Lines Matching +full:can +full:- +full:disable
1 .. SPDX-License-Identifier: GPL-2.0
4 WHAT IS Flash-Friendly File System (F2FS)?
7 NAND flash memory-based storage devices, such as SSD, eMMC, and SD cards, have
13 F2FS is a file system exploiting NAND flash memory-based storage devices, which
14 is based on Log-structured File System (LFS). The design has been focused on
18 Since a NAND flash memory-based storage device shows different characteristic
20 F2FS and its tools support various parameters not only for configuring on-disk
26 - git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.git
30 - linux-f2fs-devel@lists.sourceforge.net
35 Log-structured File System (LFS)
36 --------------------------------
37 "A log-structured file system writes all modifications to disk sequentially in
38 a log-like structure, thereby speeding up both file writing and crash recovery.
40 files can be read back from the log efficiently. In order to maintain large free
44 implementation of a log-structured file system", ACM Trans. Computer Systems
48 ----------------------
57 [1] Bityutskiy, A. 2005. JFFS3 design issues. http://www.linux-mtd.infradead.org/
60 -----------------
61 Since LFS is based on out-of-place writes, it produces so many obsolete blocks
71 3. It checks the cross-reference between the data and its parent index structure.
82 ---------------
83 - Enlarge the random write area for better performance, but provide the high
85 - Align FS data structures to the operational units in FTL as best efforts
88 ----------------------
89 - Use a term, “node”, that represents inodes as well as various pointer blocks
90 - Introduce Node Address Table (NAT) containing the locations of all the “node”
94 -----------------
95 - Support a background cleaning process
96 - Support greedy and cost-benefit algorithms for victim selection policies
97 - Support multi-head logs for static/dynamic hot and cold data separation
98 - Introduce adaptive logging for efficient block allocation
113 gc_merge When background_gc is on, this option can be enabled to
115 it can eliminate the sluggish issue caused by slow foreground
118 nogc_merge Disable GC merge feature.
119 disable_roll_forward Disable the roll-forward recovery routine
120 norecovery Disable the roll-forward recovery routine, mounted read-
121 only (i.e., -o ro,disable_roll_forward)
122 discard/nodiscard Enable/disable real-time discard in f2fs, if discard is
125 no_heap Disable heap-style segment allocation which finds free
128 nouser_xattr Disable Extended User Attributes. Note: xattr is enabled
130 noacl Disable POSIX Access Control List. Note: acl is enabled
135 disable_ext_identify Disable the extension list configured by mkfs, so f2fs
138 noinline_xattr Disable the inline xattrs feature.
142 files can be written into inode block.
144 directory entries can be written into inode block. The
147 noinline_dentry Disable the inline dentry feature.
152 nobarrier This option can be used if underlying storage guarantees
159 can be sacrificed.
160 extent_cache Enable an extent cache based on rb-tree, it can cache
164 noextent_cache Disable an extent cache based on rb-tree explicitly, see
166 noinline_data Disable the inline data feature, inline data feature is
210 grpjquota=<file> information can be properly updated during recovery flow,
217 noquota Disable all plain disk quota option.
219 layer. This supports "off", "user-based", and
220 "fs-based". In "off" mode (default), f2fs does not pass
221 down hints. In "user-based" mode, f2fs tries to pass
222 down hints given by users. And in "fs-based" mode, f2fs
234 non-atomic files likewise "nobarrier" mount option.
241 checkpoint=%s[:%u[%]] Set to "disable" to turn off checkpointing. Set to "enable"
247 run garbage collection to ensure that all available space can
251 avoid additional garbage collection. This can be given as a
253 with checkpoint=disable:100% would always succeed, but it may
255 would be unusable can be viewed at /sys/fs/f2fs/<disk>/unusable
257 checkpoint_merge When checkpoint is enabled, this can be used to create a kernel
260 we can eliminate the sluggish issue caused by slow checkpoint
267 nocheckpoint_merge Disable checkpoint merge feature.
269 "lz4", "zstd" and "lzo-rle" algorithm.
273 lz4 3 - 16
274 zstd 1 - 22
278 compress_extension=%s Support adding specified extension, so that f2fs can enable
280 with '.ext' has high compression rate, we can set the '.ext'
283 For other files, we can still enable compression via ioctl.
285 can be set to enable compression for all files.
286 nocompress_extension=%s Support adding specified extension, so that f2fs can disable
288 If you know exactly which files cannot be compressed, you can use this.
289 The same extension name can't appear in both compress and nocompress
303 choosing the target file and the timing. The user can do manual
310 files using the blk-crypto framework rather than
311 filesystem-layer encryption. This allows the use of
312 inline encryption hardware. The on-disk format is
314 Documentation/block/inline-encryption.rst.
315 atgc Enable age-threshold garbage collection, it provides high
317 discard_unit=%s Control discard unit, the argument can be "block", "segment"
335 - major file system information managed by f2fs currently
336 - average SIT information about whole segments
337 - current memory footprint consumed by f2fs.
342 Information about mounted f2fs file systems can be found in
345 The files in each per-device directory are shown in table below.
348 (see also Documentation/ABI/testing/sysfs-fs-f2fs)
366 # mkfs.f2fs -l label /dev/block_device
367 # mount -t f2fs /dev/block_device /mnt/f2fs
370 ---------
372 which builds a basic on-disk layout.
377 ``-l [label]`` Give a volume label, up to 512 unicode name.
378 ``-a [0 or 1]`` Split start location of each area for heap-based allocation.
381 ``-o [int]`` Set overprovision ratio in percent over volume size.
384 ``-s [int]`` Set the number of segments per section.
387 ``-z [int]`` Set the number of sections per zone.
390 ``-e [str]`` Set basic extension list. e.g. "mp3,gif,mov"
391 ``-t [0 or 1]`` Disable discard command or not.
399 ---------
400 The fsck.f2fs is a tool to check the consistency of an f2fs-formatted
401 partition, which examines whether the filesystem metadata and user-made data
402 are cross-referenced correctly or not.
407 -d debug level [default:0]
412 ---------
416 The dump.f2fs is used to debug on-disk data structures of the f2fs filesystem.
417 It shows on-disk inode information recognized by a given inode number, and is
423 -d debug level [default:0]
424 -i inode no (hex)
425 -s [SIT dump segno from #1~#2 (decimal), for all 0~-1]
426 -a [SSA dump segno from #1~#2 (decimal), for all 0~-1]
430 # dump.f2fs -i [ino] /dev/sdx
431 # dump.f2fs -s 0~-1 /dev/sdx (SIT dump)
432 # dump.f2fs -a 0~-1 /dev/sdx (SSA dump)
437 ----------
444 -----------
445 The resize.f2fs lets a user resize the f2fs-formatted disk image, while preserving
451 -----------
452 The defrag.f2fs can be used to defragment scattered written data as well as
453 filesystem metadata across the disk. This can improve the write speed by giving
459 -------
461 f2fs-specific ones, which is very useful for QA tests.
468 On-disk Layout
469 --------------
474 segment size identically, but users can easily modify the sizes by mkfs.
479 align with the zone size <-|
480 |-> align with the segment size
498 - Superblock (SB)
503 - Checkpoint (CP)
507 - Segment Information Table (SIT)
511 - Node Address Table (NAT)
515 - Segment Summary Area (SSA)
519 - Main Area
522 In order to avoid misalignment between file system and flash-based storage, F2FS
531 ------------------------------
542 +--------+----------+---------+
544 +--------+----------+---------+
548 +-------+-------+--------+--------+--------+--------+
550 +-------+-------+--------+--------+--------+--------+
553 `----------------------------------------'
556 ---------------
569 |- data (923)
570 |- direct node (2)
571 | `- data (1018)
572 |- indirect node (2)
573 | `- direct node (1018)
574 | `- data (1018)
575 `- double indirect node (1)
576 `- indirect node (1018)
577 `- direct node (1018)
578 `- data (1018)
586 -------------------
590 - hash hash value of the file name
591 - ino inode number
592 - len the length of file name
593 - type file type such as directory, symlink, etc
605 +--------------------------------+
607 +--------------------------------+
611 +--------+----------+----------+------------+
613 +--------+----------+----------+------------+
617 +------+------+-----+------+
619 +------+------+-----+------+
622 F2FS implements multi-level hash tables for directory structure. Each level has
628 ----------------------
632 ----------------------
636 level #1 | A(2B) - A(2B)
638 level #2 | A(2B) - A(2B) - A(2B) - A(2B)
640 level #N/2 | A(2B) - A(2B) - A(2B) - A(2B) - A(2B) - ... - A(2B)
642 level #N | A(4B) - A(4B) - A(4B) - A(4B) - A(4B) - ... - A(4B)
646 ,- 2, if n < MAX_DIR_HASH_DEPTH / 2,
648 `- 4, Otherwise
650 ,- 2^(n + dir_level),
653 `- 2^((MAX_DIR_HASH_DEPTH / 2) - 1),
672 --------------> Dir <--------------
676 child - child [hole] - child
678 child - child - child [hole] - [hole] - child
685 ------------------------
690 - Hot node contains direct node blocks of directories.
691 - Warm node contains direct node blocks except hot node blocks.
692 - Cold node contains indirect node blocks
693 - Hot data contains dentry blocks
694 - Warm data contains data blocks except hot and cold data blocks
695 - Cold data contains multimedia data or migrated data blocks
697 LFS has two schemes for free space management: threaded log and copy-and-compac-
698 tion. The copy-and-compaction scheme which is known as cleaning, is well-suited
703 scheme where the copy-and-compaction scheme is adopted by default, but the
707 In order to align F2FS with underlying flash-based storage, F2FS allocates a
711 logs from different zones as much as possible, since FTL can write the data in
715 ----------------
717 F2FS does cleaning both on demand and in the background. On-demand cleaning is
722 F2FS supports two victim selection policies: greedy and cost-benefit algorithms.
724 of valid blocks. In the cost-benefit algorithm, F2FS selects a victim segment
727 algorithm for on-demand cleaner, while background cleaner adopts cost-benefit
734 Write-hint Policy
735 -----------------
739 2) whint_mode=user-based. F2FS tries to pass down hints given by
752 -- buffered io
760 -- direct io
769 3) whint_mode=fs-based. F2FS passes down hints with its policy.
781 -- buffered io
789 -- direct io
799 -------------------
814 fallocate(fd, DEFAULT_MODE), it allocates on-disk block addressess having
825 --------------------------
827 - New term named cluster is defined as basic unit of compression, file can
830 cluster can be compressed or not.
832 - In cluster metadata layout, one special block address is used to indicate
834 metadata maps cluster to [1, 4 << n - 1] physical blocks, in where f2fs
837 - In order to eliminate write amplification during overwrite, F2FS only
838 support compression on write-once file, data can be compressed only when
842 - To enable compression on regular inode, there are four ways:
846 * mount w/ -o compress_extension=ext; touch file.ext
847 * mount w/ -o compress_extension=*; touch any_file
849 - To disable compression on regular inode, there are two ways:
851 * chattr -c file
852 * mount w/ -o nocompress_extension=ext; touch file.ext
854 - Priority in between FS_COMPR_FL, FS_NOCOMP_FS, extensions:
858 should be compresse, bar.zip should be non-compressed. chattr +c dir/bar.zip
859 can enable compress on bar.zip.
860 * compress_extension=so; nocompress_extension=zip; chattr -c dir; touch
862 compresse, bar.zip and baz.txt should be non-compressed.
863 chattr+c dir/bar.zip; chattr+c dir/baz.txt; can enable compress on bar.zip
866 - At this point, compression feature doesn't expose compressed space to user
879 +-----------------------------------------------+
881 +-----------------------------------------------+
885 +----------+---------+---------+---------+ +---------+---------+---------+---------+
887 +----------+---------+---------+---------+ +---------+---------+---------+---------+
891 +-------------+-------------+----------+----------------------------+
893 +-------------+-------------+----------+----------------------------+
896 --------------------------
909 target file and the timing. The user can do manual compression/decompression on the
924 ----------------------------
926 - ZNS defines a per-zone capacity which can be equal or less than the
927 zone-size. Zone-capacity is the number of usable blocks in the zone.
928 F2FS checks if zone-capacity is less than zone-size, if it is, then any
929 segment which starts after the zone-capacity is marked as not-free in
933 zone-capacity is not aligned to default segment size(2MB), then a segment
934 can start before the zone-capacity and span across zone-capacity boundary.
936 past the zone-capacity are considered unusable in these segments.