1 files changed, 15 insertions, 25 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d70feb545066..d5e71d4646dd 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4169,19 +4169,6 @@ static struct extent_map *get_extent_skip_holes(struct inode *inode,
         return NULL;
 }
 
-static noinline int count_ext_ref(u64 inum, u64 offset, u64 root_id, void *ctx)
-{
-        unsigned long cnt = *((unsigned long *)ctx);
-
-        cnt++;
-        *((unsigned long *)ctx) = cnt;
-
-        /* Now we're sure that the extent is shared. */
-        if (cnt > 1)
-                return 1;
-        return 0;
-}
-
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                 __u64 start, __u64 len, get_extent_t *get_extent)
 {
@@ -4198,6 +4185,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
         struct extent_map *em = NULL;
         struct extent_state *cached_state = NULL;
         struct btrfs_path *path;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
         int end = 0;
         u64 em_start = 0;
         u64 em_len = 0;
@@ -4218,8 +4206,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
          * lookup the last file extent.  We're not using i_size here
          * because there might be preallocation past i_size
          */
-        ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root,
-                                       path, btrfs_ino(inode), -1, 0);
+        ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode), -1,
+                                       0);
         if (ret < 0) {
                 btrfs_free_path(path);
                 return ret;
@@ -4312,25 +4300,27 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                 } else if (em->block_start == EXTENT_MAP_DELALLOC) {
                         flags |= (FIEMAP_EXTENT_DELALLOC |
                                   FIEMAP_EXTENT_UNKNOWN);
-                } else {
-                        unsigned long ref_cnt = 0;
+                } else if (fieinfo->fi_extents_max) {
+                        u64 bytenr = em->block_start -
+                                (em->start - em->orig_start);
 
                         disko = em->block_start + offset_in_extent;
 
                         /*
                          * As btrfs supports shared space, this information
                          * can be exported to userspace tools via
-                         * flag FIEMAP_EXTENT_SHARED.
+                         * flag FIEMAP_EXTENT_SHARED.  If fi_extents_max == 0
+                         * then we're just getting a count and we can skip the
+                         * lookup stuff.
                          */
-                        ret = iterate_inodes_from_logical(
-                                        em->block_start,
-                                        BTRFS_I(inode)->root->fs_info,
-                                        path, count_ext_ref, &ref_cnt);
-                        if (ret < 0 && ret != -ENOENT)
+                        ret = btrfs_check_shared(NULL, root->fs_info,
+                                                 root->objectid,
+                                                 btrfs_ino(inode), bytenr);
+                        if (ret < 0)
                                 goto out_free;
-
-                        if (ref_cnt > 1)
+                        if (ret)
                                 flags |= FIEMAP_EXTENT_SHARED;
+                        ret = 0;
                 }
                 if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
                         flags |= FIEMAP_EXTENT_ENCODED;