This patch supports reverse mapping which gets handle from object. For keeping handle per object, it allocates ZS_HANDLE_SIZE greater than size user requested and stores handle in there. IOW, *(mapped address by zs_map_object - ZS_HANDLE_SIZE) == handle.
Signed-off-by: Minchan Kim <[email protected]> --- mm/zsmalloc.c | 55 +++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 35 insertions(+), 20 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 5f3f9119705e..1eec2a539f77 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -213,8 +213,12 @@ struct size_class { * This must be power of 2 and less than or equal to ZS_ALIGN */ struct link_free { - /* Handle of next free chunk (encodes <PFN, obj_idx>) */ - void *next; + union { + /* Handle of next free chunk (encodes <PFN, obj_idx>) */ + void *next; + /* Handle of object allocated to user */ + unsigned long handle; + }; }; struct zs_pool { @@ -245,7 +249,9 @@ struct mapping_area { }; static unsigned long __zs_malloc(struct zs_pool *pool, - struct size_class *class, gfp_t flags); + struct size_class *class, gfp_t flags, + unsigned long handle); + static void __zs_free(struct zs_pool *pool, struct size_class *class, unsigned long handle); @@ -618,7 +624,7 @@ static unsigned long handle_to_obj(struct zs_pool *pool, unsigned long handle) static unsigned long alloc_handle(struct zs_pool *pool) { return __zs_malloc(pool, pool->handle_class, - pool->flags & ~__GFP_HIGHMEM); + pool->flags & ~__GFP_HIGHMEM, 0); } static void free_handle(struct zs_pool *pool, unsigned long handle) @@ -873,18 +879,22 @@ static void __zs_unmap_object(struct mapping_area *area, { int sizes[2]; void *addr; - char *buf = area->vm_buf; + char *buf; /* no write fastpath */ if (area->vm_mm == ZS_MM_RO) goto out; - sizes[0] = PAGE_SIZE - off; + /* We shouldn't overwrite handle */ + buf = area->vm_buf + ZS_HANDLE_SIZE; + size -= ZS_HANDLE_SIZE; + + sizes[0] = PAGE_SIZE - off - ZS_HANDLE_SIZE; sizes[1] = size - sizes[0]; /* copy per-cpu buffer to object */ addr = kmap_atomic(pages[0]); - memcpy(addr + off, buf, sizes[0]); + memcpy(addr + off + ZS_HANDLE_SIZE, buf, sizes[0]); kunmap_atomic(addr); addr = kmap_atomic(pages[1]); memcpy(addr, buf + sizes[0], sizes[1]); @@ -1138,7 +1148,7 @@ void zs_destroy_pool(struct zs_pool *pool) EXPORT_SYMBOL_GPL(zs_destroy_pool); static unsigned long __zs_malloc(struct zs_pool *pool, - struct size_class *class, gfp_t flags) + struct size_class *class, gfp_t flags, unsigned long handle) { unsigned long obj; struct link_free *link; @@ -1168,10 +1178,19 @@ static unsigned long __zs_malloc(struct zs_pool *pool, vaddr = kmap_atomic(m_page); link = (struct link_free *)vaddr + m_offset / sizeof(*link); first_page->freelist = link->next; - memset(link, POISON_INUSE, sizeof(*link)); + link->handle = handle; kunmap_atomic(vaddr); first_page->inuse++; + + if (handle) { + unsigned long *h_addr; + + /* associate handle with obj */ + h_addr = handle_to_addr(pool, handle); + *h_addr = obj; + } + /* Now move the zspage to another fullness group, if required */ fix_fullness_group(class, first_page); spin_unlock(&class->lock); @@ -1192,9 +1211,8 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) { unsigned long obj, handle; struct size_class *class; - unsigned long *h_addr; - if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE)) + if (unlikely(!size || (size + ZS_HANDLE_SIZE) > ZS_MAX_ALLOC_SIZE)) return 0; /* allocate handle */ @@ -1202,18 +1220,15 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) if (!handle) goto out; - /* allocate obj */ + /* allocate obj and associate it with handle */ + size += ZS_HANDLE_SIZE; class = pool->size_class[get_size_class_index(size)]; - obj = __zs_malloc(pool, class, pool->flags); + obj = __zs_malloc(pool, class, pool->flags, handle); if (!obj) { - __zs_free(pool, pool->handle_class, handle); + free_handle(pool, handle); handle = 0; goto out; } - - /* associate handle with obj */ - h_addr = handle_to_addr(pool, handle); - *h_addr = obj; out: return handle; } @@ -1335,7 +1350,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle, if (off + class->size <= PAGE_SIZE) { /* this object is contained entirely within a page */ area->vm_addr = kmap_atomic(page); - return area->vm_addr + off; + return area->vm_addr + off + ZS_HANDLE_SIZE; } /* this object spans two pages */ @@ -1343,7 +1358,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle, pages[1] = get_next_page(page); BUG_ON(!pages[1]); - return __zs_map_object(area, pages, off, class->size); + return __zs_map_object(area, pages, off, class->size) + ZS_HANDLE_SIZE; } EXPORT_SYMBOL_GPL(zs_map_object); -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
