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, 101 insertions, 0 deletions

diff --git a/include/rdma/ib_cache.h b/include/rdma/ib_cache.h
new file mode 100644
index 000000000..eed46d966
--- /dev/null
+++ b/include/rdma/ib_cache.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/*
+ * Copyright (c) 2004 Topspin Communications.  All rights reserved.
+ * Copyright (c) 2005 Intel Corporation. All rights reserved.
+ * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
+ */
+
+#ifndef _IB_CACHE_H
+#define _IB_CACHE_H
+
+#include <rdma/ib_verbs.h>
+
+int rdma_query_gid(struct ib_device *device, u32 port_num, int index,
+		   union ib_gid *gid);
+void *rdma_read_gid_hw_context(const struct ib_gid_attr *attr);
+const struct ib_gid_attr *rdma_find_gid(struct ib_device *device,
+					const union ib_gid *gid,
+					enum ib_gid_type gid_type,
+					struct net_device *ndev);
+const struct ib_gid_attr *rdma_find_gid_by_port(struct ib_device *ib_dev,
+						const union ib_gid *gid,
+						enum ib_gid_type gid_type,
+						u32 port,
+						struct net_device *ndev);
+const struct ib_gid_attr *rdma_find_gid_by_filter(
+	struct ib_device *device, const union ib_gid *gid, u32 port_num,
+	bool (*filter)(const union ib_gid *gid, const struct ib_gid_attr *,
+		       void *),
+	void *context);
+
+int rdma_read_gid_l2_fields(const struct ib_gid_attr *attr,
+			    u16 *vlan_id, u8 *smac);
+struct net_device *rdma_read_gid_attr_ndev_rcu(const struct ib_gid_attr *attr);
+
+/**
+ * ib_get_cached_pkey - Returns a cached PKey table entry
+ * @device_handle: The device to query.
+ * @port_num: The port number of the device to query.
+ * @index: The index into the cached PKey table to query.
+ * @pkey: The PKey value found at the specified index.
+ *
+ * ib_get_cached_pkey() fetches the specified PKey table entry stored in
+ * the local software cache.
+ */
+int ib_get_cached_pkey(struct ib_device    *device_handle,
+		       u32                  port_num,
+		       int                  index,
+		       u16                 *pkey);
+
+/**
+ * ib_find_cached_pkey - Returns the PKey table index where a specified
+ *   PKey value occurs.
+ * @device: The device to query.
+ * @port_num: The port number of the device to search for the PKey.
+ * @pkey: The PKey value to search for.
+ * @index: The index into the cached PKey table where the PKey was found.
+ *
+ * ib_find_cached_pkey() searches the specified PKey table in
+ * the local software cache.
+ */
+int ib_find_cached_pkey(struct ib_device    *device,
+			u32                  port_num,
+			u16                  pkey,
+			u16                 *index);
+
+/**
+ * ib_get_cached_lmc - Returns a cached lmc table entry
+ * @device: The device to query.
+ * @port_num: The port number of the device to query.
+ * @lmc: The lmc value for the specified port for that device.
+ *
+ * ib_get_cached_lmc() fetches the specified lmc table entry stored in
+ * the local software cache.
+ */
+int ib_get_cached_lmc(struct ib_device *device,
+		      u32               port_num,
+		      u8                *lmc);
+
+/**
+ * ib_get_cached_port_state - Returns a cached port state table entry
+ * @device: The device to query.
+ * @port_num: The port number of the device to query.
+ * @port_active: port_state for the specified port for that device.
+ *
+ * ib_get_cached_port_state() fetches the specified port_state table entry stored in
+ * the local software cache.
+ */
+int ib_get_cached_port_state(struct ib_device *device,
+			     u32               port_num,
+			      enum ib_port_state *port_active);
+
+bool rdma_is_zero_gid(const union ib_gid *gid);
+const struct ib_gid_attr *rdma_get_gid_attr(struct ib_device *device,
+					    u32 port_num, int index);
+void rdma_put_gid_attr(const struct ib_gid_attr *attr);
+void rdma_hold_gid_attr(const struct ib_gid_attr *attr);
+ssize_t rdma_query_gid_table(struct ib_device *device,
+			     struct ib_uverbs_gid_entry *entries,
+			     size_t max_entries);
+
+#endif /* _IB_CACHE_H */