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| author | Chao Yu <chao2.yu@samsung.com> | 2014-05-28 08:56:09 +0800 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2014-06-04 13:34:30 +0900 |
| commit | bfec07d0f8ed78b10df3ca3bc23e27de1166ea45 (patch) | |
| tree | c6134dfc647176474944cbb244bd15de4d4607ac | |
| parent | d631abdac9d541d282a1461b5aeae70aa3866e9f (diff) | |
| download | op-kernel-dev-bfec07d0f8ed78b10df3ca3bc23e27de1166ea45.zip op-kernel-dev-bfec07d0f8ed78b10df3ca3bc23e27de1166ea45.tar.gz | |
f2fs: avoid overflow when large directory feathure is enabled
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.
Changes from V1
o modify description of calculation in f2fs.txt suggested by Changman Lee.
Suggested-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
| -rw-r--r-- | Documentation/filesystems/f2fs.txt | 8 | ||||
| -rw-r--r-- | fs/f2fs/dir.c | 4 | ||||
| -rw-r--r-- | include/linux/f2fs_fs.h | 3 |
3 files changed, 9 insertions, 6 deletions
diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt index 25311e11..51afba1 100644 --- a/Documentation/filesystems/f2fs.txt +++ b/Documentation/filesystems/f2fs.txt @@ -461,11 +461,11 @@ The number of blocks and buckets are determined by, # of blocks in level #n = | `- 4, Otherwise - ,- 2^ (n + dir_level), - | if n < MAX_DIR_HASH_DEPTH / 2, + ,- 2^(n + dir_level), + | if n + dir_level < MAX_DIR_HASH_DEPTH / 2, # of buckets in level #n = | - `- 2^((MAX_DIR_HASH_DEPTH / 2 + dir_level) - 1), - Otherwise + `- 2^((MAX_DIR_HASH_DEPTH / 2) - 1), + Otherwise When F2FS finds a file name in a directory, at first a hash value of the file name is calculated. Then, F2FS scans the hash table in level #0 to find the 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) |
