Btrfs: Add back metadata checksumming

Signed-off-by: Chris Mason <chris.mason@oracle.com>

6 files changed, 245 insertions, 81 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d1c6f023a30..1af0a966f85 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -310,9 +310,11 @@ struct btrfs_fs_info {
         struct extent_buffer *sb_buffer;
         struct super_block *sb;
         struct inode *btree_inode;
+        spinlock_t hash_lock;
         struct mutex trans_mutex;
         struct mutex fs_mutex;
         struct list_head trans_list;
+        struct list_head hashers;
         struct list_head dead_roots;
         struct delayed_work trans_work;
         struct kobject super_kobj;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 16f0260fca6..1176e5420c5 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -60,7 +60,7 @@ struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
         struct extent_buffer *eb;
 
         eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->extent_tree,
-                                 bytenr, blocksize, GFP_NOFS);
+                                 bytenr, blocksize, NULL, GFP_NOFS);
         return eb;
 }
 
@@ -99,10 +99,102 @@ out:
         return em;
 }
 
+u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len)
+{
+        return crc32c(seed, data, len);
+}
+
+void btrfs_csum_final(u32 crc, char *result)
+{
+        *(__le32 *)result = ~cpu_to_le32(crc);
+}
+
+static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
+                           int verify)
+{
+        char result[BTRFS_CRC32_SIZE];
+        unsigned long len;
+        unsigned long cur_len;
+        unsigned long offset = BTRFS_CSUM_SIZE;
+        char *map_token = NULL;
+        char *kaddr;
+        unsigned long map_start;
+        unsigned long map_len;
+        int err;
+        u32 crc = ~(u32)0;
+
+        len = buf->len - offset;
+        while(len > 0) {
+                err = map_private_extent_buffer(buf, offset, 32,
+                                        &map_token, &kaddr,
+                                        &map_start, &map_len, KM_USER0);
+                if (err) {
+                        printk("failed to map extent buffer! %lu\n",
+                               offset);
+                        return 1;
+                }
+                cur_len = min(len, map_len - (offset - map_start));
+                crc = btrfs_csum_data(root, kaddr + offset - map_start,
+                                      crc, cur_len);
+                len -= cur_len;
+                offset += cur_len;
+                unmap_extent_buffer(buf, map_token, KM_USER0);
+        }
+        btrfs_csum_final(crc, result);
+
+        if (verify) {
+                if (memcmp_extent_buffer(buf, result, 0, BTRFS_CRC32_SIZE)) {
+                        printk("btrfs: %s checksum verify failed on %llu\n",
+                               root->fs_info->sb->s_id,
+                               buf->start);
+                        return 1;
+                }
+        } else {
+                write_extent_buffer(buf, result, 0, BTRFS_CRC32_SIZE);
+        }
+        return 0;
+}
+
+
+int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
+{
+        struct extent_map_tree *tree;
+        u64 start = page->index << PAGE_CACHE_SHIFT;
+        u64 found_start;
+        int found_level;
+        unsigned long len;
+        struct extent_buffer *eb;
+        tree = &BTRFS_I(page->mapping->host)->extent_tree;
+
+        if (page->private == EXTENT_PAGE_PRIVATE)
+                goto out;
+        if (!page->private)
+                goto out;
+        len = page->private >> 2;
+        if (len == 0) {
+                WARN_ON(1);
+        }
+        eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
+        read_extent_buffer_pages(tree, eb, start + PAGE_CACHE_SIZE, 1);
+        found_start = btrfs_header_bytenr(eb);
+        if (found_start != start) {
+                printk("warning: eb start incorrect %Lu buffer %Lu len %lu\n",
+                       start, found_start, len);
+        }
+        found_level = btrfs_header_level(eb);
+        csum_tree_block(root, eb, 0);
+        free_extent_buffer(eb);
+out:
+        return 0;
+}
+
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
         struct extent_map_tree *tree;
+        struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
         tree = &BTRFS_I(page->mapping->host)->extent_tree;
+
+        csum_dirty_buffer(root, page);
         return extent_write_full_page(tree, page, btree_get_extent, wbc);
 }
 int btree_readpage(struct file *file, struct page *page)
@@ -117,7 +209,6 @@ static int btree_releasepage(struct page *page, gfp_t unused_gfp_flags)
         struct extent_map_tree *tree;
         int ret;
 
-        BUG_ON(page->private != 1);
         tree = &BTRFS_I(page->mapping->host)->extent_tree;
         ret = try_release_extent_mapping(tree, page);
         if (ret == 1) {
@@ -136,46 +227,6 @@ static void btree_invalidatepage(struct page *page, unsigned long offset)
         btree_releasepage(page, GFP_NOFS);
 }
 
-int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
-                    char *result)
-{
-        return 0;
-#if 0
-        u32 crc;
-        crc = crc32c(0, data, len);
-        memcpy(result, &crc, BTRFS_CRC32_SIZE);
-        return 0;
-#endif
-}
-
-#if 0
-static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
-                           int verify)
-{
-        return 0;
-        char result[BTRFS_CRC32_SIZE];
-        int ret;
-        struct btrfs_node *node;
-
-        ret = btrfs_csum_data(root, bh->b_data + BTRFS_CSUM_SIZE,
-                              bh->b_size - BTRFS_CSUM_SIZE, result);
-        if (ret)
-                return ret;
-        if (verify) {
-                if (memcmp(bh->b_data, result, BTRFS_CRC32_SIZE)) {
-                        printk("btrfs: %s checksum verify failed on %llu\n",
-                               root->fs_info->sb->s_id,
-                               (unsigned long long)bh_blocknr(bh));
-                        return 1;
-                }
-        } else {
-                node = btrfs_buffer_node(bh);
-                memcpy(node->header.csum, result, BTRFS_CRC32_SIZE);
-        }
-        return 0;
-}
-#endif
-
 #if 0
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
@@ -215,7 +266,7 @@ int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize)
         if (!buf)
                 return 0;
         read_extent_buffer_pages(&BTRFS_I(btree_inode)->extent_tree,
-                                 buf, 0);
+                                 buf, 0, 0);
         free_extent_buffer(buf);
         return ret;
 }
@@ -225,12 +276,29 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 {
         struct extent_buffer *buf = NULL;
         struct inode *btree_inode = root->fs_info->btree_inode;
+        struct extent_map_tree *extent_tree;
+        int ret;
+
+        extent_tree = &BTRFS_I(btree_inode)->extent_tree;
 
         buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
         if (!buf)
                 return NULL;
         read_extent_buffer_pages(&BTRFS_I(btree_inode)->extent_tree,
-                                 buf, 1);
+                                 buf, 0, 1);
+        if (buf->flags & EXTENT_CSUM) {
+                return buf;
+        }
+        if (test_range_bit(extent_tree, buf->start, buf->start + buf->len - 1,
+                           EXTENT_CSUM, 1)) {
+                buf->flags |= EXTENT_CSUM;
+                return buf;
+        }
+        ret = csum_tree_block(root, buf, 1);
+        set_extent_bits(extent_tree, buf->start,
+                        buf->start + buf->len - 1,
+                        EXTENT_CSUM, GFP_NOFS);
+        buf->flags |= EXTENT_CSUM;
         return buf;
 }
 
@@ -251,13 +319,6 @@ int wait_on_tree_block_writeback(struct btrfs_root *root,
         return 0;
 }
 
-int set_tree_block_dirty(struct btrfs_root *root, struct extent_buffer *buf)
-{
-        struct inode *btree_inode = root->fs_info->btree_inode;
-        set_extent_buffer_dirty(&BTRFS_I(btree_inode)->extent_tree, buf);
-        return 0;
-}
-
 static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
                         struct btrfs_root *root,
                         struct btrfs_fs_info *fs_info,
@@ -416,7 +477,24 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 
         return root;
 }
-
+#if 0
+static int add_hasher(struct btrfs_fs_info *info, char *type) {
+        struct btrfs_hasher *hasher;
+
+        hasher = kmalloc(sizeof(*hasher), GFP_NOFS);
+        if (!hasher)
+                return -ENOMEM;
+        hasher->hash_tfm = crypto_alloc_hash(type, 0, CRYPTO_ALG_ASYNC);
+        if (!hasher->hash_tfm) {
+                kfree(hasher);
+                return -EINVAL;
+        }
+        spin_lock(&info->hash_lock);
+        list_add(&hasher->list, &info->hashers);
+        spin_unlock(&info->hash_lock);
+        return 0;
+}
+#endif
 struct btrfs_root *open_ctree(struct super_block *sb)
 {
         u32 sectorsize;
@@ -440,6 +518,9 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
         INIT_LIST_HEAD(&fs_info->trans_list);
         INIT_LIST_HEAD(&fs_info->dead_roots);
+        INIT_LIST_HEAD(&fs_info->hashers);
+        spin_lock_init(&fs_info->hash_lock);
+
         memset(&fs_info->super_kobj, 0, sizeof(fs_info->super_kobj));
         init_completion(&fs_info->kobj_unregister);
         sb_set_blocksize(sb, 4096);
@@ -479,6 +560,14 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         mutex_init(&fs_info->trans_mutex);
         mutex_init(&fs_info->fs_mutex);
 
+#if 0
+        ret = add_hasher(fs_info, "crc32c");
+        if (ret) {
+                printk("btrfs: failed hash setup, modprobe cryptomgr?\n");
+                err = -ENOMEM;
+                goto fail_iput;
+        }
+#endif
         __setup_root(512, 512, 512, tree_root,
                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
 
@@ -509,25 +598,21 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         i_size_write(fs_info->btree_inode,
                      btrfs_super_total_bytes(disk_super));
 
-
         if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
                     sizeof(disk_super->magic))) {
                 printk("btrfs: valid FS not found on %s\n", sb->s_id);
                 goto fail_sb_buffer;
         }
+
         blocksize = btrfs_level_size(tree_root,
                                      btrfs_super_root_level(disk_super));
+
         tree_root->node = read_tree_block(tree_root,
                                           btrfs_super_root(disk_super),
                                           blocksize);
         if (!tree_root->node)
                 goto fail_sb_buffer;
 
-#if 0
-        btrfs_print_leaf(tree_root, tree_root->node);
-        err = -EIO;
-        goto fail_tree_root;
-#endif
         mutex_lock(&fs_info->fs_mutex);
 
         ret = find_and_setup_root(tree_root, fs_info,
@@ -634,9 +719,19 @@ int close_ctree(struct btrfs_root *root)
 
         btrfs_free_block_groups(root->fs_info);
         del_fs_roots(fs_info);
-        extent_map_tree_cleanup(&BTRFS_I(fs_info->btree_inode)->extent_tree);
+        extent_map_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->extent_tree);
         truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
         iput(fs_info->btree_inode);
+#if 0
+        while(!list_empty(&fs_info->hashers)) {
+                struct btrfs_hasher *hasher;
+                hasher = list_entry(fs_info->hashers.next, struct btrfs_hasher,
+                                    hashers);
+                list_del(&hasher->hashers);
+                crypto_free_hash(&fs_info->hash_tfm);
+                kfree(hasher);
+        }
+#endif
         kfree(fs_info->extent_root);
         kfree(fs_info->tree_root);
         return 0;
@@ -733,5 +828,5 @@ int btrfs_read_buffer(struct extent_buffer *buf)
         struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
         struct inode *btree_inode = root->fs_info->btree_inode;
         return read_extent_buffer_pages(&BTRFS_I(btree_inode)->extent_tree,
-                                        buf, 1);
+                                        buf, 0, 1);
 }
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e4e68ea9648..6b2f2b414fa 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1178,6 +1178,10 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
         btrfs_set_buffer_uptodate(buf);
         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
                          buf->start + buf->len - 1, GFP_NOFS);
+        set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
+                        buf->start, buf->start + buf->len - 1,
+                        EXTENT_CSUM, GFP_NOFS);
+        buf->flags |= EXTENT_CSUM;
         btrfs_set_buffer_defrag(buf);
         trans->blocks_used++;
         return buf;
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index f8aaba8a30a..2a8bc4bd43a 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -81,7 +81,7 @@ void extent_map_tree_init(struct extent_map_tree *tree,
 }
 EXPORT_SYMBOL(extent_map_tree_init);
 
-void extent_map_tree_cleanup(struct extent_map_tree *tree)
+void extent_map_tree_empty_lru(struct extent_map_tree *tree)
 {
         struct extent_buffer *eb;
         while(!list_empty(&tree->buffer_lru)) {
@@ -91,7 +91,7 @@ void extent_map_tree_cleanup(struct extent_map_tree *tree)
                 free_extent_buffer(eb);
         }
 }
-EXPORT_SYMBOL(extent_map_tree_cleanup);
+EXPORT_SYMBOL(extent_map_tree_empty_lru);
 
 struct extent_map *alloc_extent_map(gfp_t mask)
 {
@@ -1464,7 +1464,7 @@ void set_page_extent_mapped(struct page *page)
         if (!PagePrivate(page)) {
                 SetPagePrivate(page);
                 WARN_ON(!page->mapping->a_ops->invalidatepage);
-                set_page_private(page, 1);
+                set_page_private(page, EXTENT_PAGE_PRIVATE);
                 page_cache_get(page);
         }
 }
@@ -1979,8 +1979,9 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_map_tree *tree,
 
         spin_lock(&tree->lru_lock);
         eb = find_lru(tree, start, len);
-        if (eb)
+        if (eb) {
                 goto lru_add;
+        }
         spin_unlock(&tree->lru_lock);
 
         if (eb) {
@@ -2007,6 +2008,7 @@ static void __free_extent_buffer(struct extent_buffer *eb)
 
 struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                                           u64 start, unsigned long len,
+                                          struct page *page0,
                                           gfp_t mask)
 {
         unsigned long num_pages = num_extent_pages(start, len);
@@ -2024,7 +2026,18 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
         if (eb->flags & EXTENT_BUFFER_FILLED)
                 return eb;
 
-        for (i = 0; i < num_pages; i++, index++) {
+        if (page0) {
+                eb->first_page = page0;
+                i = 1;
+                index++;
+                page_cache_get(page0);
+                set_page_extent_mapped(page0);
+                set_page_private(page0, EXTENT_PAGE_PRIVATE_FIRST_PAGE |
+                                 len << 2);
+        } else {
+                i = 0;
+        }
+        for (; i < num_pages; i++, index++) {
                 p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
                 if (!p) {
                         WARN_ON(1);
@@ -2036,8 +2049,13 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                         goto fail;
                 }
                 set_page_extent_mapped(p);
-                if (i == 0)
+                if (i == 0) {
                         eb->first_page = p;
+                        set_page_private(p, EXTENT_PAGE_PRIVATE_FIRST_PAGE |
+                                         len << 2);
+                } else {
+                        set_page_private(p, EXTENT_PAGE_PRIVATE);
+                }
                 if (!PageUptodate(p))
                         uptodate = 0;
                 unlock_page(p);
@@ -2057,8 +2075,7 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                                           gfp_t mask)
 {
         unsigned long num_pages = num_extent_pages(start, len);
-        unsigned long i;
-        unsigned long index = start >> PAGE_CACHE_SHIFT;
+        unsigned long i; unsigned long index = start >> PAGE_CACHE_SHIFT;
         struct extent_buffer *eb;
         struct page *p;
         struct address_space *mapping = tree->mapping;
@@ -2082,8 +2099,15 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                         goto fail;
                 }
                 set_page_extent_mapped(p);
-                if (i == 0)
+
+                if (i == 0) {
                         eb->first_page = p;
+                        set_page_private(p, EXTENT_PAGE_PRIVATE_FIRST_PAGE |
+                                         len << 2);
+                } else {
+                        set_page_private(p, EXTENT_PAGE_PRIVATE);
+                }
+
                 if (!PageUptodate(p))
                         uptodate = 0;
                 unlock_page(p);
@@ -2174,7 +2198,21 @@ int set_extent_buffer_dirty(struct extent_map_tree *tree,
 
         num_pages = num_extent_pages(eb->start, eb->len);
         for (i = 0; i < num_pages; i++) {
+                struct page *page = extent_buffer_page(eb, i);
+                /* writepage may need to do something special for the
+                 * first page, we have to make sure page->private is
+                 * properly set.  releasepage may drop page->private
+                 * on us if the page isn't already dirty.
+                 */
+                if (i == 0) {
+                        lock_page(page);
+                        set_page_private(page,
+                                         EXTENT_PAGE_PRIVATE_FIRST_PAGE |
+                                         eb->len << 2);
+                }
                 __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
+                if (i == 0)
+                        unlock_page(page);
         }
         return set_extent_dirty(tree, eb->start,
                                 eb->start + eb->len - 1, GFP_NOFS);
@@ -2217,9 +2255,12 @@ int extent_buffer_uptodate(struct extent_map_tree *tree,
 EXPORT_SYMBOL(extent_buffer_uptodate);
 
 int read_extent_buffer_pages(struct extent_map_tree *tree,
-                             struct extent_buffer *eb, int wait)
+                             struct extent_buffer *eb,
+                             u64 start,
+                             int wait)
 {
         unsigned long i;
+        unsigned long start_i;
         struct page *page;
         int err;
         int ret = 0;
@@ -2232,9 +2273,16 @@ int read_extent_buffer_pages(struct extent_map_tree *tree,
                            EXTENT_UPTODATE, 1)) {
                 return 0;
         }
+        if (start) {
+                WARN_ON(start < eb->start);
+                start_i = (start >> PAGE_CACHE_SHIFT) -
+                        (eb->start >> PAGE_CACHE_SHIFT);
+        } else {
+                start_i = 0;
+        }
 
         num_pages = num_extent_pages(eb->start, eb->len);
-        for (i = 0; i < num_pages; i++) {
+        for (i = start_i; i < num_pages; i++) {
                 page = extent_buffer_page(eb, i);
                 if (PageUptodate(page)) {
                         continue;
@@ -2260,7 +2308,7 @@ int read_extent_buffer_pages(struct extent_map_tree *tree,
                 return ret;
         }
 
-        for (i = 0; i < num_pages; i++) {
+        for (i = start_i; i < num_pages; i++) {
                 page = extent_buffer_page(eb, i);
                 wait_on_page_locked(page);
                 if (!PageUptodate(page)) {
@@ -2314,7 +2362,7 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
 }
 EXPORT_SYMBOL(read_extent_buffer);
 
-static int __map_extent_buffer(struct extent_buffer *eb, unsigned long start,
+int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
                                unsigned long min_len, char **token, char **map,
                                unsigned long *map_start,
                                unsigned long *map_len, int km)
@@ -2337,6 +2385,10 @@ static int __map_extent_buffer(struct extent_buffer *eb, unsigned long start,
                 offset = 0;
                 *map_start = (i << PAGE_CACHE_SHIFT) - start_offset;
         }
+        if (start + min_len >= eb->len) {
+printk("bad mapping eb start %Lu len %lu, wanted %lu %lu\n", eb->start, eb->len, start, min_len);
+                WARN_ON(1);
+        }
 
         p = extent_buffer_page(eb, i);
         WARN_ON(!PageUptodate(p));
@@ -2346,6 +2398,7 @@ static int __map_extent_buffer(struct extent_buffer *eb, unsigned long start,
         *map_len = PAGE_CACHE_SIZE - offset;
         return 0;
 }
+EXPORT_SYMBOL(map_private_extent_buffer);
 
 int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
                       unsigned long min_len,
@@ -2360,8 +2413,8 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
                 eb->map_token = NULL;
                 save = 1;
         }
-        err = __map_extent_buffer(eb, start, min_len, token, map,
-                                   map_start, map_len, km);
+        err = map_private_extent_buffer(eb, start, min_len, token, map,
+                                       map_start, map_len, km);
         if (!err && save) {
                 eb->map_token = *token;
                 eb->kaddr = *map;
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index f1dc28d260e..39d78d31b6a 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -17,8 +17,17 @@
 #define EXTENT_DEFRAG (1 << 6)
 #define EXTENT_DEFRAG_DONE (1 << 7)
 #define EXTENT_BUFFER_FILLED (1 << 8)
+#define EXTENT_CSUM (1 << 9)
 #define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
 
+/*
+ * page->private values.  Every page that is controlled by the extent
+ * map has page->private set to one.
+ */
+
+#define EXTENT_PAGE_PRIVATE 1
+#define EXTENT_PAGE_PRIVATE_FIRST_PAGE 3
+
 
 struct extent_map_ops {
         int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
@@ -89,7 +98,7 @@ typedef struct extent_map *(get_extent_t)(struct inode *inode,
 
 void extent_map_tree_init(struct extent_map_tree *tree,
                           struct address_space *mapping, gfp_t mask);
-void extent_map_tree_cleanup(struct extent_map_tree *tree);
+void extent_map_tree_empty_lru(struct extent_map_tree *tree);
 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
                                          u64 start, u64 end);
 int add_extent_mapping(struct extent_map_tree *tree,
@@ -143,13 +152,14 @@ void set_page_extent_mapped(struct page *page);
 
 struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                                           u64 start, unsigned long len,
+                                          struct page *page0,
                                           gfp_t mask);
 struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                                          u64 start, unsigned long len,
                                           gfp_t mask);
 void free_extent_buffer(struct extent_buffer *eb);
 int read_extent_buffer_pages(struct extent_map_tree *tree,
-                             struct extent_buffer *eb, int wait);
+                             struct extent_buffer *eb, u64 start, int wait);
 
 static inline void extent_buffer_get(struct extent_buffer *eb)
 {
@@ -187,5 +197,9 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long offset,
                       unsigned long min_len, char **token, char **map,
                       unsigned long *map_start,
                       unsigned long *map_len, int km);
+int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
+                      unsigned long min_len, char **token, char **map,
+                      unsigned long *map_start,
+                      unsigned long *map_len, int km);
 void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);
 #endif
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 84f496c838c..80f84b48a70 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1713,10 +1713,6 @@ static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
         struct extent_map_tree *tree;
         int ret;
 
-        if (page->private != 1) {
-                WARN_ON(1);
-                return try_to_free_buffers(page);
-        }
         tree = &BTRFS_I(page->mapping->host)->extent_tree;
         ret = try_release_extent_mapping(tree, page);
         if (ret == 1) {