[f2fs-dev] [PATCH RESEND v2] f2fs: validate before set/clear free nat bitmap

[LiFan]

In flush_nat_entries, all dirty nats will be flushed and if their new address
isn't NULL_ADDR, their bitmaps will be updated, the free_nid_count of the
bitmaps will be increased regardless of whether the nats have already been
occupied before. This could lead to wrong free_nid_count.
So this patch checks the status of the bits before actually set/clear them.

Fixes: 586d1492f301 ("f2fs: skip scanning free nid bitmap of full NAT blocks")

Signed-off-by: Fan li <fanofcode...@samsung.com>
---
 fs/f2fs/node.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index d234c6e..b965a53 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1906,15 +1906,18 @@ static void update_free_nid_bitmap(struct f2fs_sb_info 
*sbi, nid_t nid,
        if (!test_bit_le(nat_ofs, nm_i->nat_block_bitmap))
                return;
 
-       if (set)
+       if (set) {
+               if (test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))
+                       return;
                __set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
-       else
-               __clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
-
-       if (set)
                nm_i->free_nid_count[nat_ofs]++;
-       else if (!build)
-               nm_i->free_nid_count[nat_ofs]--;
+       } else {
+               if (!test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))
+                       return;
+               __clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
+               if (!build)
+                       nm_i->free_nid_count[nat_ofs]--;
+       }
 }
 
 static void scan_nat_page(struct f2fs_sb_info *sbi,
--
2.7.4