nilfs2: suppress false positive WARN_ONs for sufile after an FS error

After applying the commit associated with the Fixes tag, metadata file
buffers can be evicted from memory even after being marked dirty.

Consequently, operations such as rolling back sufile changes upon
error - which modify the buffer and were previously assumed incapable
of failure - can now fail.

This behavior causes syzbot to trigger a WARN_ON check immediately
following sufile function calls within the log writer.

Resolve this issue by introducing a macro, nilfs_sufile_warn_on_error(),
which uses WARN_ONCE to report unexpected errors only when the filesystem
has not degraded to read-only mode, returning -EIO or -EROFS accordingly.
Replace existing WARN_ON checks for unexpected errors following sufile
operations with this new macro.

Additionally, for nilfs_segctor_truncate_segments() - where an error must
be propagated to halt log writing if a sufile operation fails - modify
the function to return the error code appropriately.

Reported-by: syzbot+5957361606d7b750b874@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5957361606d7b750b874
Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Cc: stable+noautosel@kernel.org # Warning suppression primarily; will request backport individually if needed
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>

0 files changed, 0 insertions, 0 deletions