resize2fs: Allow (non-optimal) on-line resizing for flex_bg filesystems

The current method of adding one block group at a time to a mounted
filesystem means it is impossible to accomodate the flex_bg allocation
method of placing the metadata together in a single block group.  For
now we "fix" this issue by using the traditional layout for new block
groups, where each block group is self-contained and contains its own
bitmap blocks and inode tables.  This means we don't get the layout
advantages of flex_bg in the new block groups, but at least it allows
on-line resizing to function.

Long term, we will need to create a new ioctl which does much more of
the resizing work in the kernel.

We also fix a bug in the ext3/ext4 ioctl fallback code so we stop
trying the ext3 ioctl for every single block group when resizing an
ext4 filesystem.

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

diff --git a/resize/online.c b/resize/online.c
index f4d24ce..d581553 100644 (file)
--- a/resize/online.c
+++ b/resize/online.c
@@ -93,6 +93,17 @@ errcode_t online_resize_fs(ext2_filsys fs, const char *mtpt,
        if (retval)
                return retval;
 
+       /* The current method of adding one block group at a time to a
+        * mounted filesystem means it is impossible to accomodate the
+        * flex_bg allocation method of placing the metadata together
+        * in a single block group.  For now we "fix" this issue by
+        * using the traditional layout for new block groups, where
+        * each block group is self-contained and contains its own
+        * bitmap blocks and inode tables.  This means we don't get
+        * the layout advantages of flex_bg in the new block groups,
+        * but at least it allows on-line resizing to function.
+        */
+       new_fs->super->s_feature_incompat &= ~EXT4_FEATURE_INCOMPAT_FLEX_BG;
        retval = adjust_fs_info(new_fs, fs, *new_size);
        if (retval)
                return retval;
@@ -154,7 +165,7 @@ errcode_t online_resize_fs(ext2_filsys fs, const char *mtpt,
                    ioctl(fd, EXT2_IOC_GROUP_ADD, &input) == 0)
                        continue;
                else
-                       use_old_ioctl = 1;
+                       use_old_ioctl = 0;
 
                input64.group = input.group;
                input64.block_bitmap = input.block_bitmap;