[PATCH] mkfs: inode/block size error messages confusing

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

As reported by Brain:

# ./mkfs/mkfs.xfs -f /dev/test/scratch -b size=512
illegal inode size 512
allowable inode size with 512 byte blocks is 256
# ./mkfs/mkfs.xfs -f /dev/test/scratch -b size=512 -i size=256
Minimum inode size for CRCs is 512 bytes
Usage: mkfs.xfs
...

Fix mkfs to catch the block size as being too small, rather than
leaving it for inode size detection to enforce.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 include/xfs_types.h | 3 +++
 mkfs/xfs_mkfs.c     | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/include/xfs_types.h b/include/xfs_types.h
index 65c6e66..accb95d 100644
--- a/include/xfs_types.h
+++ b/include/xfs_types.h
@@ -100,11 +100,14 @@ typedef __uint64_t	xfs_filblks_t;	/* number of blocks in a file */
  * Minimum and maximum blocksize and sectorsize.
  * The blocksize upper limit is pretty much arbitrary.
  * The sectorsize upper limit is due to sizeof(sb_sectsize).
+ * CRC enable filesystems use 512 byte inodes, meaning 512 byte block sizes
+ * cannot be used.
  */
 #define XFS_MIN_BLOCKSIZE_LOG	9	/* i.e. 512 bytes */
 #define XFS_MAX_BLOCKSIZE_LOG	16	/* i.e. 65536 bytes */
 #define XFS_MIN_BLOCKSIZE	(1 << XFS_MIN_BLOCKSIZE_LOG)
 #define XFS_MAX_BLOCKSIZE	(1 << XFS_MAX_BLOCKSIZE_LOG)
+#define XFS_MIN_CRC_BLOCKSIZE	(1 << (XFS_MIN_BLOCKSIZE_LOG + 1))
 #define XFS_MIN_SECTORSIZE_LOG	9	/* i.e. 512 bytes */
 #define XFS_MAX_SECTORSIZE_LOG	15	/* i.e. 32768 bytes */
 #define XFS_MIN_SECTORSIZE	(1 << XFS_MIN_SECTORSIZE_LOG)
diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 0218491..e2a052d 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -1758,6 +1758,12 @@ _("cannot specify both crc and ftype\n"));
 		fprintf(stderr, _("illegal block size %d\n"), blocksize);
 		usage();
 	}
+	if (crcs_enabled && blocksize < XFS_MIN_CRC_BLOCKSIZE) {
+		fprintf(stderr,
+_("Minimum block size for CRC enabled filesystems is %d bytes.\n"),
+			XFS_MIN_CRC_BLOCKSIZE);
+		usage();
+	}
 
 	memset(&ft, 0, sizeof(ft));
 	get_topology(&xi, &ft, force_overwrite);