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| author | zhong jiang <zhongjiang@huawei.com> | 2017-02-23 02:46:51 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-23 03:41:31 +0300 |
| commit | f201ebd87652cf1519792f8662bb3f862c76aa33 (patch) | |
| tree | 3dfc4774407bcc51d5cb91066af04cdc7eb8d3b8 | |
| parent | 083fb8edda0487d192e8c117f625563b920cf7a4 (diff) | |
| download | linux-f201ebd87652cf1519792f8662bb3f862c76aa33.tar.xz | |
mm/z3fold.c: limit first_num to the actual range of possible buddy indexes
At present, Tying the first_num size to NCHUNKS_ORDER is confusing. the
number of chunks is completely unrelated to the number of buddies.
The patch limits the first_num to actual range of possible buddy indexes.
and that is more reasonable and obvious without functional change.
Link: http://lkml.kernel.org/r/1476776569-29504-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Suggested-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/z3fold.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index 8f9e89ca1d31..207e5ddc87a2 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -50,7 +50,7 @@ #define ZHDR_SIZE_ALIGNED CHUNK_SIZE #define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT) -#define BUDDY_MASK ((1 << NCHUNKS_ORDER) - 1) +#define BUDDY_MASK (0x3) struct z3fold_pool; struct z3fold_ops { @@ -109,7 +109,7 @@ struct z3fold_header { unsigned short middle_chunks; unsigned short last_chunks; unsigned short start_middle; - unsigned short first_num:NCHUNKS_ORDER; + unsigned short first_num:2; }; /* @@ -179,7 +179,11 @@ static struct z3fold_header *handle_to_z3fold_header(unsigned long handle) return (struct z3fold_header *)(handle & PAGE_MASK); } -/* Returns buddy number */ +/* + * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle + * but that doesn't matter. because the masking will result in the + * correct buddy number. + */ static enum buddy handle_to_buddy(unsigned long handle) { struct z3fold_header *zhdr = handle_to_z3fold_header(handle); |