From bfec07d0f8ed78b10df3ca3bc23e27de1166ea45 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Wed, 28 May 2014 08:56:09 +0800 Subject: 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 Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- Documentation/filesystems/f2fs.txt | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt index 25311e113e75..51afba17bbae 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 -- cgit v1.2.3