Btrfs: deal with NULL space info

After a balance it is briefly possible for the space info
field in the inode to be NULL.  This adds some checks
to make sure things properly deal with the NULL value.

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

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5f3544e5f3cb1179ba70dc3fc2077c65f940f0cb..1b9b87870f5195bfd838c1e7fe081219c7bcdd0e 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2778,6 +2778,8 @@ int btrfs_check_metadata_free_space(struct btrfs_root *root)
        /* get the space info for where the metadata will live */
        alloc_target = btrfs_get_alloc_profile(root, 0);
        meta_sinfo = __find_space_info(info, alloc_target);
+       if (!meta_sinfo)
+               goto alloc;
 
 again:
        spin_lock(&meta_sinfo->lock);
@@ -2795,7 +2797,7 @@ again:
                if (!meta_sinfo->full) {
                        meta_sinfo->force_alloc = 1;
                        spin_unlock(&meta_sinfo->lock);
-
+alloc:
                        trans = btrfs_start_transaction(root, 1);
                        if (!trans)
                                return -ENOMEM;
@@ -2803,6 +2805,10 @@ again:
                        ret = do_chunk_alloc(trans, root->fs_info->extent_root,
                                             2 * 1024 * 1024, alloc_target, 0);
                        btrfs_end_transaction(trans, root);
+                       if (!meta_sinfo) {
+                               meta_sinfo = __find_space_info(info,
+                                                              alloc_target);
+                       }
                        goto again;
                }
                spin_unlock(&meta_sinfo->lock);
@@ -2838,6 +2844,9 @@ int btrfs_check_data_free_space(struct btrfs_root *root, struct inode *inode,
        bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 
        data_sinfo = BTRFS_I(inode)->space_info;
+       if (!data_sinfo)
+               goto alloc;
+
 again:
        /* make sure we have enough space to handle the data first */
        spin_lock(&data_sinfo->lock);
@@ -2856,7 +2865,7 @@ again:
 
                        data_sinfo->force_alloc = 1;
                        spin_unlock(&data_sinfo->lock);
-
+alloc:
                        alloc_target = btrfs_get_alloc_profile(root, 1);
                        trans = btrfs_start_transaction(root, 1);
                        if (!trans)
@@ -2868,6 +2877,11 @@ again:
                        btrfs_end_transaction(trans, root);
                        if (ret)
                                return ret;
+
+                       if (!data_sinfo) {
+                               btrfs_set_inode_space_info(root, inode);
+                               data_sinfo = BTRFS_I(inode)->space_info;
+                       }
                        goto again;
                }
                spin_unlock(&data_sinfo->lock);