Btrfs: Retry metadata reads in the face of checksum failures

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

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index efce173..ff4e9c6 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -569,7 +569,16 @@ static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 static int noinline check_block(struct btrfs_root *root,
                                struct btrfs_path *path, int level)
 {
-       return 0;
+       u64 found_start;
+       if (btrfs_header_level(path->nodes[level]) != level)
+           printk("warning: bad level %Lu wanted %d found %d\n",
+                  path->nodes[level]->start, level,
+                  btrfs_header_level(path->nodes[level]));
+       found_start = btrfs_header_bytenr(path->nodes[level]);
+       if (found_start != path->nodes[level]->start) {
+           printk("warning: bad bytentr %Lu found %Lu\n",
+                  path->nodes[level]->start, found_start);
+       }
 #if 0
        struct extent_buffer *buf = path->nodes[level];
 

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 94ff87d..59bdf04 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -156,7 +156,6 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
                        memcpy(&found, result, BTRFS_CRC32_SIZE);
 
                        read_extent_buffer(buf, &val, 0, BTRFS_CRC32_SIZE);
-                       WARN_ON(1);
                        printk("btrfs: %s checksum verify failed on %llu "
                               "wanted %X found %X from_this_trans %d "
                               "level %d\n",
@@ -171,6 +170,40 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
        return 0;
 }
 
+static int btree_read_extent_buffer_pages(struct btrfs_root *root,
+                                         struct extent_buffer *eb,
+                                         u64 start)
+{
+       struct extent_io_tree *io_tree;
+       int ret;
+       int num_copies = 0;
+       int mirror_num = 0;
+
+       io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
+       while (1) {
+               ret = read_extent_buffer_pages(io_tree, eb, start, 1,
+                                              btree_get_extent, mirror_num);
+               if (!ret) {
+                       if (mirror_num)
+printk("good read %Lu mirror %d total %d\n", eb->start, mirror_num, num_copies);
+                       return ret;
+               }
+               num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
+                                             eb->start, eb->len);
+printk("failed to read %Lu mirror %d total %d\n", eb->start, mirror_num, num_copies);
+               if (num_copies == 1) {
+printk("reading %Lu failed only one copy\n", eb->start);
+                       return ret;
+               }
+               mirror_num++;
+               if (mirror_num > num_copies) {
+printk("bailing at mirror %d of %d\n", mirror_num, num_copies);
+                       return ret;
+               }
+       }
+printk("read extent buffer page last\n");
+       return -EIO;
+}
 
 int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
 {
@@ -180,6 +213,8 @@ int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
        int found_level;
        unsigned long len;
        struct extent_buffer *eb;
+       int ret;
+
        tree = &BTRFS_I(page->mapping->host)->io_tree;
 
        if (page->private == EXTENT_PAGE_PRIVATE)
@@ -191,8 +226,8 @@ int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
                WARN_ON(1);
        }
        eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
-       read_extent_buffer_pages(tree, eb, start + PAGE_CACHE_SIZE, 1,
-                                btree_get_extent);
+       ret = btree_read_extent_buffer_pages(root, eb, start + PAGE_CACHE_SIZE);
+       BUG_ON(ret);
        btrfs_clear_buffer_defrag(eb);
        found_start = btrfs_header_bytenr(eb);
        if (found_start != start) {
@@ -240,7 +275,7 @@ int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
        unsigned long len;
        struct extent_buffer *eb;
        struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
-       int ret;
+       int ret = 0;
 
        tree = &BTRFS_I(page->mapping->host)->io_tree;
        if (page->private == EXTENT_PAGE_PRIVATE)
@@ -252,25 +287,26 @@ int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
                WARN_ON(1);
        }
        eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
-       read_extent_buffer_pages(tree, eb, start + PAGE_CACHE_SIZE, 1,
-                                btree_get_extent);
+
        btrfs_clear_buffer_defrag(eb);
        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);
-               WARN_ON(1);
+printk("bad start on %Lu found %Lu\n", eb->start, found_start);
+               ret = -EIO;
                goto err;
        }
        if (eb->first_page != page) {
                printk("bad first page %lu %lu\n", eb->first_page->index,
                       page->index);
                WARN_ON(1);
+               ret = -EIO;
                goto err;
        }
        found_level = btrfs_header_level(eb);
 
        ret = csum_tree_block(root, eb, 1);
+       if (ret)
+               ret = -EIO;
 
        end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
        end = eb->start + end - 1;
@@ -278,7 +314,7 @@ int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
 err:
        free_extent_buffer(eb);
 out:
-       return 0;
+       return ret;
 }
 
 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
@@ -329,7 +365,8 @@ int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
        return 0;
 }
 
-static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
+static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
+                                int mirror_num)
 {
        struct btrfs_root *root = BTRFS_I(inode)->root;
        u64 offset;
@@ -338,7 +375,7 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
        offset = bio->bi_sector << 9;
 
        if (rw & (1 << BIO_RW)) {
-               return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio);
+               return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num);
        }
 
        ret = btrfs_bio_wq_end_io(root->fs_info, bio, 1);
@@ -349,7 +386,7 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
                submit_bio(rw, bio);
                return 0;
        }
-       return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio);
+       return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num);
 }
 
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
@@ -459,7 +496,7 @@ int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize)
        if (!buf)
                return 0;
        read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
-                                buf, 0, 0, btree_get_extent);
+                                buf, 0, 0, btree_get_extent, 0);
        free_extent_buffer(buf);
        return ret;
 }
@@ -522,8 +559,7 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
        if (!buf)
                return NULL;
 
-       ret = read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree, buf, 0,
-                                      1, btree_get_extent);
+       ret = btree_read_extent_buffer_pages(root, buf, 0);
 
        if (ret == 0) {
                buf->flags |= EXTENT_UPTODATE;
@@ -1366,10 +1402,8 @@ int btrfs_clear_buffer_defrag(struct extent_buffer *buf)
 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;
        int ret;
-       ret = read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
-                                       buf, 0, 1, btree_get_extent);
+       ret = btree_read_extent_buffer_pages(root, buf, 0);
        if (ret == 0) {
                buf->flags |= EXTENT_UPTODATE;
        }

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index cfc383c..2f15937 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1546,7 +1546,7 @@ static int end_bio_extent_readpage(struct bio *bio,
                                    !(state->state & EXTENT_LOCKED))
                                        state = NULL;
                        }
-                       if (!state) {
+                       if (!state && uptodate) {
                                spin_unlock_irqrestore(&tree->lock, flags);
                                set_extent_uptodate(tree, start, end,
                                                    GFP_ATOMIC);
@@ -1567,8 +1567,10 @@ static int end_bio_extent_readpage(struct bio *bio,
                        } else {
                                state = NULL;
                        }
-                       set_state_cb(tree, clear, EXTENT_UPTODATE);
-                       clear->state |= EXTENT_UPTODATE;
+                       if (uptodate) {
+                               set_state_cb(tree, clear, EXTENT_UPTODATE);
+                               clear->state |= EXTENT_UPTODATE;
+                       }
                        clear_state_bit(tree, clear, EXTENT_LOCKED,
                                        1, 0);
                        if (cur == start)
@@ -1685,7 +1687,7 @@ extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
        return bio;
 }
 
-static int submit_one_bio(int rw, struct bio *bio)
+static int submit_one_bio(int rw, struct bio *bio, int mirror_num)
 {
        u64 maxsector;
        int ret = 0;
@@ -1722,7 +1724,8 @@ static int submit_one_bio(int rw, struct bio *bio)
                WARN_ON(1);
        }
        if (tree->ops && tree->ops->submit_bio_hook)
-               tree->ops->submit_bio_hook(page->mapping->host, rw, bio);
+               tree->ops->submit_bio_hook(page->mapping->host, rw, bio,
+                                          mirror_num);
        else
                submit_bio(rw, bio);
        if (bio_flagged(bio, BIO_EOPNOTSUPP))
@@ -1737,7 +1740,8 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
                              struct block_device *bdev,
                              struct bio **bio_ret,
                              unsigned long max_pages,
-                             bio_end_io_t end_io_func)
+                             bio_end_io_t end_io_func,
+                             int mirror_num)
 {
        int ret = 0;
        struct bio *bio;
@@ -1749,7 +1753,7 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
                    (tree->ops && tree->ops->merge_bio_hook &&
                     tree->ops->merge_bio_hook(page, offset, size, bio)) ||
                    bio_add_page(bio, page, size, offset) < size) {
-                       ret = submit_one_bio(rw, bio);
+                       ret = submit_one_bio(rw, bio, mirror_num);
                        bio = NULL;
                } else {
                        return 0;
@@ -1769,7 +1773,7 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
        if (bio_ret) {
                *bio_ret = bio;
        } else {
-               ret = submit_one_bio(rw, bio);
+               ret = submit_one_bio(rw, bio, mirror_num);
        }
 
        return ret;
@@ -1798,7 +1802,7 @@ void set_page_extent_head(struct page *page, unsigned long len)
 static int __extent_read_full_page(struct extent_io_tree *tree,
                                   struct page *page,
                                   get_extent_t *get_extent,
-                                  struct bio **bio)
+                                  struct bio **bio, int mirror_num)
 {
        struct inode *inode = page->mapping->host;
        u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
@@ -1901,7 +1905,7 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
                        ret = submit_extent_page(READ, tree, page,
                                         sector, iosize, page_offset,
                                         bdev, bio, nr,
-                                        end_bio_extent_readpage);
+                                        end_bio_extent_readpage, mirror_num);
                }
                if (ret)
                        SetPageError(page);
@@ -1923,9 +1927,9 @@ int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
        struct bio *bio = NULL;
        int ret;
 
-       ret = __extent_read_full_page(tree, page, get_extent, &bio);
+       ret = __extent_read_full_page(tree, page, get_extent, &bio, 0);
        if (bio)
-               submit_one_bio(READ, bio);
+               submit_one_bio(READ, bio, 0);
        return ret;
 }
 EXPORT_SYMBOL(extent_read_full_page);
@@ -2077,7 +2081,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
                        ret = submit_extent_page(WRITE, tree, page, sector,
                                                 iosize, page_offset, bdev,
                                                 &epd->bio, max_nr,
-                                                end_bio_extent_writepage);
+                                                end_bio_extent_writepage, 0);
                        if (ret)
                                SetPageError(page);
                }
@@ -2244,7 +2248,7 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
 
        write_cache_pages(mapping, &wbc_writepages, __extent_writepage, &epd);
        if (epd.bio) {
-               submit_one_bio(WRITE, epd.bio);
+               submit_one_bio(WRITE, epd.bio, 0);
        }
        return ret;
 }
@@ -2265,7 +2269,7 @@ int extent_writepages(struct extent_io_tree *tree,
 
        ret = write_cache_pages(mapping, wbc, __extent_writepage, &epd);
        if (epd.bio) {
-               submit_one_bio(WRITE, epd.bio);
+               submit_one_bio(WRITE, epd.bio, 0);
        }
        return ret;
 }
@@ -2297,7 +2301,8 @@ int extent_readpages(struct extent_io_tree *tree,
                        page_cache_get(page);
                        if (!pagevec_add(&pvec, page))
                                __pagevec_lru_add(&pvec);
-                       __extent_read_full_page(tree, page, get_extent, &bio);
+                       __extent_read_full_page(tree, page, get_extent,
+                                               &bio, 0);
                }
                page_cache_release(page);
        }
@@ -2305,7 +2310,7 @@ int extent_readpages(struct extent_io_tree *tree,
                __pagevec_lru_add(&pvec);
        BUG_ON(!list_empty(pages));
        if (bio)
-               submit_one_bio(READ, bio);
+               submit_one_bio(READ, bio, 0);
        return 0;
 }
 EXPORT_SYMBOL(extent_readpages);
@@ -2430,7 +2435,7 @@ int extent_prepare_write(struct extent_io_tree *tree,
                        ret = submit_extent_page(READ, tree, page,
                                         sector, iosize, page_offset, em->bdev,
                                         NULL, 1,
-                                        end_bio_extent_preparewrite);
+                                        end_bio_extent_preparewrite, 0);
                        iocount++;
                        block_start = block_start + iosize;
                } else {
@@ -2696,6 +2701,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
                mark_page_accessed(page0);
                set_page_extent_mapped(page0);
                set_page_extent_head(page0, len);
+               uptodate = PageUptodate(page0);
        } else {
                i = 0;
        }
@@ -3006,7 +3012,7 @@ EXPORT_SYMBOL(extent_buffer_uptodate);
 int read_extent_buffer_pages(struct extent_io_tree *tree,
                             struct extent_buffer *eb,
                             u64 start, int wait,
-                            get_extent_t *get_extent)
+                            get_extent_t *get_extent, int mirror_num)
 {
        unsigned long i;
        unsigned long start_i;
@@ -3062,8 +3068,10 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
                if (!PageUptodate(page)) {
                        if (start_i == 0)
                                inc_all_pages = 1;
+                       ClearPageError(page);
                        err = __extent_read_full_page(tree, page,
-                                                     get_extent, &bio);
+                                                     get_extent, &bio,
+                                                     mirror_num);
                        if (err) {
                                ret = err;
                        }
@@ -3073,7 +3081,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
        }
 
        if (bio)
-               submit_one_bio(READ, bio);
+               submit_one_bio(READ, bio, mirror_num);
 
        if (ret || !wait) {
                return ret;

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 9d2991d..8d6b8a1 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -27,7 +27,8 @@ struct extent_state;
 struct extent_io_ops {
        int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
        int (*writepage_io_hook)(struct page *page, u64 start, u64 end);
-       int (*submit_bio_hook)(struct inode *inode, int rw, struct bio *bio);
+       int (*submit_bio_hook)(struct inode *inode, int rw, struct bio *bio,
+                              int mirror_num);
        int (*merge_bio_hook)(struct page *page, unsigned long offset,
                              size_t size, struct bio *bio);
        int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
@@ -172,7 +173,7 @@ struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
 void free_extent_buffer(struct extent_buffer *eb);
 int read_extent_buffer_pages(struct extent_io_tree *tree,
                             struct extent_buffer *eb, u64 start, int wait,
-                            get_extent_t *get_extent);
+                            get_extent_t *get_extent, int mirror_num);
 
 static inline void extent_buffer_get(struct extent_buffer *eb)
 {

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e1ef1ac..8c2d5d0 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -314,7 +314,7 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
        map_tree = &root->fs_info->mapping_tree;
        map_length = length;
        ret = btrfs_map_block(map_tree, READ, logical,
-                             &map_length, NULL);
+                             &map_length, NULL, 0);
 
        if (map_length < length + size) {
                return 1;
@@ -322,7 +322,8 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
        return 0;
 }
 
-int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
+int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
+                         int mirror_num)
 {
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_trans_handle *trans;
@@ -347,7 +348,7 @@ int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
        BUG_ON(ret);
        mutex_unlock(&root->fs_info->fs_mutex);
 mapit:
-       return btrfs_map_bio(root, rw, bio);
+       return btrfs_map_bio(root, rw, bio, mirror_num);
 }
 
 int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 008d364..3b927f6 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -788,9 +788,31 @@ void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree)
        }
 }
 
+int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len)
+{
+       struct extent_map *em;
+       struct map_lookup *map;
+       struct extent_map_tree *em_tree = &map_tree->map_tree;
+       int ret;
+
+       spin_lock(&em_tree->lock);
+       em = lookup_extent_mapping(em_tree, logical, len);
+       BUG_ON(!em);
+
+       BUG_ON(em->start > logical || em->start + em->len < logical);
+       map = (struct map_lookup *)em->bdev;
+       if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1))
+               ret = map->num_stripes;
+       else
+               ret = 1;
+       free_extent_map(em);
+       spin_unlock(&em_tree->lock);
+       return ret;
+}
+
 int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                    u64 logical, u64 *length,
-                   struct btrfs_multi_bio **multi_ret)
+                   struct btrfs_multi_bio **multi_ret, int mirror_num)
 {
        struct extent_map *em;
        struct map_lookup *map;
@@ -822,6 +844,9 @@ again:
        map = (struct map_lookup *)em->bdev;
        offset = logical - em->start;
 
+       if (mirror_num > map->num_stripes)
+               mirror_num = 0;
+
        /* if our multi bio struct is too small, back off and try again */
        if (multi_ret && (rw & (1 << BIO_RW)) &&
            stripes_allocated < map->num_stripes &&
@@ -862,7 +887,9 @@ again:
        if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
                if (rw & (1 << BIO_RW))
                        multi->num_stripes = map->num_stripes;
-               else {
+               else if (mirror_num) {
+                       stripe_index = mirror_num - 1;
+               } else {
                        int i;
                        u64 least = (u64)-1;
                        struct btrfs_device *cur;
@@ -880,6 +907,8 @@ again:
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
                if (rw & (1 << BIO_RW))
                        multi->num_stripes = map->num_stripes;
+               else if (mirror_num)
+                       stripe_index = mirror_num - 1;
        } else {
                /*
                 * after this do_div call, stripe_nr is the number of stripes
@@ -938,7 +967,8 @@ static int end_bio_multi_stripe(struct bio *bio,
 #endif
 }
 
-int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio)
+int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
+                 int mirror_num)
 {
        struct btrfs_mapping_tree *map_tree;
        struct btrfs_device *dev;
@@ -960,7 +990,8 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio)
        map_tree = &root->fs_info->mapping_tree;
        map_length = length;
 
-       ret = btrfs_map_block(map_tree, rw, logical, &map_length, &multi);
+       ret = btrfs_map_block(map_tree, rw, logical, &map_length, &multi,
+                             mirror_num);
        BUG_ON(ret);
 
        total_devs = multi->num_stripes;

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 10ca010..3d5d0a9 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -93,7 +93,7 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
                           u64 owner, u64 num_bytes, u64 *start);
 int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                    u64 logical, u64 *length,
-                   struct btrfs_multi_bio **multi_ret);
+                   struct btrfs_multi_bio **multi_ret, int mirror_num);
 int btrfs_read_sys_array(struct btrfs_root *root);
 int btrfs_read_chunk_tree(struct btrfs_root *root);
 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
@@ -101,7 +101,8 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                      u64 *num_bytes, u64 type);
 void btrfs_mapping_init(struct btrfs_mapping_tree *tree);
 void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree);
-int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio);
+int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
+                 int mirror_num);
 int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf);
 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                       int flags, void *holder);
@@ -112,4 +113,5 @@ int btrfs_add_device(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root,
                     struct btrfs_device *device);
 int btrfs_cleanup_fs_uuids(void);
+int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len);
 #endif