block_group = 8, inode_bitmap = 1051 WARNING: CPU: 0 PID: 511 at fs/buffer.c:1181 mark_buffer_dirty+0x1b3/0x1d0 The root cause of the issue lies in the improper implementation of ext4's buffer_head read fault injection. The actual completion of buffer_head read and the buffer_head fault injection are not atomic, which can lead to the uptodate flag being cleared on normally used buffer_heads in race conditions. [CPU0] [CPU1] [CPU2] ext4_read_inode_bitmap ext4_read_bh() ext4_read_inode_bitmap if (buffer_uptodate(bh)) return bh jbd2_journal_commit_transaction __jbd2_journal_refile_buffer __jbd2_journal_unfile_buffer __jbd2_journal_temp_unlink_buffer ext4_simulate_fail_bh() clear_buffer_uptodate mark_buffer_dirty WARN_ON_ONCE(!buffer_uptodate(bh)) The best approach would be to perform fault injection in the IO completion callback function, rather than after IO completion. However, the IO completion callback function cannot get the fault injection code in sb. Fix it by passing the result of fault injection into the bh read function, we simulate faults within the bh read function itself. This requires adding an extra parameter to the bh read functions that need fault injection. Fixes: 46f870d690fe ("ext4: simulate various I/O and checksum errors when reading metadata") Signed-off-by: Long Li Link: https://patch.msgid.link/20240906091746.510163-1-leo.lilong@huawei.com Signed-off-by: Theodore Ts'o

ext4: replace read-only check for shutdown check in mmp code

2023-07-29T22:37:53+00:00

The multi-mount protection kthread checks for read-only filesystem and aborts in that case. The remount code actually handles stopping of the kthread on remount so the only purpose of the check is in case of emergency remount read-only. Replace the check for read-only filesystem with a check for shutdown filesystem as running MMP on such is risky anyway and it makes ordering of things during remount simpler. Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20230616165109.21695-11-jack@suse.cz Signed-off-by: Theodore Ts'o

ext4: fix lockdep warning when enabling MMP

2023-05-08T01:11:18+00:00

When we enable MMP in ext4_multi_mount_protect() during mount or remount, we end up calling sb_start_write() from write_mmp_block(). This triggers lockdep warning because freeze protection ranks above s_umount semaphore we are holding during mount / remount. The problem is harmless because we are guaranteed the filesystem is not frozen during mount / remount but still let's fix the warning by not grabbing freeze protection from ext4_multi_mount_protect(). Cc: stable@kernel.org Reported-by: syzbot+6b7df7d5506b32467149@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=ab7e5b6f400b7778d46f01841422e5718fb81843 Signed-off-by: Jan Kara Reviewed-by: Christian Brauner Link: https://lore.kernel.org/r/20230411121019.21940-1-jack@suse.cz Signed-off-by: Theodore Ts'o

ext4: reflect error codes from ext4_multi_mount_protect() to its callers

2023-04-28T16:56:40+00:00

This will allow more fine-grained errno codes to be returned by the mount system call. Cc: Andreas Dilger Signed-off-by: Theodore Ts'o

treewide: use get_random_u32_{above,below}() instead of manual loop

2022-11-18T01:15:22+00:00

These cases were done with this Coccinelle: @@ expression E; identifier I; @@ - do { ... when != I - I = get_random_u32(); ... when != I - } while (I > E); + I = get_random_u32_below(E + 1); @@ expression E; identifier I; @@ - do { ... when != I - I = get_random_u32(); ... when != I - } while (I >= E); + I = get_random_u32_below(E); @@ expression E; identifier I; @@ - do { ... when != I - I = get_random_u32(); ... when != I - } while (I < E); + I = get_random_u32_above(E - 1); @@ expression E; identifier I; @@ - do { ... when != I - I = get_random_u32(); ... when != I - } while (I <= E); + I = get_random_u32_above(E); @@ identifier I; @@ - do { ... when != I - I = get_random_u32(); ... when != I - } while (!I); + I = get_random_u32_above(0); @@ identifier I; @@ - do { ... when != I - I = get_random_u32(); ... when != I - } while (I == 0); + I = get_random_u32_above(0); @@ expression E; @@ - E + 1 + get_random_u32_below(U32_MAX - E) + get_random_u32_above(E) Reviewed-by: Kees Cook Reviewed-by: Greg Kroah-Hartman Signed-off-by: Jason A. Donenfeld