ext4: mark fc as ineligible using an handle in ext4_xattr_set()

commit 04e6ce8f06 upstream.

Calling ext4_fc_mark_ineligible() with a NULL handle is racy and may result
in a fast-commit being done before the filesystem is effectively marked as
ineligible.  This patch moves the call to this function so that an handle
can be used.  If a transaction fails to start, then there's not point in
trying to mark the filesystem as ineligible, and an error will eventually be
returned to user-space.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Luis Henriques (SUSE) <luis.henriques@linux.dev>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240923104909.18342-3-luis.henriques@linux.dev
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ext4/xattr.c

@@ -2554,6 +2554,8 @@ retry:
 
 		error = ext4_xattr_set_handle(handle, inode, name_index, name,
 					      value, value_len, flags);
+		ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR,
+					handle);
 		error2 = ext4_journal_stop(handle);
 		if (error == -ENOSPC &&
 		    ext4_should_retry_alloc(sb, &retries))
@@ -2561,7 +2563,6 @@ retry:
 		if (error == 0)
 			error = error2;
 	}
-	ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, NULL);
 
 	return error;
 }