allow in-inode EAs on ext4 root inode

The ext3 root inode was treated specially with respect to in-inode extended attributes, for reasons detailed in the removed comment below. The first mkfs-created inodes would not get extra_i_size or the EXT3_STATE_XATTR flag set in ext3_read_inode, which disallowed reading or setting in-inode EAs on the root.

However, in ext4, ext4_mark_inode_dirty calls ext4_expand_extra_isize for all inodes; once this is done EAs may be placed in the root ext4 inode body.

But for reasons above, it won't be found after a reboot.

testcase:

setfattr -n user.name -v value mntpt/
setfattr -n user.name2 -v value2 mntpt/
umount mntpt/; remount mntpt/
getfattr -d mntpt/

name2/value2 has gone missing; debugfs shows it in the inode body, but it is not found there by getattr.

The following fixes it up; newer mkfs appears to properly zero the inodes, so this workaround isn't needed for ext4.

---

Index: linux-2.6.24-rc6-mm1/fs/ext4/inode.c
===================================================================
@@ -2750,13 +2750,7 @@ void ext4_read_inode(struct inode * inod
 		ei->i_data[block] = raw_inode->i_block[block];
 	INIT_LIST_HEAD(&ei->i_orphan);
 
-	if (inode->i_ino >= EXT4_FIRST_INO(inode->i_sb) + 1 &&
-	    EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
-		/*
-		 * When mke2fs creates big inodes it does not zero out
-		 * the unused bytes above EXT4_GOOD_OLD_INODE_SIZE,
-		 * so ignore those first few inodes.
-		 */
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
 		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
 		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
 		    EXT4_INODE_SIZE(inode->i_sb)) {

Thanks, I've included this into the ext4 patch queue and into the 2.6.24-git6-ext4-1 tree.

- Ted