Hi, Chao
Good catch. Please, modify Documentation/filesytems/f2fs.txt
On Tue, May 27, 2014 at 09:06:52AM +0800, Chao Yu wrote:
> When large directory feathure is enable, We have one case which could cause
> overflow in dir_buckets() as following:
> special case: level + dir_level >= 32 and level < MAX_DIR_HASH_DEPTH / 2.
>
> Here we define MAX_DIR_BUCKETS to limit the return value when the condition
> could trigger potential overflow.
>
> Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> ---
> fs/f2fs/dir.c | 4 ++--
> include/linux/f2fs_fs.h | 3 +++
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index c3f1485..966acb0 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -23,10 +23,10 @@ static unsigned long dir_blocks(struct inode *inode)
>
> static unsigned int dir_buckets(unsigned int level, int dir_level)
> {
> - if (level < MAX_DIR_HASH_DEPTH / 2)
> + if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
> return 1 << (level + dir_level);
> else
> - return 1 << ((MAX_DIR_HASH_DEPTH / 2 + dir_level) - 1);
> + return MAX_DIR_BUCKETS;
> }
>
> static unsigned int bucket_blocks(unsigned int level)
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index 8c03f71..ba6f312 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -394,6 +394,9 @@ typedef __le32 f2fs_hash_t;
> /* MAX level for dir lookup */
> #define MAX_DIR_HASH_DEPTH 63
>
> +/* MAX buckets in one level of dir */
> +#define MAX_DIR_BUCKETS (1 << ((MAX_DIR_HASH_DEPTH / 2) - 1))
> +
> #define SIZE_OF_DIR_ENTRY 11 /* by byte */
> #define SIZE_OF_DENTRY_BITMAP ((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
> BITS_PER_BYTE)
> --
> 1.7.10.4
>
>
>
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