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/drivers/crypto/caam/debugfs.h b/drivers/crypto/caam/debugfs.h
new file mode 100644
index 000000000..ef238c71f
--- /dev/null
+++ b/drivers/crypto/caam/debugfs.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
+/* Copyright 2019, 2023 NXP */
+
+#ifndef CAAM_DEBUGFS_H
+#define CAAM_DEBUGFS_H
+
+struct dentry;
+struct caam_drv_private;
+struct caam_perfmon;
+
+#ifdef CONFIG_DEBUG_FS
+void caam_debugfs_init(struct caam_drv_private *ctrlpriv,
+		       struct caam_perfmon __force *perfmon, struct dentry *root);
+#else
+static inline void caam_debugfs_init(struct caam_drv_private *ctrlpriv,
+				     struct caam_perfmon __force *perfmon,
+				     struct dentry *root)
+{}
+#endif
+
+#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI)
+void caam_debugfs_qi_congested(void);
+void caam_debugfs_qi_init(struct caam_drv_private *ctrlpriv);
+#else
+static inline void caam_debugfs_qi_congested(void) {}
+static inline void caam_debugfs_qi_init(struct caam_drv_private *ctrlpriv) {}
+#endif
+
+#endif /* CAAM_DEBUGFS_H */