netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/crypto/qce/cipher.h b/drivers/crypto/qce/cipher.h
new file mode 100644
index 000000000..850f257d0
--- /dev/null
+++ b/drivers/crypto/qce/cipher.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2010-2014, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef _CIPHER_H_
+#define _CIPHER_H_
+
+#include "common.h"
+#include "core.h"
+
+#define QCE_MAX_KEY_SIZE	64
+
+struct qce_cipher_ctx {
+	u8 enc_key[QCE_MAX_KEY_SIZE];
+	unsigned int enc_keylen;
+	struct crypto_skcipher *fallback;
+};
+
+/**
+ * struct qce_cipher_reqctx - holds private cipher objects per request
+ * @flags: operation flags
+ * @iv: pointer to the IV
+ * @ivsize: IV size
+ * @src_nents: source entries
+ * @dst_nents: destination entries
+ * @result_sg: scatterlist used for result buffer
+ * @dst_tbl: destination sg table
+ * @dst_sg: destination sg pointer table beginning
+ * @src_tbl: source sg table
+ * @src_sg: source sg pointer table beginning;
+ * @cryptlen: crypto length
+ */
+struct qce_cipher_reqctx {
+	unsigned long flags;
+	u8 *iv;
+	unsigned int ivsize;
+	int src_nents;
+	int dst_nents;
+	struct scatterlist result_sg;
+	struct sg_table dst_tbl;
+	struct scatterlist *dst_sg;
+	struct scatterlist *src_sg;
+	unsigned int cryptlen;
+	struct skcipher_request fallback_req;	// keep at the end
+};
+
+static inline struct qce_alg_template *to_cipher_tmpl(struct crypto_skcipher *tfm)
+{
+	struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
+	return container_of(alg, struct qce_alg_template, alg.skcipher);
+}
+
+extern const struct qce_algo_ops skcipher_ops;
+
+#endif /* _CIPHER_H_ */