diff options
| -rw-r--r-- | mm/z3fold.c | 114 |
1 files changed, 64 insertions, 50 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index 2273789..98ab01f 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -34,29 +34,58 @@ /***************** * Structures *****************/ +struct z3fold_pool; +struct z3fold_ops { + int (*evict)(struct z3fold_pool *pool, unsigned long handle); +}; + +enum buddy { + HEADLESS = 0, + FIRST, + MIDDLE, + LAST, + BUDDIES_MAX +}; + +/* + * struct z3fold_header - z3fold page metadata occupying the first chunk of each + * z3fold page, except for HEADLESS pages + * @buddy: links the z3fold page into the relevant list in the pool + * @first_chunks: the size of the first buddy in chunks, 0 if free + * @middle_chunks: the size of the middle buddy in chunks, 0 if free + * @last_chunks: the size of the last buddy in chunks, 0 if free + * @first_num: the starting number (for the first handle) + */ +struct z3fold_header { + struct list_head buddy; + unsigned short first_chunks; + unsigned short middle_chunks; + unsigned short last_chunks; + unsigned short start_middle; + unsigned short first_num:2; +}; + /* * NCHUNKS_ORDER determines the internal allocation granularity, effectively * adjusting internal fragmentation. It also determines the number of * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the - * allocation granularity will be in chunks of size PAGE_SIZE/64. As one chunk - * in allocated page is occupied by z3fold header, NCHUNKS will be calculated - * to 63 which shows the max number of free chunks in z3fold page, also there - * will be 63 freelists per pool. + * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks + * in the beginning of an allocated page are occupied by z3fold header, so + * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y), + * which shows the max number of free chunks in z3fold page, also there will + * be 63, or 62, respectively, freelists per pool. */ #define NCHUNKS_ORDER 6 #define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER) #define CHUNK_SIZE (1 << CHUNK_SHIFT) -#define ZHDR_SIZE_ALIGNED CHUNK_SIZE +#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE) +#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT) +#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT) #define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT) #define BUDDY_MASK (0x3) -struct z3fold_pool; -struct z3fold_ops { - int (*evict)(struct z3fold_pool *pool, unsigned long handle); -}; - /** * struct z3fold_pool - stores metadata for each z3fold pool * @lock: protects all pool fields and first|last_chunk fields of any @@ -86,32 +115,6 @@ struct z3fold_pool { const struct zpool_ops *zpool_ops; }; -enum buddy { - HEADLESS = 0, - FIRST, - MIDDLE, - LAST, - BUDDIES_MAX -}; - -/* - * struct z3fold_header - z3fold page metadata occupying the first chunk of each - * z3fold page, except for HEADLESS pages - * @buddy: links the z3fold page into the relevant list in the pool - * @first_chunks: the size of the first buddy in chunks, 0 if free - * @middle_chunks: the size of the middle buddy in chunks, 0 if free - * @last_chunks: the size of the last buddy in chunks, 0 if free - * @first_num: the starting number (for the first handle) - */ -struct z3fold_header { - struct list_head buddy; - unsigned short first_chunks; - unsigned short middle_chunks; - unsigned short last_chunks; - unsigned short start_middle; - unsigned short first_num:2; -}; - /* * Internal z3fold page flags */ @@ -121,6 +124,7 @@ enum z3fold_page_flags { MIDDLE_CHUNK_MAPPED, }; + /***************** * Helpers *****************/ @@ -204,9 +208,10 @@ static int num_free_chunks(struct z3fold_header *zhdr) */ if (zhdr->middle_chunks != 0) { int nfree_before = zhdr->first_chunks ? - 0 : zhdr->start_middle - 1; + 0 : zhdr->start_middle - ZHDR_CHUNKS; int nfree_after = zhdr->last_chunks ? - 0 : NCHUNKS - zhdr->start_middle - zhdr->middle_chunks; + 0 : TOTAL_CHUNKS - + (zhdr->start_middle + zhdr->middle_chunks); nfree = max(nfree_before, nfree_after); } else nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks; @@ -254,26 +259,35 @@ static void z3fold_destroy_pool(struct z3fold_pool *pool) kfree(pool); } +static inline void *mchunk_memmove(struct z3fold_header *zhdr, + unsigned short dst_chunk) +{ + void *beg = zhdr; + return memmove(beg + (dst_chunk << CHUNK_SHIFT), + beg + (zhdr->start_middle << CHUNK_SHIFT), + zhdr->middle_chunks << CHUNK_SHIFT); +} + /* Has to be called with lock held */ static int z3fold_compact_page(struct z3fold_header *zhdr) { struct page *page = virt_to_page(zhdr); - void *beg = zhdr; + if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private)) + return 0; /* can't move middle chunk, it's used */ - if (!test_bit(MIDDLE_CHUNK_MAPPED, &page->private) && - zhdr->middle_chunks != 0 && - zhdr->first_chunks == 0 && zhdr->last_chunks == 0) { - memmove(beg + ZHDR_SIZE_ALIGNED, - beg + (zhdr->start_middle << CHUNK_SHIFT), - zhdr->middle_chunks << CHUNK_SHIFT); + if (zhdr->middle_chunks == 0) + return 0; /* nothing to compact */ + + if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) { + /* move to the beginning */ + mchunk_memmove(zhdr, ZHDR_CHUNKS); zhdr->first_chunks = zhdr->middle_chunks; zhdr->middle_chunks = 0; zhdr->start_middle = 0; zhdr->first_num++; - return 1; } - return 0; + return 1; } /** @@ -365,7 +379,7 @@ found: zhdr->last_chunks = chunks; else { zhdr->middle_chunks = chunks; - zhdr->start_middle = zhdr->first_chunks + 1; + zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS; } if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 || @@ -778,8 +792,8 @@ MODULE_ALIAS("zpool-z3fold"); static int __init init_z3fold(void) { - /* Make sure the z3fold header will fit in one chunk */ - BUILD_BUG_ON(sizeof(struct z3fold_header) > ZHDR_SIZE_ALIGNED); + /* Make sure the z3fold header is not larger than the page size */ + BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE); zpool_register_driver(&z3fold_zpool_driver); return 0; |
