Merge branch 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull btrfs fixes from Chris Mason:
 "I fixed up a regression from 4.0 where conversion between different
  raid levels would sometimes bail out without converting.

  Filipe tracked down a race where it was possible to double allocate
  chunks on the drive.

  Mark has a fix for fiemap.  All three will get bundled off for stable
  as well"

* 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix regression in raid level conversion
  Btrfs: fix racy system chunk allocation when setting block group ro
  btrfs: clear 'ret' in btrfs_check_shared() loop

3 files changed, 38 insertions, 0 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 9de772ee0031..614aaa1969bd 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -880,6 +880,8 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
  * indirect refs to their parent bytenr.
  * When roots are found, they're added to the roots list
  *
+ * NOTE: This can return values > 0
+ *
  * FIXME some caching might speed things up
  */
 static int find_parent_nodes(struct btrfs_trans_handle *trans,
@@ -1198,6 +1200,19 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
         return ret;
 }
 
+/**
+ * btrfs_check_shared - tell us whether an extent is shared
+ *
+ * @trans: optional trans handle
+ *
+ * btrfs_check_shared uses the backref walking code but will short
+ * circuit as soon as it finds a root or inode that doesn't match the
+ * one passed in. This provides a significant performance benefit for
+ * callers (such as fiemap) which want to know whether the extent is
+ * shared but do not need a ref count.
+ *
+ * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
+ */
 int btrfs_check_shared(struct btrfs_trans_handle *trans,
                        struct btrfs_fs_info *fs_info, u64 root_objectid,
                        u64 inum, u64 bytenr)
@@ -1226,11 +1241,13 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
                 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
                                         roots, NULL, root_objectid, inum);
                 if (ret == BACKREF_FOUND_SHARED) {
+                        /* this is the only condition under which we return 1 */
                         ret = 1;
                         break;
                 }
                 if (ret < 0 && ret != -ENOENT)
                         break;
+                ret = 0;
                 node = ulist_next(tmp, &uiter);
                 if (!node)
                         break;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7effed6f2fa6..0ec3acd14cbf 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8829,6 +8829,24 @@ again:
                 goto again;
         }
 
+        /*
+         * if we are changing raid levels, try to allocate a corresponding
+         * block group with the new raid level.
+         */
+        alloc_flags = update_block_group_flags(root, cache->flags);
+        if (alloc_flags != cache->flags) {
+                ret = do_chunk_alloc(trans, root, alloc_flags,
+                                     CHUNK_ALLOC_FORCE);
+                /*
+                 * ENOSPC is allowed here, we may have enough space
+                 * already allocated at the new raid level to
+                 * carry on
+                 */
+                if (ret == -ENOSPC)
+                        ret = 0;
+                if (ret < 0)
+                        goto out;
+        }
 
         ret = set_block_group_ro(cache, 0);
         if (!ret)
@@ -8842,7 +8860,9 @@ again:
 out:
         if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
                 alloc_flags = update_block_group_flags(root, cache->flags);
+                lock_chunks(root->fs_info->chunk_root);
                 check_system_chunk(trans, root, alloc_flags);
+                unlock_chunks(root->fs_info->chunk_root);
         }
         mutex_unlock(&root->fs_info->ro_block_group_mutex);
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 96aebf3bcd5b..174f5e1e00ab 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4625,6 +4625,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 {
         u64 chunk_offset;
 
+        ASSERT(mutex_is_locked(&extent_root->fs_info->chunk_mutex));
         chunk_offset = find_next_chunk(extent_root->fs_info);
         return __btrfs_alloc_chunk(trans, extent_root, chunk_offset, type);
 }