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Diffstat (limited to 'Documentation/filesystems/f2fs.rst')
| -rw-r--r-- | Documentation/filesystems/f2fs.rst | 122 |
1 files changed, 78 insertions, 44 deletions
diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index e5bb89452aff..a8d02fe5be83 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. |