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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>,
	David Wysochanski <dwysocha@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: [PATCH 24/32] afs: Use new fscache read helper API
Date: Mon, 25 Jan 2021 21:35:35 +0000	[thread overview]
Message-ID: <161161053540.2537118.14904446369309535330.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <161161025063.2537118.2009249444682241405.stgit@warthog.procyon.org.uk>

Make AFS use the new fscache read helpers to implement the VM read
operations:

 - afs_readpage() now hands off responsibility to fscache_readpage().

 - afs_readpages() is gone and replaced with afs_readahead().

 - afs_readahead() just hands off responsibility to fscache_readahead().

These make use of the cache if a cookie is supplied, otherwise just call
the ->issue_op() method a sufficient number of times to complete the entire
request.

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

 fs/afs/Kconfig    |    1 
 fs/afs/file.c     |  323 +++++++++++++----------------------------------------
 fs/afs/fsclient.c |    1 
 fs/afs/internal.h |    2 
 4 files changed, 81 insertions(+), 246 deletions(-)

diff --git a/fs/afs/Kconfig b/fs/afs/Kconfig
index 1ad211d72b3b..fc8ba9142f2f 100644
--- a/fs/afs/Kconfig
+++ b/fs/afs/Kconfig
@@ -4,6 +4,7 @@ config AFS_FS
 	depends on INET
 	select AF_RXRPC
 	select DNS_RESOLVER
+	select NETFS_SUPPORT
 	help
 	  If you say Y here, you will get an experimental Andrew File System
 	  driver. It currently only supports unsecured read-only AFS access.
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 231e9fd7882b..8ae9c7089e73 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -14,6 +14,7 @@
 #include <linux/gfp.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/mm.h>
+#include <linux/netfs.h>
 #include "internal.h"
 
 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
@@ -22,8 +23,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 			       unsigned int length);
 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
 
-static int afs_readpages(struct file *filp, struct address_space *mapping,
-			 struct list_head *pages, unsigned nr_pages);
+static void afs_readahead(struct readahead_control *ractl);
 
 const struct file_operations afs_file_operations = {
 	.open		= afs_open,
@@ -48,7 +48,7 @@ const struct inode_operations afs_file_inode_operations = {
 
 const struct address_space_operations afs_fs_aops = {
 	.readpage	= afs_readpage,
-	.readpages	= afs_readpages,
+	.readahead	= afs_readahead,
 	.set_page_dirty	= afs_set_page_dirty,
 	.launder_page	= afs_launder_page,
 	.releasepage	= afs_releasepage,
@@ -185,61 +185,17 @@ int afs_release(struct inode *inode, struct file *file)
 }
 
 /*
- * Handle completion of a read operation.
+ * Allocate a new read record.
  */
-static void afs_file_read_done(struct afs_read *req)
+struct afs_read *afs_alloc_read(gfp_t gfp)
 {
-	struct afs_vnode *vnode = req->vnode;
-	struct page *page;
-	pgoff_t index = req->pos >> PAGE_SHIFT;
-	pgoff_t last = index + req->nr_pages - 1;
-
-	XA_STATE(xas, &vnode->vfs_inode.i_mapping->i_pages, index);
-
-	if (iov_iter_count(req->iter) > 0) {
-		/* The read was short - clear the excess buffer. */
-		_debug("afterclear %zx %zx %llx/%llx",
-		       req->iter->iov_offset,
-		       iov_iter_count(req->iter),
-		       req->actual_len, req->len);
-		iov_iter_zero(iov_iter_count(req->iter), req->iter);
-	}
-
-	rcu_read_lock();
-	xas_for_each(&xas, page, last) {
-		page_endio(page, false, 0);
-		put_page(page);
-	}
-	rcu_read_unlock();
-
-	task_io_account_read(req->len);
-	req->cleanup = NULL;
-}
-
-/*
- * Dispose of our locks and refs on the pages if the read failed.
- */
-static void afs_file_read_cleanup(struct afs_read *req)
-{
-	struct page *page;
-	pgoff_t index = req->pos >> PAGE_SHIFT;
-	pgoff_t last = index + req->nr_pages - 1;
-
-	if (req->iter) {
-		XA_STATE(xas, &req->vnode->vfs_inode.i_mapping->i_pages, index);
-
-		_enter("%lu,%u,%zu", index, req->nr_pages, iov_iter_count(req->iter));
+	struct afs_read *req;
 
-		rcu_read_lock();
-		xas_for_each(&xas, page, last) {
-			BUG_ON(xa_is_value(page));
-			BUG_ON(PageCompound(page));
+	req = kzalloc(sizeof(struct afs_read), gfp);
+	if (req)
+		refcount_set(&req->usage, 1);
 
-			page_endio(page, false, req->error);
-			put_page(page);
-		}
-		rcu_read_unlock();
-	}
+	return req;
 }
 
 /*
@@ -258,14 +214,20 @@ void afs_put_read(struct afs_read *req)
 static void afs_fetch_data_notify(struct afs_operation *op)
 {
 	struct afs_read *req = op->fetch.req;
+	struct netfs_read_subrequest *subreq = req->subreq;
 	int error = op->error;
 
 	if (error == -ECONNABORTED)
 		error = afs_abort_to_error(op->ac.abort_code);
 	req->error = error;
 
-	if (req->done)
+	if (subreq) {
+		__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+		netfs_subreq_terminated(subreq, error ?: req->actual_len);
+		req->subreq = NULL;
+	} else if (req->done) {
 		req->done(req);
+	}
 }
 
 static void afs_fetch_data_success(struct afs_operation *op)
@@ -319,222 +281,91 @@ int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
 	return afs_do_sync_operation(op);
 }
 
-/*
- * read page from file, directory or symlink, given a key to use
- */
-static int afs_page_filler(struct key *key, struct page *page)
+static void afs_req_issue_op(struct netfs_read_subrequest *subreq)
 {
-	struct inode *inode = page->mapping->host;
-	struct afs_vnode *vnode = AFS_FS_I(inode);
-	struct afs_read *req;
+	struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
+	struct afs_read *fsreq;
 	int ret;
 
-	_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
+	fsreq = afs_alloc_read(GFP_NOFS);
+	if (!fsreq) {
+		subreq->error = -ENOMEM;
+		return;
+	}
 
-	BUG_ON(!PageLocked(page));
+	fsreq->subreq	= subreq;
+	fsreq->pos	= subreq->start + subreq->transferred;
+	fsreq->len	= subreq->len   - subreq->transferred;
+	fsreq->key	= subreq->rreq->netfs_priv;
+	fsreq->vnode	= vnode;
+	fsreq->iter	= &fsreq->def_iter;
 
-	ret = -ESTALE;
-	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
-		goto error;
+	iov_iter_xarray(&fsreq->def_iter, READ,
+			&fsreq->vnode->vfs_inode.i_mapping->i_pages,
+			fsreq->pos, fsreq->len);
 
-	req = kzalloc(sizeof(struct afs_read), GFP_KERNEL);
-	if (!req)
-		goto enomem;
-
-	refcount_set(&req->usage, 1);
-	req->vnode		= vnode;
-	req->key		= key_get(key);
-	req->pos		= (loff_t)page->index << PAGE_SHIFT;
-	req->len		= thp_size(page);
-	req->nr_pages		= thp_nr_pages(page);
-	req->done		= afs_file_read_done;
-	req->cleanup		= afs_file_read_cleanup;
-
-	get_page(page);
-	iov_iter_xarray(&req->def_iter, READ, &page->mapping->i_pages,
-			req->pos, req->len);
-	req->iter = &req->def_iter;
-
-	ret = afs_fetch_data(vnode, req);
+	ret = afs_fetch_data(fsreq->vnode, fsreq);
 	if (ret < 0)
-		goto fetch_error;
-
-	afs_put_read(req);
-	_leave(" = 0");
-	return 0;
-
-fetch_error:
-	switch (ret) {
-	case -EINTR:
-	case -ENOMEM:
-	case -ERESTARTSYS:
-	case -EAGAIN:
-		afs_put_read(req);
-		goto error;
-	case -ENOENT:
-		_debug("got NOENT from server - marking file deleted and stale");
-		set_bit(AFS_VNODE_DELETED, &vnode->flags);
-		ret = -ESTALE;
-		/* Fall through */
-	default:
-		page_endio(page, false, ret);
-		afs_put_read(req);
-		_leave(" = %d", ret);
-		return ret;
-	}
-
-enomem:
-	ret = -ENOMEM;
-error:
-	unlock_page(page);
-	_leave(" = %d", ret);
-	return ret;
+		subreq->error = ret;
 }
 
-/*
- * read page from file, directory or symlink, given a file to nominate the key
- * to be used
- */
-static int afs_readpage(struct file *file, struct page *page)
+static int afs_symlink_readpage(struct page *page)
 {
-	struct key *key;
+	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
+	struct afs_read *fsreq;
 	int ret;
 
-	if (file) {
-		key = afs_file_key(file);
-		ASSERT(key != NULL);
-		ret = afs_page_filler(key, page);
-	} else {
-		struct inode *inode = page->mapping->host;
-		key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
-		if (IS_ERR(key)) {
-			ret = PTR_ERR(key);
-		} else {
-			ret = afs_page_filler(key, page);
-			key_put(key);
-		}
-	}
-	return ret;
-}
-
-/*
- * Read a contiguous set of pages.
- */
-static int afs_readpages_one(struct file *file, struct address_space *mapping,
-			     struct list_head *pages)
-{
-	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
-	struct afs_read *req;
-	struct list_head *p;
-	struct page *first, *page;
-	pgoff_t index;
-	int ret, n;
-
-	/* Count the number of contiguous pages at the front of the list.  Note
-	 * that the list goes prev-wards rather than next-wards.
-	 */
-	first = lru_to_page(pages);
-	index = first->index + 1;
-	n = 1;
-	for (p = first->lru.prev; p != pages; p = p->prev) {
-		page = list_entry(p, struct page, lru);
-		if (page->index != index)
-			break;
-		index++;
-		n++;
-	}
-
-	req = kzalloc(sizeof(struct afs_read), GFP_NOFS);
-	if (!req)
+	fsreq = afs_alloc_read(GFP_NOFS);
+	if (!fsreq)
 		return -ENOMEM;
 
-	refcount_set(&req->usage, 1);
-	req->vnode = vnode;
-	req->key = key_get(afs_file_key(file));
-	req->done = afs_file_read_done;
-	req->cleanup = afs_file_read_cleanup;
-	req->pos = first->index;
-	req->pos <<= PAGE_SHIFT;
-
-	/* Add pages to the LRU until it fails.  We keep the pages ref'd and
-	 * locked until the read is complete.
-	 *
-	 * Note that it's possible for the file size to change whilst we're
-	 * doing this, but we rely on the server returning less than we asked
-	 * for if the file shrank.  We also rely on this to deal with a partial
-	 * page at the end of the file.
-	 */
-	do {
-		page = lru_to_page(pages);
-		list_del(&page->lru);
-		index = page->index;
-		if (add_to_page_cache_lru(page, mapping, index,
-					  readahead_gfp_mask(mapping))) {
-			put_page(page);
-			break;
-		}
-
-		req->nr_pages++;
-	} while (req->nr_pages < n);
-
-	if (req->nr_pages == 0) {
-		afs_put_read(req);
-		return 0;
-	}
-
-	req->len = req->nr_pages * PAGE_SIZE;
-	iov_iter_xarray(&req->def_iter, READ, &file->f_mapping->i_pages,
-			req->pos, req->len);
-	req->iter = &req->def_iter;
+	fsreq->pos	= page->index * PAGE_SIZE;
+	fsreq->len	= PAGE_SIZE;
+	fsreq->vnode	= vnode;
+	fsreq->iter	= &fsreq->def_iter;
+	iov_iter_xarray(&fsreq->def_iter, READ, &page->mapping->i_pages,
+			fsreq->pos, fsreq->len);
 
-	ret = afs_fetch_data(vnode, req);
-	if (ret < 0)
-		goto error;
+	ret = afs_fetch_data(fsreq->vnode, fsreq);
+	page_endio(page, false, ret);
+	return ret;
+}
 
-	afs_put_read(req);
-	return 0;
+static void afs_init_rreq(struct netfs_read_request *rreq, struct file *file)
+{
+	rreq->netfs_priv = key_get(afs_file_key(file));
+}
 
-error:
-	if (ret == -ENOENT) {
-		_debug("got NOENT from server - marking file deleted and stale");
-		set_bit(AFS_VNODE_DELETED, &vnode->flags);
-		ret = -ESTALE;
-	}
+static int afs_begin_cache_operation(struct netfs_read_request *rreq)
+{
+	struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
 
-	afs_put_read(req);
-	return ret;
+	return fscache_begin_read_operation(rreq, afs_vnode_cache(vnode));
 }
 
-/*
- * read a set of pages
- */
-static int afs_readpages(struct file *file, struct address_space *mapping,
-			 struct list_head *pages, unsigned nr_pages)
+static void afs_priv_cleanup(struct address_space *mapping, void *netfs_priv)
 {
-	struct key *key = afs_file_key(file);
-	struct afs_vnode *vnode;
-	int ret = 0;
-
-	_enter("{%d},{%lu},,%d",
-	       key_serial(key), mapping->host->i_ino, nr_pages);
+	key_put(netfs_priv);
+}
 
-	ASSERT(key != NULL);
+static const struct netfs_read_request_ops afs_req_ops = {
+	.init_rreq		= afs_init_rreq,
+	.begin_cache_operation	= afs_begin_cache_operation,
+	.issue_op		= afs_req_issue_op,
+	.cleanup		= afs_priv_cleanup,
+};
 
-	vnode = AFS_FS_I(mapping->host);
-	if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
-		_leave(" = -ESTALE");
-		return -ESTALE;
-	}
+static int afs_readpage(struct file *file, struct page *page)
+{
+	if (!file)
+		return afs_symlink_readpage(page);
 
-	/* attempt to read as many of the pages as possible */
-	while (!list_empty(pages)) {
-		ret = afs_readpages_one(file, mapping, pages);
-		if (ret < 0)
-			break;
-	}
+	return netfs_readpage(file, page, &afs_req_ops, NULL);
+}
 
-	_leave(" = %d [netting]", ret);
-	return ret;
+static void afs_readahead(struct readahead_control *ractl)
+{
+	netfs_readahead(ractl, &afs_req_ops, NULL);
 }
 
 /*
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 5e34f4dbd385..2f695a260442 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -10,6 +10,7 @@
 #include <linux/sched.h>
 #include <linux/circ_buf.h>
 #include <linux/iversion.h>
+#include <linux/netfs.h>
 #include "internal.h"
 #include "afs_fs.h"
 #include "xdr_fs.h"
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index d46389406021..090720a9943d 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -207,6 +207,7 @@ struct afs_read {
 	loff_t			file_size;	/* File size returned by server */
 	struct key		*key;		/* The key to use to reissue the read */
 	struct afs_vnode	*vnode;		/* The file being read into. */
+	struct netfs_read_subrequest *subreq;	/* Fscache helper read request this belongs to */
 	afs_dataversion_t	data_version;	/* Version number returned by server */
 	refcount_t		usage;
 	unsigned int		call_debug_id;
@@ -1049,6 +1050,7 @@ extern void afs_put_wb_key(struct afs_wb_key *);
 extern int afs_open(struct inode *, struct file *);
 extern int afs_release(struct inode *, struct file *);
 extern int afs_fetch_data(struct afs_vnode *, struct afs_read *);
+extern struct afs_read *afs_alloc_read(gfp_t);
 extern void afs_put_read(struct afs_read *);
 
 static inline struct afs_read *afs_get_read(struct afs_read *req)



  parent reply	other threads:[~2021-01-25 22:26 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
2021-01-25 21:31 ` [PATCH 01/32] iov_iter: Add ITER_XARRAY David Howells
2021-01-25 21:31 ` [PATCH 02/32] vm: Add wait/unlock functions for PG_fscache David Howells
2021-01-25 21:31 ` [PATCH 03/32] mm: Implement readahead_control pageset expansion David Howells
2021-01-25 21:31 ` [PATCH 04/32] vfs: Export rw_verify_area() for use by cachefiles David Howells
2021-01-25 21:31 ` [PATCH 05/32] netfs: Make a netfs helper module David Howells
2021-01-25 21:32 ` [PATCH 06/32] netfs: Provide readahead and readpage netfs helpers David Howells
2021-01-25 21:32 ` [PATCH 07/32] netfs: Add tracepoints David Howells
2021-01-25 21:32 ` [PATCH 08/32] netfs: Gather stats David Howells
2021-01-25 21:32 ` [PATCH 09/32] netfs: Add write_begin helper David Howells
2021-01-25 21:32 ` [PATCH 10/32] netfs: Define an interface to talk to a cache David Howells
2021-01-25 21:32 ` [PATCH 11/32] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache David Howells
2021-01-25 21:33 ` [PATCH 12/32] afs: Disable use of the fscache I/O routines David Howells
2021-01-25 21:33 ` [PATCH 13/32] afs: Pass page into dirty region helpers to provide THP size David Howells
2021-01-25 21:33 ` [PATCH 14/32] afs: Print the operation debug_id when logging an unexpected data version David Howells
2021-01-25 21:33 ` [PATCH 15/32] afs: Move key to afs_read struct David Howells
2021-01-25 21:34 ` [PATCH 16/32] afs: Don't truncate iter during data fetch David Howells
2021-01-25 21:34 ` [PATCH 17/32] afs: Log remote unmarshalling errors David Howells
2021-01-25 21:34 ` [PATCH 18/32] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2021-01-25 21:34 ` [PATCH 19/32] afs: Use ITER_XARRAY for writing David Howells
2021-01-25 21:34 ` [PATCH 20/32] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2021-01-25 21:35 ` [PATCH 21/32] afs: Extract writeback extension into its own function David Howells
2021-01-25 21:35 ` [PATCH 22/32] afs: Prepare for use of THPs David Howells
2021-01-25 21:35 ` [PATCH 23/32] afs: Use the fs operation ops to handle FetchData completion David Howells
2021-01-25 21:35 ` David Howells [this message]
2021-01-25 21:35 ` [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages() David Howells
2021-01-26  3:59   ` Matthew Wilcox
2021-01-26 15:33     ` David Wysochanski
2021-01-25 21:36 ` [PATCH 26/32] NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds David Howells
2021-01-25 21:36 ` [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc David Howells
2021-01-26  4:05   ` Matthew Wilcox
2021-01-26 15:24     ` David Wysochanski
2021-01-25 21:36 ` [PATCH 28/32] NFS: Call readpage_async_filler() from nfs_readpage_async() David Howells
2021-01-25 21:36 ` [PATCH 29/32] NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async() David Howells
2021-01-25 21:37 ` [PATCH 30/32] NFS: Allow internal use of read structs and functions David Howells
2021-01-25 21:37 ` [PATCH 31/32] NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage David Howells
2021-01-25 21:37 ` [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache David Howells
2021-01-26  1:36   ` Matthew Wilcox
2021-01-26 15:24     ` Chuck Lever
2021-01-26 19:10       ` David Wysochanski
2021-01-26 18:25     ` David Wysochanski

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