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, 60 insertions, 0 deletions

diff --git a/drivers/crypto/caam/dpseci-debugfs.c b/drivers/crypto/caam/dpseci-debugfs.c
new file mode 100644
index 000000000..020a9d8a8
--- /dev/null
+++ b/drivers/crypto/caam/dpseci-debugfs.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/* Copyright 2019 NXP */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/debugfs.h>
+#include "dpseci-debugfs.h"
+
+static int dpseci_dbg_fqs_show(struct seq_file *file, void *offset)
+{
+	struct dpaa2_caam_priv *priv = file->private;
+	u32 fqid, fcnt, bcnt;
+	int i, err;
+
+	seq_printf(file, "FQ stats for %s:\n", dev_name(priv->dev));
+	seq_printf(file, "%s%16s%16s\n",
+		   "Rx-VFQID",
+		   "Pending frames",
+		   "Pending bytes");
+
+	for (i = 0; i <  priv->num_pairs; i++) {
+		fqid = priv->rx_queue_attr[i].fqid;
+		err = dpaa2_io_query_fq_count(NULL, fqid, &fcnt, &bcnt);
+		if (err)
+			continue;
+
+		seq_printf(file, "%5d%16u%16u\n", fqid, fcnt, bcnt);
+	}
+
+	seq_printf(file, "%s%16s%16s\n",
+		   "Tx-VFQID",
+		   "Pending frames",
+		   "Pending bytes");
+
+	for (i = 0; i <  priv->num_pairs; i++) {
+		fqid = priv->tx_queue_attr[i].fqid;
+		err = dpaa2_io_query_fq_count(NULL, fqid, &fcnt, &bcnt);
+		if (err)
+			continue;
+
+		seq_printf(file, "%5d%16u%16u\n", fqid, fcnt, bcnt);
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(dpseci_dbg_fqs);
+
+void dpaa2_dpseci_debugfs_init(struct dpaa2_caam_priv *priv)
+{
+	priv->dfs_root = debugfs_create_dir(dev_name(priv->dev), NULL);
+
+	debugfs_create_file("fq_stats", 0444, priv->dfs_root, priv,
+			    &dpseci_dbg_fqs_fops);
+}
+
+void dpaa2_dpseci_debugfs_exit(struct dpaa2_caam_priv *priv)
+{
+	debugfs_remove_recursive(priv->dfs_root);
+}