buffer: detect metadata write errors with buffer_write_io_error()

Both places in this file that report a metadata write error to a caller do
it by testing !buffer_uptodate() after waiting for the write.  That works
only because the write completion handlers clear BH_Uptodate when the write
fails, which is what this series is removing: a buffer whose write failed
still holds the correct data, and saying otherwise makes callers rewrite,
re-read or WARN over a buffer that was never wrong.

BH_Write_EIO is the flag that actually means "the last write of this buffer
failed", and both handlers already set it via mark_buffer_write_io_error().
Test that instead.

No behaviour change: today a failed write through bh_end_write() or
bh_end_async_write() sets BH_Write_EIO and clears BH_Uptodate together, so
the two tests agree.  They stop agreeing at the end of the series, and this
one stays right.

Acked-by: Weidong Zhu <weizhu@fiu.edu>
Signed-off-by: Chao Shi <coshi036@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/2b309196b883cc8979800911a47668e225401b2c.1785951556.git.coshi036@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions