xfs: Bump minimal size to 300M

From the xfsprogs source code:

* We don't support filesystems smaller than 300MB anymore.  Tiny
* filesystems have never been XFS' design target.  This limit has been
* carefully calculated to prevent formatting with a log smaller than
* the "realistic" size.
*
* If the realistic log size is 64MB, there are four AGs, and the log
* AG should be at least 1/8 free after formatting, this gives us:
*
* 64MB * (8 / 7) * 4 = 293MB

So let's accommodate and bump the minimal XFS filesystem size to 300M.

src/shared/resize-fs.h

@@ -8,7 +8,7 @@
 int resize_fs(int fd, uint64_t sz, uint64_t *ret_size);
 
 #define BTRFS_MINIMAL_SIZE (256U*1024U*1024U)
-#define XFS_MINIMAL_SIZE (16U*1024U*1024U)
+#define XFS_MINIMAL_SIZE (300U*1024U*1024U)
 #define EXT4_MINIMAL_SIZE (1024U*1024U)
 
 uint64_t minimal_size_by_fs_magic(statfs_f_type_t magic);