kernel/linux.git/fs/f2fs/segment.c, branch v6.18.21

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

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

f2fs: add error checking in do_write_page()

2025-08-11T17:03:27+00:00

Otherwise, the filesystem may unaware of potential file corruption. Signed-off-by: mason.zhang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim

f2fs: Pass a folio to f2fs_submit_merged_write_cond()

2025-07-22T15:58:05+00:00

Most callers pass NULL, and the one that passes a page already has a folio. Also convert __submit_merged_write_cond() to take a folio. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim

f2fs: Pass a folio to ADDRS_PER_PAGE()

2025-07-22T15:56:59+00:00

All callers now have a folio so pass it in. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim

f2fs: Pass a folio to IS_DNODE()

2025-07-22T15:56:50+00:00

All callers now have a folio so pass it in. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim