kernel/linux.git/fs/f2fs/segment.c, branch v6.6.141

f2fs: fix to do sanity check on dcc->discard_cmd_cnt conditionally

2026-05-17T15:13:48+00:00

[ Upstream commit 6af249c996f7d73a3435f9e577956fa259347d18 ] Syzbot reported a f2fs bug as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:1900! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 6527 Comm: syz.5.110 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:f2fs_issue_discard_timeout+0x59b/0x5a0 fs/f2fs/segment.c:1900 Code: d9 80 e1 07 80 c1 03 38 c1 0f 8c d6 fe ff ff 48 89 df e8 a8 5e fa fd e9 c9 fe ff ff e8 4e 46 94 fd 90 0f 0b e8 46 46 94 fd 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 RSP: 0018:ffffc9000494f940 EFLAGS: 00010283 RAX: ffffffff843009ca RBX: 0000000000000001 RCX: 0000000000080000 RDX: ffffc9001ca78000 RSI: 00000000000029f3 RDI: 00000000000029f4 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffed100893a431 R12: 1ffff1100893a430 R13: 1ffff1100c2b702c R14: dffffc0000000000 R15: ffff8880449d2160 FS: 00007ffa35fed6c0(0000) GS:ffff88812643d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2b68634000 CR3: 0000000039f62000 CR4: 00000000003526f0 Call Trace: __f2fs_remount fs/f2fs/super.c:2960 [inline] f2fs_reconfigure+0x108a/0x1710 fs/f2fs/super.c:5443 reconfigure_super+0x227/0x8a0 fs/super.c:1080 do_remount fs/namespace.c:3391 [inline] path_mount+0xdc5/0x10e0 fs/namespace.c:4151 do_mount fs/namespace.c:4172 [inline] __do_sys_mount fs/namespace.c:4361 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4338 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ffa37dbda0a The root cause is there will be race condition in between f2fs_ioc_fitrim() and f2fs_remount(): - f2fs_remount - f2fs_ioc_fitrim - f2fs_issue_discard_timeout - __issue_discard_cmd - __drop_discard_cmd - __wait_all_discard_cmd - f2fs_trim_fs - f2fs_write_checkpoint - f2fs_clear_prefree_segments - f2fs_issue_discard - __issue_discard_async - __queue_discard_cmd - __update_discard_tree_range - __insert_discard_cmd - __create_discard_cmd : atomic_inc(&dcc->discard_cmd_cnt); - sanity check on dcc->discard_cmd_cnt (expect discard_cmd_cnt to be zero) This will only happen when fitrim races w/ remount rw, if we remount to readonly filesystem, remount will wait until mnt_pcp.mnt_writers to zero, that means fitrim is not in process at that time. Cc: stable@kernel.org Fixes: 2482c4325dfe ("f2fs: detect bug_on in f2fs_wait_discard_bios") Reported-by: syzbot+62538b67389ee582837a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/69b07d7c.050a0220.8df7.09a1.GAE@google.com Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ dereferenced flags pointer (`*flags & SB_RDONLY`) to match `int *flags` remount signature ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix age extent cache insertion skip on counter overflow

2026-01-11T14:21:59+00:00

commit 27bf6a637b7613fc85fa6af468b7d612d78cd5c0 upstream. The age extent cache uses last_blocks (derived from allocated_data_blocks) to determine data age. However, there's a conflict between the deletion marker (last_blocks=0) and legitimate last_blocks=0 cases when allocated_data_blocks overflows to 0 after reaching ULLONG_MAX. In this case, valid extents are incorrectly skipped due to the "if (!tei->last_blocks)" check in __update_extent_tree_range(). This patch fixes the issue by: 1. Reserving ULLONG_MAX as an invalid/deletion marker 2. Limiting allocated_data_blocks to range [0, ULLONG_MAX-1] 3. Using F2FS_EXTENT_AGE_INVALID for deletion scenarios 4. Adjusting overflow age calculation from ULLONG_MAX to (ULLONG_MAX-1) Reproducer (using a patched kernel with allocated_data_blocks initialized to ULLONG_MAX - 3 for quick testing): Step 1: Mount and check initial state # dd if=/dev/zero of=/tmp/test.img bs=1M count=100 # mkfs.f2fs -f /tmp/test.img # mkdir -p /mnt/f2fs_test # mount -t f2fs -o loop,age_extent_cache /tmp/test.img /mnt/f2fs_test # cat /sys/kernel/debug/f2fs/status | grep -A 4 "Block Age" Allocated Data Blocks: 18446744073709551612 # ULLONG_MAX - 3 Inner Struct Count: tree: 1(0), node: 0 Step 2: Create files and write data to trigger overflow # touch /mnt/f2fs_test/{1,2,3,4}.txt; sync # cat /sys/kernel/debug/f2fs/status | grep -A 4 "Block Age" Allocated Data Blocks: 18446744073709551613 # ULLONG_MAX - 2 Inner Struct Count: tree: 5(0), node: 1 # dd if=/dev/urandom of=/mnt/f2fs_test/1.txt bs=4K count=1; sync # cat /sys/kernel/debug/f2fs/status | grep -A 4 "Block Age" Allocated Data Blocks: 18446744073709551614 # ULLONG_MAX - 1 Inner Struct Count: tree: 5(0), node: 2 # dd if=/dev/urandom of=/mnt/f2fs_test/2.txt bs=4K count=1; sync # cat /sys/kernel/debug/f2fs/status | grep -A 4 "Block Age" Allocated Data Blocks: 18446744073709551615 # ULLONG_MAX Inner Struct Count: tree: 5(0), node: 3 # dd if=/dev/urandom of=/mnt/f2fs_test/3.txt bs=4K count=1; sync # cat /sys/kernel/debug/f2fs/status | grep -A 4 "Block Age" Allocated Data Blocks: 0 # Counter overflowed! Inner Struct Count: tree: 5(0), node: 4 Step 3: Trigger the bug - next write should create node but gets skipped # dd if=/dev/urandom of=/mnt/f2fs_test/4.txt bs=4K count=1; sync # cat /sys/kernel/debug/f2fs/status | grep -A 4 "Block Age" Allocated Data Blocks: 1 Inner Struct Count: tree: 5(0), node: 4 Expected: node: 5 (new extent node for 4.txt) Actual: node: 4 (extent insertion was incorrectly skipped due to last_blocks = allocated_data_blocks = 0 in __get_new_block_age) After this fix, the extent node is correctly inserted and node count becomes 5 as expected. Fixes: 71644dff4811 ("f2fs: add block_age-based extent cache") Cc: stable@kernel.org Signed-off-by: Xiaole He Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix to set atomic write status more clear

2025-06-27T10:08:56+00:00

[ Upstream commit db03c20c0850dc8d2bcabfa54b9438f7d666c863 ] 1. After we start atomic write in a database file, before committing all data, we'd better not set inode w/ vfs dirty status to avoid redundant updates, instead, we only set inode w/ atomic dirty status. 2. After we commit all data, before committing metadata, we need to clear atomic dirty status, and set vfs dirty status to allow vfs flush dirty inode. Cc: Daeho Jeong Reported-by: Zhiguo Niu Signed-off-by: Chao Yu Reviewed-by: Daeho Jeong Reviewed-by: Zhiguo Niu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: fix to drop all discards after creating snapshot on lvm device

2024-12-14T18:59:45+00:00

[ Upstream commit bc8aeb04fd80cb8cfae3058445c84410fd0beb5e ] Piergiorgio reported a bug in bugzilla as below: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 969 at fs/f2fs/segment.c:1330 RIP: 0010:__submit_discard_cmd+0x27d/0x400 [f2fs] Call Trace: __issue_discard_cmd+0x1ca/0x350 [f2fs] issue_discard_thread+0x191/0x480 [f2fs] kthread+0xcf/0x100 ret_from_fork+0x31/0x50 ret_from_fork_asm+0x1a/0x30 w/ below testcase, it can reproduce this bug quickly: - pvcreate /dev/vdb - vgcreate myvg1 /dev/vdb - lvcreate -L 1024m -n mylv1 myvg1 - mount /dev/myvg1/mylv1 /mnt/f2fs - dd if=/dev/zero of=/mnt/f2fs/file bs=1M count=20 - sync - rm /mnt/f2fs/file - sync - lvcreate -L 1024m -s -n mylv1-snapshot /dev/myvg1/mylv1 - umount /mnt/f2fs The root cause is: it will update discard_max_bytes of mounted lvm device to zero after creating snapshot on this lvm device, then, __submit_discard_cmd() will pass parameter @nr_sects w/ zero value to __blkdev_issue_discard(), it returns a NULL bio pointer, result in panic. This patch changes as below for fixing: 1. Let's drop all remained discards in f2fs_unfreeze() if snapshot of lvm device is created. 2. Checking discard_max_bytes before submitting discard during __submit_discard_cmd(). Cc: stable@vger.kernel.org Fixes: 35ec7d574884 ("f2fs: split discard command in prior to block layer") Reported-by: Piergiorgio Sartor Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219484 Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: check curseg->inited before write_sum_page in change_curseg

2024-12-09T09:32:26+00:00

[ Upstream commit 43563069e1c1df417d2eed6eca8a22fc6b04691d ] In the __f2fs_init_atgc_curseg->get_atssr_segment calling, curseg->segno is NULL_SEGNO, indicating that there is no summary block that needs to be written. Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection") Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: fix the wrong f2fs_bug_on condition in f2fs_do_replace_block

2024-12-09T09:32:26+00:00

[ Upstream commit c3af1f13476ec23fd99c98d060a89be28c1e8871 ] This f2fs_bug_on was introduced by commit 2c1905042c8c ("f2fs: check segment type in __f2fs_replace_block") when there were only 6 curseg types. After commit d0b9e42ab615 ("f2fs: introduce inmem curseg") was introduced, the condition should be changed to checking curseg->seg_type. Fixes: d0b9e42ab615 ("f2fs: introduce inmem curseg") Signed-off-by: LongPing Wei Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: prevent atomic file from being dirtied before commit

2024-10-04T14:29:37+00:00

[ Upstream commit fccaa81de87e80b1809906f7e438e5766fbdc172 ] Keep atomic file clean while updating and make it dirtied during commit in order to avoid unnecessary and excessive inode updates in the previous fix. Fixes: 4bf78322346f ("f2fs: mark inode dirty for FI_ATOMIC_COMMITTED flag") Signed-off-by: Daeho Jeong Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: fix to do sanity check in update_sit_entry

2024-08-29T15:33:38+00:00

[ Upstream commit 36959d18c3cf09b3c12157c6950e18652067de77 ] If GET_SEGNO return NULL_SEGNO for some unecpected case, update_sit_entry will access invalid memory address, cause system crash. It is better to do sanity check about GET_SEGNO just like update_segment_mtime & locate_dirty_segment. Also remove some redundant judgment code. Signed-off-by: Zhiguo Niu Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: stop checkpoint when get a out-of-bounds segment

2024-08-29T15:33:36+00:00

[ Upstream commit f9e28904e6442019043a8e94ec6747a064d06003 ] There is low probability that an out-of-bounds segment will be got on a small-capacity device. In order to prevent subsequent write requests allocating block address from this invalid segment, which may cause unexpected issue, stop checkpoint should be performed. Also introduce a new stop cp reason: STOP_CP_REASON_NO_SEGMENT. Note, f2fs_stop_checkpoint(, false) is complex and it may sleep, so we should move it outside segmap_lock spinlock coverage in get_new_segment(). Signed-off-by: Zhiguo Niu Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: assign CURSEG_ALL_DATA_ATGC if blkaddr is valid

2024-08-11T10:47:16+00:00

[ Upstream commit 8cb1f4080dd91c6e6b01dbea013a3f42341cb6a1 ] mkdir /mnt/test/comp f2fs_io setflags compression /mnt/test/comp dd if=/dev/zero of=/mnt/test/comp/testfile bs=16k count=1 truncate --size 13 /mnt/test/comp/testfile In the above scenario, we can get a BUG_ON. kernel BUG at fs/f2fs/segment.c:3589! Call Trace: do_write_page+0x78/0x390 [f2fs] f2fs_outplace_write_data+0x62/0xb0 [f2fs] f2fs_do_write_data_page+0x275/0x740 [f2fs] f2fs_write_single_data_page+0x1dc/0x8f0 [f2fs] f2fs_write_multi_pages+0x1e5/0xae0 [f2fs] f2fs_write_cache_pages+0xab1/0xc60 [f2fs] f2fs_write_data_pages+0x2d8/0x330 [f2fs] do_writepages+0xcf/0x270 __writeback_single_inode+0x44/0x350 writeback_sb_inodes+0x242/0x530 __writeback_inodes_wb+0x54/0xf0 wb_writeback+0x192/0x310 wb_workfn+0x30d/0x400 The reason is we gave CURSEG_ALL_DATA_ATGC to COMPR_ADDR where the page was set the gcing flag by set_cluster_dirty(). Cc: stable@vger.kernel.org Fixes: 4961acdd65c9 ("f2fs: fix to tag gcing flag on page during block migration") Reviewed-by: Chao Yu Tested-by: Will McVicker Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin