<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/fs/f2fs/sysfs.c, branch v5.12</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>f2fs: add ckpt_thread_ioprio sysfs node</title>
<updated>2021-02-03T21:03:58+00:00</updated>
<author>
<name>Daeho Jeong</name>
<email>daehojeong@google.com</email>
</author>
<published>2021-01-21T13:45:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e65920661708b7c0f3db45c9cd5d0095034ee37f'/>
<id>e65920661708b7c0f3db45c9cd5d0095034ee37f</id>
<content type='text'>
Added "ckpt_thread_ioprio" sysfs node to give a way to change checkpoint
merge daemon's io priority. Its default value is "be,3", which means
"BE" I/O class and I/O priority "3". We can select the class between "rt"
and "be", and set the I/O priority within valid range of it.
"," delimiter is necessary in between I/O class and priority number.

Signed-off-by: Daeho Jeong &lt;daehojeong@google.com&gt;
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Added "ckpt_thread_ioprio" sysfs node to give a way to change checkpoint
merge daemon's io priority. Its default value is "be,3", which means
"BE" I/O class and I/O priority "3". We can select the class between "rt"
and "be", and set the I/O priority within valid range of it.
"," delimiter is necessary in between I/O class and priority number.

Signed-off-by: Daeho Jeong &lt;daehojeong@google.com&gt;
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: introduce sb_status sysfs node</title>
<updated>2021-01-27T23:20:06+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2021-01-14T01:41:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=0bfe9f790448012ef38abf4e78feb2e691e2d366'/>
<id>0bfe9f790448012ef38abf4e78feb2e691e2d366</id>
<content type='text'>
Introduce /sys/fs/f2fs/&lt;devname&gt;/stat/sb_status to show superblock
status in real time as a hexadecimal value.

value           sb status macro                 description

0x1             SBI_IS_DIRTY,                   /* dirty flag for checkpoint */
0x2             SBI_IS_CLOSE,                   /* specify unmounting */
0x4             SBI_NEED_FSCK,                  /* need fsck.f2fs to fix */
0x8             SBI_POR_DOING,                  /* recovery is doing or not */
0x10            SBI_NEED_SB_WRITE,              /* need to recover superblock */
0x20            SBI_NEED_CP,                    /* need to checkpoint */
0x40            SBI_IS_SHUTDOWN,                /* shutdown by ioctl */
0x80            SBI_IS_RECOVERED,               /* recovered orphan/data */
0x100           SBI_CP_DISABLED,                /* CP was disabled last mount */
0x200           SBI_CP_DISABLED_QUICK,          /* CP was disabled quickly */
0x400           SBI_QUOTA_NEED_FLUSH,           /* need to flush quota info in CP */
0x800           SBI_QUOTA_SKIP_FLUSH,           /* skip flushing quota in current CP */
0x1000          SBI_QUOTA_NEED_REPAIR,          /* quota file may be corrupted */
0x2000          SBI_IS_RESIZEFS,                /* resizefs is in process */

Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Introduce /sys/fs/f2fs/&lt;devname&gt;/stat/sb_status to show superblock
status in real time as a hexadecimal value.

value           sb status macro                 description

0x1             SBI_IS_DIRTY,                   /* dirty flag for checkpoint */
0x2             SBI_IS_CLOSE,                   /* specify unmounting */
0x4             SBI_NEED_FSCK,                  /* need fsck.f2fs to fix */
0x8             SBI_POR_DOING,                  /* recovery is doing or not */
0x10            SBI_NEED_SB_WRITE,              /* need to recover superblock */
0x20            SBI_NEED_CP,                    /* need to checkpoint */
0x40            SBI_IS_SHUTDOWN,                /* shutdown by ioctl */
0x80            SBI_IS_RECOVERED,               /* recovered orphan/data */
0x100           SBI_CP_DISABLED,                /* CP was disabled last mount */
0x200           SBI_CP_DISABLED_QUICK,          /* CP was disabled quickly */
0x400           SBI_QUOTA_NEED_FLUSH,           /* need to flush quota info in CP */
0x800           SBI_QUOTA_SKIP_FLUSH,           /* skip flushing quota in current CP */
0x1000          SBI_QUOTA_NEED_REPAIR,          /* quota file may be corrupted */
0x2000          SBI_IS_RESIZEFS,                /* resizefs is in process */

Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: introduce a new per-sb directory in sysfs</title>
<updated>2021-01-27T23:20:02+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2020-12-09T08:43:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5d4daa579e56adc97fb77c7dfda6c1f747c9ef25'/>
<id>5d4daa579e56adc97fb77c7dfda6c1f747c9ef25</id>
<content type='text'>
Add a new directory 'stat' in path of /sys/fs/f2fs/&lt;devname&gt;/, later
we can add new readonly stat sysfs file into this directory, it will
make &lt;devname&gt; directory less mess.

Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add a new directory 'stat' in path of /sys/fs/f2fs/&lt;devname&gt;/, later
we can add new readonly stat sysfs file into this directory, it will
make &lt;devname&gt; directory less mess.

Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'f2fs-for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs</title>
<updated>2020-12-17T19:18:00+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-12-17T19:18:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ff49c86f27e4726a86f5034543e6e684daf41955'/>
<id>ff49c86f27e4726a86f5034543e6e684daf41955</id>
<content type='text'>
Pull f2fs updates from Jaegeuk Kim:
 "In this round, we've made more work into per-file compression support.

  For example, F2FS_IOC_GET | SET_COMPRESS_OPTION provides a way to
  change the algorithm or cluster size per file. F2FS_IOC_COMPRESS |
  DECOMPRESS_FILE provides a way to compress and decompress the existing
  normal files manually.

  There is also a new mount option, compress_mode=fs|user, which can
  control who compresses the data.

  Chao also added a checksum feature with a mount option so that
  we are able to detect any corrupted cluster.

  In addition, Daniel contributed casefolding with encryption patch,
  which will be used for Android devices.

  Summary:

  Enhancements:
   - add ioctls and mount option to manage per-file compression feature
   - support casefolding with encryption
   - support checksum for compressed cluster
   - avoid IO starvation by replacing mutex with rwsem
   - add sysfs, max_io_bytes, to control max bio size

  Bug fixes:
   - fix use-after-free issue when compression and fsverity are enabled
   - fix consistency corruption during fault injection test
   - fix data offset for lseek
   - get rid of buffer_head which has 32bits limit in fiemap
   - fix some bugs in multi-partitions support
   - fix nat entry count calculation in shrinker
   - fix some stat information

  And, we've refactored some logics and fix minor bugs as well"

* tag 'f2fs-for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (36 commits)
  f2fs: compress: fix compression chksum
  f2fs: fix shift-out-of-bounds in sanity_check_raw_super()
  f2fs: fix race of pending_pages in decompression
  f2fs: fix to account inline xattr correctly during recovery
  f2fs: inline: fix wrong inline inode stat
  f2fs: inline: correct comment in f2fs_recover_inline_data
  f2fs: don't check PAGE_SIZE again in sanity_check_raw_super()
  f2fs: convert to F2FS_*_INO macro
  f2fs: introduce max_io_bytes, a sysfs entry, to limit bio size
  f2fs: don't allow any writes on readonly mount
  f2fs: avoid race condition for shrinker count
  f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
  f2fs: add compress_mode mount option
  f2fs: Remove unnecessary unlikely()
  f2fs: init dirty_secmap incorrectly
  f2fs: remove buffer_head which has 32bits limit
  f2fs: fix wrong block count instead of bytes
  f2fs: use new conversion functions between blks and bytes
  f2fs: rename logical_to_blk and blk_to_logical
  f2fs: fix kbytes written stat for multi-device case
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull f2fs updates from Jaegeuk Kim:
 "In this round, we've made more work into per-file compression support.

  For example, F2FS_IOC_GET | SET_COMPRESS_OPTION provides a way to
  change the algorithm or cluster size per file. F2FS_IOC_COMPRESS |
  DECOMPRESS_FILE provides a way to compress and decompress the existing
  normal files manually.

  There is also a new mount option, compress_mode=fs|user, which can
  control who compresses the data.

  Chao also added a checksum feature with a mount option so that
  we are able to detect any corrupted cluster.

  In addition, Daniel contributed casefolding with encryption patch,
  which will be used for Android devices.

  Summary:

  Enhancements:
   - add ioctls and mount option to manage per-file compression feature
   - support casefolding with encryption
   - support checksum for compressed cluster
   - avoid IO starvation by replacing mutex with rwsem
   - add sysfs, max_io_bytes, to control max bio size

  Bug fixes:
   - fix use-after-free issue when compression and fsverity are enabled
   - fix consistency corruption during fault injection test
   - fix data offset for lseek
   - get rid of buffer_head which has 32bits limit in fiemap
   - fix some bugs in multi-partitions support
   - fix nat entry count calculation in shrinker
   - fix some stat information

  And, we've refactored some logics and fix minor bugs as well"

* tag 'f2fs-for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (36 commits)
  f2fs: compress: fix compression chksum
  f2fs: fix shift-out-of-bounds in sanity_check_raw_super()
  f2fs: fix race of pending_pages in decompression
  f2fs: fix to account inline xattr correctly during recovery
  f2fs: inline: fix wrong inline inode stat
  f2fs: inline: correct comment in f2fs_recover_inline_data
  f2fs: don't check PAGE_SIZE again in sanity_check_raw_super()
  f2fs: convert to F2FS_*_INO macro
  f2fs: introduce max_io_bytes, a sysfs entry, to limit bio size
  f2fs: don't allow any writes on readonly mount
  f2fs: avoid race condition for shrinker count
  f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
  f2fs: add compress_mode mount option
  f2fs: Remove unnecessary unlikely()
  f2fs: init dirty_secmap incorrectly
  f2fs: remove buffer_head which has 32bits limit
  f2fs: fix wrong block count instead of bytes
  f2fs: use new conversion functions between blks and bytes
  f2fs: rename logical_to_blk and blk_to_logical
  f2fs: fix kbytes written stat for multi-device case
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: introduce max_io_bytes, a sysfs entry, to limit bio size</title>
<updated>2020-12-07T16:41:25+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2020-12-03T17:52:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=10208567f11bd572331cbbcb9a89c61a143811a1'/>
<id>10208567f11bd572331cbbcb9a89c61a143811a1</id>
<content type='text'>
This patch adds max_io_bytes to limit bio size when f2fs tries to merge
consecutive IOs. This can give a testing point to split out bios and check
end_io handles those bios correctly. This is used to capture a recent bug
on the decompression and fsverity flow.

Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch adds max_io_bytes to limit bio size when f2fs tries to merge
consecutive IOs. This can give a testing point to split out bios and check
end_io handles those bios correctly. This is used to capture a recent bug
on the decompression and fsverity flow.

Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: fix kbytes written stat for multi-device case</title>
<updated>2020-12-03T06:00:22+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2020-11-27T13:20:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3a0a9cbc44bbb8a23a3fc12edfd1834452360a50'/>
<id>3a0a9cbc44bbb8a23a3fc12edfd1834452360a50</id>
<content type='text'>
For multi-device case, one f2fs image includes multi devices, so it
needs to account bytes written of all block devices belong to the image
rather than one main block device, fix it.

Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
For multi-device case, one f2fs image includes multi devices, so it
needs to account bytes written of all block devices belong to the image
rather than one main block device, fix it.

Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: remove a few bd_part checks</title>
<updated>2020-12-01T21:53:40+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2020-11-24T08:21:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9499ffc7521742e3fea32f6ac6c1213b6fc4e914'/>
<id>9499ffc7521742e3fea32f6ac6c1213b6fc4e914</id>
<content type='text'>
bd_part is never NULL for a block device in use by a file system, so
remove the checks.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Hannes Reinecke &lt;hare@suse.de&gt;
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
bd_part is never NULL for a block device in use by a file system, so
remove the checks.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Hannes Reinecke &lt;hare@suse.de&gt;
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: wait for sysfs kobject removal before freeing f2fs_sb_info</title>
<updated>2020-10-14T20:23:30+00:00</updated>
<author>
<name>Jamie Iles</name>
<email>jamie@nuviainc.com</email>
</author>
<published>2020-10-12T13:09:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ae284d87abade58c8db7760c808f311ef1ce693c'/>
<id>ae284d87abade58c8db7760c808f311ef1ce693c</id>
<content type='text'>
syzkaller found that with CONFIG_DEBUG_KOBJECT_RELEASE=y, unmounting an
f2fs filesystem could result in the following splat:

  kobject: 'loop5' ((____ptrval____)): kobject_release, parent 0000000000000000 (delayed 250)
  kobject: 'f2fs_xattr_entry-7:5' ((____ptrval____)): kobject_release, parent 0000000000000000 (delayed 750)
  ------------[ cut here ]------------
  ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x98
  WARNING: CPU: 0 PID: 699 at lib/debugobjects.c:485 debug_print_object+0x180/0x240
  Kernel panic - not syncing: panic_on_warn set ...
  CPU: 0 PID: 699 Comm: syz-executor.5 Tainted: G S                5.9.0-rc8+ #101
  Hardware name: linux,dummy-virt (DT)
  Call trace:
   dump_backtrace+0x0/0x4d8
   show_stack+0x34/0x48
   dump_stack+0x174/0x1f8
   panic+0x360/0x7a0
   __warn+0x244/0x2ec
   report_bug+0x240/0x398
   bug_handler+0x50/0xc0
   call_break_hook+0x160/0x1d8
   brk_handler+0x30/0xc0
   do_debug_exception+0x184/0x340
   el1_dbg+0x48/0xb0
   el1_sync_handler+0x170/0x1c8
   el1_sync+0x80/0x100
   debug_print_object+0x180/0x240
   debug_check_no_obj_freed+0x200/0x430
   slab_free_freelist_hook+0x190/0x210
   kfree+0x13c/0x460
   f2fs_put_super+0x624/0xa58
   generic_shutdown_super+0x120/0x300
   kill_block_super+0x94/0xf8
   kill_f2fs_super+0x244/0x308
   deactivate_locked_super+0x104/0x150
   deactivate_super+0x118/0x148
   cleanup_mnt+0x27c/0x3c0
   __cleanup_mnt+0x28/0x38
   task_work_run+0x10c/0x248
   do_notify_resume+0x9d4/0x1188
   work_pending+0x8/0x34c

Like the error handling for f2fs_register_sysfs(), we need to wait for
the kobject to be destroyed before returning to prevent a potential
use-after-free.

Fixes: bf9e697ecd42 ("f2fs: expose features to sysfs entry")
Cc: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Cc: Chao Yu &lt;chao@kernel.org&gt;
Signed-off-by: Jamie Iles &lt;jamie@nuviainc.com&gt;
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
syzkaller found that with CONFIG_DEBUG_KOBJECT_RELEASE=y, unmounting an
f2fs filesystem could result in the following splat:

  kobject: 'loop5' ((____ptrval____)): kobject_release, parent 0000000000000000 (delayed 250)
  kobject: 'f2fs_xattr_entry-7:5' ((____ptrval____)): kobject_release, parent 0000000000000000 (delayed 750)
  ------------[ cut here ]------------
  ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x98
  WARNING: CPU: 0 PID: 699 at lib/debugobjects.c:485 debug_print_object+0x180/0x240
  Kernel panic - not syncing: panic_on_warn set ...
  CPU: 0 PID: 699 Comm: syz-executor.5 Tainted: G S                5.9.0-rc8+ #101
  Hardware name: linux,dummy-virt (DT)
  Call trace:
   dump_backtrace+0x0/0x4d8
   show_stack+0x34/0x48
   dump_stack+0x174/0x1f8
   panic+0x360/0x7a0
   __warn+0x244/0x2ec
   report_bug+0x240/0x398
   bug_handler+0x50/0xc0
   call_break_hook+0x160/0x1d8
   brk_handler+0x30/0xc0
   do_debug_exception+0x184/0x340
   el1_dbg+0x48/0xb0
   el1_sync_handler+0x170/0x1c8
   el1_sync+0x80/0x100
   debug_print_object+0x180/0x240
   debug_check_no_obj_freed+0x200/0x430
   slab_free_freelist_hook+0x190/0x210
   kfree+0x13c/0x460
   f2fs_put_super+0x624/0xa58
   generic_shutdown_super+0x120/0x300
   kill_block_super+0x94/0xf8
   kill_f2fs_super+0x244/0x308
   deactivate_locked_super+0x104/0x150
   deactivate_super+0x118/0x148
   cleanup_mnt+0x27c/0x3c0
   __cleanup_mnt+0x28/0x38
   task_work_run+0x10c/0x248
   do_notify_resume+0x9d4/0x1188
   work_pending+0x8/0x34c

Like the error handling for f2fs_register_sysfs(), we need to wait for
the kobject to be destroyed before returning to prevent a potential
use-after-free.

Fixes: bf9e697ecd42 ("f2fs: expose features to sysfs entry")
Cc: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Cc: Chao Yu &lt;chao@kernel.org&gt;
Signed-off-by: Jamie Iles &lt;jamie@nuviainc.com&gt;
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: support age threshold based garbage collection</title>
<updated>2020-09-11T18:11:15+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2020-08-04T13:14:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=093749e296e29a4b0162eb925a6701a01e8c9a98'/>
<id>093749e296e29a4b0162eb925a6701a01e8c9a98</id>
<content type='text'>
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 &lt;yuchao0@huawei.com&gt;
[Jaegeuk Kim: fix a bug along with pinfile in-mem segment &amp; clean up]
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;yuchao0@huawei.com&gt;
[Jaegeuk Kim: fix a bug along with pinfile in-mem segment &amp; clean up]
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: Use generic casefolding support</title>
<updated>2020-09-10T21:03:31+00:00</updated>
<author>
<name>Daniel Rosenberg</name>
<email>drosen@google.com</email>
</author>
<published>2020-07-08T09:12:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=eca4873ee1b63ee051e0eed91099fa42c97b2438'/>
<id>eca4873ee1b63ee051e0eed91099fa42c97b2438</id>
<content type='text'>
This switches f2fs over to the generic support provided in
the previous patch.

Since casefolded dentries behave the same in ext4 and f2fs, we decrease
the maintenance burden by unifying them, and any optimizations will
immediately apply to both.

Signed-off-by: Daniel Rosenberg &lt;drosen@google.com&gt;
Reviewed-by: Eric Biggers &lt;ebiggers@google.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This switches f2fs over to the generic support provided in
the previous patch.

Since casefolded dentries behave the same in ext4 and f2fs, we decrease
the maintenance burden by unifying them, and any optimizations will
immediately apply to both.

Signed-off-by: Daniel Rosenberg &lt;drosen@google.com&gt;
Reviewed-by: Eric Biggers &lt;ebiggers@google.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
