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, 113 insertions, 0 deletions

diff --git a/drivers/crypto/bcm/util.h b/drivers/crypto/bcm/util.h
new file mode 100644
index 000000000..61c256384
--- /dev/null
+++ b/drivers/crypto/bcm/util.h
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2016 Broadcom
+ */
+
+#ifndef _UTIL_H
+#define _UTIL_H
+
+#include <linux/kernel.h>
+#include <linux/delay.h>
+
+#include "spu.h"
+
+extern int flow_debug_logging;
+extern int packet_debug_logging;
+extern int debug_logging_sleep;
+
+#ifdef DEBUG
+#define flow_log(...)	                \
+	do {	                              \
+		if (flow_debug_logging) {	        \
+			printk(__VA_ARGS__);	          \
+			if (debug_logging_sleep)	      \
+				msleep(debug_logging_sleep);	\
+		}	                                \
+	} while (0)
+#define flow_dump(msg, var, var_len)	   \
+	do {	                                 \
+		if (flow_debug_logging) {	           \
+			print_hex_dump(KERN_ALERT, msg, DUMP_PREFIX_NONE,  \
+					16, 1, var, var_len, false); \
+				if (debug_logging_sleep)	       \
+					msleep(debug_logging_sleep);   \
+		}                                    \
+	} while (0)
+
+#define packet_log(...)               \
+	do {                                \
+		if (packet_debug_logging) {       \
+			printk(__VA_ARGS__);            \
+			if (debug_logging_sleep)        \
+				msleep(debug_logging_sleep);  \
+		}                                 \
+	} while (0)
+#define packet_dump(msg, var, var_len)   \
+	do {                                   \
+		if (packet_debug_logging) {          \
+			print_hex_dump(KERN_ALERT, msg, DUMP_PREFIX_NONE,  \
+					16, 1, var, var_len, false); \
+			if (debug_logging_sleep)           \
+				msleep(debug_logging_sleep);     \
+		}                                    \
+	} while (0)
+
+void __dump_sg(struct scatterlist *sg, unsigned int skip, unsigned int len);
+
+#define dump_sg(sg, skip, len)     __dump_sg(sg, skip, len)
+
+#else /* !DEBUG_ON */
+
+static inline void flow_log(const char *format, ...)
+{
+}
+
+static inline void flow_dump(const char *msg, const void *var, size_t var_len)
+{
+}
+
+static inline void packet_log(const char *format, ...)
+{
+}
+
+static inline void packet_dump(const char *msg, const void *var, size_t var_len)
+{
+}
+
+static inline void dump_sg(struct scatterlist *sg, unsigned int skip,
+			   unsigned int len)
+{
+}
+
+#endif /* DEBUG_ON */
+
+int spu_sg_at_offset(struct scatterlist *sg, unsigned int skip,
+		     struct scatterlist **sge, unsigned int *sge_offset);
+
+/* Copy sg data, from skip, length len, to dest */
+void sg_copy_part_to_buf(struct scatterlist *src, u8 *dest,
+			 unsigned int len, unsigned int skip);
+/* Copy src into scatterlist from offset, length len */
+void sg_copy_part_from_buf(struct scatterlist *dest, u8 *src,
+			   unsigned int len, unsigned int skip);
+
+int spu_sg_count(struct scatterlist *sg_list, unsigned int skip, int nbytes);
+u32 spu_msg_sg_add(struct scatterlist **to_sg,
+		   struct scatterlist **from_sg, u32 *skip,
+		   u8 from_nents, u32 tot_len);
+
+void add_to_ctr(u8 *ctr_pos, unsigned int increment);
+
+/* produce a message digest from data of length n bytes */
+int do_shash(unsigned char *name, unsigned char *result,
+	     const u8 *data1, unsigned int data1_len,
+	     const u8 *data2, unsigned int data2_len,
+	     const u8 *key, unsigned int key_len);
+
+char *spu_alg_name(enum spu_cipher_alg alg, enum spu_cipher_mode mode);
+
+void spu_setup_debugfs(void);
+void spu_free_debugfs(void);
+void format_value_ccm(unsigned int val, u8 *buf, u8 len);
+
+#endif