[PATCH 02/14] bcachefs: Fix BCH_ERR_data_read_csum_err_maybe_userspace in retry path

[Kent Overstreet <kent.overstreet@linux.dev>]

When we do a read to a buffer that's mapped into userspace, it's
possible to get a spurious checksum error if userspace was modified the
buffer at the same time.

When we retry those, they have to be bounced before we know definitively
whether we're reading corrupt data.

But the retry path propagates read flags differently, so needs special
handling.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/io_read.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index 72a0a6f643d8..af963999e1a7 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -1283,6 +1283,9 @@ void __bch2_read(struct bch_fs *c, struct bch_read_bio *rbio,
 		swap(bvec_iter.bi_size, bytes);
 		bio_advance_iter(&rbio->bio, &bvec_iter, bytes);
 err:
+		if (ret == -BCH_ERR_data_read_retry_csum_err_maybe_userspace)
+			flags |= BCH_READ_must_bounce;
+
 		if (ret &&
 		    !bch2_err_matches(ret, BCH_ERR_transaction_restart) &&
 		    !bch2_err_matches(ret, BCH_ERR_data_read_retry))
-- 
2.47.2