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From: David Howells <dhowells@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
	linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
	ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH 39/76] cachefiles: Implement new fscache I/O backend API
Date: Fri, 20 Nov 2020 15:11:02 +0000	[thread overview]
Message-ID: <160588506244.3465195.14835834211702469652.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <160588455242.3465195.3214733858273019178.stgit@warthog.procyon.org.uk>

Implement the new fscache I/O backend API in cachefiles.  The
cachefiles_object struct carries a non-accounted file to the cachefiles
object (so that it doesn't cause ENFILE).

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/cachefiles/Makefile    |    1 +
 fs/cachefiles/interface.c |   13 +++++++
 fs/cachefiles/internal.h  |   19 ++++++++++
 fs/cachefiles/io.c        |   85 +++++++++++++++++++++++++++++++++++++++++++++
 fs/cachefiles/namei.c     |    3 ++
 5 files changed, 120 insertions(+), 1 deletion(-)
 create mode 100644 fs/cachefiles/io.c

diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile
index 3455d3646547..d894d317d6e7 100644
--- a/fs/cachefiles/Makefile
+++ b/fs/cachefiles/Makefile
@@ -7,6 +7,7 @@ cachefiles-y := \
 	bind.o \
 	daemon.o \
 	interface.o \
+	io.o \
 	key.o \
 	main.o \
 	namei.o \
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 3f6d2be690bc..dc8c875223bb 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -453,6 +453,18 @@ static unsigned int cachefiles_get_object_usage(const struct fscache_object *_ob
 	return atomic_read(&object->usage);
 }
 
+static const struct fscache_op_ops cachefiles_io_ops = {
+	.wait_for_operation	= __fscache_wait_for_operation,
+	.end_operation		= __fscache_end_operation,
+	.read			= cachefiles_read,
+	.write			= cachefiles_write,
+};
+
+static void cachefiles_begin_operation(struct fscache_op_resources *opr)
+{
+	opr->ops = &cachefiles_io_ops;
+}
+
 const struct fscache_cache_ops cachefiles_cache_ops = {
 	.name			= "cachefiles",
 	.alloc_object		= cachefiles_alloc_object,
@@ -466,4 +478,5 @@ const struct fscache_cache_ops cachefiles_cache_ops = {
 	.put_object		= cachefiles_put_object,
 	.get_object_usage	= cachefiles_get_object_usage,
 	.sync_cache		= cachefiles_sync_cache,
+	.begin_operation	= cachefiles_begin_operation,
 };
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 16d15291a629..caa6dfbaf333 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -115,6 +115,22 @@ extern const struct fscache_cache_ops cachefiles_cache_ops;
 extern struct fscache_object *cachefiles_grab_object(struct fscache_object *_object,
 						     enum fscache_obj_ref_trace why);
 
+/*
+ * io.c
+ */
+extern int cachefiles_read(struct fscache_op_resources *opr,
+			   loff_t start_pos,
+			   struct iov_iter *iter,
+			   bool seek_data,
+			   fscache_io_terminated_t term_func,
+			   void *term_func_priv);
+extern int cachefiles_write(struct fscache_op_resources *opr,
+			    loff_t start_pos,
+			    struct iov_iter *iter,
+			    fscache_io_terminated_t term_func,
+			    void *term_func_priv);
+extern bool cachefiles_open_object(struct cachefiles_object *obj);
+
 /*
  * key.c
  */
@@ -216,7 +232,8 @@ do {									\
 									\
 	___cache = container_of((object)->fscache.cache,		\
 				struct cachefiles_cache, cache);	\
-	cachefiles_io_error(___cache, FMT, ##__VA_ARGS__);		\
+	cachefiles_io_error(___cache, FMT " [o=%08x]", ##__VA_ARGS__,	\
+			    object->fscache.debug_id);			\
 } while (0)
 
 
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
new file mode 100644
index 000000000000..f1d5976aa28c
--- /dev/null
+++ b/fs/cachefiles/io.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Data I/O routines
+ *
+ * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/xattr.h>
+#include "internal.h"
+#include <trace/events/fscache.h>
+
+/*
+ * Initiate a read from the cache.
+ */
+int cachefiles_read(struct fscache_op_resources *opr,
+		    loff_t start_pos,
+		    struct iov_iter *iter,
+		    bool seek_data,
+		    fscache_io_terminated_t term_func,
+		    void *term_func_priv)
+{
+	fscache_wait_for_operation(opr, FSCACHE_WANT_READ);
+	fscache_count_io_operation(opr->object->cookie);
+	if (term_func)
+		term_func(term_func_priv, -ENODATA);
+	return -ENODATA;
+}
+
+/*
+ * Initiate a write to the cache.
+ */
+int cachefiles_write(struct fscache_op_resources *opr,
+		     loff_t start_pos,
+		     struct iov_iter *iter,
+		     fscache_io_terminated_t term_func,
+		     void *term_func_priv)
+{
+	fscache_wait_for_operation(opr, FSCACHE_WANT_WRITE);
+	fscache_count_io_operation(opr->object->cookie);
+	if (term_func)
+		term_func(term_func_priv, -ENOBUFS);
+	return -ENOBUFS;
+}
+
+/*
+ * Open a cache object.
+ */
+bool cachefiles_open_object(struct cachefiles_object *object)
+{
+	struct cachefiles_cache *cache =
+		container_of(object->fscache.cache, struct cachefiles_cache, cache);
+	struct file *file;
+	struct path path;
+
+	path.mnt = cache->mnt;
+	path.dentry = object->backer;
+
+	file = open_with_fake_path(&path,
+				   O_RDWR | O_LARGEFILE | O_DIRECT,
+				   d_backing_inode(object->backer),
+				   cache->cache_cred);
+	if (IS_ERR(file))
+		goto error;
+
+	if (!S_ISREG(file_inode(file)->i_mode))
+		goto error_file;
+
+	if (unlikely(!file->f_op->read_iter) ||
+	    unlikely(!file->f_op->write_iter)) {
+		pr_notice("Cache does not support read_iter and write_iter\n");
+		goto error_file;
+	}
+
+	object->backing_file = file;
+	return true;
+
+error_file:
+	fput(file);
+error:
+	return false;
+}
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 0a7e2031efa2..4b515054d92e 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -490,6 +490,9 @@ bool cachefiles_walk_to_object(struct cachefiles_object *parent,
 		} else {
 			BUG(); // TODO: open file in data-class subdir
 		}
+
+		if (!cachefiles_open_object(object))
+			goto check_error;
 	}
 
 	if (object->new)



  parent reply	other threads:[~2020-11-20 15:12 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-20 15:02 [RFC PATCH 00/76] fscache: Modernisation David Howells
2020-11-20 15:02 ` [RFC PATCH 01/76] nfs, cifs, ceph, 9p: Disable use of fscache prior to its rewrite David Howells
2020-11-20 15:02 ` [RFC PATCH 02/76] afs: Disable use of the fscache I/O routines David Howells
2020-11-20 15:03 ` [RFC PATCH 03/76] fscache: Add a cookie debug ID and use that in traces David Howells
2020-11-20 15:03 ` [RFC PATCH 04/76] fscache: Procfile to display cookies David Howells
2020-11-20 15:03 ` [RFC PATCH 05/76] fscache: Remove the old I/O API David Howells
2020-11-20 15:03 ` [RFC PATCH 06/76] fscache: Remove the netfs data from the cookie David Howells
2020-11-20 15:04 ` [RFC PATCH 07/76] fscache: Remove struct fscache_cookie_def David Howells
2020-11-20 15:04 ` [RFC PATCH 08/76] fscache: Remove store_limit* from struct fscache_object David Howells
2020-11-20 15:04 ` [RFC PATCH 09/76] fscache: Remove fscache_check_consistency() David Howells
2020-11-20 15:04 ` [RFC PATCH 10/76] fscache: Remove fscache_attr_changed() David Howells
2020-11-20 15:04 ` [RFC PATCH 11/76] fscache: Remove obsolete stats David Howells
2020-11-20 15:05 ` [RFC PATCH 12/76] fscache: Remove old I/O tracepoints David Howells
2020-11-20 15:05 ` [RFC PATCH 13/76] fscache: Temporarily disable fscache_invalidate() David Howells
2020-11-20 15:05 ` [RFC PATCH 14/76] fscache: Remove the I/O operation manager David Howells
2020-11-20 15:05 ` [RFC PATCH 15/76] fscache: Change %p in format strings to something else David Howells
2020-11-20 15:06 ` [RFC PATCH 16/76] cachefiles: " David Howells
2020-11-20 15:06 ` [RFC PATCH 17/76] iov_iter: Add ITER_XARRAY David Howells
2020-11-20 15:06 ` [RFC PATCH 18/76] vm: Add wait/unlock functions for PG_fscache David Howells
2020-11-20 15:06 ` [RFC PATCH 19/76] mm: Implement readahead_control pageset expansion David Howells
2020-11-20 15:06 ` [RFC PATCH 20/76] mm: Stop generic_file_buffered_read() from grabbing a superfluous page David Howells
2020-11-20 15:07 ` [RFC PATCH 21/76] vfs: Export rw_verify_area() for use by cachefiles David Howells
2020-11-20 15:07 ` [RFC PATCH 22/76] vfs: Provide S_CACHE_FILE inode flag David Howells
2020-11-20 15:07 ` [RFC PATCH 23/76] cachefiles: Remove tree of active files and use " David Howells
2020-11-20 15:07 ` [RFC PATCH 24/76] fscache: Provide a simple thread pool for running ops asynchronously David Howells
2020-11-20 15:07 ` [RFC PATCH 25/76] fscache: Replace the object management state machine David Howells
2020-11-20 15:08 ` [RFC PATCH 26/76] fscache: Rewrite the I/O API based on iov_iter David Howells
2020-11-20 15:08 ` [RFC PATCH 27/76] fscache: Keep track of size of a file last set independently on the server David Howells
2020-11-20 15:08 ` [RFC PATCH 28/76] fscache, cachefiles: Fix disabled histogram warnings David Howells
2020-11-20 15:08 ` [RFC PATCH 29/76] fscache: Recast assertion in terms of cookie not being an index David Howells
2020-11-20 15:08 ` [RFC PATCH 30/76] vfs, fscache: Force ->write_inode() to occur if cookie pinned for writeback David Howells
2020-11-20 15:09 ` [RFC PATCH 31/76] fscache: Allow ->put_super() to be used to wait for cache operations David Howells
2020-11-20 15:09 ` [RFC PATCH 32/76] netfs: Make a netfs helper module David Howells
2020-11-20 15:09 ` [RFC PATCH 33/76] netfs: Provide readahead and readpage netfs helpers David Howells
2020-11-20 15:09 ` [RFC PATCH 34/76] netfs: Use the cache David Howells
2020-11-20 15:10 ` [RFC PATCH 35/76] fscache: read-helper: Add tracepoints David Howells
2020-11-20 15:10 ` [RFC PATCH 36/76] cachefiles: Remove some redundant checks on unsigned values David Howells
2020-11-20 15:10 ` [RFC PATCH 37/76] cachefiles: trace: Log coherency checks David Howells
2020-11-20 15:10 ` [RFC PATCH 38/76] cachefiles: Split cachefiles_drop_object() up a bit David Howells
2020-11-20 15:11 ` David Howells [this message]
2020-11-20 15:11 ` [RFC PATCH 40/76] cachefiles: Merge object->backer into object->dentry David Howells
2020-11-20 15:11 ` [RFC PATCH 41/76] cachefiles: Implement a content-present indicator and bitmap David Howells
2020-11-20 15:11 ` [RFC PATCH 42/76] cachefiles: Shape requests from the fscache read helper David Howells
2020-11-20 15:11 ` [RFC PATCH 43/76] cachefiles: Round the cachefile size up to DIO block size David Howells
2020-11-20 15:12 ` [RFC PATCH 44/76] cachefiles: Implement read and write parts of new I/O API David Howells
2020-11-20 15:12 ` [RFC PATCH 45/76] cachefiles: Add I/O tracepoints David Howells
2020-11-20 15:12 ` [RFC PATCH 46/76] fscache: Display cache-specific data in /proc/fs/fscache/objects David Howells
2020-11-20 15:12 ` [RFC PATCH 47/76] fscache: Remove more obsolete stats David Howells
2020-11-20 15:12 ` [RFC PATCH 48/76] fscache: Always create /proc/fs/fscache/stats if configured David Howells
2020-11-20 15:13 ` [RFC PATCH 49/76] netfs: Stats David Howells
2020-11-20 15:13 ` [RFC PATCH 50/76] fscache: New stats David Howells
2020-11-20 15:13 ` [RFC PATCH 51/76] fscache, cachefiles: Rewrite invalidation David Howells
2020-11-20 15:13 ` [RFC PATCH 52/76] fscache: disable cookie when doing an invalidation for DIO write David Howells
2020-11-20 15:13 ` [RFC PATCH 53/76] fscache: Implement "will_modify" parameter on fscache_use_cookie() David Howells
2020-11-20 15:14 ` [RFC PATCH 54/76] fscache: Provide resize operation David Howells
2020-11-20 15:14 ` [RFC PATCH 55/76] fscache: Remove the update operation David Howells
2020-11-20 15:14 ` [RFC PATCH 56/76] afs: Pass page into dirty region helpers to provide THP size David Howells
2020-11-20 15:14 ` [RFC PATCH 57/76] afs: Print the operation debug_id when logging an unexpected data version David Howells
2020-11-20 15:14 ` [RFC PATCH 58/76] afs: Move key to afs_read struct David Howells
2020-11-20 15:15 ` [RFC PATCH 59/76] afs: Don't truncate iter during data fetch David Howells
2020-11-20 15:15 ` [RFC PATCH 60/76] afs: Log remote unmarshalling errors David Howells
2020-11-20 15:15 ` [RFC PATCH 61/76] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2020-11-20 15:15 ` [RFC PATCH 62/76] afs: Use ITER_XARRAY for writing David Howells
2020-11-20 15:16 ` [RFC PATCH 63/76] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2020-11-20 15:16 ` [RFC PATCH 64/76] afs: Extract writeback extension into its own function David Howells
2020-11-20 15:16 ` [RFC PATCH 65/76] afs: Prepare for use of THPs David Howells
2020-11-20 15:16 ` [RFC PATCH 66/76] afs: Use the fs operation ops to handle FetchData completion David Howells
2020-11-20 15:17 ` [RFC PATCH 67/76] afs: Use new fscache read helper API David Howells
2020-11-20 15:17 ` [RFC PATCH 68/76] netfs: Add write_begin helper David Howells
2020-11-20 15:17 ` [RFC PATCH 69/76] fscache: Add support for writing to the cache David Howells
2020-11-20 15:17 ` [RFC PATCH 70/76] afs: Use the fscache_write_begin() helper David Howells
2020-11-20 15:18 ` [RFC PATCH 71/76] afs: Copy local writes to the cache when writing to the server David Howells
2020-11-20 15:18 ` [RFC PATCH 72/76] afs: Invoke fscache_resize_cookie() when handling ATTR_SIZE for setattr David Howells
2020-11-20 15:18 ` [RFC PATCH 73/76] afs: Add O_DIRECT read support David Howells
2020-11-20 15:18 ` [RFC PATCH 74/76] afs: Skip truncation on the server of data we haven't written yet David Howells
2020-11-20 15:19 ` [RFC PATCH 75/76] afs: Make afs_write_begin() return the THP subpage David Howells
2020-11-20 15:19 ` [RFC PATCH 76/76] afs: Fix speculative status fetch going out of order wrt to modifications David Howells

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