Btrfs: export btrfs space shared info to userspace

[cascardo/linux.git] / fs / btrfs / extent_io.c

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 22bda32..2bf6f46 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -20,6 +20,7 @@
 #include "check-integrity.h"
 #include "locking.h"
 #include "rcu-string.h"
+#include "backref.h"
 
 static struct kmem_cache *extent_state_cache;
 static struct kmem_cache *extent_buffer_cache;
@@ -1490,10 +1491,8 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
                cur_start = state->end + 1;
                node = rb_next(node);
                total_bytes += state->end - state->start + 1;
-               if (total_bytes >= max_bytes) {
-                       *end = *start + max_bytes - 1;
+               if (total_bytes >= max_bytes)
                        break;
-               }
                if (!node)
                        break;
        }
@@ -1635,10 +1634,9 @@ again:
 
        /*
         * make sure to limit the number of pages we try to lock down
-        * if we're looping.
         */
-       if (delalloc_end + 1 - delalloc_start > max_bytes && loops)
-               delalloc_end = delalloc_start + PAGE_CACHE_SIZE - 1;
+       if (delalloc_end + 1 - delalloc_start > max_bytes)
+               delalloc_end = delalloc_start + max_bytes - 1;
 
        /* step two, lock all the pages after the page that has start */
        ret = lock_delalloc_pages(inode, locked_page,
@@ -1649,8 +1647,7 @@ again:
                 */
                free_extent_state(cached_state);
                if (!loops) {
-                       unsigned long offset = (*start) & (PAGE_CACHE_SIZE - 1);
-                       max_bytes = PAGE_CACHE_SIZE - offset;
+                       max_bytes = PAGE_CACHE_SIZE;
                        loops = 1;
                        goto again;
                } else {
@@ -4066,6 +4063,19 @@ 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)
 {
@@ -4132,7 +4142,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                last = found_key.offset;
                last_for_get_extent = last + 1;
        }
-       btrfs_free_path(path);
+       btrfs_release_path(path);
 
        /*
         * we might have some extents allocated but more delalloc past those
@@ -4202,7 +4212,24 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                        flags |= (FIEMAP_EXTENT_DELALLOC |
                                  FIEMAP_EXTENT_UNKNOWN);
                } else {
+                       unsigned long ref_cnt = 0;
+
                        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.
+                        */
+                       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)
+                               goto out_free;
+
+                       if (ref_cnt > 1)
+                               flags |= FIEMAP_EXTENT_SHARED;
                }
                if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
                        flags |= FIEMAP_EXTENT_ENCODED;
@@ -4234,6 +4261,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 out_free:
        free_extent_map(em);
 out:
+       btrfs_free_path(path);
        unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
                             &cached_state, GFP_NOFS);
        return ret;