1 files changed, 510 insertions, 0 deletions

diff --git a/drivers/staging/zram/xvmalloc.c b/drivers/staging/zram/xvmalloc.c
new file mode 100644
index 00000000000..1f9c5082b6d
--- /dev/null
+++ b/drivers/staging/zram/xvmalloc.c
@@ -0,0 +1,510 @@
+/*
+ * xvmalloc memory allocator
+ *
+ * Copyright (C) 2008, 2009, 2010  Nitin Gupta
+ *
+ * This code is released using a dual license strategy: BSD/GPL
+ * You can choose the licence that better fits your requirements.
+ *
+ * Released under the terms of 3-clause BSD License
+ * Released under the terms of GNU General Public License Version 2.0
+ */
+
+#ifdef CONFIG_ZRAM_DEBUG
+#define DEBUG
+#endif
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+
+#include "xvmalloc.h"
+#include "xvmalloc_int.h"
+
+static void stat_inc(u64 *value)
+{
+        *value = *value + 1;
+}
+
+static void stat_dec(u64 *value)
+{
+        *value = *value - 1;
+}
+
+static int test_flag(struct block_header *block, enum blockflags flag)
+{
+        return block->prev & BIT(flag);
+}
+
+static void set_flag(struct block_header *block, enum blockflags flag)
+{
+        block->prev |= BIT(flag);
+}
+
+static void clear_flag(struct block_header *block, enum blockflags flag)
+{
+        block->prev &= ~BIT(flag);
+}
+
+/*
+ * Given <page, offset> pair, provide a dereferencable pointer.
+ * This is called from xv_malloc/xv_free path, so it
+ * needs to be fast.
+ */
+static void *get_ptr_atomic(struct page *page, u16 offset, enum km_type type)
+{
+        unsigned char *base;
+
+        base = kmap_atomic(page, type);
+        return base + offset;
+}
+
+static void put_ptr_atomic(void *ptr, enum km_type type)
+{
+        kunmap_atomic(ptr, type);
+}
+
+static u32 get_blockprev(struct block_header *block)
+{
+        return block->prev & PREV_MASK;
+}
+
+static void set_blockprev(struct block_header *block, u16 new_offset)
+{
+        block->prev = new_offset | (block->prev & FLAGS_MASK);
+}
+
+static struct block_header *BLOCK_NEXT(struct block_header *block)
+{
+        return (struct block_header *)
+                ((char *)block + block->size + XV_ALIGN);
+}
+
+/*
+ * Get index of free list containing blocks of maximum size
+ * which is less than or equal to given size.
+ */
+static u32 get_index_for_insert(u32 size)
+{
+        if (unlikely(size > XV_MAX_ALLOC_SIZE))
+                size = XV_MAX_ALLOC_SIZE;
+        size &= ~FL_DELTA_MASK;
+        return (size - XV_MIN_ALLOC_SIZE) >> FL_DELTA_SHIFT;
+}
+
+/*
+ * Get index of free list having blocks of size greater than
+ * or equal to requested size.
+ */
+static u32 get_index(u32 size)
+{
+        if (unlikely(size < XV_MIN_ALLOC_SIZE))
+                size = XV_MIN_ALLOC_SIZE;
+        size = ALIGN(size, FL_DELTA);
+        return (size - XV_MIN_ALLOC_SIZE) >> FL_DELTA_SHIFT;
+}
+
+/**
+ * find_block - find block of at least given size
+ * @pool: memory pool to search from
+ * @size: size of block required
+ * @page: page containing required block
+ * @offset: offset within the page where block is located.
+ *
+ * Searches two level bitmap to locate block of at least
+ * the given size. If such a block is found, it provides
+ * <page, offset> to identify this block and returns index
+ * in freelist where we found this block.
+ * Otherwise, returns 0 and <page, offset> params are not touched.
+ */
+static u32 find_block(struct xv_pool *pool, u32 size,
+                        struct page **page, u32 *offset)
+{
+        ulong flbitmap, slbitmap;
+        u32 flindex, slindex, slbitstart;
+
+        /* There are no free blocks in this pool */
+        if (!pool->flbitmap)
+                return 0;
+
+        /* Get freelist index correspoding to this size */
+        slindex = get_index(size);
+        slbitmap = pool->slbitmap[slindex / BITS_PER_LONG];
+        slbitstart = slindex % BITS_PER_LONG;
+
+        /*
+         * If freelist is not empty at this index, we found the
+         * block - head of this list. This is approximate best-fit match.
+         */
+        if (test_bit(slbitstart, &slbitmap)) {
+                *page = pool->freelist[slindex].page;
+                *offset = pool->freelist[slindex].offset;
+                return slindex;
+        }
+
+        /*
+         * No best-fit found. Search a bit further in bitmap for a free block.
+         * Second level bitmap consists of series of 32-bit chunks. Search
+         * further in the chunk where we expected a best-fit, starting from
+         * index location found above.
+         */
+        slbitstart++;
+        slbitmap >>= slbitstart;
+
+        /* Skip this search if we were already at end of this bitmap chunk */
+        if ((slbitstart != BITS_PER_LONG) && slbitmap) {
+                slindex += __ffs(slbitmap) + 1;
+                *page = pool->freelist[slindex].page;
+                *offset = pool->freelist[slindex].offset;
+                return slindex;
+        }
+
+        /* Now do a full two-level bitmap search to find next nearest fit */
+        flindex = slindex / BITS_PER_LONG;
+
+        flbitmap = (pool->flbitmap) >> (flindex + 1);
+        if (!flbitmap)
+                return 0;
+
+        flindex += __ffs(flbitmap) + 1;
+        slbitmap = pool->slbitmap[flindex];
+        slindex = (flindex * BITS_PER_LONG) + __ffs(slbitmap);
+        *page = pool->freelist[slindex].page;
+        *offset = pool->freelist[slindex].offset;
+
+        return slindex;
+}
+
+/*
+ * Insert block at <page, offset> in freelist of given pool.
+ * freelist used depends on block size.
+ */
+static void insert_block(struct xv_pool *pool, struct page *page, u32 offset,
+                        struct block_header *block)
+{
+        u32 flindex, slindex;
+        struct block_header *nextblock;
+
+        slindex = get_index_for_insert(block->size);
+        flindex = slindex / BITS_PER_LONG;
+
+        block->link.prev_page = NULL;
+        block->link.prev_offset = 0;
+        block->link.next_page = pool->freelist[slindex].page;
+        block->link.next_offset = pool->freelist[slindex].offset;
+        pool->freelist[slindex].page = page;
+        pool->freelist[slindex].offset = offset;
+
+        if (block->link.next_page) {
+                nextblock = get_ptr_atomic(block->link.next_page,
+                                        block->link.next_offset, KM_USER1);
+                nextblock->link.prev_page = page;
+                nextblock->link.prev_offset = offset;
+                put_ptr_atomic(nextblock, KM_USER1);
+                /* If there was a next page then the free bits are set. */
+                return;
+        }
+
+        __set_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]);
+        __set_bit(flindex, &pool->flbitmap);
+}
+
+/*
+ * Remove block from freelist. Index 'slindex' identifies the freelist.
+ */
+static void remove_block(struct xv_pool *pool, struct page *page, u32 offset,
+                        struct block_header *block, u32 slindex)
+{
+        u32 flindex = slindex / BITS_PER_LONG;
+        struct block_header *tmpblock;
+
+        if (block->link.prev_page) {
+                tmpblock = get_ptr_atomic(block->link.prev_page,
+                                block->link.prev_offset, KM_USER1);
+                tmpblock->link.next_page = block->link.next_page;
+                tmpblock->link.next_offset = block->link.next_offset;
+                put_ptr_atomic(tmpblock, KM_USER1);
+        }
+
+        if (block->link.next_page) {
+                tmpblock = get_ptr_atomic(block->link.next_page,
+                                block->link.next_offset, KM_USER1);
+                tmpblock->link.prev_page = block->link.prev_page;
+                tmpblock->link.prev_offset = block->link.prev_offset;
+                put_ptr_atomic(tmpblock, KM_USER1);
+        }
+
+        /* Is this block is at the head of the freelist? */
+        if (pool->freelist[slindex].page == page
+           && pool->freelist[slindex].offset == offset) {
+
+                pool->freelist[slindex].page = block->link.next_page;
+                pool->freelist[slindex].offset = block->link.next_offset;
+
+                if (pool->freelist[slindex].page) {
+                        struct block_header *tmpblock;
+                        tmpblock = get_ptr_atomic(pool->freelist[slindex].page,
+                                        pool->freelist[slindex].offset,
+                                        KM_USER1);
+                        tmpblock->link.prev_page = NULL;
+                        tmpblock->link.prev_offset = 0;
+                        put_ptr_atomic(tmpblock, KM_USER1);
+                } else {
+                        /* This freelist bucket is empty */
+                        __clear_bit(slindex % BITS_PER_LONG,
+                                    &pool->slbitmap[flindex]);
+                        if (!pool->slbitmap[flindex])
+                                __clear_bit(flindex, &pool->flbitmap);
+                }
+        }
+
+        block->link.prev_page = NULL;
+        block->link.prev_offset = 0;
+        block->link.next_page = NULL;
+        block->link.next_offset = 0;
+}
+
+/*
+ * Allocate a page and add it to freelist of given pool.
+ */
+static int grow_pool(struct xv_pool *pool, gfp_t flags)
+{
+        struct page *page;
+        struct block_header *block;
+
+        page = alloc_page(flags);
+        if (unlikely(!page))
+                return -ENOMEM;
+
+        stat_inc(&pool->total_pages);
+
+        spin_lock(&pool->lock);
+        block = get_ptr_atomic(page, 0, KM_USER0);
+
+        block->size = PAGE_SIZE - XV_ALIGN;
+        set_flag(block, BLOCK_FREE);
+        clear_flag(block, PREV_FREE);
+        set_blockprev(block, 0);
+
+        insert_block(pool, page, 0, block);
+
+        put_ptr_atomic(block, KM_USER0);
+        spin_unlock(&pool->lock);
+
+        return 0;
+}
+
+/*
+ * Create a memory pool. Allocates freelist, bitmaps and other
+ * per-pool metadata.
+ */
+struct xv_pool *xv_create_pool(void)
+{
+        u32 ovhd_size;
+        struct xv_pool *pool;
+
+        ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
+        pool = kzalloc(ovhd_size, GFP_KERNEL);
+        if (!pool)
+                return NULL;
+
+        spin_lock_init(&pool->lock);
+
+        return pool;
+}
+EXPORT_SYMBOL_GPL(xv_create_pool);
+
+void xv_destroy_pool(struct xv_pool *pool)
+{
+        kfree(pool);
+}
+EXPORT_SYMBOL_GPL(xv_destroy_pool);
+
+/**
+ * xv_malloc - Allocate block of given size from pool.
+ * @pool: pool to allocate from
+ * @size: size of block to allocate
+ * @page: page no. that holds the object
+ * @offset: location of object within page
+ *
+ * On success, <page, offset> identifies block allocated
+ * and 0 is returned. On failure, <page, offset> is set to
+ * 0 and -ENOMEM is returned.
+ *
+ * Allocation requests with size > XV_MAX_ALLOC_SIZE will fail.
+ */
+int xv_malloc(struct xv_pool *pool, u32 size, struct page **page,
+                u32 *offset, gfp_t flags)
+{
+        int error;
+        u32 index, tmpsize, origsize, tmpoffset;
+        struct block_header *block, *tmpblock;
+
+        *page = NULL;
+        *offset = 0;
+        origsize = size;
+
+        if (unlikely(!size || size > XV_MAX_ALLOC_SIZE))
+                return -ENOMEM;
+
+        size = ALIGN(size, XV_ALIGN);
+
+        spin_lock(&pool->lock);
+
+        index = find_block(pool, size, page, offset);
+
+        if (!*page) {
+                spin_unlock(&pool->lock);
+                if (flags & GFP_NOWAIT)
+                        return -ENOMEM;
+                error = grow_pool(pool, flags);
+                if (unlikely(error))
+                        return error;
+
+                spin_lock(&pool->lock);
+                index = find_block(pool, size, page, offset);
+        }
+
+        if (!*page) {
+                spin_unlock(&pool->lock);
+                return -ENOMEM;
+        }
+
+        block = get_ptr_atomic(*page, *offset, KM_USER0);
+
+        remove_block(pool, *page, *offset, block, index);
+
+        /* Split the block if required */
+        tmpoffset = *offset + size + XV_ALIGN;
+        tmpsize = block->size - size;
+        tmpblock = (struct block_header *)((char *)block + size + XV_ALIGN);
+        if (tmpsize) {
+                tmpblock->size = tmpsize - XV_ALIGN;
+                set_flag(tmpblock, BLOCK_FREE);
+                clear_flag(tmpblock, PREV_FREE);
+
+                set_blockprev(tmpblock, *offset);
+                if (tmpblock->size >= XV_MIN_ALLOC_SIZE)
+                        insert_block(pool, *page, tmpoffset, tmpblock);
+
+                if (tmpoffset + XV_ALIGN + tmpblock->size != PAGE_SIZE) {
+                        tmpblock = BLOCK_NEXT(tmpblock);
+                        set_blockprev(tmpblock, tmpoffset);
+                }
+        } else {
+                /* This block is exact fit */
+                if (tmpoffset != PAGE_SIZE)
+                        clear_flag(tmpblock, PREV_FREE);
+        }
+
+        block->size = origsize;
+        clear_flag(block, BLOCK_FREE);
+
+        put_ptr_atomic(block, KM_USER0);
+        spin_unlock(&pool->lock);
+
+        *offset += XV_ALIGN;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(xv_malloc);
+
+/*
+ * Free block identified with <page, offset>
+ */
+void xv_free(struct xv_pool *pool, struct page *page, u32 offset)
+{
+        void *page_start;
+        struct block_header *block, *tmpblock;
+
+        offset -= XV_ALIGN;
+
+        spin_lock(&pool->lock);
+
+        page_start = get_ptr_atomic(page, 0, KM_USER0);
+        block = (struct block_header *)((char *)page_start + offset);
+
+        /* Catch double free bugs */
+        BUG_ON(test_flag(block, BLOCK_FREE));
+
+        block->size = ALIGN(block->size, XV_ALIGN);
+
+        tmpblock = BLOCK_NEXT(block);
+        if (offset + block->size + XV_ALIGN == PAGE_SIZE)
+                tmpblock = NULL;
+
+        /* Merge next block if its free */
+        if (tmpblock && test_flag(tmpblock, BLOCK_FREE)) {
+                /*
+                 * Blocks smaller than XV_MIN_ALLOC_SIZE
+                 * are not inserted in any free list.
+                 */
+                if (tmpblock->size >= XV_MIN_ALLOC_SIZE) {
+                        remove_block(pool, page,
+                                    offset + block->size + XV_ALIGN, tmpblock,
+                                    get_index_for_insert(tmpblock->size));
+                }
+                block->size += tmpblock->size + XV_ALIGN;
+        }
+
+        /* Merge previous block if its free */
+        if (test_flag(block, PREV_FREE)) {
+                tmpblock = (struct block_header *)((char *)(page_start) +
+                                                get_blockprev(block));
+                offset = offset - tmpblock->size - XV_ALIGN;
+
+                if (tmpblock->size >= XV_MIN_ALLOC_SIZE)
+                        remove_block(pool, page, offset, tmpblock,
+                                    get_index_for_insert(tmpblock->size));
+
+                tmpblock->size += block->size + XV_ALIGN;
+                block = tmpblock;
+        }
+
+        /* No used objects in this page. Free it. */
+        if (block->size == PAGE_SIZE - XV_ALIGN) {
+                put_ptr_atomic(page_start, KM_USER0);
+                spin_unlock(&pool->lock);
+
+                __free_page(page);
+                stat_dec(&pool->total_pages);
+                return;
+        }
+
+        set_flag(block, BLOCK_FREE);
+        if (block->size >= XV_MIN_ALLOC_SIZE)
+                insert_block(pool, page, offset, block);
+
+        if (offset + block->size + XV_ALIGN != PAGE_SIZE) {
+                tmpblock = BLOCK_NEXT(block);
+                set_flag(tmpblock, PREV_FREE);
+                set_blockprev(tmpblock, offset);
+        }
+
+        put_ptr_atomic(page_start, KM_USER0);
+        spin_unlock(&pool->lock);
+}
+EXPORT_SYMBOL_GPL(xv_free);
+
+u32 xv_get_object_size(void *obj)
+{
+        struct block_header *blk;
+
+        blk = (struct block_header *)((char *)(obj) - XV_ALIGN);
+        return blk->size;
+}
+EXPORT_SYMBOL_GPL(xv_get_object_size);
+
+/*
+ * Returns total memory used by allocator (userdata + metadata)
+ */
+u64 xv_get_total_size_bytes(struct xv_pool *pool)
+{
+        return pool->total_pages << PAGE_SHIFT;
+}
+EXPORT_SYMBOL_GPL(xv_get_total_size_bytes);