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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>,
	Jeff Layton <jlayton@redhat.com>
Cc: dhowells@redhat.com, Matthew Wilcox <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	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 31/61] cachefiles: Implement new fscache I/O backend API
Date: Mon, 04 May 2020 18:12:09 +0100	[thread overview]
Message-ID: <158861232949.340223.21702873867667105.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <158861203563.340223.7585359869938129395.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 |    3 ++
 fs/cachefiles/internal.h  |   14 +++++++
 fs/cachefiles/io.c        |   88 +++++++++++++++++++++++++++++++++++++++++++++
 fs/cachefiles/namei.c     |    3 ++
 5 files changed, 109 insertions(+)
 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 47596b58c2da..747211363ae0 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -469,4 +469,7 @@ 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,
+	.shape_extent		= cachefiles_shape_extent,
+	.read			= cachefiles_read,
+	.write			= cachefiles_write,
 };
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 16d15291a629..9f9e33893b4f 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -115,6 +115,20 @@ 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 unsigned int cachefiles_shape_extent(struct fscache_object *object,
+					    struct fscache_extent *extent,
+					    loff_t i_size, bool for_write);
+extern int cachefiles_read(struct fscache_object *object,
+			   struct fscache_io_request *req,
+			   struct iov_iter *iter);
+extern int cachefiles_write(struct fscache_object *object,
+			    struct fscache_io_request *req,
+			    struct iov_iter *iter);
+extern bool cachefiles_open_object(struct cachefiles_object *obj);
+
 /*
  * key.c
  */
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
new file mode 100644
index 000000000000..d472e9d9173c
--- /dev/null
+++ b/fs/cachefiles/io.c
@@ -0,0 +1,88 @@
+// 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"
+
+/*
+ * Determine the size of a data extent in a cache object.  This must be written
+ * as a whole unit, but can be read piecemeal.
+ */
+unsigned int cachefiles_shape_extent(struct fscache_object *object,
+				     struct fscache_extent *extent,
+				     loff_t i_size, bool for_write)
+{
+	return 0;
+}
+
+/*
+ * Initiate a read from the cache.
+ */
+int cachefiles_read(struct fscache_object *object,
+		    struct fscache_io_request *req,
+		    struct iov_iter *iter)
+{
+	req->error = -ENODATA;
+	if (req->io_done)
+		req->io_done(req);
+	return -ENODATA;
+}
+
+/*
+ * Initiate a write to the cache.
+ */
+int cachefiles_write(struct fscache_object *object,
+		     struct fscache_io_request *req,
+		     struct iov_iter *iter)
+{
+	req->error = -ENOBUFS;
+	if (req->io_done)
+		req->io_done(req);
+	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 ad7edd41ce27..c33b5ee65ac1 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -492,6 +492,9 @@ 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:[~2020-05-04 17:12 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04 17:07 [RFC PATCH 00/61] fscache, cachefiles: Rewrite the I/O interface in terms of kiocb/iov_iter David Howells
2020-05-04 17:07 ` David Howells
2020-05-04 17:07 ` [RFC PATCH 01/61] afs: Make afs_zap_data() static David Howells
2020-05-04 17:07 ` [RFC PATCH 02/61] iov_iter: Add ITER_MAPPING David Howells
2020-05-04 17:07   ` David Howells
2020-05-04 17:07 ` [RFC PATCH 03/61] vm: Add wait/unlock functions for PG_fscache David Howells
2020-05-04 17:08 ` [RFC PATCH 04/61] vfs: Export rw_verify_area() for use by cachefiles David Howells
2020-05-04 17:08 ` [RFC PATCH 05/61] vfs: Provide S_CACHE_FILE inode flag David Howells
2020-05-04 17:08   ` David Howells
2020-05-04 17:08 ` [RFC PATCH 06/61] afs: Disable use of the fscache I/O routines David Howells
2020-05-04 17:08 ` [RFC PATCH 07/61] fscache: Add a cookie debug ID and use that in traces David Howells
2020-05-04 17:08 ` [RFC PATCH 08/61] fscache: Procfile to display cookies David Howells
2020-05-04 17:08 ` [RFC PATCH 09/61] fscache: Temporarily disable network filesystems' use of fscache David Howells
2020-05-04 17:08 ` [RFC PATCH 10/61] fscache: Remove the old I/O API David Howells
2020-05-04 17:08   ` David Howells
2020-05-04 17:09 ` [RFC PATCH 11/61] fscache: Remove the netfs data from the cookie David Howells
2020-05-04 17:09 ` [RFC PATCH 12/61] fscache: Remove struct fscache_cookie_def David Howells
2020-05-04 17:09   ` David Howells
2020-05-04 17:09 ` [RFC PATCH 13/61] fscache: Remove store_limit* from struct fscache_object David Howells
2020-05-04 17:09 ` [RFC PATCH 14/61] fscache: Remove fscache_check_consistency() David Howells
2020-05-04 17:09   ` David Howells
2020-05-04 17:09 ` [RFC PATCH 15/61] fscache: Remove fscache_attr_changed() David Howells
2020-05-04 17:09 ` [RFC PATCH 16/61] fscache: Remove obsolete stats David Howells
2020-05-04 17:09   ` David Howells
2020-05-04 17:10 ` [RFC PATCH 17/61] fscache: Remove old I/O tracepoints David Howells
2020-05-04 17:10 ` [RFC PATCH 18/61] fscache: Temporarily disable fscache_invalidate() David Howells
2020-05-04 17:10 ` [RFC PATCH 19/61] fscache: Remove the I/O operation manager David Howells
2020-05-04 17:10   ` David Howells
2020-05-04 17:10 ` [RFC PATCH 20/61] cachefiles: Remove tree of active files and use S_CACHE_FILE inode flag David Howells
2020-05-04 17:10   ` David Howells
2020-05-04 17:10 ` [RFC PATCH 21/61] fscache: Provide a simple thread pool for running ops asynchronously David Howells
2020-05-04 17:10   ` David Howells
2020-05-04 17:10 ` [RFC PATCH 22/61] fscache: Replace the object management state machine David Howells
2020-05-04 17:10 ` [RFC PATCH 23/61] fscache: Rewrite the I/O API based on iov_iter David Howells
2020-05-04 17:11 ` [RFC PATCH 24/61] fscache: Remove fscache_wait_on_invalidate() David Howells
2020-05-04 17:11   ` David Howells
2020-05-04 17:11 ` [RFC PATCH 25/61] fscache: Keep track of size of a file last set independently on the server David Howells
2020-05-04 17:11 ` [RFC PATCH 26/61] fscache, cachefiles: Fix disabled histogram warnings David Howells
2020-05-04 17:11 ` [RFC PATCH 27/61] fscache: Recast assertion in terms of cookie not being an index David Howells
2020-05-04 17:11 ` [RFC PATCH 28/61] cachefiles: Remove some redundant checks on unsigned values David Howells
2020-05-04 17:11 ` [RFC PATCH 29/61] cachefiles: trace: Log coherency checks David Howells
2020-05-04 17:12 ` [RFC PATCH 30/61] cachefiles: Split cachefiles_drop_object() up a bit David Howells
2020-05-04 17:12   ` David Howells
2020-05-04 17:12 ` David Howells [this message]
2020-05-04 17:12 ` [RFC PATCH 32/61] cachefiles: Merge object->backer into object->dentry David Howells
2020-05-04 17:12   ` David Howells
2020-05-04 17:12 ` [RFC PATCH 33/61] cachefiles: Implement a content-present indicator and bitmap David Howells
2020-05-04 17:12 ` [RFC PATCH 34/61] cachefiles: Implement extent shaper David Howells
2020-05-04 17:12 ` [RFC PATCH 35/61] cachefiles: Round the cachefile size up to DIO block size David Howells
2020-05-04 17:12 ` [RFC PATCH 36/61] cachefiles: Implement read and write parts of new I/O API David Howells
2020-05-04 17:13 ` [RFC PATCH 37/61] cachefiles: Add I/O tracepoints David Howells
2020-05-04 17:13 ` [RFC PATCH 38/61] fscache: Add read helper David Howells
2020-05-04 17:13   ` David Howells
2020-05-04 17:13 ` [RFC PATCH 39/61] fscache: Display cache-specific data in /proc/fs/fscache/objects David Howells
2020-05-04 17:13   ` David Howells
2020-05-04 17:13 ` [RFC PATCH 40/61] fscache: Remove more obsolete stats David Howells
2020-05-04 17:13 ` [RFC PATCH 41/61] fscache: New stats David Howells
2020-05-04 17:13 ` [RFC PATCH 42/61] fscache, cachefiles: Rewrite invalidation David Howells
2020-05-04 17:13 ` [RFC PATCH 43/61] fscache: Implement "will_modify" parameter on fscache_use_cookie() David Howells
2020-05-04 17:14 ` [RFC PATCH 44/61] fscache: Provide resize operation David Howells
2020-05-04 17:14   ` David Howells
2020-05-04 17:14 ` [RFC PATCH 45/61] fscache: Remove the update operation David Howells
2020-05-04 17:14   ` David Howells
2020-05-04 17:14 ` [RFC PATCH 46/61] cachefiles: Shape write requests David Howells
2020-05-04 17:14 ` [RFC PATCH 47/61] afs: Remove afs_zero_fid as it's not used David Howells
2020-05-04 17:14 ` [RFC PATCH 48/61] afs: Move key to afs_read struct David Howells
2020-05-04 17:14   ` David Howells
2020-05-04 17:14 ` [RFC PATCH 49/61] afs: Don't truncate iter during data fetch David Howells
2020-05-04 17:15 ` [RFC PATCH 50/61] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2020-05-04 17:15   ` David Howells
2020-05-04 17:15 ` [RFC PATCH 51/61] afs: Use ITER_MAPPING for writing David Howells
2020-05-04 17:15 ` [RFC PATCH 52/61] afs: Interpose struct fscache_io_request into struct afs_read David Howells
2020-05-04 17:15   ` David Howells
2020-05-04 17:15 ` [RFC PATCH 53/61] afs: Note the amount transferred in fetch-data delivery David Howells
2020-05-04 17:15 ` [RFC PATCH 54/61] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2020-05-05 11:59   ` Matthew Wilcox
2020-05-06  7:57   ` David Howells
2020-05-06 11:09     ` Matthew Wilcox
2020-05-06 14:24     ` David Howells
2020-05-08 14:39     ` David Howells
2020-05-08 14:39       ` David Howells
2020-05-04 17:15 ` [RFC PATCH 55/61] afs: Use new fscache I/O API David Howells
2020-05-04 17:15 ` [RFC PATCH 56/61] afs: Copy local writes to the cache when writing to the server David Howells
2020-05-04 17:16 ` [RFC PATCH 57/61] afs: Invoke fscache_resize_cookie() when handling ATTR_SIZE for setattr David Howells
2020-05-04 17:16 ` [RFC PATCH 58/61] fscache: Rewrite the main document David Howells
2020-05-04 17:16 ` [RFC PATCH 59/61] fscache: Remove the obsolete API bits from the documentation David Howells
2020-05-04 17:16 ` [RFC PATCH 60/61] fscache: Document the new netfs API David Howells
2020-05-04 17:16 ` [RFC PATCH 61/61] fscache: Document the rewritten cache backend API David Howells
2020-05-04 17:54 ` [RFC PATCH 00/61] fscache, cachefiles: Rewrite the I/O interface in terms of kiocb/iov_iter Jeff Layton
2020-05-04 17:54   ` Jeff Layton
2020-05-05  6:05 ` Christoph Hellwig
2020-05-05  6:05   ` Christoph Hellwig

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