From: Theodore Ts'o Date: Mon, 31 Dec 2018 04:20:39 +0000 (-0500) Subject: ext4: avoid kernel warning when writing the superblock to a dead device X-Git-Tag: v5.0-rc1~6^2~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e86807862e6880809f191c4cea7f88a489f0ed34;p=thirdparty%2Flinux.git ext4: avoid kernel warning when writing the superblock to a dead device The xfstests generic/475 test switches the underlying device with dm-error while running a stress test. This results in a large number of file system errors, and since we can't lock the buffer head when marking the superblock dirty in the ext4_grp_locked_error() case, it's possible the superblock to be !buffer_uptodate() without buffer_write_io_error() being true. We need to set buffer_uptodate() before we call mark_buffer_dirty() or this will trigger a WARN_ON. It's safe to do this since the superblock must have been properly read into memory or the mount would have been successful. So if buffer_uptodate() is not set, we can safely assume that this happened due to a failed attempt to write the superblock. Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org --- diff --git a/fs/ext4/super.c b/fs/ext4/super.c index d6c142d73d99a..fb12d3c17c1b1 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4902,7 +4902,7 @@ static int ext4_commit_super(struct super_block *sb, int sync) ext4_superblock_csum_set(sb); if (sync) lock_buffer(sbh); - if (buffer_write_io_error(sbh)) { + if (buffer_write_io_error(sbh) || !buffer_uptodate(sbh)) { /* * Oh, dear. A previous attempt to write the * superblock failed. This could happen because the