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, 54 insertions, 0 deletions

diff --git a/drivers/mfd/madera.h b/drivers/mfd/madera.h
new file mode 100644
index 000000000..900205678
--- /dev/null
+++ b/drivers/mfd/madera.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * MFD internals for Cirrus Logic Madera codecs
+ *
+ * Copyright 2015-2018 Cirrus Logic
+ */
+
+#ifndef MADERA_MFD_H
+#define MADERA_MFD_H
+
+#include <linux/of.h>
+#include <linux/pm.h>
+
+struct madera;
+
+extern const struct dev_pm_ops madera_pm_ops;
+extern const struct of_device_id madera_of_match[];
+
+int madera_dev_init(struct madera *madera);
+int madera_dev_exit(struct madera *madera);
+
+const char *madera_name_from_type(enum madera_type type);
+
+extern const struct regmap_config cs47l15_16bit_spi_regmap;
+extern const struct regmap_config cs47l15_32bit_spi_regmap;
+extern const struct regmap_config cs47l15_16bit_i2c_regmap;
+extern const struct regmap_config cs47l15_32bit_i2c_regmap;
+int cs47l15_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l35_16bit_spi_regmap;
+extern const struct regmap_config cs47l35_32bit_spi_regmap;
+extern const struct regmap_config cs47l35_16bit_i2c_regmap;
+extern const struct regmap_config cs47l35_32bit_i2c_regmap;
+int cs47l35_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l85_16bit_spi_regmap;
+extern const struct regmap_config cs47l85_32bit_spi_regmap;
+extern const struct regmap_config cs47l85_16bit_i2c_regmap;
+extern const struct regmap_config cs47l85_32bit_i2c_regmap;
+int cs47l85_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l90_16bit_spi_regmap;
+extern const struct regmap_config cs47l90_32bit_spi_regmap;
+extern const struct regmap_config cs47l90_16bit_i2c_regmap;
+extern const struct regmap_config cs47l90_32bit_i2c_regmap;
+int cs47l90_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l92_16bit_spi_regmap;
+extern const struct regmap_config cs47l92_32bit_spi_regmap;
+extern const struct regmap_config cs47l92_16bit_i2c_regmap;
+extern const struct regmap_config cs47l92_32bit_i2c_regmap;
+int cs47l92_patch(struct madera *madera);
+
+#endif