linux.git/fs/f2fs/segment.c, branch v4.14

f2fs: fix potential panic during fstrim

2017-10-03T15:06:05+00:00

As Ju Hyung Park reported:

"When 'fstrim' is called for manual trim, a BUG() can be triggered
randomly with this patch.

I'm seeing this issue on both x86 Desktop and arm64 Android phone.

On x86 Desktop, this was caused during Ubuntu boot-up. I have a
cronjob installed which calls 'fstrim -v /' during boot. On arm64
Android, this was caused during GC looping with 1ms gc_min_sleep_time
& gc_max_sleep_time."

Root cause of this issue is that f2fs_wait_discard_bios can only be
used by f2fs_put_super, because during put_super there must be no
other referrers, so it can ignore discard entry's reference count
when removing the entry, otherwise in other caller we will hit bug_on
in __remove_discard_cmd as there may be other issuer added reference
count in discard entry.

Thread A				Thread B
					- issue_discard_thread
- f2fs_ioc_fitrim
 - f2fs_trim_fs
  - f2fs_wait_discard_bios
   - __issue_discard_cmd
    - __submit_discard_cmd
					 - __wait_discard_cmd
					  - dc->ref++
					  - __wait_one_discard_bio
   - __wait_discard_cmd
    - __remove_discard_cmd
     - f2fs_bug_on(sbi, dc->ref)

Fixes: 969d1b180d987c2be02de890d0fff0f66a0e80de
Reported-by: Ju Hyung Park 
Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

Merge tag 'f2fs-for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

2017-09-13T03:05:58+00:00

Pull f2fs updates from Jaegeuk Kim:
 "In this round, we've mostly tuned f2fs to provide better user
  experience for Android. Especially, we've worked on atomic write
  feature again with SQLite community in order to support it officially.
  And we added or modified several facilities to analyze and enhance IO
  behaviors.

  Major changes include:
   - add app/fs io stat
   - add inode checksum feature
   - support project/journalled quota
   - enhance atomic write with new ioctl() which exposes feature set
   - enhance background gc/discard/fstrim flows with new gc_urgent mode
   - add F2FS_IOC_FS{GET,SET}XATTR
   - fix some quota flows"

* tag 'f2fs-for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (63 commits)
  f2fs: hurry up to issue discard after io interruption
  f2fs: fix to show correct discard_granularity in sysfs
  f2fs: detect dirty inode in evict_inode
  f2fs: clear radix tree dirty tag of pages whose dirty flag is cleared
  f2fs: speed up gc_urgent mode with SSR
  f2fs: better to wait for fstrim completion
  f2fs: avoid race in between read xattr & write xattr
  f2fs: make get_lock_data_page to handle encrypted inode
  f2fs: use generic terms used for encrypted block management
  f2fs: introduce f2fs_encrypted_file for clean-up
  Revert "f2fs: add a new function get_ssr_cost"
  f2fs: constify super_operations
  f2fs: fix to wake up all sleeping flusher
  f2fs: avoid race in between atomic_read & atomic_inc
  f2fs: remove unneeded parameter of change_curseg
  f2fs: update i_flags correctly
  f2fs: don't check inode's checksum if it was dirtied or writebacked
  f2fs: don't need to update inode checksum for recovery
  f2fs: trigger fdatasync for non-atomic_write file
  f2fs: fix to avoid race in between aio and gc
  ...

f2fs: hurry up to issue discard after io interruption

2017-09-12T17:02:55+00:00

Once we encounter I/O interruption during issuing discards, we will delay
long time before next round, but if system status is I/O idle during the
time, it may loses opportunity to issue discards. So this patch changes
to hurry up to issue discard after io interruption.

Besides, this patch also fixes to issue discards accurately with assigned
rate.

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

f2fs: speed up gc_urgent mode with SSR

2017-09-12T00:22:18+00:00

This patch activates SSR in gc_urgent mode.

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

f2fs: better to wait for fstrim completion

2017-09-12T00:22:12+00:00

In android, we'd better wait for fstrim completion instead of issuing the
discard commands asynchronous.

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

f2fs: use generic terms used for encrypted block management

2017-09-06T03:21:48+00:00

This patch renames functions regarding to buffer management via META_MAPPING
used for encrypted blocks especially. We can actually use them in generic way.

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

f2fs: fix to wake up all sleeping flusher

2017-09-05T17:50:23+00:00

In scenario of remount_ro vs flush, after flush_thread exits in
->remount_fs, flusher will only clean up golbal issue_list, but
without waking up flushers waiting on that list, result in hang
related user threads.

In order to fix this issue, this patch enables the flusher to
take charge of issue_flush thread: executes merged flush command,
and wake up all sleeping flushers.

Fixes: 5eba8c5d1fb3 ("f2fs: fix to access nullified flush_cmd_control pointer")
Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: avoid race in between atomic_read & atomic_inc

2017-09-05T17:50:22+00:00

Previously, we will miss merging flush command during fsync due to below
race condition:

Thread A 		Thread B		Thread C
- f2fs_issue_flush
 - atomic_read(&issing_flush)
			- f2fs_issue_flush
			 - atomic_read(&issing_flush)
						- f2fs_issue_flush
						 - atomic_read(&issing_flush)
  - atomic_inc(&issing_flush)
			  - atomic_inc(&issing_flush)
						  - atomic_inc(&issing_flush)
   - submit_flush_wait
			   - submit_flush_wait
						   - submit_flush_wait

It needs to use atomic_inc_return instead to avoid such race.

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

f2fs: remove unneeded parameter of change_curseg

2017-09-05T17:50:21+00:00

allocate_segment_by_default is the only caller of change_curseg passing
@reuse with 'false', but commit 763bfe1bc575 ("f2fs: remove reusing any
prefree segments") removes the calling, after that, @reuse in
change_curseg always be true, so, let's clean up the unneeded parameter.

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

f2fs: wake up discard_thread iff there is a candidate

2017-08-29T17:05:33+00:00

This patch fixes to avoid needless wake ups.

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