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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 <tytso@mit.edu>
Cc: stable@vger.kernel.org
This commit is contained in:
Theodore Ts'o 2018-12-30 23:20:39 -05:00
parent 2b08b1f12c
commit e86807862e
1 changed files with 1 additions and 1 deletions
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2
fs/ext4/super.c
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@ -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