[PATCH 04/19] buffer: clear BH_Write_EIO when a buffer is forgotten

[Chao Shi <coshi036@gmail.com>]

BH_Write_EIO records that the last write of this buffer failed.  It is
cleared when the buffer is submitted for write again - see the
test_set_buffer_req() check in __bh_submit() - but a filesystem freeing a
metadata block never submits it again.  It calls bforget() and hands the
block back to the allocator, so the flag outlives the block it refers to.

That does not matter much today, because the write error is also recorded
by clearing BH_Uptodate and the buffer is discarded soon after.  It starts
to matter in the rest of this series, which stops clearing BH_Uptodate on
write error and makes BH_Write_EIO the way a failed metadata write is
reported.

bforget() is where a filesystem says it no longer cares about this
buffer's contents, so clear the error there alongside the dirty flag.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chao Shi <coshi036@gmail.com>
---
 fs/buffer.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/buffer.c b/fs/buffer.c
index 04fcc34e4fa6..7889c30d8715 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1091,6 +1091,7 @@ EXPORT_SYMBOL(__brelse);
 void __bforget(struct buffer_head *bh)
 {
 	clear_buffer_dirty(bh);
+	clear_buffer_write_io_error(bh);
 	remove_assoc_queue(bh);
 	__brelse(bh);
 }
-- 
2.43.0