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, 57 insertions, 0 deletions

diff --git a/drivers/bcma/scan.h b/drivers/bcma/scan.h
new file mode 100644
index 000000000..e53079a3d
--- /dev/null
+++ b/drivers/bcma/scan.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef BCMA_SCAN_H_
+#define BCMA_SCAN_H_
+
+#define BCMA_ADDR_BASE		0x18000000
+#define BCMA_WRAP_BASE		0x18100000
+
+#define SCAN_ER_VALID		0x00000001
+#define SCAN_ER_TAGX		0x00000006 /* we have to ignore 0x8 bit when checking tag for SCAN_ER_TAG_ADDR */
+#define SCAN_ER_TAG		0x0000000E
+#define  SCAN_ER_TAG_CI		0x00000000
+#define  SCAN_ER_TAG_MP		0x00000002
+#define  SCAN_ER_TAG_ADDR	0x00000004
+#define  SCAN_ER_TAG_END	0x0000000E
+#define SCAN_ER_BAD		0xFFFFFFFF
+
+#define SCAN_CIA_CLASS		0x000000F0
+#define SCAN_CIA_CLASS_SHIFT	4
+#define SCAN_CIA_ID		0x000FFF00
+#define SCAN_CIA_ID_SHIFT	8
+#define SCAN_CIA_MANUF		0xFFF00000
+#define SCAN_CIA_MANUF_SHIFT	20
+
+#define SCAN_CIB_NMP		0x000001F0
+#define SCAN_CIB_NMP_SHIFT	4
+#define SCAN_CIB_NSP		0x00003E00
+#define SCAN_CIB_NSP_SHIFT	9
+#define SCAN_CIB_NMW		0x0007C000
+#define SCAN_CIB_NMW_SHIFT	14
+#define SCAN_CIB_NSW		0x00F80000
+#define SCAN_CIB_NSW_SHIFT	19
+#define SCAN_CIB_REV		0xFF000000
+#define SCAN_CIB_REV_SHIFT	24
+
+#define SCAN_ADDR_AG32		0x00000008
+#define SCAN_ADDR_SZ		0x00000030
+#define SCAN_ADDR_SZ_SHIFT	4
+#define  SCAN_ADDR_SZ_4K	0x00000000
+#define  SCAN_ADDR_SZ_8K	0x00000010
+#define  SCAN_ADDR_SZ_16K	0x00000020
+#define  SCAN_ADDR_SZ_SZD	0x00000030
+#define SCAN_ADDR_TYPE		0x000000C0
+#define  SCAN_ADDR_TYPE_SLAVE	0x00000000
+#define  SCAN_ADDR_TYPE_BRIDGE	0x00000040
+#define  SCAN_ADDR_TYPE_SWRAP	0x00000080
+#define  SCAN_ADDR_TYPE_MWRAP	0x000000C0
+#define SCAN_ADDR_PORT		0x00000F00
+#define SCAN_ADDR_PORT_SHIFT	8
+#define SCAN_ADDR_ADDR		0xFFFFF000
+
+#define SCAN_ADDR_SZ_BASE	0x00001000	/* 4KB */
+
+#define SCAN_SIZE_SZ_ALIGN	0x00000FFF
+#define SCAN_SIZE_SZ		0xFFFFF000
+#define SCAN_SIZE_SG32		0x00000008
+
+#endif /* BCMA_SCAN_H_ */