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

[f2fs-dev] [PATCH] 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 increaced 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 beforeactually
set/clear them.

Signed-off-by: Fan li <fanofcode.li@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

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

[Chao Yu]

On 2017/11/10 15:41, LiFan wrote:
> 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 increaced 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 beforeactually
> set/clear them.

Thanks for fixing this. :)

Please add:

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

> 
> Signed-off-by: Fan li <fanofcode.li@samsung.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,

> ---
>  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,
>