fscrypt: stop using PG_error to track error status

As a step towards freeing the PG_error flag for other uses, change ext4
and f2fs to stop using PG_error to track decryption errors.  Instead, if
a decryption error occurs, just mark the whole bio as failed.  The
coarser granularity isn't really a problem since it isn't any worse than
what the block layer provides, and errors from a multi-page readahead
aren't reported to applications unless a single-page read fails too.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <chao@kernel.org> # for f2fs part
Link: https://lore.kernel.org/r/20220815235052.86545-2-ebiggers@kernel.org

1 files changed, 10 insertions, 6 deletions

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 2217fe5ece6f..1b4403136d05 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -25,21 +25,25 @@
  * then this function isn't applicable.  This function may sleep, so it must be
  * called from a workqueue rather than from the bio's bi_end_io callback.
  *
- * This function sets PG_error on any pages that contain any blocks that failed
- * to be decrypted.  The filesystem must not mark such pages uptodate.
+ * Return: %true on success; %false on failure.  On failure, bio->bi_status is
+ *	   also set to an error status.
  */
-void fscrypt_decrypt_bio(struct bio *bio)
+bool fscrypt_decrypt_bio(struct bio *bio)
 {
 	struct bio_vec *bv;
 	struct bvec_iter_all iter_all;
 
 	bio_for_each_segment_all(bv, bio, iter_all) {
 		struct page *page = bv->bv_page;
-		int ret = fscrypt_decrypt_pagecache_blocks(page, bv->bv_len,
+		int err = fscrypt_decrypt_pagecache_blocks(page, bv->bv_len,
 							   bv->bv_offset);
-		if (ret)
-			SetPageError(page);
+
+		if (err) {
+			bio->bi_status = errno_to_blk_status(err);
+			return false;
+		}
 	}
+	return true;
 }
 EXPORT_SYMBOL(fscrypt_decrypt_bio);