ext4: fix error handling in ext4_restore_inline_data()

While running "./check -I 200 generic/475" it sometimes gives below
kernel BUG(). Ideally we should not call ext4_write_inline_data() if
ext4_create_inline_data() has failed.

<log snip>
[73131.453234] kernel BUG at fs/ext4/inline.c:223!

<code snip>
 212 static void ext4_write_inline_data(struct inode *inode, struct ext4_iloc *iloc,
 213                                    void *buffer, loff_t pos, unsigned int len)
 214 {
<...>
 223         BUG_ON(!EXT4_I(inode)->i_inline_off);
 224         BUG_ON(pos + len > EXT4_I(inode)->i_inline_size);

This patch handles the error and prints out a emergency msg saying potential
data loss for the given inode (since we couldn't restore the original
inline_data due to some previous error).

[ 9571.070313] EXT4-fs (dm-0): error restoring inline_data for inode -- potential data loss! (inode 1703982, error -30)

Reported-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/9f4cd7dfd54fa58ff27270881823d94ddf78dd07.1642416995.git.riteshh@linux.ibm.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org