tree 447e74364a93adf14c433bc001db8b08c284a12d
parent c3fb549e882439540a573750576899cf67b354c4
author Sayali Lokhande <sayalil@codeaurora.org> 1568265080 +0530
committer Sayali Lokhande <sayalil@codeaurora.org> 1569473418 +0530

f2fs: avoid infinite GC loop due to stale atomic files

If committing atomic pages is failed when doing f2fs_do_sync_file(), we can
get committed pages but atomic_file being still set like:

- inmem:    0, atomic IO:    4 (Max.   10), volatile IO:    0 (Max.    0)

If GC selects this block, we can get an infinite loop like this:

f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8,
  oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA
f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA,
  sector = 18533696, size = 4096
f2fs_get_victim: dev = (253,7), type = No TYPE,
  policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1,
  ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234
f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0,
  i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c

In that moment, we can observe:

[Before]
Try to move 5084219 blocks (BG: 384508)
  - data blocks : 4962373 (274483)
  - node blocks : 121846 (110025)
Skipped : atomic write 4534686 (10)

[After]
Try to move 5088973 blocks (BG: 384508)
  - data blocks : 4967127 (274483)
  - node blocks : 121846 (110025)
Skipped : atomic write 4539440 (10)

So, refactor atomic_write flow like this:
1. start_atomic_write
 - add inmem_list and set atomic_file

2. write()
 - register it in inmem_pages

3. commit_atomic_write
 - if no error, f2fs_drop_inmem_pages()
 - f2fs_commit_inmme_pages() failed
   : __revoked_inmem_pages() was done
 - f2fs_do_sync_file failed
   : abort_atomic_write later

4. abort_atomic_write
 - f2fs_drop_inmem_pages

5. f2fs_drop_inmem_pages
 - clear atomic_file
 - remove inmem_list

Based on this change, when GC fails to move block in atomic_file,
f2fs_drop_inmem_pages_all() can call f2fs_drop_inmem_pages().

Change-Id: I876038ae8ab980a9d7ab30f3a4416a9a7b9c9998
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Git-commit: 743b620cb0516f6b6cbc45b48df00fe6d14d00ba
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>