kernel/linux.git/fs/f2fs/data.c, branch v6.6.145

f2fs: fix potential deadlock in f2fs_balance_fs()

2026-07-24T14:02:36+00:00

[ Upstream commit dd3114870771562036fdcf5abe813956f36d224d ] When the f2fs filesystem space is nearly exhausted, we encounter deadlock issues as below: INFO: task A:1890 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:A state:D stack:0 pid:1890 tgid:1626 ppid:1153 flags:0x00000204 Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 schedule+0x3c/0x118 io_schedule+0x44/0x68 folio_wait_bit_common+0x174/0x370 folio_wait_bit+0x20/0x38 folio_wait_writeback+0x54/0xc8 truncate_inode_partial_folio+0x70/0x1e0 truncate_inode_pages_range+0x1b0/0x450 truncate_pagecache+0x54/0x88 f2fs_file_write_iter+0x3e8/0xb80 do_iter_readv_writev+0xf0/0x1e0 vfs_writev+0x138/0x2c8 do_writev+0x88/0x130 __arm64_sys_writev+0x28/0x40 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x30/0xf8 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x190/0x198 INFO: task kworker/u8:11:2680853 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:11 state:D stack:0 pid:2680853 tgid:2680853 ppid:2 flags:0x00000208 Workqueue: writeback wb_workfn (flush-254:0) Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 schedule+0x3c/0x118 io_schedule+0x44/0x68 folio_wait_bit_common+0x174/0x370 __filemap_get_folio+0x214/0x348 pagecache_get_page+0x20/0x70 f2fs_get_read_data_page+0x150/0x3e8 f2fs_get_lock_data_page+0x2c/0x160 move_data_page+0x50/0x478 do_garbage_collect+0xd38/0x1528 f2fs_gc+0x240/0x7e0 f2fs_balance_fs+0x1a0/0x208 f2fs_write_single_data_page+0x6e4/0x730 f2fs_write_cache_pages+0x378/0x9b0 f2fs_write_data_pages+0x2e4/0x388 do_writepages+0x8c/0x2c8 __writeback_single_inode+0x4c/0x498 writeback_sb_inodes+0x234/0x4a8 __writeback_inodes_wb+0x58/0x118 wb_writeback+0x2f8/0x3c0 wb_workfn+0x2c4/0x508 process_one_work+0x180/0x408 worker_thread+0x258/0x368 kthread+0x118/0x128 ret_from_fork+0x10/0x200 INFO: task kworker/u8:8:2641297 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:8 state:D stack:0 pid:2641297 tgid:2641297 ppid:2 flags:0x00000208 Workqueue: writeback wb_workfn (flush-254:0) Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 rt_mutex_schedule+0x30/0x60 __rt_mutex_slowlock_locked.constprop.0+0x460/0x8a8 rwbase_write_lock+0x24c/0x378 down_write+0x1c/0x30 f2fs_balance_fs+0x184/0x208 f2fs_write_inode+0xf4/0x328 __writeback_single_inode+0x370/0x498 writeback_sb_inodes+0x234/0x4a8 __writeback_inodes_wb+0x58/0x118 wb_writeback+0x2f8/0x3c0 wb_workfn+0x2c4/0x508 process_one_work+0x180/0x408 worker_thread+0x258/0x368 kthread+0x118/0x128 ret_from_fork+0x10/0x20 INFO: task B:1902 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:B state:D stack:0 pid:1902 tgid:1626 ppid:1153 flags:0x0000020c Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 rt_mutex_schedule+0x30/0x60 __rt_mutex_slowlock_locked.constprop.0+0x460/0x8a8 rwbase_write_lock+0x24c/0x378 down_write+0x1c/0x30 f2fs_balance_fs+0x184/0x208 f2fs_map_blocks+0x94c/0x1110 f2fs_file_write_iter+0x228/0xb80 do_iter_readv_writev+0xf0/0x1e0 vfs_writev+0x138/0x2c8 do_writev+0x88/0x130 __arm64_sys_writev+0x28/0x40 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x30/0xf8 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x190/0x198 INFO: task sync:2769849 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:sync state:D stack:0 pid:2769849 tgid:2769849 ppid:736 flags:0x0000020c Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 schedule+0x3c/0x118 wb_wait_for_completion+0xb0/0xe8 sync_inodes_sb+0xc8/0x2b0 sync_inodes_one_sb+0x24/0x38 iterate_supers+0xa8/0x138 ksys_sync+0x54/0xc8 __arm64_sys_sync+0x18/0x30 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x30/0xf8 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x190/0x198 The root cause is a potential deadlock between the following tasks: kworker/u8:11 Thread A - f2fs_write_single_data_page - f2fs_do_write_data_page - folio_start_writeback(X) - f2fs_outplace_write_data - bio_add_folio(X) - folio_unlock(X) - truncate_inode_pages_range - __filemap_get_folio(X, FGP_LOCK) - truncate_inode_partial_folio(X) - folio_wait_writeback(X) - f2fs_balance_fs - f2fs_gc - do_garbage_collect - move_data_page - f2fs_get_lock_data_page - __filemap_get_folio(X, FGP_LOCK) Both threads try to access folio X. Thread A holds the lock but waits for writeback, while kworker waits for the lock. This causes a deadlock. Other threads also enter D state, waiting for locks such as gc_lock and writepages. OPU/IPU DATA folio are all affected by this issue. To avoid such potential deadlocks, always commit these cached folios before triggering f2fs_gc() in f2fs_balance_fs(). Suggested-by: Chao Yu Reviewed-by: Chao Yu Signed-off-by: Ruipeng Qi Signed-off-by: Jaegeuk Kim Stable-dep-of: 8b4468ec023d ("f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: keep atomic write retry from zeroing original data

2026-07-04T11:42:26+00:00

commit 6d874b65aadce56ac78f76129dbcfc2599b638f8 upstream. A partial atomic write reserves a block in the COW inode before reading the original data page for the untouched bytes in that page. If that read fails, write_begin returns an error but leaves the COW inode entry as NEW_ADDR. A retry of the same partial write then finds the COW entry, treats it as existing COW data, and f2fs_write_begin() zeroes the whole folio because blkaddr is NEW_ADDR. If the retry is committed, the bytes outside the retried write range are committed as zeroes instead of preserving the original file contents. Only use the COW inode as the read source when it already has a real data block. If the COW entry is still NEW_ADDR, treat it as a reservation to reuse: keep reading the old data from the original inode and avoid reserving or accounting the same atomic block again. Cc: stable@kernel.org Fixes: 3db1de0e582c ("f2fs: change the current atomic write way") Signed-off-by: Wenjie Qi Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io()

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

[ Upstream commit 2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 ] The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference. The concurrent scenario that triggers the panic is as follows: F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic. This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition. Cc: stable@kernel.org Fixes: 50fa53eccf9f ("f2fs: fix to avoid broken of dnode block list") Reported-by: syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim [ folio => page ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix incorrect multidevice info in trace_f2fs_map_blocks()

2026-05-17T15:13:43+00:00

commit eb2ca3ca983551a80e16a4a25df5a4ce59df8484 upstream. When f2fs_map_blocks()->f2fs_map_blocks_cached() hits the read extent cache, map->m_multidev_dio is not updated, which leads to incorrect multidevice information being reported by trace_f2fs_map_blocks(). This patch updates map->m_multidev_dio in f2fs_map_blocks_cached() when the read extent cache is hit. Cc: stable@kernel.org Fixes: 0094e98bd147 ("f2fs: factor a f2fs_map_blocks_cached helper") Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix fiemap boundary handling when read extent cache is incomplete

2026-05-17T15:13:43+00:00

commit 95e159ad3e52f7478cfd22e44ec37c9f334f8993 upstream. f2fs_fiemap() calls f2fs_map_blocks() to obtain the block mapping a file, and then merges contiguous mappings into extents. If the mapping is found in the read extent cache, node blocks do not need to be read. However, in the following scenario, a contiguous extent can be split into two extents: $ dd if=/dev/zero of=data.128M bs=1M count=128 $ losetup -f data.128M $ mkfs.f2fs /dev/loop0 -f $ mount -o mode=lfs /dev/loop0 /mnt/f2fs/ $ cd /mnt/f2fs/ $ dd if=/dev/zero of=data.72M bs=1M count=72 && sync $ dd if=/dev/zero of=data.4M bs=1M count=4 && sync $ dd if=/dev/zero of=data.4M bs=1M count=2 seek=2 conv=notrunc && sync $ echo 3 > /proc/sys/vm/drop_caches $ dd if=/dev/zero of=data.4M bs=1M count=2 seek=0 conv=notrunc && sync $ dd if=/dev/zero of=data.4M bs=1M count=2 seek=0 conv=notrunc && sync $ f2fs_io fiemap 0 1024 data.4M Fiemap: offset = 0 len = 1024 logical addr. physical addr. length flags 0 0000000000000000 0000000006400000 0000000000200000 00001000 1 0000000000200000 0000000006600000 0000000000200000 00001001 Although the physical addresses of the ranges 0～2MB and 2M～4MB are contiguous, the mapping for the 2M～4MB range is not present in memory. When the physical addresses for the 0～2MB range are updated, no merge happens because the adjacent mapping is missing from the in-memory cache. As a result, fiemap reports two separate extents instead of a single contiguous one. The root cause is that the read extent cache does not guarantee that all blocks of an extent are present in memory. Therefore, when the extent length returned by f2fs_map_blocks_cached() is smaller than maxblocks, the remaining mappings are retrieved via f2fs_get_dnode_of_data() to ensure correct fiemap extent boundary handling. Cc: stable@kernel.org Fixes: cd8fc5226bef ("f2fs: remove the create argument to f2fs_map_blocks") Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix to avoid mapping wrong physical block for swapfile

2026-02-19T15:28:27+00:00

[ Upstream commit 5c145c03188bc9ba1c29e0bc4d527a5978fc47f9 ] Xiaolong Guo reported a f2fs bug in bugzilla [1] [1] https://bugzilla.kernel.org/show_bug.cgi?id=220951 Quoted: "When using stress-ng's swap stress test on F2FS filesystem with kernel 6.6+, the system experiences data corruption leading to either: 1 dm-verity corruption errors and device reboot 2 F2FS node corruption errors and boot hangs The issue occurs specifically when: 1 Using F2FS filesystem (ext4 is unaffected) 2 Swapfile size is less than F2FS section size (2MB) 3 Swapfile has fragmented physical layout (multiple non-contiguous extents) 4 Kernel version is 6.6+ (6.1 is unaffected) The root cause is in check_swap_activate() function in fs/f2fs/data.c. When the first extent of a small swapfile (< 2MB) is not aligned to section boundaries, the function incorrectly treats it as the last extent, failing to map subsequent extents. This results in incorrect swap_extent creation where only the first extent is mapped, causing subsequent swap writes to overwrite wrong physical locations (other files' data). Steps to Reproduce 1 Setup a device with F2FS-formatted userdata partition 2 Compile stress-ng from https://github.com/ColinIanKing/stress-ng 3 Run swap stress test: (Android devices) adb shell "cd /data/stressng; ./stress-ng-64 --metrics-brief --timeout 60 --swap 0" Log: 1 Ftrace shows in kernel 6.6, only first extent is mapped during second f2fs_map_blocks call in check_swap_activate(): stress-ng-swap-8990: f2fs_map_blocks: ino=11002, file offset=0, start blkaddr=0x43143, len=0x1 (Only 4KB mapped, not the full swapfile) 2 in kernel 6.1, both extents are correctly mapped: stress-ng-swap-5966: f2fs_map_blocks: ino=28011, file offset=0, start blkaddr=0x13cd4, len=0x1 stress-ng-swap-5966: f2fs_map_blocks: ino=28011, file offset=1, start blkaddr=0x60c84b, len=0xff The problematic code is in check_swap_activate(): if ((pblock - SM_I(sbi)->main_blkaddr) % blks_per_sec || nr_pblocks % blks_per_sec || !f2fs_valid_pinned_area(sbi, pblock)) { bool last_extent = false; not_aligned++; nr_pblocks = roundup(nr_pblocks, blks_per_sec); if (cur_lblock + nr_pblocks > sis->max) nr_pblocks -= blks_per_sec; /* this extent is last one */ if (!nr_pblocks) { nr_pblocks = last_lblock - cur_lblock; last_extent = true; } ret = f2fs_migrate_blocks(inode, cur_lblock, nr_pblocks); if (ret) { if (ret == -ENOENT) ret = -EINVAL; goto out; } if (!last_extent) goto retry; } When the first extent is unaligned and roundup(nr_pblocks, blks_per_sec) exceeds sis->max, we subtract blks_per_sec resulting in nr_pblocks = 0. The code then incorrectly assumes this is the last extent, sets nr_pblocks = last_lblock - cur_lblock (entire swapfile), and performs migration. After migration, it doesn't retry mapping, so subsequent extents are never processed. " In order to fix this issue, we need to lookup block mapping info after we migrate all blocks in the tail of swapfile. Cc: stable@kernel.org Fixes: 9703d69d9d15 ("f2fs: support file pinning for zoned devices") Cc: Daeho Jeong Reported-and-tested-by: Xiaolong Guo Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220951 Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ f2fs_is_sequential_zone_area() => !f2fs_valid_pinned_area() ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix to avoid UAF in f2fs_write_end_io()

2026-02-19T15:28:27+00:00

[ Upstream commit ce2739e482bce8d2c014d76c4531c877f382aa54 ] As syzbot reported an use-after-free issue in f2fs_write_end_io(). It is caused by below race condition: loop device umount - worker_thread - loop_process_work - do_req_filebacked - lo_rw_aio - lo_rw_aio_complete - blk_mq_end_request - blk_update_request - f2fs_write_end_io - dec_page_count - folio_end_writeback - kill_f2fs_super - kill_block_super - f2fs_put_super : free(sbi) : get_pages(, F2FS_WB_CP_DATA) accessed sbi which is freed In kill_f2fs_super(), we will drop all page caches of f2fs inodes before call free(sbi), it guarantee that all folios should end its writeback, so it should be safe to access sbi before last folio_end_writeback(). Let's relocate ckpt thread wakeup flow before folio_end_writeback() to resolve this issue. Cc: stable@kernel.org Fixes: e234088758fc ("f2fs: avoid wait if IO end up when do_checkpoint for better performance") Reported-by: syzbot+b4444e3c972a7a124187@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b4444e3c972a7a124187 Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ folio => page ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix to avoid updating compression context during writeback

2026-01-11T14:22:27+00:00

[ Upstream commit 10b591e7fb7cdc8c1e53e9c000dc0ef7069aaa76 ] Bai, Shuangpeng reported a bug as below: Oops: divide error: 0000 [#1] SMP KASAN PTI CPU: 0 UID: 0 PID: 11441 Comm: syz.0.46 Not tainted 6.17.0 #1 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:f2fs_all_cluster_page_ready+0x106/0x550 fs/f2fs/compress.c:857 Call Trace: f2fs_write_cache_pages fs/f2fs/data.c:3078 [inline] __f2fs_write_data_pages fs/f2fs/data.c:3290 [inline] f2fs_write_data_pages+0x1c19/0x3600 fs/f2fs/data.c:3317 do_writepages+0x38e/0x640 mm/page-writeback.c:2634 filemap_fdatawrite_wbc mm/filemap.c:386 [inline] __filemap_fdatawrite_range mm/filemap.c:419 [inline] file_write_and_wait_range+0x2ba/0x3e0 mm/filemap.c:794 f2fs_do_sync_file+0x6e6/0x1b00 fs/f2fs/file.c:294 generic_write_sync include/linux/fs.h:3043 [inline] f2fs_file_write_iter+0x76e/0x2700 fs/f2fs/file.c:5259 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x7e9/0xe00 fs/read_write.c:686 ksys_write+0x19d/0x2d0 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf7/0x470 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The bug was triggered w/ below race condition: fsync setattr ioctl - f2fs_do_sync_file - file_write_and_wait_range - f2fs_write_cache_pages : inode is non-compressed : cc.cluster_size = F2FS_I(inode)->i_cluster_size = 0 - tag_pages_for_writeback - f2fs_setattr - truncate_setsize - f2fs_truncate - f2fs_fileattr_set - f2fs_setflags_common - set_compress_context : F2FS_I(inode)->i_cluster_size = 4 : set_inode_flag(inode, FI_COMPRESSED_FILE) - f2fs_compressed_file : return true - f2fs_all_cluster_page_ready : "pgidx % cc->cluster_size" trigger dividing 0 issue Let's change as below to fix this issue: - introduce a new atomic type variable .writeback in structure f2fs_inode_info to track the number of threads which calling f2fs_write_cache_pages(). - use .i_sem lock to protect .writeback update. - check .writeback before update compression context in f2fs_setflags_common() to avoid race w/ ->writepages. Fixes: 4c8ff7095bef ("f2fs: support data compression") Cc: stable@kernel.org Reported-by: Bai, Shuangpeng Tested-by: Bai, Shuangpeng Closes: https://lore.kernel.org/lkml/44D8F7B3-68AD-425F-9915-65D27591F93F@psu.edu Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix wrong block mapping for multi-devices

2025-10-23T14:16:23+00:00

commit 9d5c4f5c7a2c7677e1b3942772122b032c265aae upstream. Assuming the disk layout as below, disk0: 0 --- 0x00035abfff disk1: 0x00035ac000 --- 0x00037abfff disk2: 0x00037ac000 --- 0x00037ebfff and we want to read data from offset=13568 having len=128 across the block devices, we can illustrate the block addresses like below. 0 .. 0x00037ac000 ------------------- 0x00037ebfff, 0x00037ec000 ------- | ^ ^ ^ | fofs 0 13568 13568+128 | ------------------------------------------------------ | LBA 0x37e8aa9 0x37ebfa9 0x37ec029 --- map 0x3caa9 0x3ffa9 In this example, we should give the relative map of the target block device ranging from 0x3caa9 to 0x3ffa9 where the length should be calculated by 0x37ebfff + 1 - 0x37ebfa9. In the below equation, however, map->m_pblk was supposed to be the original address instead of the one from the target block address. - map->m_len = min(map->m_len, dev->end_blk + 1 - map->m_pblk); Cc: stable@vger.kernel.org Fixes: 71f2c8206202 ("f2fs: multidevice: support direct IO") Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix zero-sized extent for precache extents

2025-10-15T09:58:02+00:00

[ Upstream commit 8175c864391753b210f3dcfae1aeed686a226ebb ] Script to reproduce: f2fs_io write 1 0 1881 rand dsync testfile f2fs_io fallocate 0 7708672 4096 testfile f2fs_io write 1 1881 1 rand buffered testfile fsync testfile umount mount f2fs_io precache_extents testfile When the data layout is something like this: dnode1: dnode2: [0] A [0] NEW_ADDR [1] A+1 [1] 0x0 ... [1016] A+1016 [1017] B (B!=A+1017) [1017] 0x0 During precache_extents, we map the last block(valid blkaddr) in dnode1: map->m_flags |= F2FS_MAP_MAPPED; map->m_pblk = blkaddr(valid blkaddr); map->m_len = 1; then we goto next_dnode, meet the first block in dnode2(hole), goto sync_out: map->m_flags & F2FS_MAP_MAPPED == true, and we make zero-sized extent: map->m_len = 1 ofs = start_pgofs - map->m_lblk = 1882 - 1881 = 1 ei.fofs = start_pgofs = 1882 ei.len = map->m_len - ofs = 1 - 1 = 0 Rebased on patch[1], this patch can cover these cases to avoid zero-sized extent: A,B,C is valid blkaddr case1: dnode1: dnode2: [0] A [0] NEW_ADDR [1] A+1 [1] 0x0 ... .... [1016] A+1016 [1017] B (B!=A+1017) [1017] 0x0 case2: dnode1: dnode2: [0] A [0] C (C!=B+1) [1] A+1 [1] C+1 ... .... [1016] A+1016 [1017] B (B!=A+1017) [1017] 0x0 case3: dnode1: dnode2: [0] A [0] C (C!=B+2) [1] A+1 [1] C+1 ... .... [1015] A+1015 [1016] B (B!=A+1016) [1017] B+1 [1017] 0x0 [1] https://lore.kernel.org/linux-f2fs-devel/20250912081250.44383-1-chao@kernel.org/ Fixes: c4020b2da4c9 ("f2fs: support F2FS_IOC_PRECACHE_EXTENTS") Signed-off-by: wangzijie Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin