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, 29 insertions, 0 deletions

diff --git a/net/wireless/ethtool.c b/net/wireless/ethtool.c
new file mode 100644
index 000000000..46e4317cb
--- /dev/null
+++ b/net/wireless/ethtool.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/utsname.h>
+#include <net/cfg80211.h>
+#include "core.h"
+#include "rdev-ops.h"
+
+void cfg80211_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct device *pdev = wiphy_dev(wdev->wiphy);
+
+	if (pdev->driver)
+		strscpy(info->driver, pdev->driver->name,
+			sizeof(info->driver));
+	else
+		strscpy(info->driver, "N/A", sizeof(info->driver));
+
+	strscpy(info->version, init_utsname()->release, sizeof(info->version));
+
+	if (wdev->wiphy->fw_version[0])
+		strscpy(info->fw_version, wdev->wiphy->fw_version,
+			sizeof(info->fw_version));
+	else
+		strscpy(info->fw_version, "N/A", sizeof(info->fw_version));
+
+	strscpy(info->bus_info, dev_name(pdev),
+		sizeof(info->bus_info));
+}
+EXPORT_SYMBOL(cfg80211_get_drvinfo);