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authorChao Yu <chao2.yu@samsung.com>2014-05-28 08:56:09 +0800
committerJaegeuk Kim <jaegeuk@kernel.org>2014-06-04 13:34:30 +0900
commitbfec07d0f8ed78b10df3ca3bc23e27de1166ea45 (patch)
treec6134dfc647176474944cbb244bd15de4d4607ac /Documentation/filesystems
parentd631abdac9d541d282a1461b5aeae70aa3866e9f (diff)
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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>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/f2fs.txt8
1 files changed, 4 insertions, 4 deletions
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
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