linux.git/fs/f2fs/segment.h, branch v5.16

f2fs: introduce fragment allocation mode mount option

2021-10-26T21:04:30+00:00

Added two options into "mode=" mount option to make it possible for
developers to simulate filesystem fragmentation/after-GC situation
itself. The developers use these modes to understand filesystem
fragmentation/after-GC condition well, and eventually get some
insights to handle them better.

"fragment:segment": f2fs allocates a new segment in ramdom position.
		With this, we can simulate the after-GC condition.
"fragment:block" : We can scatter block allocation with
		"max_fragment_chunk" and "max_fragment_hole" sysfs
		nodes. f2fs will allocate 1..
		blocks in a chunk and make a hole in the length of
		1.. by turns	in a newly allocated
		free segment. Plus, this mode implicitly enables
		"fragment:segment" option for more randomness.

Reviewed-by: Chao Yu 
Signed-off-by: Daeho Jeong 
Signed-off-by: Jaegeuk Kim

f2fs: correct comment in segment.h

2021-08-13T18:57:08+00:00

s/two/three

Signed-off-by: Yangtao Li 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

Merge tag 'f2fs-for-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

2021-05-05T01:03:38+00:00

Pull f2fs updates from Jaegeuk Kim:
 "In this round, we added a new mount option, "checkpoint_merge", which
  introduces a kernel thread dealing with the f2fs checkpoints. Once we
  start to manage the IO priority along with blk-cgroup, the checkpoint
  operation can be processed in a lower priority under the process
  context. Since the checkpoint holds all the filesystem operations, we
  give a higher priority to the checkpoint thread all the time.

  Enhancements:
   - introduce gc_merge mount option to introduce a checkpoint thread
   - improve to run discard thread efficiently
   - allow modular compression algorithms
   - expose # of overprivision segments to sysfs
   - expose runtime compression stat to sysfs

  Bug fixes:
   - fix OOB memory access by the node id lookup
   - avoid touching checkpointed data in the checkpoint-disabled mode
   - fix the resizing flow to avoid kernel panic and race conditions
   - fix block allocation issues on pinned files
   - address some swapfile issues
   - fix hugtask problem and kernel panic during atomic write operations
   - don't start checkpoint thread in RO

  And, we've cleaned up some kernel coding style and build warnings. In
  addition, we fixed some minor race conditions and error handling
  routines"

* tag 'f2fs-for-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (48 commits)
  f2fs: drop inplace IO if fs status is abnormal
  f2fs: compress: remove unneed check condition
  f2fs: clean up left deprecated IO trace codes
  f2fs: avoid using native allocate_segment_by_default()
  f2fs: remove unnecessary struct declaration
  f2fs: fix to avoid NULL pointer dereference
  f2fs: avoid duplicated codes for cleanup
  f2fs: document: add description about compressed space handling
  f2fs: clean up build warnings
  f2fs: fix the periodic wakeups of discard thread
  f2fs: fix to avoid accessing invalid fio in f2fs_allocate_data_block()
  f2fs: fix to avoid GC/mmap race with f2fs_truncate()
  f2fs: set checkpoint_merge by default
  f2fs: Fix a hungtask problem in atomic write
  f2fs: fix to restrict mount condition on readonly block device
  f2fs: introduce gc_merge mount option
  f2fs: fix to cover __allocate_new_section() with curseg_lock
  f2fs: fix wrong alloc_type in f2fs_do_replace_block
  f2fs: delete empty compress.h
  f2fs: fix a typo in inode.c
  ...

f2fs: fix to avoid touching checkpointed data in get_victim()

2021-03-26T17:27:01+00:00

In CP disabling mode, there are two issues when using LFS or SSR | AT_SSR
mode to select victim:

1. LFS is set to find source section during GC, the victim should have
no checkpointed data, since after GC, section could not be set free for
reuse.

Previously, we only check valid chpt blocks in current segment rather
than section, fix it.

2. SSR | AT_SSR are set to find target segment for writes which can be
fully filled by checkpointed and newly written blocks, we should never
select such segment, otherwise it can cause panic or data corruption
during allocation, potential case is described as below:

 a) target segment has 'n' (n < 512) ckpt valid blocks
 b) GC migrates 'n' valid blocks to other segment (segment is still
    in dirty list)
 c) GC migrates '512 - n' blocks to target segment (segment has 'n'
    cp_vblocks and '512 - n' vblocks)
 d) If GC selects target segment via {AT,}SSR allocator, however there
    is no free space in targe segment.

Fixes: 4354994f097d ("f2fs: checkpoint disabling")
Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: remove unused FORCE_FG_GC macro

2021-03-12T21:16:42+00:00

FORCE_FG_GC was introduced by commit 6aefd93b0137 ("f2fs: introduce
background_gc=sync mount option"), but never be used, remove it.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

block: rename BIO_MAX_PAGES to BIO_MAX_VECS

2021-03-11T14:47:48+00:00

Ever since the addition of multipage bio_vecs BIO_MAX_PAGES has been
horribly confusingly misnamed.  Rename it to BIO_MAX_VECS to stop
confusing users of the bio API.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Matthew Wilcox (Oracle) 
Reviewed-by: Martin K. Petersen 
Link: https://lore.kernel.org/r/20210311110137.1132391-2-hch@lst.de
Signed-off-by: Jens Axboe

f2fs: handle unallocated section and zone on pinned/atgc

2021-01-27T23:19:59+00:00

If we have large section/zone, unallocated segment makes them corrupted.

E.g.,

  - Pinned file:       -1 119304647 119304647
  - ATGC   data:       -1 119304647 119304647

Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: fix wrong total_sections check and fsmeta check

2020-09-29T08:48:34+00:00

Meta area is not included in section_count computation.
So the minimum number of total_sections is 1 meanwhile it cannot be
greater than segment_count_main.

The minimum number of meta segments is 8 (SB + 2 (CP + SIT + NAT) + SSA).

Signed-off-by: Wang Xiaojun 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: change return value of reserved_segments to unsigned int

2020-09-29T08:48:33+00:00

The type of SM_I(sbi)->reserved_segments is unsigned int,
so change the return value to unsigned int.
The type cast can be removed in reserved_sections as a result.

Signed-off-by: Xiaojun Wang 
Reviewed-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: support age threshold based garbage collection

2020-09-11T18:11:15+00:00

There are several issues in current background GC algorithm:
- valid blocks is one of key factors during cost overhead calculation,
so if segment has less valid block, however even its age is young or
it locates hot segment, CB algorithm will still choose the segment as
victim, it's not appropriate.
- GCed data/node will go to existing logs, no matter in-there datas'
update frequency is the same or not, it may mix hot and cold data
again.
- GC alloctor mainly use LFS type segment, it will cost free segment
more quickly.

This patch introduces a new algorithm named age threshold based
garbage collection to solve above issues, there are three steps
mainly:

1. select a source victim:
- set an age threshold, and select candidates beased threshold:
e.g.
 0 means youngest, 100 means oldest, if we set age threshold to 80
 then select dirty segments which has age in range of [80, 100] as
 candiddates;
- set candidate_ratio threshold, and select candidates based the
ratio, so that we can shrink candidates to those oldest segments;
- select target segment with fewest valid blocks in order to
migrate blocks with minimum cost;

2. select a target victim:
- select candidates beased age threshold;
- set candidate_radius threshold, search candidates whose age is
around source victims, searching radius should less than the
radius threshold.
- select target segment with most valid blocks in order to avoid
migrating current target segment.

3. merge valid blocks from source victim into target victim with
SSR alloctor.

Test steps:
- create 160 dirty segments:
 * half of them have 128 valid blocks per segment
 * left of them have 384 valid blocks per segment
- run background GC

Benefit: GC count and block movement count both decrease obviously:

- Before:
  - Valid: 86
  - Dirty: 1
  - Prefree: 11
  - Free: 6001 (6001)

GC calls: 162 (BG: 220)
  - data segments : 160 (160)
  - node segments : 2 (2)
Try to move 41454 blocks (BG: 41454)
  - data blocks : 40960 (40960)
  - node blocks : 494 (494)

IPU: 0 blocks
SSR: 0 blocks in 0 segments
LFS: 41364 blocks in 81 segments

- After:

  - Valid: 87
  - Dirty: 0
  - Prefree: 4
  - Free: 6008 (6008)

GC calls: 75 (BG: 76)
  - data segments : 74 (74)
  - node segments : 1 (1)
Try to move 12813 blocks (BG: 12813)
  - data blocks : 12544 (12544)
  - node blocks : 269 (269)

IPU: 0 blocks
SSR: 12032 blocks in 77 segments
LFS: 855 blocks in 2 segments

Signed-off-by: Chao Yu 
[Jaegeuk Kim: fix a bug along with pinfile in-mem segment & clean up]
Signed-off-by: Jaegeuk Kim