kernel/linux.git/fs/f2fs/segment.c, branch v6.19.11

f2fs: fix incomplete block usage in compact SSA summaries

2026-02-19T15:33:26+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

2026-02-19T15:33:25+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: ignore discard return value

2025-12-04T02:00:06+00:00

__blkdev_issue_discard() always returns 0, making the error assignment in __submit_discard_cmd() dead code. Initialize err to 0 and remove the error assignment from the __blkdev_issue_discard() call to err. Move fault injection code into already present if branch where err is set to -EIO. This preserves the fault injection behavior while removing dead error handling. Reviewed-by: Martin K. Petersen Reviewed-by: Johannes Thumshirn Reviewed-by: Christoph Hellwig Reviewed-by: Chao Yu Signed-off-by: Chaitanya Kulkarni Signed-off-by: Jaegeuk Kim

f2fs: change default schedule timeout value

2025-12-04T02:00:05+00:00

This patch changes default schedule timeout value from 20ms to 1ms, in order to give caller more chances to check whether IO or non-IO congestion condition has already been mitigable. In addition, default interval of periodical discard submission is kept to 20ms. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim

f2fs: introduce f2fs_schedule_timeout()

2025-12-04T02:00:05+00:00

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

f2fs: use memalloc_retry_wait() as much as possible

2025-12-04T02:00:05+00:00

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

f2fs: revert summary entry count from 2048 to 512 in 16kb block support

2025-12-04T02:00:04+00:00

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

f2fs: fix age extent cache insertion skip on counter overflow

2025-12-04T02:00:03+00:00

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

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

f2fs: Use allocate_section_policy to control write priority in multi-devices setups

2025-08-29T20:48:47+00:00

Introduces two new sys nodes: allocate_section_hint and allocate_section_policy. The allocate_section_hint identifies the boundary between devices, measured in sections; it defaults to the end of the device for single storage setups, and the end of the first device for multiple storage setups. The allocate_section_policy determines the write strategy, with a default value of 0 for normal sequential write strategy. A value of 1 prioritizes writes before the allocate_section_hint, while a value of 2 prioritizes writes after it. This strategy addresses the issue where, despite F2FS supporting multiple devices, SOC vendors lack multi-devices support (currently only supporting zoned devices). As a workaround, multiple storage devices are mapped to a single dm device. Both this workaround and the F2FS multi-devices solution may require prioritizing writing to certain devices, such as a device with better performance or when switching is needed due to performance degradation near a device's end. For scenarios with more than two devices, sort them at mount time to utilize this feature. When using this feature with a single storage device, it has almost no impact. However, for configurations where multiple storage devices are mapped to the same dm device using F2FS, utilizing this feature can provide some optimization benefits. Therefore, I believe it should not be limited to just multi-devices usage. Signed-off-by: Liao Yuanhong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim