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authorLinus Torvalds <torvalds@linux-foundation.org>2025-10-03 14:05:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2025-10-03 14:05:12 -0700
commit86d563ac5fb0c6f404e82692581bb67a6f35e5de (patch)
tree7b3645c17758d80745eb63a68196e90966ea06c7 /Documentation/filesystems
parentf0712c203862b00139b34fcbb1710b479af2b101 (diff)
parent4e715744bf7b4e5521cc3b77f310060f862cb719 (diff)
downloadtip-86d563ac5fb0c6f404e82692581bb67a6f35e5de.tar.gz
Merge tag 'f2fs-for-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim: "This focuses on two primary updates for Android devices. First, it sets hash-based file name lookup as the default method to improve performance, while retaining an option to fall back to a linear lookup. Second, it resolves a persistent issue with the 'checkpoint=enable' feature. The update further boosts performance by prefetching node blocks, merging FUA writes more efficiently, and optimizing block allocation policies. The release is rounded out by a comprehensive set of bug fixes that address memory safety, data integrity, and potential system hangs, along with minor documentation and code clean-ups. Enhancements: - add mount option and sysfs entry to tune the lookup mode - dump more information and add a timeout when enabling/disabling checkpoints - readahead node blocks in F2FS_GET_BLOCK_PRECACHE mode - merge FUA command with the existing writes - allocate HOT_DATA for IPU writes - Use allocate_section_policy to control write priority in multi-devices setups - add reserved nodes for privileged users - Add bggc_io_aware to adjust the priority of BG_GC when issuing IO - show the list of donation files Bug fixes: - add missing dput() when printing the donation list - fix UAF issue in f2fs_merge_page_bio() - add sanity check on ei.len in __update_extent_tree_range() - fix infinite loop in __insert_extent_tree() - fix zero-sized extent for precache extents - fix to mitigate overhead of f2fs_zero_post_eof_page() - fix to avoid migrating empty section - fix to truncate first page in error path of f2fs_truncate() - fix to update map->m_next_extent correctly in f2fs_map_blocks() - fix wrong layout information on 16KB page - fix to do sanity check on node footer for non inode dnode - fix to avoid NULL pointer dereference in f2fs_check_quota_consistency() - fix to detect potential corrupted nid in free_nid_list - fix to clear unusable_cap for checkpoint=enable - fix to zero data after EOF for compressed file correctly - fix to avoid overflow while left shift operation - fix condition in __allow_reserved_blocks()" * tag 'f2fs-for-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (43 commits) f2fs: add missing dput() when printing the donation list f2fs: fix UAF issue in f2fs_merge_page_bio() f2fs: readahead node blocks in F2FS_GET_BLOCK_PRECACHE mode f2fs: add sanity check on ei.len in __update_extent_tree_range() f2fs: fix infinite loop in __insert_extent_tree() f2fs: fix zero-sized extent for precache extents f2fs: fix to mitigate overhead of f2fs_zero_post_eof_page() f2fs: fix to avoid migrating empty section f2fs: fix to truncate first page in error path of f2fs_truncate() f2fs: fix to update map->m_next_extent correctly in f2fs_map_blocks() f2fs: fix wrong layout information on 16KB page f2fs: clean up error handing of f2fs_submit_page_read() f2fs: avoid unnecessary folio_clear_uptodate() for cleanup f2fs: merge FUA command with the existing writes f2fs: allocate HOT_DATA for IPU writes f2fs: Use allocate_section_policy to control write priority in multi-devices setups Documentation: f2fs: Reword title Documentation: f2fs: Indent compression_mode option list Documentation: f2fs: Wrap snippets in literal code blocks Documentation: f2fs: Span write hint table section rows ...
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/f2fs.rst122
1 files changed, 78 insertions, 44 deletions
diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index e5bb89452aff29..a8d02fe5be8399 100644
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -1,8 +1,11 @@
.. SPDX-License-Identifier: GPL-2.0
-==========================================
-WHAT IS Flash-Friendly File System (F2FS)?
-==========================================
+=================================
+Flash-Friendly File System (F2FS)
+=================================
+
+Overview
+========
NAND flash memory-based storage devices, such as SSD, eMMC, and SD cards, have
been equipped on a variety systems ranging from mobile to server systems. Since
@@ -173,9 +176,12 @@ data_flush Enable data flushing before checkpoint in order to
persist data of regular and symlink.
reserve_root=%d Support configuring reserved space which is used for
allocation from a privileged user with specified uid or
- gid, unit: 4KB, the default limit is 0.2% of user blocks.
-resuid=%d The user ID which may use the reserved blocks.
-resgid=%d The group ID which may use the reserved blocks.
+ gid, unit: 4KB, the default limit is 12.5% of user blocks.
+reserve_node=%d Support configuring reserved nodes which are used for
+ allocation from a privileged user with specified uid or
+ gid, the default limit is 12.5% of all nodes.
+resuid=%d The user ID which may use the reserved blocks and nodes.
+resgid=%d The group ID which may use the reserved blocks and nodes.
fault_injection=%d Enable fault injection in all supported types with
specified injection rate.
fault_type=%d Support configuring fault injection type, should be
@@ -291,9 +297,13 @@ compress_algorithm=%s Control compress algorithm, currently f2fs supports "lzo"
"lz4", "zstd" and "lzo-rle" algorithm.
compress_algorithm=%s:%d Control compress algorithm and its compress level, now, only
"lz4" and "zstd" support compress level config.
+
+ ========= ===========
algorithm level range
+ ========= ===========
lz4 3 - 16
zstd 1 - 22
+ ========= ===========
compress_log_size=%u Support configuring compress cluster size. The size will
be 4KB * (1 << %u). The default and minimum sizes are 16KB.
compress_extension=%s Support adding specified extension, so that f2fs can enable
@@ -357,6 +367,7 @@ errors=%s Specify f2fs behavior on critical errors. This supports modes:
panic immediately, continue without doing anything, and remount
the partition in read-only mode. By default it uses "continue"
mode.
+
====================== =============== =============== ========
mode continue remount-ro panic
====================== =============== =============== ========
@@ -370,6 +381,25 @@ errors=%s Specify f2fs behavior on critical errors. This supports modes:
====================== =============== =============== ========
nat_bits Enable nat_bits feature to enhance full/empty nat blocks access,
by default it's disabled.
+lookup_mode=%s Control the directory lookup behavior for casefolded
+ directories. This option has no effect on directories
+ that do not have the casefold feature enabled.
+
+ ================== ========================================
+ Value Description
+ ================== ========================================
+ perf (Default) Enforces a hash-only lookup.
+ The linear search fallback is always
+ disabled, ignoring the on-disk flag.
+ compat Enables the linear search fallback for
+ compatibility with directory entries
+ created by older kernel that used a
+ different case-folding algorithm.
+ This mode ignores the on-disk flag.
+ auto F2FS determines the mode based on the
+ on-disk `SB_ENC_NO_COMPAT_FALLBACK_FL`
+ flag.
+ ================== ========================================
======================== ============================================================
Debugfs Entries
@@ -795,11 +825,13 @@ ioctl(COLD) COLD_DATA WRITE_LIFE_EXTREME
extension list " "
-- buffered io
+------------------------------------------------------------------
N/A COLD_DATA WRITE_LIFE_EXTREME
N/A HOT_DATA WRITE_LIFE_SHORT
N/A WARM_DATA WRITE_LIFE_NOT_SET
-- direct io
+------------------------------------------------------------------
WRITE_LIFE_EXTREME COLD_DATA WRITE_LIFE_EXTREME
WRITE_LIFE_SHORT HOT_DATA WRITE_LIFE_SHORT
WRITE_LIFE_NOT_SET WARM_DATA WRITE_LIFE_NOT_SET
@@ -915,24 +947,26 @@ compression enabled files (refer to "Compression implementation" section for how
enable compression on a regular inode).
1) compress_mode=fs
-This is the default option. f2fs does automatic compression in the writeback of the
-compression enabled files.
+
+ This is the default option. f2fs does automatic compression in the writeback of the
+ compression enabled files.
2) compress_mode=user
-This disables the automatic compression and gives the user discretion of choosing the
-target file and the timing. The user can do manual compression/decompression on the
-compression enabled files using F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
-ioctls like the below.
-To decompress a file,
+ This disables the automatic compression and gives the user discretion of choosing the
+ target file and the timing. The user can do manual compression/decompression on the
+ compression enabled files using F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
+ ioctls like the below.
+
+To decompress a file::
-fd = open(filename, O_WRONLY, 0);
-ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE);
+ fd = open(filename, O_WRONLY, 0);
+ ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE);
-To compress a file,
+To compress a file::
-fd = open(filename, O_WRONLY, 0);
-ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE);
+ fd = open(filename, O_WRONLY, 0);
+ ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE);
NVMe Zoned Namespace devices
----------------------------
@@ -962,32 +996,32 @@ reserved and used by another filesystem or for different purposes. Once that
external usage is complete, the device aliasing file can be deleted, releasing
the reserved space back to F2FS for its own use.
-<use-case>
-
-# ls /dev/vd*
-/dev/vdb (32GB) /dev/vdc (32GB)
-# mkfs.ext4 /dev/vdc
-# mkfs.f2fs -c /dev/vdc@vdc.file /dev/vdb
-# mount /dev/vdb /mnt/f2fs
-# ls -l /mnt/f2fs
-vdc.file
-# df -h
-/dev/vdb 64G 33G 32G 52% /mnt/f2fs
-
-# mount -o loop /dev/vdc /mnt/ext4
-# df -h
-/dev/vdb 64G 33G 32G 52% /mnt/f2fs
-/dev/loop7 32G 24K 30G 1% /mnt/ext4
-# umount /mnt/ext4
-
-# f2fs_io getflags /mnt/f2fs/vdc.file
-get a flag on /mnt/f2fs/vdc.file ret=0, flags=nocow(pinned),immutable
-# f2fs_io setflags noimmutable /mnt/f2fs/vdc.file
-get a flag on noimmutable ret=0, flags=800010
-set a flag on /mnt/f2fs/vdc.file ret=0, flags=noimmutable
-# rm /mnt/f2fs/vdc.file
-# df -h
-/dev/vdb 64G 753M 64G 2% /mnt/f2fs
+.. code-block::
+
+ # ls /dev/vd*
+ /dev/vdb (32GB) /dev/vdc (32GB)
+ # mkfs.ext4 /dev/vdc
+ # mkfs.f2fs -c /dev/vdc@vdc.file /dev/vdb
+ # mount /dev/vdb /mnt/f2fs
+ # ls -l /mnt/f2fs
+ vdc.file
+ # df -h
+ /dev/vdb 64G 33G 32G 52% /mnt/f2fs
+
+ # mount -o loop /dev/vdc /mnt/ext4
+ # df -h
+ /dev/vdb 64G 33G 32G 52% /mnt/f2fs
+ /dev/loop7 32G 24K 30G 1% /mnt/ext4
+ # umount /mnt/ext4
+
+ # f2fs_io getflags /mnt/f2fs/vdc.file
+ get a flag on /mnt/f2fs/vdc.file ret=0, flags=nocow(pinned),immutable
+ # f2fs_io setflags noimmutable /mnt/f2fs/vdc.file
+ get a flag on noimmutable ret=0, flags=800010
+ set a flag on /mnt/f2fs/vdc.file ret=0, flags=noimmutable
+ # rm /mnt/f2fs/vdc.file
+ # df -h
+ /dev/vdb 64G 753M 64G 2% /mnt/f2fs
So, the key idea is, user can do any file operations on /dev/vdc, and
reclaim the space after the use, while the space is counted as /data.
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-12-12 09:57:34 +0000