Commit Graph

16 Commits

Author SHA1 Message Date
Jaegeuk Kim b7250d2d84 f2fs: fix calculation of max. gc cost in the SSR case
In the SSR case, the max gc cost should be the number of pages in a segment.
Otherwise, f2fs is able to fail getting dirty segments frequently for SSR.

In get_victim_by_default() previously,

while(1) {
   ...
   cost = get_gc_cost(); <- cost is between 0 ~ 512.
   ...
   if (cost == get_max_cost(sbi, &p)) <- max cost is UINT_MAX due to GC_CB type
	continue;

   if (nsearched++ >= MAX_VICTIM_SEARCH)
	break;
}

So, if there are a number of fully valid segments in series, f2fs cannot skip
those segments by comparing the cost and max cost of each segment.

Note that, the cost is the number of valid blocks at the time of the last
checkpoint.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:02 +09:00
Jaegeuk Kim 437275272f f2fs: clarify and enhance the f2fs_gc flow
This patch makes clearer the ambiguous f2fs_gc flow as follows.

1. Remove intermediate checkpoint condition during f2fs_gc
 (i.e., should_do_checkpoint() and GC_BLOCKED)

2. Remove unnecessary return values of f2fs_gc because of #1.
 (i.e., GC_NODE, GC_OK, etc)

3. Simplify write_checkpoint() because of #2.

4. Clarify the main f2fs_gc flow.
 o monitor how many freed sections during one iteration of do_garbage_collect().
 o do GC more without checkpoints if we can't get enough free sections.
 o do checkpoint once we've got enough free sections through forground GCs.

5. Adopt thread-logging (Slack-Space-Recycle) scheme more aggressively on data
  log types. See. get_ssr_segement()

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:02 +09:00
Namjae Jeon 25718423ea f2fs: mark gc_thread as NULL when thread creation is failed
When gc thread creation is failed, mark gc_thread as NULL to avoid
crash while trying to stop invalid thread in stop_gc_thread->kthread_stop.
Instead make it return from:
	if (!gc_th)
       return;

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:02 +09:00
Namjae Jeon ec7b1f2dd1 f2fs: name gc task as per the block device
Currently GC task is started for each f2fs formatted/mounted device.
But, when we check the task list, using 'ps', there is no distinguishing
factor between the tasks. So, name the task as per the block device just
like the flusher threads.
Also, remove the macro GC_THREAD_NAME and instead use the name: f2fs_gc
to avoid name length truncation, as the command length is 16
-> TASK_COMM_LEN 16 and example name like:
f2fs_gc_task:8:16 -> this exceeds name length

Before Patch for 2 F2FS formatted partitions:
root  28061  0.0  0.0  0 0 ? S 10:31   0:00 [f2fs_gc_task]
root  28087  0.0  0.0  0 0 ? S 10:32   0:00 [f2fs_gc_task]

After Patch:
root  16756  0.0  0.0  0  0 ?  S  14:57   0:00 [f2fs_gc-8:18]
root  16765  0.0  0.0  0  0 ?  S  14:57   0:00 [f2fs_gc-8:19]

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:02 +09:00
Changman Lee 48600e44c1 f2fs: remove unnecessary gc option check and balance_fs
1. If f2fs is mounted with background_gc_off option, checking
    BG_GC is not redundant.
 2. f2fs_balance_fs is checked in f2fs_gc, so this is also redundant.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:02 +09:00
Jaegeuk Kim d4686d56ec f2fs: avoid balanc_fs during evict_inode
1. Background

Previously, if f2fs tries to move data blocks of an *evicting* inode during the
cleaning process, it stops the process incompletely and then restarts the whole
process, since it needs a locked inode to grab victim data pages in its address
space. In order to get a locked inode, iget_locked() by f2fs_iget() is normally
used, but, it waits if the inode is on freeing.

So, here is a deadlock scenario.
1. f2fs_evict_inode()       <- inode "A"
  2. f2fs_balance_fs()
    3. f2fs_gc()
      4. gc_data_segment()
        5. f2fs_iget()      <- inode "A" too!

If step #1 and #5 treat a same inode "A", step #5 would fall into deadlock since
the inode "A" is on freeing. In order to resolve this, f2fs_iget_nowait() which
skips __wait_on_freeing_inode() was introduced in step #5, and stops f2fs_gc()
to complete f2fs_evict_inode().

1. f2fs_evict_inode()           <- inode "A"
  2. f2fs_balance_fs()
    3. f2fs_gc()
      4. gc_data_segment()
        5. f2fs_iget_nowait()   <- inode "A", then stop f2fs_gc() w/ -ENOENT

2. Problem and Solution

In the above scenario, however, f2fs cannot finish f2fs_evict_inode() only if:
 o there are not enough free sections, and
 o f2fs_gc() tries to move data blocks of the *evicting* inode repeatedly.

So, the final solution is to use f2fs_iget() and remove f2fs_balance_fs() in
f2fs_evict_inode().
The f2fs_evict_inode() actually truncates all the data and node blocks, which
means that it doesn't produce any dirty node pages accordingly.
So, we don't need to do f2fs_balance_fs() in practical.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:01 +09:00
Namjae Jeon 3786dfdf4f f2fs: avoid redundant call to has_not_enough_free_secs in f2fs_gc
After doing a write_checkpoint from garbage collection path if there is still
need to do more garbage collection, gc_more label is used to jump and start
the process again. And in that process, first step before getting victim is to
check if there are not enough free sections, which is already done before
doing a jump to gc_more. We can avoid the redundant call to check free
sections, by checking the gc_type flag which will remain FG_GC(value 1) under
this condition.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:00 +09:00
Changman Lee d6212a5f18 f2fs: add un/freeze_fs into super_operations
This patch supports ioctl FIFREEZE and FITHAW to snapshot filesystem.
Before calling f2fs_freeze, all writers would be suspended and sync_fs
would be completed. So no f2fs has to do something.
Just background gc operation should be skipped due to generate dirty
nodes and data until unfreeze.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-02-12 07:15:00 +09:00
Jaegeuk Kim 9af45ef5ab f2fs: add comments of start_bidx_of_node
The caller of start_bidx_of_node() should give proper node offsets which
point only direct node blocks. Otherwise, it is a caller's bug.
This patch adds comments to make it clear.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-01-22 10:48:59 +09:00
Namjae Jeon 6e6093a8f1 f2fs: add __init to functions in init_f2fs_fs
Add __init to functions in init_f2fs_fs for code consistency.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-01-22 10:48:38 +09:00
Jaegeuk Kim 408e937561 f2fs: revisit the f2fs_gc flow
I'd like to revisit the f2fs_gc flow and rewrite as follows.

1. In practical, the nGC parameter of f2fs_gc is meaningless. So, let's
  remove it.
2. Background GC marks victim blocks as dirty one at a time.
3. Foreground GC should do cleaning job until acquiring enough free
  sections. Afterwards, it needs to do checkpoint.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2013-01-10 07:42:59 +09:00
Jaegeuk Kim 2b50638dec f2fs: clean up unused variables and return values
This patch cleans up a couple of unnecessary codes related to unused variables
and return values.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2012-12-28 11:27:52 +09:00
Jaegeuk Kim ce19a5d432 f2fs: clean up the start_bidx_of_node function
This patch also resolves the following warning reported by kbuild test robot.

fs/f2fs/gc.c: In function 'start_bidx_of_node':
fs/f2fs/gc.c:453:21: warning: 'bidx' may be used uninitialized in this function

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2012-12-28 11:27:52 +09:00
Namjae Jeon 1042d60f91 f2fs: remove unneeded initialization
No need to initialize  "struct f2fs_gc_kthread *gc_th = NULL",
as gc_th = NULL, will be taken care by the return values of kmalloc().
And fix codes in other places.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
2012-12-11 13:43:44 +09:00
Jaegeuk Kim 0a8165d7c2 f2fs: adjust kernel coding style
As pointed out by Randy Dunlap, this patch removes all usage of "/**" for comment
blocks. Instead, just use "/*".

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2012-12-11 13:43:42 +09:00
Jaegeuk Kim 7bc0900347 f2fs: add garbage collection functions
This adds on-demand and background cleaning functions.

- The basic background cleaning policy is trying to do cleaning jobs as much as
  possible whenever the system is idle. Once the background cleaning is done,
  the cleaner sleeps an amount of time not to interfere with VFS calls. The time
  is dynamically adjusted according to the status of whole segments, which is
  decreased when the following conditions are satisfied.

  . GC is not conducted currently, and
  . IO subsystem is idle by checking the number of requets in bdev's request
     list, and
  . There are enough dirty segments.

  Otherwise, the time is increased incrementally until to the maximum time.
  Note that, min and max times are 10 secs and 30 secs by default.

- F2FS adopts a default victim selection policy where background cleaning uses
  a cost-benefit algorithm, while on-demand cleaning uses a greedy algorithm.

- The method of moving data during the cleaning is slightly different between
  background and on-demand cleaning schemes. In the case of background cleaning,
  F2FS loads the data, and marks them as dirty. Then, F2FS expects that the data
  will be moved by flusher or VM. In the case of on-demand cleaning, F2FS should
  move the data right away.

- In order to identify valid blocks in a victim segment, F2FS scans the bitmap
  of the segment managed as an SIT entry.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
2012-12-11 13:43:41 +09:00