kernel/linux.git/fs/f2fs/segment.c, branch v6.18.48

f2fs: introduce f2fs_schedule_timeout()

2026-07-18T14:53:04+00:00

[ Upstream commit 76e780d88c771921ea643fb8a6c8d0b08c17cb7b ] In f2fs retry logic, we will call f2fs_io_schedule_timeout() to sleep as uninterruptible state (waiting for IO) for a while, however, in several paths below, we are not blocked by IO: - f2fs_write_single_data_page() return -EAGAIN due to racing on cp_rwsem. - f2fs_flush_device_cache() failed to submit preflush command. - __issue_discard_cmd_range() sleeps periodically in between two in batch discard submissions. So, in order to reveal state of task more accurate, let's introduce f2fs_schedule_timeout() and call it in above paths in where we are waiting for non-IO reasons. Then we can get real reason of uninterruptible sleep for a thread in tracepoint, perfetto, etc. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: 8712353ed80f ("f2fs: fix to do sanity check on f2fs_get_node_folio_ra()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: use memalloc_retry_wait() as much as possible

2026-07-18T14:53:04+00:00

[ Upstream commit 30a8496694f1a93328e5d7f19206380346918b5a ] memalloc_retry_wait() is recommended in memory allocation retry logic, use it as much as possible. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: 8712353ed80f ("f2fs: fix to do sanity check on f2fs_get_node_folio_ra()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()

2026-07-18T14:53:04+00:00

[ Upstream commit 8b4468ec023d0d1b4669dfb867588997cc03a06b ] When we mount device w/ gc_merge mount option, we may suffer below potential deadlock: Kworker GC trehad Truncator - f2fs_write_cache_pages - f2fs_write_single_data_page - f2fs_do_write_data_page - folio_start_writeback --- set writeback flag on folio - f2fs_outplace_write_data : cached folio in internal bio cache - f2fs_balance_fs - wake_up(gc_thread) : wake up gc thread to run foreground GC - finish_wait(fggc_wq) : wait on the waitqueue --- wait on GC thread to finish the work - truncate_inode_pages_range - __filemap_get_folio(, FGP_LOCK) --- lock folio - truncate_inode_partial_folio - folio_wait_writeback --- wait on writeback being cleared - do_garbage_collect - move_data_page - f2fs_get_lock_data_folio - lock on folio --- blocked on folio's lock In order to avoid such deadlock, let's call below functions to commit cached bios in GC_MERGE path of f2fs_balance_fs() as the same as we did in NOGC_MERGE path. - f2fs_submit_merged_write(sbi, DATA); - f2fs_submit_all_merged_ipu_writes(sbi); Cc: stable@kernel.org Fixes: 351df4b20115 ("f2fs: add segment operations") Cc: Ruipeng Qi Reported: Sandeep Dhavale Signed-off-by: Chao Yu Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix potential deadlock in f2fs_balance_fs()

2026-07-18T14:53:04+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: fix to do sanity check on dcc->discard_cmd_cnt conditionally

2026-04-27T13:27:29+00:00

commit 6af249c996f7d73a3435f9e577956fa259347d18 upstream. 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 Signed-off-by: Greg Kroah-Hartman

f2fs: fix incomplete block usage in compact SSA summaries

2026-02-19T15:31:36+00:00

commit 91b76f1059b60f453b51877f29f0e35693737383 upstream. In a previous commit, a bug was introduced where compact SSA summaries failed to utilize the entire block space in non-4KB block size configurations, leading to inefficient space management. This patch fixes the calculation logic to ensure that compact SSA summaries can fully occupy the block regardless of the block size. Reported-by: Chris Mason Fixes: e48e16f3e37f ("f2fs: support non-4KB block size without packed_ssa feature") Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Cc: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

f2fs: support non-4KB block size without packed_ssa feature

2026-02-19T15:31:36+00:00

commit e48e16f3e37fac76e2f0c14c58df2b0398a323b0 upstream. Currently, F2FS requires the packed_ssa feature to be enabled when utilizing non-4KB block sizes (e.g., 16KB). This restriction limits the flexibility of filesystem formatting options. This patch allows F2FS to support non-4KB block sizes even when the packed_ssa feature is disabled. It adjusts the SSA calculation logic to correctly handle summary entries in larger blocks without the packed layout. Cc: stable@kernel.org Fixes: 7ee8bc3942f2 ("f2fs: revert summary entry count from 2048 to 512 in 16kb block support") Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman

f2fs: fix age extent cache insertion skip on counter overflow

2026-01-02T11:57:17+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: revert summary entry count from 2048 to 512 in 16kb block support

2025-12-18T13:03:35+00:00

[ Upstream commit 7ee8bc3942f20964ad730871b885688ea3a2961a ] The recent increase in the number of Segment Summary Area (SSA) entries from 512 to 2048 was an unintentional change in logic of 16kb block support. This commit corrects the issue. To better utilize the space available from the erroneous 2048-entry calculation, we are implementing a solution to share the currently unused SSA space with neighboring segments. This enhances overall SSA utilization without impacting the established 8MB segment size. Fixes: d7e9a9037de2 ("f2fs: Support Block Size == Page Size") Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: allocate HOT_DATA for IPU writes

2025-09-02T20:16:04+00:00

Let's split IPU writes in hot data area to improve the GC efficiency. Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim