f2fs: fix to avoid data update racing between GC and DIO

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Datas in file can be operated by GC and DIO simultaneously, so we will
face race case as below:

For write case:
Thread A				Thread B
- generic_file_direct_write
 - invalidate_inode_pages2_range
 - f2fs_direct_IO
  - do_blockdev_direct_IO
   - do_direct_IO
    - get_more_blocks
					- f2fs_gc
					 - do_garbage_collect
					  - gc_data_segment
					   - move_data_page
					    - do_write_data_page
					    migrate data block to new block address
   - dio_bio_submit
   update user data to old block address

For read case:
Thread A                                Thread B
- generic_file_direct_write
 - invalidate_inode_pages2_range
 - f2fs_direct_IO
  - do_blockdev_direct_IO
   - do_direct_IO
    - get_more_blocks
					- f2fs_balance_fs
					 - f2fs_gc
					  - do_garbage_collect
					   - gc_data_segment
					    - move_data_page
					     - do_write_data_page
					     migrate data block to new block address
					  - write_checkpoint
					   - do_checkpoint
					    - clear_prefree_segments
					     - f2fs_issue_discard
                                             discard old block adress
   - dio_bio_submit
   update user buffer from obsolete block address

In order to fix this, for one file, we should let DIO and GC getting exclusion
against with each other.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

...

This commit is contained in:

Chao Yu 2016-07-13 09:18:29 +08:00 • committed by Jaegeuk Kim

parent 44a83499dd

commit 82e0a5aa5d

4 changed files with 28 additions and 1 deletions

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6

fs/f2fs/data.c

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1

fs/f2fs/f2fs.h

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20

fs/f2fs/gc.c

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2

fs/f2fs/super.c

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