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1What: /sys/fs/f2fs/<disk>/gc_max_sleep_time
2Date: July 2013
3Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
4Description: Controls the maximum sleep time for gc_thread. Time
5 is in milliseconds.
6
7What: /sys/fs/f2fs/<disk>/gc_min_sleep_time
8Date: July 2013
9Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
10Description: Controls the minimum sleep time for gc_thread. Time
11 is in milliseconds.
12
13What: /sys/fs/f2fs/<disk>/gc_no_gc_sleep_time
14Date: July 2013
15Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
16Description: Controls the default sleep time for gc_thread. Time
17 is in milliseconds.
18
19What: /sys/fs/f2fs/<disk>/gc_idle
20Date: July 2013
21Contact: "Namjae Jeon" <namjae.jeon@samsung.com>
22Description: Controls the victim selection policy for garbage collection.
23 Setting gc_idle = 0(default) will disable this option. Setting:
24
25 =========== ===============================================
26 gc_idle = 1 will select the Cost Benefit approach & setting
27 gc_idle = 2 will select the greedy approach & setting
28 gc_idle = 3 will select the age-threshold based approach.
29 =========== ===============================================
30
31What: /sys/fs/f2fs/<disk>/reclaim_segments
32Date: October 2013
33Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
34Description: This parameter controls the number of prefree segments to be
35 reclaimed. If the number of prefree segments is larger than
36 the number of segments in the proportion to the percentage
37 over total volume size, f2fs tries to conduct checkpoint to
38 reclaim the prefree segments to free segments.
39 By default, 5% over total # of segments.
40
41What: /sys/fs/f2fs/<disk>/main_blkaddr
42Date: November 2019
43Contact: "Ramon Pantin" <pantin@google.com>
44Description: Shows first block address of MAIN area.
45
46What: /sys/fs/f2fs/<disk>/ipu_policy
47Date: November 2013
48Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
49Description: Controls the in-place-update policy.
50 updates in f2fs. User can set:
51
52 ===== =============== ===================================================
53 value policy description
54 0x00 DISABLE disable IPU(=default option in LFS mode)
55 0x01 FORCE all the time
56 0x02 SSR if SSR mode is activated
57 0x04 UTIL if FS utilization is over threshold
58 0x08 SSR_UTIL if SSR mode is activated and FS utilization is over
59 threshold
60 0x10 FSYNC activated in fsync path only for high performance
61 flash storages. IPU will be triggered only if the
62 # of dirty pages over min_fsync_blocks.
63 (=default option)
64 0x20 ASYNC do IPU given by asynchronous write requests
65 0x40 NOCACHE disable IPU bio cache
66 0x80 HONOR_OPU_WRITE use OPU write prior to IPU write if inode has
67 FI_OPU_WRITE flag
68 ===== =============== ===================================================
69
70 Refer segment.h for details.
71
72What: /sys/fs/f2fs/<disk>/min_ipu_util
73Date: November 2013
74Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
75Description: Controls the FS utilization condition for the in-place-update
76 policies. It is used by F2FS_IPU_UTIL and F2FS_IPU_SSR_UTIL policies.
77
78What: /sys/fs/f2fs/<disk>/min_fsync_blocks
79Date: September 2014
80Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
81Description: Controls the dirty page count condition for the in-place-update
82 policies.
83
84What: /sys/fs/f2fs/<disk>/min_seq_blocks
85Date: August 2018
86Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
87Description: Controls the dirty page count condition for batched sequential
88 writes in writepages.
89
90What: /sys/fs/f2fs/<disk>/min_hot_blocks
91Date: March 2017
92Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
93Description: Controls the dirty page count condition for redefining hot data.
94
95What: /sys/fs/f2fs/<disk>/min_ssr_sections
96Date: October 2017
97Contact: "Chao Yu" <yuchao0@huawei.com>
98Description: Controls the free section threshold to trigger SSR allocation.
99 If this is large, SSR mode will be enabled early.
100
101What: /sys/fs/f2fs/<disk>/max_small_discards
102Date: November 2013
103Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
104Description: Controls the issue rate of discard commands that consist of small
105 blocks less than 2MB. The candidates to be discarded are cached during
106 checkpoint, and issued by issue_discard thread after checkpoint.
107 It is enabled by default.
108
109What: /sys/fs/f2fs/<disk>/max_ordered_discard
110Date: October 2022
111Contact: "Yangtao Li" <frank.li@vivo.com>
112Description: Controls the maximum ordered discard, the unit size is one block(4KB).
113 Set it to 16 by default.
114
115What: /sys/fs/f2fs/<disk>/max_discard_request
116Date: December 2021
117Contact: "Konstantin Vyshetsky" <vkon@google.com>
118Description: Controls the number of discards a thread will issue at a time.
119 Higher number will allow the discard thread to finish its work
120 faster, at the cost of higher latency for incoming I/O.
121
122What: /sys/fs/f2fs/<disk>/min_discard_issue_time
123Date: December 2021
124Contact: "Konstantin Vyshetsky" <vkon@google.com>
125Description: Controls the interval the discard thread will wait between
126 issuing discard requests when there are discards to be issued and
127 no I/O aware interruptions occur.
128
129What: /sys/fs/f2fs/<disk>/mid_discard_issue_time
130Date: December 2021
131Contact: "Konstantin Vyshetsky" <vkon@google.com>
132Description: Controls the interval the discard thread will wait between
133 issuing discard requests when there are discards to be issued and
134 an I/O aware interruption occurs.
135
136What: /sys/fs/f2fs/<disk>/max_discard_issue_time
137Date: December 2021
138Contact: "Konstantin Vyshetsky" <vkon@google.com>
139Description: Controls the interval the discard thread will wait when there are
140 no discard operations to be issued.
141
142What: /sys/fs/f2fs/<disk>/discard_granularity
143Date: July 2017
144Contact: "Chao Yu" <yuchao0@huawei.com>
145Description: Controls discard granularity of inner discard thread. Inner thread
146 will not issue discards with size that is smaller than granularity.
147 The unit size is one block(4KB), now only support configuring
148 in range of [1, 512]. Default value is 16.
149 For small devices, default value is 1.
150
151What: /sys/fs/f2fs/<disk>/umount_discard_timeout
152Date: January 2019
153Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
154Description: Set timeout to issue discard commands during umount.
155 Default: 5 secs
156
157What: /sys/fs/f2fs/<disk>/pending_discard
158Date: November 2021
159Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
160Description: Shows the number of pending discard commands in the queue.
161
162What: /sys/fs/f2fs/<disk>/max_victim_search
163Date: January 2014
164Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
165Description: Controls the number of trials to find a victim segment
166 when conducting SSR and cleaning operations. The default value
167 is 4096 which covers 8GB block address range.
168
169What: /sys/fs/f2fs/<disk>/migration_granularity
170Date: October 2018
171Contact: "Chao Yu" <yuchao0@huawei.com>
172Description: Controls migration granularity of garbage collection on large
173 section, it can let GC move partial segment{s} of one section
174 in one GC cycle, so that dispersing heavy overhead GC to
175 multiple lightweight one.
176
177What: /sys/fs/f2fs/<disk>/dir_level
178Date: March 2014
179Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
180Description: Controls the directory level for large directory. If a
181 directory has a number of files, it can reduce the file lookup
182 latency by increasing this dir_level value. Otherwise, it
183 needs to decrease this value to reduce the space overhead.
184 The default value is 0.
185
186What: /sys/fs/f2fs/<disk>/ram_thresh
187Date: March 2014
188Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
189Description: Controls the memory footprint used by free nids and cached
190 nat entries. By default, 1 is set, which indicates
191 10 MB / 1 GB RAM.
192
193What: /sys/fs/f2fs/<disk>/cp_interval
194Date: October 2015
195Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
196Description: Controls the checkpoint timing, set to 60 seconds by default.
197
198What: /sys/fs/f2fs/<disk>/idle_interval
199Date: January 2016
200Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
201Description: Controls the idle timing of system, if there is no FS operation
202 during given interval.
203 Set to 5 seconds by default.
204
205What: /sys/fs/f2fs/<disk>/discard_idle_interval
206Date: September 2018
207Contact: "Chao Yu" <yuchao0@huawei.com>
208Contact: "Sahitya Tummala" <quic_stummala@quicinc.com>
209Description: Controls the idle timing of discard thread given
210 this time interval.
211 Default is 5 secs.
212
213What: /sys/fs/f2fs/<disk>/gc_idle_interval
214Date: September 2018
215Contact: "Chao Yu" <yuchao0@huawei.com>
216Contact: "Sahitya Tummala" <quic_stummala@quicinc.com>
217Description: Controls the idle timing for gc path. Set to 5 seconds by default.
218
219What: /sys/fs/f2fs/<disk>/iostat_enable
220Date: August 2017
221Contact: "Chao Yu" <yuchao0@huawei.com>
222Description: Controls to enable/disable IO stat.
223
224What: /sys/fs/f2fs/<disk>/ra_nid_pages
225Date: October 2015
226Contact: "Chao Yu" <chao2.yu@samsung.com>
227Description: Controls the count of nid pages to be readaheaded.
228 When building free nids, F2FS reads NAT blocks ahead for
229 speed up. Default is 0.
230
231What: /sys/fs/f2fs/<disk>/dirty_nats_ratio
232Date: January 2016
233Contact: "Chao Yu" <chao2.yu@samsung.com>
234Description: Controls dirty nat entries ratio threshold, if current
235 ratio exceeds configured threshold, checkpoint will
236 be triggered for flushing dirty nat entries.
237
238What: /sys/fs/f2fs/<disk>/lifetime_write_kbytes
239Date: January 2016
240Contact: "Shuoran Liu" <liushuoran@huawei.com>
241Description: Shows total written kbytes issued to disk.
242
243What: /sys/fs/f2fs/<disk>/features
244Date: July 2017
245Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
246Description: <deprecated: should use /sys/fs/f2fs/<disk>/feature_list/>
247 Shows all enabled features in current device.
248 Supported features:
249 encryption, blkzoned, extra_attr, projquota, inode_checksum,
250 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
251 verity, sb_checksum, casefold, readonly, compression, pin_file.
252
253What: /sys/fs/f2fs/<disk>/feature_list/
254Date: June 2021
255Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
256Description: Expand /sys/fs/f2fs/<disk>/features to meet sysfs rule.
257 Supported on-disk features:
258 encryption, block_zoned (aka blkzoned), extra_attr,
259 project_quota (aka projquota), inode_checksum,
260 flexible_inline_xattr, quota_ino, inode_crtime, lost_found,
261 verity, sb_checksum, casefold, readonly, compression.
262 Note that, pin_file is moved into /sys/fs/f2fs/features/.
263
264What: /sys/fs/f2fs/features/
265Date: July 2017
266Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
267Description: Shows all enabled kernel features.
268 Supported features:
269 encryption, block_zoned, extra_attr, project_quota,
270 inode_checksum, flexible_inline_xattr, quota_ino,
271 inode_crtime, lost_found, verity, sb_checksum,
272 casefold, readonly, compression, test_dummy_encryption_v2,
273 atomic_write, pin_file, encrypted_casefold, linear_lookup.
274
275What: /sys/fs/f2fs/<disk>/inject_rate
276Date: May 2016
277Contact: "Sheng Yong" <shengyong1@huawei.com>
278Description: Controls the injection rate of arbitrary faults.
279
280What: /sys/fs/f2fs/<disk>/inject_type
281Date: May 2016
282Contact: "Sheng Yong" <shengyong1@huawei.com>
283Description: Controls the injection type of arbitrary faults.
284
285What: /sys/fs/f2fs/<disk>/dirty_segments
286Date: October 2017
287Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
288Description: Shows the number of dirty segments.
289
290What: /sys/fs/f2fs/<disk>/reserved_blocks
291Date: June 2017
292Contact: "Chao Yu" <yuchao0@huawei.com>
293Description: Controls target reserved blocks in system, the threshold
294 is soft, it could exceed current available user space.
295
296What: /sys/fs/f2fs/<disk>/current_reserved_blocks
297Date: October 2017
298Contact: "Yunlong Song" <yunlong.song@huawei.com>
299Contact: "Chao Yu" <yuchao0@huawei.com>
300Description: Shows current reserved blocks in system, it may be temporarily
301 smaller than target_reserved_blocks, but will gradually
302 increase to target_reserved_blocks when more free blocks are
303 freed by user later.
304
305What: /sys/fs/f2fs/<disk>/gc_urgent
306Date: August 2017
307Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
308Description: Do background GC aggressively when set. Set to 0 by default.
309 gc urgent high(1): does GC forcibly in a period of given
310 gc_urgent_sleep_time and ignores I/O idling check. uses greedy
311 GC approach and turns SSR mode on.
312 gc urgent low(2): lowers the bar of checking I/O idling in
313 order to process outstanding discard commands and GC a
314 little bit aggressively. always uses cost benefit GC approach,
315 and will override age-threshold GC approach if ATGC is enabled
316 at the same time.
317 gc urgent mid(3): does GC forcibly in a period of given
318 gc_urgent_sleep_time and executes a mid level of I/O idling check.
319 always uses cost benefit GC approach, and will override
320 age-threshold GC approach if ATGC is enabled at the same time.
321
322What: /sys/fs/f2fs/<disk>/gc_urgent_sleep_time
323Date: August 2017
324Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
325Description: Controls sleep time of GC urgent mode. Set to 500ms by default.
326
327What: /sys/fs/f2fs/<disk>/readdir_ra
328Date: November 2017
329Contact: "Sheng Yong" <shengyong1@huawei.com>
330Description: Controls readahead inode block in readdir. Enabled by default.
331
332What: /sys/fs/f2fs/<disk>/gc_pin_file_thresh
333Date: January 2018
334Contact: Jaegeuk Kim <jaegeuk@kernel.org>
335Description: This indicates how many GC can be failed for the pinned
336 file. If it exceeds this, F2FS doesn't guarantee its pinning
337 state. 2048 trials is set by default, and 65535 as maximum.
338
339What: /sys/fs/f2fs/<disk>/extension_list
340Date: February 2018
341Contact: "Chao Yu" <yuchao0@huawei.com>
342Description: Used to control configure extension list:
343 - Query: cat /sys/fs/f2fs/<disk>/extension_list
344 - Add: echo '[h/c]extension' > /sys/fs/f2fs/<disk>/extension_list
345 - Del: echo '[h/c]!extension' > /sys/fs/f2fs/<disk>/extension_list
346 - [h] means add/del hot file extension
347 - [c] means add/del cold file extension
348
349What: /sys/fs/f2fs/<disk>/unusable
350Date: April 2019
351Contact: "Daniel Rosenberg" <drosen@google.com>
352Description: If checkpoint=disable, it displays the number of blocks that
353 are unusable.
354 If checkpoint=enable it displays the number of blocks that
355 would be unusable if checkpoint=disable were to be set.
356
357What: /sys/fs/f2fs/<disk>/encoding
358Date: July 2019
359Contact: "Daniel Rosenberg" <drosen@google.com>
360Description: Displays name and version of the encoding set for the filesystem.
361 If no encoding is set, displays (none)
362
363What: /sys/fs/f2fs/<disk>/free_segments
364Date: September 2019
365Contact: "Hridya Valsaraju" <hridya@google.com>
366Description: Number of free segments in disk.
367
368What: /sys/fs/f2fs/<disk>/cp_foreground_calls
369Date: September 2019
370Contact: "Hridya Valsaraju" <hridya@google.com>
371Description: Number of checkpoint operations performed on demand. Available when
372 CONFIG_F2FS_STAT_FS=y.
373
374What: /sys/fs/f2fs/<disk>/cp_background_calls
375Date: September 2019
376Contact: "Hridya Valsaraju" <hridya@google.com>
377Description: Number of checkpoint operations performed in the background to
378 free segments. Available when CONFIG_F2FS_STAT_FS=y.
379
380What: /sys/fs/f2fs/<disk>/gc_foreground_calls
381Date: September 2019
382Contact: "Hridya Valsaraju" <hridya@google.com>
383Description: Number of garbage collection operations performed on demand.
384 Available when CONFIG_F2FS_STAT_FS=y.
385
386What: /sys/fs/f2fs/<disk>/gc_background_calls
387Date: September 2019
388Contact: "Hridya Valsaraju" <hridya@google.com>
389Description: Number of garbage collection operations triggered in background.
390 Available when CONFIG_F2FS_STAT_FS=y.
391
392What: /sys/fs/f2fs/<disk>/moved_blocks_foreground
393Date: September 2019
394Contact: "Hridya Valsaraju" <hridya@google.com>
395Description: Number of blocks moved by garbage collection in foreground.
396 Available when CONFIG_F2FS_STAT_FS=y.
397
398What: /sys/fs/f2fs/<disk>/moved_blocks_background
399Date: September 2019
400Contact: "Hridya Valsaraju" <hridya@google.com>
401Description: Number of blocks moved by garbage collection in background.
402 Available when CONFIG_F2FS_STAT_FS=y.
403
404What: /sys/fs/f2fs/<disk>/avg_vblocks
405Date: September 2019
406Contact: "Hridya Valsaraju" <hridya@google.com>
407Description: Average number of valid blocks.
408 Available when CONFIG_F2FS_STAT_FS=y.
409
410What: /sys/fs/f2fs/<disk>/defrag_blocks
411Date: February 2026
412Contact: "Jinbao Liu" <liujinbao1@xiaomi.com>
413Description: Number of blocks moved by defragment.
414 Available when CONFIG_F2FS_STAT_FS=y.
415
416What: /sys/fs/f2fs/<disk>/mounted_time_sec
417Date: February 2020
418Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
419Description: Show the mounted time in secs of this partition.
420
421What: /sys/fs/f2fs/<disk>/data_io_flag
422Date: April 2020
423Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
424Description: Give a way to attach REQ_META|FUA to data writes
425 given temperature-based bits. Now the bits indicate:
426
427 +-------------------+-------------------+
428 | REQ_META | REQ_FUA |
429 +------+------+-----+------+------+-----+
430 | 5 | 4 | 3 | 2 | 1 | 0 |
431 +------+------+-----+------+------+-----+
432 | Cold | Warm | Hot | Cold | Warm | Hot |
433 +------+------+-----+------+------+-----+
434
435What: /sys/fs/f2fs/<disk>/node_io_flag
436Date: June 2020
437Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
438Description: Give a way to attach REQ_META|FUA to node writes
439 given temperature-based bits. Now the bits indicate:
440
441 +-------------------+-------------------+
442 | REQ_META | REQ_FUA |
443 +------+------+-----+------+------+-----+
444 | 5 | 4 | 3 | 2 | 1 | 0 |
445 +------+------+-----+------+------+-----+
446 | Cold | Warm | Hot | Cold | Warm | Hot |
447 +------+------+-----+------+------+-----+
448
449What: /sys/fs/f2fs/<disk>/iostat_period_ms
450Date: April 2020
451Contact: "Daeho Jeong" <daehojeong@google.com>
452Description: Give a way to change iostat_period time. 3secs by default.
453 The new iostat trace gives stats gap given the period.
454What: /sys/fs/f2fs/<disk>/max_io_bytes
455Date: December 2020
456Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
457Description: This gives a control to limit the bio size in f2fs.
458 Default is zero, which will follow underlying block layer limit,
459 whereas, if it has a certain bytes value, f2fs won't submit a
460 bio larger than that size.
461
462What: /sys/fs/f2fs/<disk>/stat/sb_status
463Date: December 2020
464Contact: "Chao Yu" <yuchao0@huawei.com>
465Description: Show status of f2fs superblock in real time.
466
467 ====== ===================== =================================
468 value sb status macro description
469 0x1 SBI_IS_DIRTY dirty flag for checkpoint
470 0x2 SBI_IS_CLOSE specify unmounting
471 0x4 SBI_NEED_FSCK need fsck.f2fs to fix
472 0x8 SBI_POR_DOING recovery is doing or not
473 0x10 SBI_NEED_SB_WRITE need to recover superblock
474 0x20 SBI_NEED_CP need to checkpoint
475 0x40 SBI_IS_SHUTDOWN shutdown by ioctl
476 0x80 SBI_IS_RECOVERED recovered orphan/data
477 0x100 SBI_CP_DISABLED CP was disabled last mount
478 0x200 SBI_CP_DISABLED_QUICK CP was disabled quickly
479 0x400 SBI_QUOTA_NEED_FLUSH need to flush quota info in CP
480 0x800 SBI_QUOTA_SKIP_FLUSH skip flushing quota in current CP
481 0x1000 SBI_QUOTA_NEED_REPAIR quota file may be corrupted
482 0x2000 SBI_IS_RESIZEFS resizefs is in process
483 0x4000 SBI_IS_FREEZING freefs is in process
484 ====== ===================== =================================
485
486What: /sys/fs/f2fs/<disk>/stat/cp_status
487Date: September 2022
488Contact: "Chao Yu" <chao.yu@oppo.com>
489Description: Show status of f2fs checkpoint in real time.
490
491 =============================== ==============================
492 cp flag value
493 CP_UMOUNT_FLAG 0x00000001
494 CP_ORPHAN_PRESENT_FLAG 0x00000002
495 CP_COMPACT_SUM_FLAG 0x00000004
496 CP_ERROR_FLAG 0x00000008
497 CP_FSCK_FLAG 0x00000010
498 CP_FASTBOOT_FLAG 0x00000020
499 CP_CRC_RECOVERY_FLAG 0x00000040
500 CP_NAT_BITS_FLAG 0x00000080
501 CP_TRIMMED_FLAG 0x00000100
502 CP_NOCRC_RECOVERY_FLAG 0x00000200
503 CP_LARGE_NAT_BITMAP_FLAG 0x00000400
504 CP_QUOTA_NEED_FSCK_FLAG 0x00000800
505 CP_DISABLED_FLAG 0x00001000
506 CP_DISABLED_QUICK_FLAG 0x00002000
507 CP_RESIZEFS_FLAG 0x00004000
508 =============================== ==============================
509
510What: /sys/fs/f2fs/<disk>/stat/issued_discard
511Date: December 2023
512Contact: "Zhiguo Niu" <zhiguo.niu@unisoc.com>
513Description: Shows the number of issued discard.
514
515What: /sys/fs/f2fs/<disk>/stat/queued_discard
516Date: December 2023
517Contact: "Zhiguo Niu" <zhiguo.niu@unisoc.com>
518Description: Shows the number of queued discard.
519
520What: /sys/fs/f2fs/<disk>/stat/undiscard_blks
521Date: December 2023
522Contact: "Zhiguo Niu" <zhiguo.niu@unisoc.com>
523Description: Shows the total number of undiscard blocks.
524
525What: /sys/fs/f2fs/<disk>/ckpt_thread_ioprio
526Date: January 2021
527Contact: "Daeho Jeong" <daehojeong@google.com>
528Description: Give a way to change checkpoint merge daemon's io priority.
529 Its default value is "rt,3", which means "RT" I/O class and
530 I/O priority "3". We can select the class between "rt" and "be",
531 and set the I/O priority within valid range of it. "," delimiter
532 is necessary in between I/O class and priority number.
533
534What: /sys/fs/f2fs/<disk>/ovp_segments
535Date: March 2021
536Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
537Description: Shows the number of overprovision segments.
538
539What: /sys/fs/f2fs/<disk>/compr_written_block
540Date: March 2021
541Contact: "Daeho Jeong" <daehojeong@google.com>
542Description: Show the block count written after compression since mount. Note
543 that when the compressed blocks are deleted, this count doesn't
544 decrease. If you write "0" here, you can initialize
545 compr_written_block and compr_saved_block to "0".
546
547What: /sys/fs/f2fs/<disk>/compr_saved_block
548Date: March 2021
549Contact: "Daeho Jeong" <daehojeong@google.com>
550Description: Show the saved block count with compression since mount. Note
551 that when the compressed blocks are deleted, this count doesn't
552 decrease. If you write "0" here, you can initialize
553 compr_written_block and compr_saved_block to "0".
554
555What: /sys/fs/f2fs/<disk>/compr_new_inode
556Date: March 2021
557Contact: "Daeho Jeong" <daehojeong@google.com>
558Description: Show the count of inode newly enabled for compression since mount.
559 Note that when the compression is disabled for the files, this count
560 doesn't decrease. If you write "0" here, you can initialize
561 compr_new_inode to "0".
562
563What: /sys/fs/f2fs/<disk>/atgc_candidate_ratio
564Date: May 2021
565Contact: "Chao Yu" <yuchao0@huawei.com>
566Description: When ATGC is on, it controls candidate ratio in order to limit total
567 number of potential victim in all candidates, the value should be in
568 range of [0, 100], by default it was initialized as 20(%).
569
570What: /sys/fs/f2fs/<disk>/atgc_candidate_count
571Date: May 2021
572Contact: "Chao Yu" <yuchao0@huawei.com>
573Description: When ATGC is on, it controls candidate count in order to limit total
574 number of potential victim in all candidates, by default it was
575 initialized as 10 (sections).
576
577What: /sys/fs/f2fs/<disk>/atgc_age_weight
578Date: May 2021
579Contact: "Chao Yu" <yuchao0@huawei.com>
580Description: When ATGC is on, it controls age weight to balance weight proportion
581 in between aging and valid blocks, the value should be in range of
582 [0, 100], by default it was initialized as 60(%).
583
584What: /sys/fs/f2fs/<disk>/atgc_age_threshold
585Date: May 2021
586Contact: "Chao Yu" <yuchao0@huawei.com>
587Description: When ATGC is on, it controls age threshold to bypass GCing young
588 candidates whose age is not beyond the threshold, by default it was
589 initialized as 604800 seconds (equals to 7 days).
590
591What: /sys/fs/f2fs/<disk>/atgc_enabled
592Date: Feb 2024
593Contact: "Jinbao Liu" <liujinbao1@xiaomi.com>
594Description: It represents whether ATGC is on or off. The value is 1 which
595 indicates that ATGC is on, and 0 indicates that it is off.
596
597What: /sys/fs/f2fs/<disk>/gc_reclaimed_segments
598Date: July 2021
599Contact: "Daeho Jeong" <daehojeong@google.com>
600Description: Show how many segments have been reclaimed by GC during a specific
601 GC mode (0: GC normal, 1: GC idle CB, 2: GC idle greedy,
602 3: GC idle AT, 4: GC urgent high, 5: GC urgent low 6: GC urgent mid)
603 You can re-initialize this value to "0".
604
605What: /sys/fs/f2fs/<disk>/gc_segment_mode
606Date: July 2021
607Contact: "Daeho Jeong" <daehojeong@google.com>
608Description: You can control for which gc mode the "gc_reclaimed_segments" node shows.
609 Refer to the description of the modes in "gc_reclaimed_segments".
610
611What: /sys/fs/f2fs/<disk>/seq_file_ra_mul
612Date: July 2021
613Contact: "Daeho Jeong" <daehojeong@google.com>
614Description: You can control the multiplier value of bdi device readahead window size
615 between 2 (default) and 256 for POSIX_FADV_SEQUENTIAL advise option.
616
617What: /sys/fs/f2fs/<disk>/max_fragment_chunk
618Date: August 2021
619Contact: "Daeho Jeong" <daehojeong@google.com>
620Description: With "mode=fragment:block" mount options, we can scatter block allocation.
621 f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole
622 in the length of 1..<max_fragment_hole> by turns. This value can be set
623 between 1..512 and the default value is 4.
624
625What: /sys/fs/f2fs/<disk>/max_fragment_hole
626Date: August 2021
627Contact: "Daeho Jeong" <daehojeong@google.com>
628Description: With "mode=fragment:block" mount options, we can scatter block allocation.
629 f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole
630 in the length of 1..<max_fragment_hole> by turns. This value can be set
631 between 1..512 and the default value is 4.
632
633What: /sys/fs/f2fs/<disk>/gc_remaining_trials
634Date: October 2022
635Contact: "Yangtao Li" <frank.li@vivo.com>
636Description: You can set the trial count limit for GC urgent and idle mode with this value.
637 If GC thread gets to the limit, the mode will turn back to GC normal mode.
638 By default, the value is zero, which means there is no limit like before.
639
640What: /sys/fs/f2fs/<disk>/max_roll_forward_node_blocks
641Date: January 2022
642Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
643Description: Controls max # of node block writes to be used for roll forward
644 recovery. This can limit the roll forward recovery time.
645
646What: /sys/fs/f2fs/<disk>/unusable_blocks_per_sec
647Date: June 2022
648Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
649Description: Shows the number of unusable blocks in a section which was defined by
650 the zone capacity reported by underlying zoned device.
651
652What: /sys/fs/f2fs/<disk>/max_open_zones
653Date: November 2025
654Contact: "Yongpeng Yang" <yangyongpeng@xiaomi.com>
655Description: Shows the max number of zones that F2FS can write concurrently when a zoned
656 device is mounted.
657
658What: /sys/fs/f2fs/<disk>/current_atomic_write
659Date: July 2022
660Contact: "Daeho Jeong" <daehojeong@google.com>
661Description: Show the total current atomic write block count, which is not committed yet.
662 This is a read-only entry.
663
664What: /sys/fs/f2fs/<disk>/peak_atomic_write
665Date: July 2022
666Contact: "Daeho Jeong" <daehojeong@google.com>
667Description: Show the peak value of total current atomic write block count after boot.
668 If you write "0" here, you can initialize to "0".
669
670What: /sys/fs/f2fs/<disk>/committed_atomic_block
671Date: July 2022
672Contact: "Daeho Jeong" <daehojeong@google.com>
673Description: Show the accumulated total committed atomic write block count after boot.
674 If you write "0" here, you can initialize to "0".
675
676What: /sys/fs/f2fs/<disk>/revoked_atomic_block
677Date: July 2022
678Contact: "Daeho Jeong" <daehojeong@google.com>
679Description: Show the accumulated total revoked atomic write block count after boot.
680 If you write "0" here, you can initialize to "0".
681
682What: /sys/fs/f2fs/<disk>/gc_mode
683Date: October 2022
684Contact: "Yangtao Li" <frank.li@vivo.com>
685Description: Show the current gc_mode as a string.
686 This is a read-only entry.
687
688What: /sys/fs/f2fs/<disk>/discard_urgent_util
689Date: November 2022
690Contact: "Yangtao Li" <frank.li@vivo.com>
691Description: When space utilization exceeds this, do background DISCARD aggressively.
692 Does DISCARD forcibly in a period of given min_discard_issue_time when the number
693 of discards is not 0 and set discard granularity to 1.
694 Default: 80
695
696What: /sys/fs/f2fs/<disk>/hot_data_age_threshold
697Date: November 2022
698Contact: "Ping Xiong" <xiongping1@xiaomi.com>
699Description: When DATA SEPARATION is on, it controls the age threshold to indicate
700 the data blocks as hot. By default it was initialized as 262144 blocks
701 (equals to 1GB).
702
703What: /sys/fs/f2fs/<disk>/warm_data_age_threshold
704Date: November 2022
705Contact: "Ping Xiong" <xiongping1@xiaomi.com>
706Description: When DATA SEPARATION is on, it controls the age threshold to indicate
707 the data blocks as warm. By default it was initialized as 2621440 blocks
708 (equals to 10GB).
709
710What: /sys/fs/f2fs/<disk>/fault_rate
711Date: May 2016
712Contact: "Sheng Yong" <shengyong@oppo.com>
713Contact: "Chao Yu" <chao@kernel.org>
714Description: Enable fault injection in all supported types with
715 specified injection rate.
716
717What: /sys/fs/f2fs/<disk>/fault_type
718Date: May 2016
719Contact: "Sheng Yong" <shengyong@oppo.com>
720Contact: "Chao Yu" <chao@kernel.org>
721Description: Support configuring fault injection type, should be
722 enabled with fault_injection option, fault type value
723 is shown below, it supports single or combined type.
724
725 =========================== ==========
726 Type_Name Type_Value
727 =========================== ==========
728 FAULT_KMALLOC 0x00000001
729 FAULT_KVMALLOC 0x00000002
730 FAULT_PAGE_ALLOC 0x00000004
731 FAULT_PAGE_GET 0x00000008
732 FAULT_ALLOC_BIO 0x00000010 (obsolete)
733 FAULT_ALLOC_NID 0x00000020
734 FAULT_ORPHAN 0x00000040
735 FAULT_BLOCK 0x00000080
736 FAULT_DIR_DEPTH 0x00000100
737 FAULT_EVICT_INODE 0x00000200
738 FAULT_TRUNCATE 0x00000400
739 FAULT_READ_IO 0x00000800
740 FAULT_CHECKPOINT 0x00001000
741 FAULT_DISCARD 0x00002000 (obsolete)
742 FAULT_WRITE_IO 0x00004000
743 FAULT_SLAB_ALLOC 0x00008000
744 FAULT_DQUOT_INIT 0x00010000
745 FAULT_LOCK_OP 0x00020000
746 FAULT_BLKADDR_VALIDITY 0x00040000
747 FAULT_BLKADDR_CONSISTENCE 0x00080000
748 FAULT_NO_SEGMENT 0x00100000
749 FAULT_INCONSISTENT_FOOTER 0x00200000
750 FAULT_ATOMIC_TIMEOUT 0x00400000 (1000ms)
751 FAULT_VMALLOC 0x00800000
752 FAULT_LOCK_TIMEOUT 0x01000000 (1000ms)
753 FAULT_SKIP_WRITE 0x02000000
754 =========================== ==========
755
756What: /sys/fs/f2fs/<disk>/discard_io_aware_gran
757Date: January 2023
758Contact: "Yangtao Li" <frank.li@vivo.com>
759Description: Controls background discard granularity of inner discard thread
760 when is not in idle. Inner thread will not issue discards with size that
761 is smaller than granularity. The unit size is one block(4KB), now only
762 support configuring in range of [0, 512].
763 Default: 512
764
765What: /sys/fs/f2fs/<disk>/last_age_weight
766Date: January 2023
767Contact: "Ping Xiong" <xiongping1@xiaomi.com>
768Description: When DATA SEPARATION is on, it controls the weight of last data block age.
769
770What: /sys/fs/f2fs/<disk>/compress_watermark
771Date: February 2023
772Contact: "Yangtao Li" <frank.li@vivo.com>
773Description: When compress cache is on, it controls free memory watermark
774 in order to limit caching compress page. If free memory is lower
775 than watermark, then deny caching compress page. The value should be in
776 range of (0, 100], by default it was initialized as 20(%).
777
778What: /sys/fs/f2fs/<disk>/compress_percent
779Date: February 2023
780Contact: "Yangtao Li" <frank.li@vivo.com>
781Description: When compress cache is on, it controls cached page
782 percent(compress pages / free_ram) in order to limit caching compress page.
783 If cached page percent exceed threshold, then deny caching compress page.
784 The value should be in range of (0, 100], by default it was initialized
785 as 20(%).
786
787What: /sys/fs/f2fs/<disk>/discard_io_aware
788Date: November 2023
789Contact: "Chao Yu" <chao@kernel.org>
790Description: It controls to enable/disable IO aware feature for background discard.
791 By default, the value is 1 which indicates IO aware is on.
792
793What: /sys/fs/f2fs/<disk>/blkzone_alloc_policy
794Date: July 2024
795Contact: "Yuanhong Liao" <liaoyuanhong@vivo.com>
796Description: The zone UFS we are currently using consists of two parts:
797 conventional zones and sequential zones. It can be used to control which part
798 to prioritize for writes, with a default value of 0.
799
800 ======================== =========================================
801 value description
802 blkzone_alloc_policy = 0 Prioritize writing to sequential zones
803 blkzone_alloc_policy = 1 Only allow writing to sequential zones
804 blkzone_alloc_policy = 2 Prioritize writing to conventional zones
805 ======================== =========================================
806
807What: /sys/fs/f2fs/<disk>/migration_window_granularity
808Date: September 2024
809Contact: "Daeho Jeong" <daehojeong@google.com>
810Description: Controls migration window granularity of garbage collection on large
811 section. it can control the scanning window granularity for GC migration
812 in a unit of segment, while migration_granularity controls the number
813 of segments which can be migrated at the same turn.
814
815What: /sys/fs/f2fs/<disk>/reserved_segments
816Date: September 2024
817Contact: "Daeho Jeong" <daehojeong@google.com>
818Description: In order to fine tune GC behavior, we can control the number of
819 reserved segments.
820
821What: /sys/fs/f2fs/<disk>/gc_no_zoned_gc_percent
822Date: September 2024
823Contact: "Daeho Jeong" <daehojeong@google.com>
824Description: If the percentage of free sections over total sections is above this
825 number, F2FS do not garbage collection for zoned devices through the
826 background GC thread. the default number is "60".
827
828What: /sys/fs/f2fs/<disk>/gc_boost_zoned_gc_percent
829Date: September 2024
830Contact: "Daeho Jeong" <daehojeong@google.com>
831Description: If the percentage of free sections over total sections is under this
832 number, F2FS boosts garbage collection for zoned devices through the
833 background GC thread. the default number is "25".
834
835What: /sys/fs/f2fs/<disk>/gc_valid_thresh_ratio
836Date: September 2024
837Contact: "Daeho Jeong" <daehojeong@google.com>
838Description: It controls the valid block ratio threshold not to trigger excessive GC
839 for zoned devices. The initial value of it is 95(%). F2FS will stop the
840 background GC thread from initiating GC for sections having valid blocks
841 exceeding the ratio.
842
843What: /sys/fs/f2fs/<disk>/max_read_extent_count
844Date: November 2024
845Contact: "Chao Yu" <chao@kernel.org>
846Description: It controls max read extent count for per-inode, the value of threshold
847 is 10240 by default.
848
849What: /sys/fs/f2fs/tuning/reclaim_caches_kb
850Date: February 2025
851Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
852Description: It reclaims the given KBs of file-backed pages registered by
853 ioctl(F2FS_IOC_DONATE_RANGE).
854 For example, writing N tries to drop N KBs spaces in LRU.
855
856What: /sys/fs/f2fs/<disk>/carve_out
857Date: March 2025
858Contact: "Daeho Jeong" <daehojeong@google.com>
859Description: For several zoned storage devices, vendors will provide extra space which
860 was used for device level GC than specs and F2FS can use this space for
861 filesystem level GC. To do that, we can reserve the space using
862 reserved_blocks. However, it is not enough, since this extra space should
863 not be shown to users. So, with this new sysfs node, we can hide the space
864 by subtracting reserved_blocks from total bytes.
865
866What: /sys/fs/f2fs/<disk>/encoding_flags
867Date: April 2025
868Contact: "Chao Yu" <chao@kernel.org>
869Description: This is a read-only entry to show the value of sb.s_encoding_flags, the
870 value is hexadecimal.
871
872 ============================ ==========
873 Flag_Name Flag_Value
874 ============================ ==========
875 SB_ENC_STRICT_MODE_FL 0x00000001
876 SB_ENC_NO_COMPAT_FALLBACK_FL 0x00000002
877 ============================ ==========
878
879What: /sys/fs/f2fs/<disk>/reserved_pin_section
880Date: June 2025
881Contact: "Chao Yu" <chao@kernel.org>
882Description: This threshold is used to control triggering garbage collection while
883 fallocating on pinned file, so, it can guarantee there is enough free
884 reserved section before preallocating on pinned file.
885 By default, the value is ovp_sections, especially, for zoned ufs, the
886 value is 1.
887
888What: /sys/fs/f2fs/<disk>/gc_boost_gc_multiple
889Date: June 2025
890Contact: "Daeho Jeong" <daehojeong@google.com>
891Description: Set a multiplier for the background GC migration window when F2FS GC is
892 boosted. The range should be from 1 to the segment count in a section.
893 Default: 5
894
895What: /sys/fs/f2fs/<disk>/gc_boost_gc_greedy
896Date: June 2025
897Contact: "Daeho Jeong" <daehojeong@google.com>
898Description: Control GC algorithm for boost GC. 0: cost benefit, 1: greedy
899 Default: 1
900
901What: /sys/fs/f2fs/<disk>/effective_lookup_mode
902Date: August 2025
903Contact: "Daniel Lee" <chullee@google.com>
904Description:
905 This is a read-only entry to show the effective directory lookup mode
906 F2FS is currently using for casefolded directories.
907 This considers both the "lookup_mode" mount option and the on-disk
908 encoding flag, SB_ENC_NO_COMPAT_FALLBACK_FL.
909
910 Possible values are:
911 - "perf": Hash-only lookup.
912 - "compat": Hash-based lookup with a linear search fallback enabled
913 - "auto:perf": lookup_mode is auto and fallback is disabled on-disk
914 - "auto:compat": lookup_mode is auto and fallback is enabled on-disk
915
916What: /sys/fs/f2fs/<disk>/bggc_io_aware
917Date: August 2025
918Contact: "Liao Yuanhong" <liaoyuanhong@vivo.com>
919Description: Used to adjust the BG_GC priority when pending IO, with a default value
920 of 0. Specifically, for ZUFS, the default value is 1.
921
922 ================== ======================================================
923 value description
924 bggc_io_aware = 0 skip background GC if there is any kind of pending IO
925 bggc_io_aware = 1 skip background GC if there is pending read IO
926 bggc_io_aware = 2 don't aware IO for background GC
927 ================== ======================================================
928
929What: /sys/fs/f2fs/<disk>/allocate_section_hint
930Date: August 2025
931Contact: "Liao Yuanhong" <liaoyuanhong@vivo.com>
932Description: Indicates the hint section between the first device and others in multi-devices
933 setup. It defaults to the end of the first device in sections. For a single storage
934 device, it defaults to the total number of sections. It can be manually set to match
935 scenarios where multi-devices are mapped to the same dm device.
936
937What: /sys/fs/f2fs/<disk>/allocate_section_policy
938Date: August 2025
939Contact: "Liao Yuanhong" <liaoyuanhong@vivo.com>
940Description: Controls write priority in multi-devices setups. A value of 0 means normal writing.
941 A value of 1 prioritizes writing to devices before the allocate_section_hint. A value of 2
942 prioritizes writing to devices after the allocate_section_hint. The default is 0.
943
944 =========================== ==========================================================
945 value description
946 allocate_section_policy = 0 Normal writing
947 allocate_section_policy = 1 Prioritize writing to section before allocate_section_hint
948 allocate_section_policy = 2 Prioritize writing to section after allocate_section_hint
949 =========================== ==========================================================
950
951What: /sys/fs/f2fs/<disk>/max_lock_elapsed_time
952Date: December 2025
953Contact: "Chao Yu" <chao@kernel.org>
954Description: This is a threshold, once a thread enters critical region that lock covers, total
955 elapsed time exceeds this threshold, f2fs will print tracepoint to dump information
956 of related context. This sysfs entry can be used to control the value of threshold,
957 by default, the value is 500 ms.
958
959What: /sys/fs/f2fs/<disk>/inject_timeout_type
960Date: December 2025
961Contact: "Chao Yu" <chao@kernel.org>
962Description: This sysfs entry can be used to change type of injected timeout:
963 ========== ===============================
964 Flag_Value Flag_Description
965 ========== ===============================
966 0x00000000 No timeout (default)
967 0x00000001 Simulate running time
968 0x00000002 Simulate IO type sleep time
969 0x00000003 Simulate Non-IO type sleep time
970 0x00000004 Simulate runnable time
971 ========== ===============================
972
973What: /sys/fs/f2fs/<disk>/adjust_lock_priority
974Date: January 2026
975Contact: "Chao Yu" <chao@kernel.org>
976Description: This sysfs entry can be used to enable/disable to adjust priority for task
977 which is in critical region covered by lock.
978 ========== ==================
979 Flag_Value Flag_Description
980 ========== ==================
981 0x00000000 Disabled (default)
982 0x00000001 cp_rwsem
983 0x00000002 node_change
984 0x00000004 node_write
985 0x00000008 gc_lock
986 0x00000010 cp_global
987 0x00000020 io_rwsem
988 ========== ==================
989
990What: /sys/fs/f2fs/<disk>/lock_duration_priority
991Date: January 2026
992Contact: "Chao Yu" <chao@kernel.org>
993Description: f2fs can tune priority of thread which has entered into critical region covered by
994 f2fs rwsemphore lock. This sysfs entry can be used to control priority value, the
995 range is [100,139], by default the value is 120.
996
997What: /sys/fs/f2fs/<disk>/critical_task_priority
998Date: February 2026
999Contact: "Chao Yu" <chao@kernel.org>
1000Description: It can be used to tune priority of f2fs critical task, e.g. f2fs_ckpt, f2fs_gc
1001 threads, limitation as below:
1002 - it requires user has CAP_SYS_NICE capability.
1003 - the range is [100, 139], by default the value is 100.