f2fs: fix concurrent problem for updating free bitmap

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alloc_nid_failed and scan_nat_page can be called at the same time,
and we haven't protected add_free_nid and update_free_nid_bitmap
with the same nid_list_lock. That could lead to

Thread A				Thread B
- __build_free_nids
 - scan_nat_page
  - add_free_nid
					- alloc_nid_failed
					 - update_free_nid_bitmap
  - update_free_nid_bitmap

scan_nat_page will clear the free bitmap since the nid is PREALLOC_NID,
but alloc_nid_failed needs to set the free bitmap. This results in
free nid with free bitmap cleared.
This patch update the bitmap under the same nid_list_lock in add_free_nid.
And use __GFP_NOFAIL to make sure to update status of free nid correctly.

Signed-off-by: Fan li <fanofcode.li@samsung.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

...

This commit is contained in:

LiFan 2017-11-22 16:07:23 +08:00 • committed by Jaegeuk Kim

parent 2ab56a59ca

commit 5921aaa185

1 changed files with 43 additions and 42 deletions

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fs/f2fs/node.c

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