ext4: enforce bigalloc restrictions (e.g., no online resizing, etc.)

At least initially if the bigalloc feature is enabled, we will not
support non-extent mapped inodes, online resizing, online defrag, or
the FITRIM ioctl.  This simplifies the initial implementation.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 823e7d9deee2..25a4bfe3f39f 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2701,6 +2701,13 @@ static int ext4_feature_set_ok(struct super_block *sb, int readonly)
                         return 0;
                 }
         }
+        if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
+            !EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
+                ext4_msg(sb, KERN_ERR,
+                         "Can't support bigalloc feature without "
+                         "extents feature\n");
+                return 0;
+        }
         return 1;
 }