linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] 9p: Convert to new fscache API
@ 2020-11-18 11:02 David Howells
  2020-11-18 11:43 ` David Howells
                   ` (4 more replies)
  0 siblings, 5 replies; 8+ messages in thread
From: David Howells @ 2020-11-18 11:02 UTC (permalink / raw)
  To: Dominique Martinet
  Cc: dhowells, Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

Hi Dominique,

Here's a rough draft of a patch to convert 9P to use the rewritten fscache
API.  It compiles, but I've no way to test it.  This is built on top of my
fscache-iter branch:

	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-iter

Notes:

 (*) I've switched to use ITER_XATTR rather than ITER_BVEC in some places.

 (*) I've added a pair of helper functions to get the cookie:

	v9fs_inode_cookie()
	v9fs_session_cache()

     These return NULL if CONFIG_9P_FSCACHE=n.

 (*) I've moved some of the fscache accesses inline.  Using the above helper
     functions, it all compiles away due to NULL pointer checks in the header
     file if fscache is disabled.

 (*) 9P's readpage and readpages now just jump into the netfs helpers, as does
     write_begin.  v9fs_req_issue_op() initiates the I/O on behalf of the
     helpers.

 (*) v9fs_write_begin() now returns the subpage and v9fs_write_end() goes back
     out to the head page.  thp_size() is also used.  This should mean you
     handle transparent huge pages (THPs) and can turn that on.

 (*) I have made an assumption that 9p_client_read() and write can handle I/Os
     larger than a page.  If this is not the case, v9fs_req_ops will need
     clamp_length() implementing.

 (*) The expand_readahead() and clamp_length() ops should perhaps be
     implemented to align and trim with respect to maximum I/O size.

 (*) iget and evict acquire and relinquish a cookie.

 (*) open and release use and unuse that cookie.

 (*) writepage writes the dirty data to the cache.

 (*) setattr resizes the cache if necessary.

 (*) The cache needs to be invalidated if a 3rd-party change happens, but I
     haven't done that.

 (*) With these changes, 9p should cache local changes too, not just data
     read.

 (*) If 9p supports DIO writes, it should invalidate a cache object with
     FSCACHE_INVAL_DIO_WRITE when one happens - thereby stopping caching for
     that file until all file handles on it are closed.

David
---
diff --git a/fs/9p/Kconfig b/fs/9p/Kconfig
index 66ca72422961..a9407693ef2d 100644
--- a/fs/9p/Kconfig
+++ b/fs/9p/Kconfig
@@ -13,7 +13,7 @@ config 9P_FS
 if 9P_FS
 config 9P_FSCACHE
 	bool "Enable 9P client caching support"
-	depends on 9P_FS=m && FSCACHE_OLD || 9P_FS=y && FSCACHE_OLD=y
+	depends on 9P_FS=m || 9P_FS=y
 	help
 	  Choose Y here to enable persistent, read-only local
 	  caching support for 9p clients using FS-Cache
diff --git a/fs/9p/cache.c b/fs/9p/cache.c
index eb2151fb6049..7df06dac3fa8 100644
--- a/fs/9p/cache.c
+++ b/fs/9p/cache.c
@@ -40,11 +40,6 @@ int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
 	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
 }
 
-const struct fscache_cookie_def v9fs_cache_session_index_def = {
-	.name		= "9P.session",
-	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-};
-
 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 {
 	/* If no cache session tag was specified, we generate a random one. */
@@ -58,47 +53,16 @@ void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 	}
 
 	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
-						&v9fs_cache_session_index_def,
+						FSCACHE_COOKIE_TYPE_INDEX,
+						"9P.session",
+						0, NULL,
 						v9ses->cachetag,
 						strlen(v9ses->cachetag),
-						NULL, 0,
-						v9ses, 0, true);
+						NULL, 0, 0);
 	p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
 		 v9ses, v9ses->fscache);
 }
 
-void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
-{
-	p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
-		 v9ses, v9ses->fscache);
-	fscache_relinquish_cookie(v9ses->fscache, NULL, false);
-	v9ses->fscache = NULL;
-}
-
-static enum
-fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
-					    const void *buffer,
-					    uint16_t buflen,
-					    loff_t object_size)
-{
-	const struct v9fs_inode *v9inode = cookie_netfs_data;
-
-	if (buflen != sizeof(v9inode->qid.version))
-		return FSCACHE_CHECKAUX_OBSOLETE;
-
-	if (memcmp(buffer, &v9inode->qid.version,
-		   sizeof(v9inode->qid.version)))
-		return FSCACHE_CHECKAUX_OBSOLETE;
-
-	return FSCACHE_CHECKAUX_OKAY;
-}
-
-const struct fscache_cookie_def v9fs_cache_inode_index_def = {
-	.name		= "9p.inode",
-	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
-	.check_aux	= v9fs_cache_inode_check_aux,
-};
-
 void v9fs_cache_inode_get_cookie(struct inode *inode)
 {
 	struct v9fs_inode *v9inode;
@@ -108,231 +72,20 @@ void v9fs_cache_inode_get_cookie(struct inode *inode)
 		return;
 
 	v9inode = V9FS_I(inode);
-	if (v9inode->fscache)
+	if (WARN_ON(v9inode->fscache))
 		return;
 
 	v9ses = v9fs_inode2v9ses(inode);
-	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
-						  &v9fs_cache_inode_index_def,
+	v9inode->fscache = fscache_acquire_cookie(v9fs_session_cache(v9ses),
+						  FSCACHE_COOKIE_TYPE_DATAFILE,
+						  "9p.inode",
+						  0, NULL,
 						  &v9inode->qid.path,
 						  sizeof(v9inode->qid.path),
 						  &v9inode->qid.version,
 						  sizeof(v9inode->qid.version),
-						  v9inode,
-						  i_size_read(&v9inode->vfs_inode),
-						  true);
+						  i_size_read(&v9inode->vfs_inode));
 
 	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 		 inode, v9inode->fscache);
 }
-
-void v9fs_cache_inode_put_cookie(struct inode *inode)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	if (!v9inode->fscache)
-		return;
-	p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
-		 inode, v9inode->fscache);
-
-	fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
-				  false);
-	v9inode->fscache = NULL;
-}
-
-void v9fs_cache_inode_flush_cookie(struct inode *inode)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	if (!v9inode->fscache)
-		return;
-	p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
-		 inode, v9inode->fscache);
-
-	fscache_relinquish_cookie(v9inode->fscache, NULL, true);
-	v9inode->fscache = NULL;
-}
-
-void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	if (!v9inode->fscache)
-		return;
-
-	mutex_lock(&v9inode->fscache_lock);
-
-	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
-		v9fs_cache_inode_flush_cookie(inode);
-	else
-		v9fs_cache_inode_get_cookie(inode);
-
-	mutex_unlock(&v9inode->fscache_lock);
-}
-
-void v9fs_cache_inode_reset_cookie(struct inode *inode)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-	struct v9fs_session_info *v9ses;
-	struct fscache_cookie *old;
-
-	if (!v9inode->fscache)
-		return;
-
-	old = v9inode->fscache;
-
-	mutex_lock(&v9inode->fscache_lock);
-	fscache_relinquish_cookie(v9inode->fscache, NULL, true);
-
-	v9ses = v9fs_inode2v9ses(inode);
-	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
-						  &v9fs_cache_inode_index_def,
-						  &v9inode->qid.path,
-						  sizeof(v9inode->qid.path),
-						  &v9inode->qid.version,
-						  sizeof(v9inode->qid.version),
-						  v9inode,
-						  i_size_read(&v9inode->vfs_inode),
-						  true);
-	p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
-		 inode, old, v9inode->fscache);
-
-	mutex_unlock(&v9inode->fscache_lock);
-}
-
-int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
-{
-	struct inode *inode = page->mapping->host;
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	BUG_ON(!v9inode->fscache);
-
-	return fscache_maybe_release_page(v9inode->fscache, page, gfp);
-}
-
-void __v9fs_fscache_invalidate_page(struct page *page)
-{
-	struct inode *inode = page->mapping->host;
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	BUG_ON(!v9inode->fscache);
-
-	if (PageFsCache(page)) {
-		fscache_wait_on_page_write(v9inode->fscache, page);
-		BUG_ON(!PageLocked(page));
-		fscache_uncache_page(v9inode->fscache, page);
-	}
-}
-
-static void v9fs_vfs_readpage_complete(struct page *page, void *data,
-				       int error)
-{
-	if (!error)
-		SetPageUptodate(page);
-
-	unlock_page(page);
-}
-
-/**
- * __v9fs_readpage_from_fscache - read a page from cache
- *
- * Returns 0 if the pages are in cache and a BIO is submitted,
- * 1 if the pages are not in cache and -error otherwise.
- */
-
-int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
-{
-	int ret;
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
-	if (!v9inode->fscache)
-		return -ENOBUFS;
-
-	ret = fscache_read_or_alloc_page(v9inode->fscache,
-					 page,
-					 v9fs_vfs_readpage_complete,
-					 NULL,
-					 GFP_KERNEL);
-	switch (ret) {
-	case -ENOBUFS:
-	case -ENODATA:
-		p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
-		return 1;
-	case 0:
-		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
-		return ret;
-	default:
-		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
-		return ret;
-	}
-}
-
-/**
- * __v9fs_readpages_from_fscache - read multiple pages from cache
- *
- * Returns 0 if the pages are in cache and a BIO is submitted,
- * 1 if the pages are not in cache and -error otherwise.
- */
-
-int __v9fs_readpages_from_fscache(struct inode *inode,
-				  struct address_space *mapping,
-				  struct list_head *pages,
-				  unsigned *nr_pages)
-{
-	int ret;
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
-	if (!v9inode->fscache)
-		return -ENOBUFS;
-
-	ret = fscache_read_or_alloc_pages(v9inode->fscache,
-					  mapping, pages, nr_pages,
-					  v9fs_vfs_readpage_complete,
-					  NULL,
-					  mapping_gfp_mask(mapping));
-	switch (ret) {
-	case -ENOBUFS:
-	case -ENODATA:
-		p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
-		return 1;
-	case 0:
-		BUG_ON(!list_empty(pages));
-		BUG_ON(*nr_pages != 0);
-		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
-		return ret;
-	default:
-		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
-		return ret;
-	}
-}
-
-/**
- * __v9fs_readpage_to_fscache - write a page to the cache
- *
- */
-
-void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
-{
-	int ret;
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
-	ret = fscache_write_page(v9inode->fscache, page,
-				 i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
-	p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
-	if (ret != 0)
-		v9fs_uncache_page(inode, page);
-}
-
-/*
- * wait for a page to complete writing to the cache
- */
-void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
-{
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
-	if (PageFsCache(page))
-		fscache_wait_on_page_write(v9inode->fscache, page);
-}
diff --git a/fs/9p/cache.h b/fs/9p/cache.h
index 00f107af443e..74be03ae7635 100644
--- a/fs/9p/cache.h
+++ b/fs/9p/cache.h
@@ -12,126 +12,19 @@
 #include <linux/spinlock.h>
 
 extern struct fscache_netfs v9fs_cache_netfs;
-extern const struct fscache_cookie_def v9fs_cache_session_index_def;
-extern const struct fscache_cookie_def v9fs_cache_inode_index_def;
 
 extern void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses);
-extern void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses);
 
 extern void v9fs_cache_inode_get_cookie(struct inode *inode);
-extern void v9fs_cache_inode_put_cookie(struct inode *inode);
-extern void v9fs_cache_inode_flush_cookie(struct inode *inode);
-extern void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp);
-extern void v9fs_cache_inode_reset_cookie(struct inode *inode);
 
 extern int __v9fs_cache_register(void);
 extern void __v9fs_cache_unregister(void);
 
-extern int __v9fs_fscache_release_page(struct page *page, gfp_t gfp);
-extern void __v9fs_fscache_invalidate_page(struct page *page);
-extern int __v9fs_readpage_from_fscache(struct inode *inode,
-					struct page *page);
-extern int __v9fs_readpages_from_fscache(struct inode *inode,
-					 struct address_space *mapping,
-					 struct list_head *pages,
-					 unsigned *nr_pages);
-extern void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page);
-extern void __v9fs_fscache_wait_on_page_write(struct inode *inode,
-					      struct page *page);
-
-static inline int v9fs_fscache_release_page(struct page *page,
-					    gfp_t gfp)
-{
-	return __v9fs_fscache_release_page(page, gfp);
-}
-
-static inline void v9fs_fscache_invalidate_page(struct page *page)
-{
-	__v9fs_fscache_invalidate_page(page);
-}
-
-static inline int v9fs_readpage_from_fscache(struct inode *inode,
-					     struct page *page)
-{
-	return __v9fs_readpage_from_fscache(inode, page);
-}
-
-static inline int v9fs_readpages_from_fscache(struct inode *inode,
-					      struct address_space *mapping,
-					      struct list_head *pages,
-					      unsigned *nr_pages)
-{
-	return __v9fs_readpages_from_fscache(inode, mapping, pages,
-					     nr_pages);
-}
-
-static inline void v9fs_readpage_to_fscache(struct inode *inode,
-					    struct page *page)
-{
-	if (PageFsCache(page))
-		__v9fs_readpage_to_fscache(inode, page);
-}
-
-static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-	fscache_uncache_page(v9inode->fscache, page);
-	BUG_ON(PageFsCache(page));
-}
-
-static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
-						   struct page *page)
-{
-	return __v9fs_fscache_wait_on_page_write(inode, page);
-}
-
 #else /* CONFIG_9P_FSCACHE */
 
 static inline void v9fs_cache_inode_get_cookie(struct inode *inode)
 {
 }
 
-static inline void v9fs_cache_inode_put_cookie(struct inode *inode)
-{
-}
-
-static inline void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *file)
-{
-}
-
-static inline int v9fs_fscache_release_page(struct page *page,
-					    gfp_t gfp) {
-	return 1;
-}
-
-static inline void v9fs_fscache_invalidate_page(struct page *page) {}
-
-static inline int v9fs_readpage_from_fscache(struct inode *inode,
-					     struct page *page)
-{
-	return -ENOBUFS;
-}
-
-static inline int v9fs_readpages_from_fscache(struct inode *inode,
-					      struct address_space *mapping,
-					      struct list_head *pages,
-					      unsigned *nr_pages)
-{
-	return -ENOBUFS;
-}
-
-static inline void v9fs_readpage_to_fscache(struct inode *inode,
-					    struct page *page)
-{}
-
-static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
-{}
-
-static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
-						   struct page *page)
-{
-	return;
-}
-
 #endif /* CONFIG_9P_FSCACHE */
 #endif /* _9P_CACHE_H */
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 39def020a074..f7f9f2f055ec 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -467,7 +467,8 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 
 #ifdef CONFIG_9P_FSCACHE
 	/* register the session for caching */
-	v9fs_cache_session_get_cookie(v9ses);
+	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+		v9fs_cache_session_get_cookie(v9ses);
 #endif
 	spin_lock(&v9fs_sessionlist_lock);
 	list_add(&v9ses->slist, &v9fs_sessionlist);
@@ -500,8 +501,7 @@ void v9fs_session_close(struct v9fs_session_info *v9ses)
 	}
 
 #ifdef CONFIG_9P_FSCACHE
-	if (v9ses->fscache)
-		v9fs_cache_session_put_cookie(v9ses);
+	fscache_relinquish_cookie(v9fs_session_cache(v9ses), false);
 	kfree(v9ses->cachetag);
 #endif
 	kfree(v9ses->uname);
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 7b763776306e..b248586d7a2c 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -109,7 +109,6 @@ struct v9fs_session_info {
 
 struct v9fs_inode {
 #ifdef CONFIG_9P_FSCACHE
-	struct mutex fscache_lock;
 	struct fscache_cookie *fscache;
 #endif
 	struct p9_qid qid;
@@ -124,6 +123,25 @@ static inline struct v9fs_inode *V9FS_I(const struct inode *inode)
 	return container_of(inode, struct v9fs_inode, vfs_inode);
 }
 
+static inline struct fscache_cookie *v9fs_inode_cookie(struct v9fs_inode *v9inode)
+{
+#ifdef CONFIG_9P_FSCACHE
+	return v9inode->fscache;
+#else
+	return NULL;
+#endif	
+}
+
+static inline struct fscache_cookie *v9fs_session_cache(struct v9fs_session_info *v9ses)
+{
+#ifdef CONFIG_9P_FSCACHE
+	return v9ses->fscache;
+#else
+	return NULL;
+#endif	
+}
+
+
 extern int v9fs_show_options(struct seq_file *m, struct dentry *root);
 
 struct p9_fid *v9fs_session_init(struct v9fs_session_info *, const char *,
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index cce9ace651a2..ae093672c986 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -19,7 +19,7 @@
 #include <linux/idr.h>
 #include <linux/sched.h>
 #include <linux/uio.h>
-#include <linux/bvec.h>
+#include <linux/netfs.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -29,89 +29,88 @@
 #include "fid.h"
 
 /**
- * v9fs_fid_readpage - read an entire page in from 9P
- *
- * @fid: fid being read
- * @page: structure to page
- *
+ * v9fs_req_issue_op - Issue a read from 9P
+ * @subreq: The read to make
  */
-static int v9fs_fid_readpage(void *data, struct page *page)
+static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq)
 {
-	struct p9_fid *fid = data;
-	struct inode *inode = page->mapping->host;
-	struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
+	struct netfs_read_request *rreq = subreq->rreq;
+	struct p9_fid *fid = rreq->netfs_priv;
 	struct iov_iter to;
+	loff_t pos = subreq->start + subreq->transferred;
+	size_t len = subreq->len   - subreq->transferred;
 	int retval, err;
 
-	p9_debug(P9_DEBUG_VFS, "\n");
+	iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len);
 
-	BUG_ON(!PageLocked(page));
+	retval = p9_client_read(fid, pos, &to, &err);
+	if (retval)
+		subreq->error = retval;
+}
 
-	retval = v9fs_readpage_from_fscache(inode, page);
-	if (retval == 0)
-		return retval;
+/**
+ * v9fs_init_rreq - Initialise a read request
+ * @rreq: The read request
+ * @file: The file being read from
+ */
+static void v9fs_init_rreq(struct netfs_read_request *rreq, struct file *file)
+{
+	struct v9fs_inode *v9inode = V9FS_I(rreq->inode);
 
-	iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE);
+	rreq->netfs_priv = file->private_data;
+	if (v9fs_inode_cookie(v9inode))
+		rreq->cookie_debug_id = v9fs_inode_cookie(v9inode)->debug_id;
+}
 
-	retval = p9_client_read(fid, page_offset(page), &to, &err);
-	if (err) {
-		v9fs_uncache_page(inode, page);
-		retval = err;
-		goto done;
-	}
+/**
+ * v9fs_is_cache_enabled - Determine if caching is enabled for an inode
+ * @inode: The inode to check
+ */
+static bool v9fs_is_cache_enabled(struct inode *inode)
+{
+	struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(inode));
 
-	zero_user(page, retval, PAGE_SIZE - retval);
-	flush_dcache_page(page);
-	SetPageUptodate(page);
+	return fscache_cookie_enabled(cookie) && !hlist_empty(&cookie->backing_objects);
+}
 
-	v9fs_readpage_to_fscache(inode, page);
-	retval = 0;
+/**
+ * v9fs_begin_cache_operation - Begin a cache operation for a read
+ * @rreq: The read request
+ */
+static int v9fs_begin_cache_operation(struct netfs_read_request *rreq)
+{
+	struct v9fs_inode *v9inode = V9FS_I(rreq->inode);
 
-done:
-	unlock_page(page);
-	return retval;
+	return fscache_begin_operation(v9fs_inode_cookie(v9inode),
+				       &rreq->cache_resources,
+				       FSCACHE_WANT_PARAMS);
 }
 
+static const struct netfs_read_request_ops v9fs_req_ops = {
+	.init_rreq		= v9fs_init_rreq,
+	.is_cache_enabled	= v9fs_is_cache_enabled,
+	.begin_cache_operation	= v9fs_begin_cache_operation,
+	.issue_op		= v9fs_req_issue_op,
+};
+
 /**
  * v9fs_vfs_readpage - read an entire page in from 9P
- *
  * @filp: file being read
  * @page: structure to page
  *
  */
-
-static int v9fs_vfs_readpage(struct file *filp, struct page *page)
+static int v9fs_vfs_readpage(struct file *file, struct page *page)
 {
-	return v9fs_fid_readpage(filp->private_data, page);
+	return netfs_readpage(file, page, &v9fs_req_ops, NULL);
 }
 
 /**
- * v9fs_vfs_readpages - read a set of pages from 9P
- *
- * @filp: file being read
- * @mapping: the address space
- * @pages: list of pages to read
- * @nr_pages: count of pages to read
- *
+ * v9fs_vfs_readahead - read a set of pages from 9P
+ * @ractl: The readahead parameters
  */
-
-static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
-			     struct list_head *pages, unsigned nr_pages)
+static void v9fs_vfs_readahead(struct readahead_control *ractl)
 {
-	int ret = 0;
-	struct inode *inode;
-
-	inode = mapping->host;
-	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
-
-	ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
-	if (ret == 0)
-		return ret;
-
-	ret = read_cache_pages(mapping, pages, v9fs_fid_readpage,
-			filp->private_data);
-	p9_debug(P9_DEBUG_VFS, "  = %d\n", ret);
-	return ret;
+	netfs_readahead(ractl, &v9fs_req_ops, NULL);
 }
 
 /**
@@ -124,7 +123,14 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 {
 	if (PagePrivate(page))
 		return 0;
-	return v9fs_fscache_release_page(page, gfp);
+#ifdef CONFIG_AFS_FSCACHE
+	if (PageFsCache(page)) {
+		if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS))
+			return 0;
+		wait_on_page_fscache(page);
+	}
+#endif
+	return 1;
 }
 
 /**
@@ -137,21 +143,27 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 static void v9fs_invalidate_page(struct page *page, unsigned int offset,
 				 unsigned int length)
 {
-	/*
-	 * If called with zero offset, we should release
-	 * the private state assocated with the page
-	 */
-	if (offset == 0 && length == PAGE_SIZE)
-		v9fs_fscache_invalidate_page(page);
+	wait_on_page_fscache(page);
+}
+
+static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error)
+{
+	struct v9fs_inode *v9inode = priv;
+
+	if (IS_ERR_VALUE(transferred_or_error) &&
+	    transferred_or_error != -ENOBUFS)
+		fscache_invalidate(v9fs_inode_cookie(v9inode),
+				   &v9inode->qid.version,
+				   i_size_read(&v9inode->vfs_inode), 0);
 }
 
 static int v9fs_vfs_writepage_locked(struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct v9fs_inode *v9inode = V9FS_I(inode);
+	loff_t start = page_offset(page);
 	loff_t size = i_size_read(inode);
 	struct iov_iter from;
-	struct bio_vec bvec;
 	int err, len;
 
 	if (page->index == size >> PAGE_SHIFT)
@@ -159,17 +171,22 @@ static int v9fs_vfs_writepage_locked(struct page *page)
 	else
 		len = PAGE_SIZE;
 
-	bvec.bv_page = page;
-	bvec.bv_offset = 0;
-	bvec.bv_len = len;
-	iov_iter_bvec(&from, WRITE, &bvec, 1, len);
+	iov_iter_xarray(&from, WRITE, &page->mapping->i_pages, start, len);
 
 	/* We should have writeback_fid always set */
 	BUG_ON(!v9inode->writeback_fid);
 
 	set_page_writeback(page);
 
-	p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);
+	p9_client_write(v9inode->writeback_fid, start, &from, &err);
+
+	if (err == 0 &&
+	    fscache_cookie_enabled(v9fs_inode_cookie(v9inode)) &&
+	    TestSetPageFsCache(page)) {
+		fscache_write_to_cache(v9fs_inode_cookie(v9inode),
+				       page->mapping, start, len, size,
+				       v9fs_write_to_cache_done, v9inode);
+	}
 
 	end_page_writeback(page);
 	return err;
@@ -205,14 +222,13 @@ static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
 static int v9fs_launder_page(struct page *page)
 {
 	int retval;
-	struct inode *inode = page->mapping->host;
 
-	v9fs_fscache_wait_on_page_write(inode, page);
 	if (clear_page_dirty_for_io(page)) {
 		retval = v9fs_vfs_writepage_locked(page);
 		if (retval)
 			return retval;
 	}
+	wait_on_page_fscache(page);
 	return 0;
 }
 
@@ -256,35 +272,24 @@ static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
 			    loff_t pos, unsigned len, unsigned flags,
 			    struct page **pagep, void **fsdata)
 {
-	int retval = 0;
+	int retval;
 	struct page *page;
-	struct v9fs_inode *v9inode;
-	pgoff_t index = pos >> PAGE_SHIFT;
-	struct inode *inode = mapping->host;
-
+	struct v9fs_inode *v9inode = V9FS_I(mapping->host);
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
-	v9inode = V9FS_I(inode);
-start:
-	page = grab_cache_page_write_begin(mapping, index, flags);
-	if (!page) {
-		retval = -ENOMEM;
-		goto out;
-	}
 	BUG_ON(!v9inode->writeback_fid);
-	if (PageUptodate(page))
-		goto out;
 
-	if (len == PAGE_SIZE)
-		goto out;
+	/* Prefetch area to be written into the cache if we're caching this
+	 * file.  We need to do this before we get a lock on the page in case
+	 * there's more than one writer competing for the same cache block.
+	 */
+	retval = netfs_write_begin(filp, mapping, pos, len, flags, &page, fsdata,
+				   &v9fs_req_ops, NULL);
+	if (retval < 0)
+		return retval;
 
-	retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
-	put_page(page);
-	if (!retval)
-		goto start;
-out:
-	*pagep = page;
+	*pagep = find_subpage(page, pos / PAGE_SIZE);
 	return retval;
 }
 
@@ -293,7 +298,8 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 			  struct page *page, void *fsdata)
 {
 	loff_t last_pos = pos + copied;
-	struct inode *inode = page->mapping->host;
+	struct inode *inode = mapping->host;
+	struct v9fs_inode *v9inode = V9FS_I(inode);
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
@@ -312,6 +318,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 	if (last_pos > inode->i_size) {
 		inode_add_bytes(inode, last_pos - inode->i_size);
 		i_size_write(inode, last_pos);
+		fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos);
 	}
 	set_page_dirty(page);
 out:
@@ -324,7 +331,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 
 const struct address_space_operations v9fs_addr_operations = {
 	.readpage = v9fs_vfs_readpage,
-	.readpages = v9fs_vfs_readpages,
+	.readahead = v9fs_vfs_readahead,
 	.set_page_dirty = __set_page_dirty_nobuffers,
 	.writepage = v9fs_vfs_writepage,
 	.write_begin = v9fs_write_begin,
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 674d22bf4f6f..eade5091654a 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -19,6 +19,7 @@
 #include <linux/idr.h>
 #include <linux/slab.h>
 #include <linux/uio.h>
+#include <linux/fscache.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -205,13 +206,23 @@ static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 
 int v9fs_dir_release(struct inode *inode, struct file *filp)
 {
+	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct p9_fid *fid;
-
+	loff_t i_size;
+	
 	fid = filp->private_data;
 	p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 		 inode, filp, fid ? fid->fid : -1);
 	if (fid)
 		p9_client_clunk(fid);
+
+	if ((filp->f_mode & FMODE_WRITE)) {
+		i_size = i_size_read(inode);
+		fscache_unuse_cookie(v9fs_inode_cookie(v9inode),
+				     &v9inode->qid.version, &i_size);
+	} else {
+		fscache_unuse_cookie(v9fs_inode_cookie(v9inode), NULL, NULL);
+	}
 	return 0;
 }
 
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index b177fd3b1eb3..d6b393c223b6 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -94,8 +94,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 		v9inode->writeback_fid = (void *) fid;
 	}
 	mutex_unlock(&v9inode->v_mutex);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-		v9fs_cache_inode_set_cookie(inode, file);
+	fscache_use_cookie(v9fs_inode_cookie(v9inode), file->f_mode & FMODE_WRITE);
 	return 0;
 out_error:
 	p9_client_clunk(file->private_data);
@@ -554,14 +553,27 @@ v9fs_vm_page_mkwrite(struct vm_fault *vmf)
 	p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n",
 		 page, (unsigned long)filp->private_data);
 
+	v9inode = V9FS_I(inode);
+
+	/* Wait for the page to be written to the cache before we allow it to
+	 * be modified.  We then assume the entire page will need writing back.
+	 */
+#ifdef CONFIG_V9FS_FSCACHE
+	if (PageFsCache(page) &&
+	    wait_on_page_bit_killable(page, PG_fscache) < 0)
+		return VM_FAULT_RETRY;
+#endif
+
+	if (PageWriteback(page) &&
+	    wait_on_page_bit_killable(page, PG_writeback) < 0)
+		return VM_FAULT_RETRY;
+
 	/* Update file times before taking page lock */
 	file_update_time(filp);
 
-	v9inode = V9FS_I(inode);
-	/* make sure the cache has finished storing the page */
-	v9fs_fscache_wait_on_page_write(inode, page);
 	BUG_ON(!v9inode->writeback_fid);
-	lock_page(page);
+	if (lock_page_killable(page) < 0)
+		return VM_FAULT_RETRY;
 	if (page->mapping != inode->i_mapping)
 		goto out_unlock;
 	wait_for_stable_page(page);
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index ae0c38ad1fcb..4cdf4660d7c2 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -228,7 +228,6 @@ struct inode *v9fs_alloc_inode(struct super_block *sb)
 		return NULL;
 #ifdef CONFIG_9P_FSCACHE
 	v9inode->fscache = NULL;
-	mutex_init(&v9inode->fscache_lock);
 #endif
 	v9inode->writeback_fid = NULL;
 	v9inode->cache_validity = 0;
@@ -377,10 +376,12 @@ void v9fs_evict_inode(struct inode *inode)
 	struct v9fs_inode *v9inode = V9FS_I(inode);
 
 	truncate_inode_pages_final(&inode->i_data);
+	fscache_clear_inode_writeback(v9fs_inode_cookie(v9inode), inode,
+				      &v9inode->qid.version);
 	clear_inode(inode);
 	filemap_fdatawrite(&inode->i_data);
 
-	v9fs_cache_inode_put_cookie(inode);
+	fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
 	/* clunk the fid stashed in writeback_fid */
 	if (v9inode->writeback_fid) {
 		p9_client_clunk(v9inode->writeback_fid);
@@ -846,8 +847,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		goto error;
 
 	file->private_data = fid;
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-		v9fs_cache_inode_set_cookie(d_inode(dentry), file);
+	fscache_use_cookie(v9fs_inode_cookie(v9inode), file->f_mode & FMODE_WRITE);
 
 	file->f_mode |= FMODE_CREATED;
 out:
@@ -1035,6 +1035,8 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	int retval;
+	struct inode *inode = d_inode(dentry);
+	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid = NULL;
 	struct p9_wstat wstat;
@@ -1078,20 +1080,22 @@ static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 
 	/* Write all dirty data */
 	if (d_is_reg(dentry))
-		filemap_write_and_wait(d_inode(dentry)->i_mapping);
+		filemap_write_and_wait(inode->i_mapping);
 
 	retval = p9_client_wstat(fid, &wstat);
 	if (retval < 0)
 		return retval;
 
 	if ((iattr->ia_valid & ATTR_SIZE) &&
-	    iattr->ia_size != i_size_read(d_inode(dentry)))
-		truncate_setsize(d_inode(dentry), iattr->ia_size);
+	    iattr->ia_size != i_size_read(inode)) {
+		truncate_setsize(inode, iattr->ia_size);
+		fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+	}
 
-	v9fs_invalidate_inode_attr(d_inode(dentry));
+	v9fs_invalidate_inode_attr(inode);
 
-	setattr_copy(d_inode(dentry), iattr);
-	mark_inode_dirty(d_inode(dentry));
+	setattr_copy(inode, iattr);
+	mark_inode_dirty(inode);
 	return 0;
 }
 
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 0028eccb665a..773ec75eefbe 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -340,8 +340,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	if (err)
 		goto err_clunk_old_fid;
 	file->private_data = ofid;
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-		v9fs_cache_inode_set_cookie(inode, file);
+	fscache_use_cookie(v9fs_inode_cookie(v9inode), file->f_mode & FMODE_WRITE);
 	file->f_mode |= FMODE_CREATED;
 out:
 	v9fs_put_acl(dacl, pacl);
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 10ef9c0f32ac..068e5c8e7586 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -786,6 +786,7 @@ int afs_drop_inode(struct inode *inode)
  */
 void afs_evict_inode(struct inode *inode)
 {
+	struct afs_vnode_cache_aux aux;
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 
 	_enter("{%llx:%llu.%d}",
@@ -799,12 +800,8 @@ void afs_evict_inode(struct inode *inode)
 
 	truncate_inode_pages_final(&inode->i_data);
 
-	if (inode->i_state & I_PINNING_FSCACHE_WB) {
-		struct afs_vnode_cache_aux aux;
-		loff_t i_size = i_size_read(&vnode->vfs_inode);
-		aux.data_version = vnode->status.data_version;
-		fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
-	}
+	aux.data_version = vnode->status.data_version;
+	fscache_clear_inode_writeback(afs_vnode_cache(vnode), inode, &aux);
 	clear_inode(inode);
 
 	while (!list_empty(&vnode->wb_keys)) {
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 0613ccea88c1..f129c159e1c1 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -682,4 +682,24 @@ static inline void fscache_unpin_writeback(struct writeback_control *wbc,
 		fscache_unuse_cookie(cookie, NULL, NULL);
 }
 
+/**
+ * fscache_clear_inode_writeback - Clear writeback resources pinned by an inode
+ * @cookie: The cookie referring to the cache object
+ * @inode: The inode to clean up
+ * @aux: Auxiliary data to apply to the inode
+ *
+ * Clear any writeback resources held by an inode when the inode is evicted.
+ * This must be called before clear_inode() is called.
+ */
+static inline void fscache_clear_inode_writeback(struct fscache_cookie *cookie,
+						 struct inode *inode,
+						 const void *aux)
+{
+	if (inode->i_state & I_PINNING_FSCACHE_WB) {
+		loff_t i_size = i_size_read(inode);
+		fscache_unuse_cookie(cookie, aux, &i_size);
+	}
+
+}
+
 #endif /* _LINUX_FSCACHE_H */


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 11:02 [PATCH] 9p: Convert to new fscache API David Howells
@ 2020-11-18 11:43 ` David Howells
  2020-11-18 12:00 ` David Howells
                   ` (3 subsequent siblings)
  4 siblings, 0 replies; 8+ messages in thread
From: David Howells @ 2020-11-18 11:43 UTC (permalink / raw)
  To: Dominique Martinet
  Cc: dhowells, Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

Apologies, I forgot to commit all the changes to my patch before posting it.
There are a couple of additional changes to v9fs_write_end.

David
---
diff --git a/fs/9p/Kconfig b/fs/9p/Kconfig
index 66ca72422961..a9407693ef2d 100644
--- a/fs/9p/Kconfig
+++ b/fs/9p/Kconfig
@@ -13,7 +13,7 @@ config 9P_FS
 if 9P_FS
 config 9P_FSCACHE
 	bool "Enable 9P client caching support"
-	depends on 9P_FS=m && FSCACHE_OLD || 9P_FS=y && FSCACHE_OLD=y
+	depends on 9P_FS=m || 9P_FS=y
 	help
 	  Choose Y here to enable persistent, read-only local
 	  caching support for 9p clients using FS-Cache
diff --git a/fs/9p/cache.c b/fs/9p/cache.c
index eb2151fb6049..7df06dac3fa8 100644
--- a/fs/9p/cache.c
+++ b/fs/9p/cache.c
@@ -40,11 +40,6 @@ int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
 	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
 }
 
-const struct fscache_cookie_def v9fs_cache_session_index_def = {
-	.name		= "9P.session",
-	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-};
-
 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 {
 	/* If no cache session tag was specified, we generate a random one. */
@@ -58,47 +53,16 @@ void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 	}
 
 	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
-						&v9fs_cache_session_index_def,
+						FSCACHE_COOKIE_TYPE_INDEX,
+						"9P.session",
+						0, NULL,
 						v9ses->cachetag,
 						strlen(v9ses->cachetag),
-						NULL, 0,
-						v9ses, 0, true);
+						NULL, 0, 0);
 	p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
 		 v9ses, v9ses->fscache);
 }
 
-void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
-{
-	p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
-		 v9ses, v9ses->fscache);
-	fscache_relinquish_cookie(v9ses->fscache, NULL, false);
-	v9ses->fscache = NULL;
-}
-
-static enum
-fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
-					    const void *buffer,
-					    uint16_t buflen,
-					    loff_t object_size)
-{
-	const struct v9fs_inode *v9inode = cookie_netfs_data;
-
-	if (buflen != sizeof(v9inode->qid.version))
-		return FSCACHE_CHECKAUX_OBSOLETE;
-
-	if (memcmp(buffer, &v9inode->qid.version,
-		   sizeof(v9inode->qid.version)))
-		return FSCACHE_CHECKAUX_OBSOLETE;
-
-	return FSCACHE_CHECKAUX_OKAY;
-}
-
-const struct fscache_cookie_def v9fs_cache_inode_index_def = {
-	.name		= "9p.inode",
-	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
-	.check_aux	= v9fs_cache_inode_check_aux,
-};
-
 void v9fs_cache_inode_get_cookie(struct inode *inode)
 {
 	struct v9fs_inode *v9inode;
@@ -108,231 +72,20 @@ void v9fs_cache_inode_get_cookie(struct inode *inode)
 		return;
 
 	v9inode = V9FS_I(inode);
-	if (v9inode->fscache)
+	if (WARN_ON(v9inode->fscache))
 		return;
 
 	v9ses = v9fs_inode2v9ses(inode);
-	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
-						  &v9fs_cache_inode_index_def,
+	v9inode->fscache = fscache_acquire_cookie(v9fs_session_cache(v9ses),
+						  FSCACHE_COOKIE_TYPE_DATAFILE,
+						  "9p.inode",
+						  0, NULL,
 						  &v9inode->qid.path,
 						  sizeof(v9inode->qid.path),
 						  &v9inode->qid.version,
 						  sizeof(v9inode->qid.version),
-						  v9inode,
-						  i_size_read(&v9inode->vfs_inode),
-						  true);
+						  i_size_read(&v9inode->vfs_inode));
 
 	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 		 inode, v9inode->fscache);
 }
-
-void v9fs_cache_inode_put_cookie(struct inode *inode)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	if (!v9inode->fscache)
-		return;
-	p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
-		 inode, v9inode->fscache);
-
-	fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
-				  false);
-	v9inode->fscache = NULL;
-}
-
-void v9fs_cache_inode_flush_cookie(struct inode *inode)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	if (!v9inode->fscache)
-		return;
-	p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
-		 inode, v9inode->fscache);
-
-	fscache_relinquish_cookie(v9inode->fscache, NULL, true);
-	v9inode->fscache = NULL;
-}
-
-void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	if (!v9inode->fscache)
-		return;
-
-	mutex_lock(&v9inode->fscache_lock);
-
-	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
-		v9fs_cache_inode_flush_cookie(inode);
-	else
-		v9fs_cache_inode_get_cookie(inode);
-
-	mutex_unlock(&v9inode->fscache_lock);
-}
-
-void v9fs_cache_inode_reset_cookie(struct inode *inode)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-	struct v9fs_session_info *v9ses;
-	struct fscache_cookie *old;
-
-	if (!v9inode->fscache)
-		return;
-
-	old = v9inode->fscache;
-
-	mutex_lock(&v9inode->fscache_lock);
-	fscache_relinquish_cookie(v9inode->fscache, NULL, true);
-
-	v9ses = v9fs_inode2v9ses(inode);
-	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
-						  &v9fs_cache_inode_index_def,
-						  &v9inode->qid.path,
-						  sizeof(v9inode->qid.path),
-						  &v9inode->qid.version,
-						  sizeof(v9inode->qid.version),
-						  v9inode,
-						  i_size_read(&v9inode->vfs_inode),
-						  true);
-	p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
-		 inode, old, v9inode->fscache);
-
-	mutex_unlock(&v9inode->fscache_lock);
-}
-
-int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
-{
-	struct inode *inode = page->mapping->host;
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	BUG_ON(!v9inode->fscache);
-
-	return fscache_maybe_release_page(v9inode->fscache, page, gfp);
-}
-
-void __v9fs_fscache_invalidate_page(struct page *page)
-{
-	struct inode *inode = page->mapping->host;
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	BUG_ON(!v9inode->fscache);
-
-	if (PageFsCache(page)) {
-		fscache_wait_on_page_write(v9inode->fscache, page);
-		BUG_ON(!PageLocked(page));
-		fscache_uncache_page(v9inode->fscache, page);
-	}
-}
-
-static void v9fs_vfs_readpage_complete(struct page *page, void *data,
-				       int error)
-{
-	if (!error)
-		SetPageUptodate(page);
-
-	unlock_page(page);
-}
-
-/**
- * __v9fs_readpage_from_fscache - read a page from cache
- *
- * Returns 0 if the pages are in cache and a BIO is submitted,
- * 1 if the pages are not in cache and -error otherwise.
- */
-
-int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
-{
-	int ret;
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
-	if (!v9inode->fscache)
-		return -ENOBUFS;
-
-	ret = fscache_read_or_alloc_page(v9inode->fscache,
-					 page,
-					 v9fs_vfs_readpage_complete,
-					 NULL,
-					 GFP_KERNEL);
-	switch (ret) {
-	case -ENOBUFS:
-	case -ENODATA:
-		p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
-		return 1;
-	case 0:
-		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
-		return ret;
-	default:
-		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
-		return ret;
-	}
-}
-
-/**
- * __v9fs_readpages_from_fscache - read multiple pages from cache
- *
- * Returns 0 if the pages are in cache and a BIO is submitted,
- * 1 if the pages are not in cache and -error otherwise.
- */
-
-int __v9fs_readpages_from_fscache(struct inode *inode,
-				  struct address_space *mapping,
-				  struct list_head *pages,
-				  unsigned *nr_pages)
-{
-	int ret;
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
-	if (!v9inode->fscache)
-		return -ENOBUFS;
-
-	ret = fscache_read_or_alloc_pages(v9inode->fscache,
-					  mapping, pages, nr_pages,
-					  v9fs_vfs_readpage_complete,
-					  NULL,
-					  mapping_gfp_mask(mapping));
-	switch (ret) {
-	case -ENOBUFS:
-	case -ENODATA:
-		p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
-		return 1;
-	case 0:
-		BUG_ON(!list_empty(pages));
-		BUG_ON(*nr_pages != 0);
-		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
-		return ret;
-	default:
-		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
-		return ret;
-	}
-}
-
-/**
- * __v9fs_readpage_to_fscache - write a page to the cache
- *
- */
-
-void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
-{
-	int ret;
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-
-	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
-	ret = fscache_write_page(v9inode->fscache, page,
-				 i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
-	p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
-	if (ret != 0)
-		v9fs_uncache_page(inode, page);
-}
-
-/*
- * wait for a page to complete writing to the cache
- */
-void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
-{
-	const struct v9fs_inode *v9inode = V9FS_I(inode);
-	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
-	if (PageFsCache(page))
-		fscache_wait_on_page_write(v9inode->fscache, page);
-}
diff --git a/fs/9p/cache.h b/fs/9p/cache.h
index 00f107af443e..74be03ae7635 100644
--- a/fs/9p/cache.h
+++ b/fs/9p/cache.h
@@ -12,126 +12,19 @@
 #include <linux/spinlock.h>
 
 extern struct fscache_netfs v9fs_cache_netfs;
-extern const struct fscache_cookie_def v9fs_cache_session_index_def;
-extern const struct fscache_cookie_def v9fs_cache_inode_index_def;
 
 extern void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses);
-extern void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses);
 
 extern void v9fs_cache_inode_get_cookie(struct inode *inode);
-extern void v9fs_cache_inode_put_cookie(struct inode *inode);
-extern void v9fs_cache_inode_flush_cookie(struct inode *inode);
-extern void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp);
-extern void v9fs_cache_inode_reset_cookie(struct inode *inode);
 
 extern int __v9fs_cache_register(void);
 extern void __v9fs_cache_unregister(void);
 
-extern int __v9fs_fscache_release_page(struct page *page, gfp_t gfp);
-extern void __v9fs_fscache_invalidate_page(struct page *page);
-extern int __v9fs_readpage_from_fscache(struct inode *inode,
-					struct page *page);
-extern int __v9fs_readpages_from_fscache(struct inode *inode,
-					 struct address_space *mapping,
-					 struct list_head *pages,
-					 unsigned *nr_pages);
-extern void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page);
-extern void __v9fs_fscache_wait_on_page_write(struct inode *inode,
-					      struct page *page);
-
-static inline int v9fs_fscache_release_page(struct page *page,
-					    gfp_t gfp)
-{
-	return __v9fs_fscache_release_page(page, gfp);
-}
-
-static inline void v9fs_fscache_invalidate_page(struct page *page)
-{
-	__v9fs_fscache_invalidate_page(page);
-}
-
-static inline int v9fs_readpage_from_fscache(struct inode *inode,
-					     struct page *page)
-{
-	return __v9fs_readpage_from_fscache(inode, page);
-}
-
-static inline int v9fs_readpages_from_fscache(struct inode *inode,
-					      struct address_space *mapping,
-					      struct list_head *pages,
-					      unsigned *nr_pages)
-{
-	return __v9fs_readpages_from_fscache(inode, mapping, pages,
-					     nr_pages);
-}
-
-static inline void v9fs_readpage_to_fscache(struct inode *inode,
-					    struct page *page)
-{
-	if (PageFsCache(page))
-		__v9fs_readpage_to_fscache(inode, page);
-}
-
-static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
-{
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-	fscache_uncache_page(v9inode->fscache, page);
-	BUG_ON(PageFsCache(page));
-}
-
-static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
-						   struct page *page)
-{
-	return __v9fs_fscache_wait_on_page_write(inode, page);
-}
-
 #else /* CONFIG_9P_FSCACHE */
 
 static inline void v9fs_cache_inode_get_cookie(struct inode *inode)
 {
 }
 
-static inline void v9fs_cache_inode_put_cookie(struct inode *inode)
-{
-}
-
-static inline void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *file)
-{
-}
-
-static inline int v9fs_fscache_release_page(struct page *page,
-					    gfp_t gfp) {
-	return 1;
-}
-
-static inline void v9fs_fscache_invalidate_page(struct page *page) {}
-
-static inline int v9fs_readpage_from_fscache(struct inode *inode,
-					     struct page *page)
-{
-	return -ENOBUFS;
-}
-
-static inline int v9fs_readpages_from_fscache(struct inode *inode,
-					      struct address_space *mapping,
-					      struct list_head *pages,
-					      unsigned *nr_pages)
-{
-	return -ENOBUFS;
-}
-
-static inline void v9fs_readpage_to_fscache(struct inode *inode,
-					    struct page *page)
-{}
-
-static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
-{}
-
-static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
-						   struct page *page)
-{
-	return;
-}
-
 #endif /* CONFIG_9P_FSCACHE */
 #endif /* _9P_CACHE_H */
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 39def020a074..f7f9f2f055ec 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -467,7 +467,8 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 
 #ifdef CONFIG_9P_FSCACHE
 	/* register the session for caching */
-	v9fs_cache_session_get_cookie(v9ses);
+	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+		v9fs_cache_session_get_cookie(v9ses);
 #endif
 	spin_lock(&v9fs_sessionlist_lock);
 	list_add(&v9ses->slist, &v9fs_sessionlist);
@@ -500,8 +501,7 @@ void v9fs_session_close(struct v9fs_session_info *v9ses)
 	}
 
 #ifdef CONFIG_9P_FSCACHE
-	if (v9ses->fscache)
-		v9fs_cache_session_put_cookie(v9ses);
+	fscache_relinquish_cookie(v9fs_session_cache(v9ses), false);
 	kfree(v9ses->cachetag);
 #endif
 	kfree(v9ses->uname);
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 7b763776306e..b248586d7a2c 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -109,7 +109,6 @@ struct v9fs_session_info {
 
 struct v9fs_inode {
 #ifdef CONFIG_9P_FSCACHE
-	struct mutex fscache_lock;
 	struct fscache_cookie *fscache;
 #endif
 	struct p9_qid qid;
@@ -124,6 +123,25 @@ static inline struct v9fs_inode *V9FS_I(const struct inode *inode)
 	return container_of(inode, struct v9fs_inode, vfs_inode);
 }
 
+static inline struct fscache_cookie *v9fs_inode_cookie(struct v9fs_inode *v9inode)
+{
+#ifdef CONFIG_9P_FSCACHE
+	return v9inode->fscache;
+#else
+	return NULL;
+#endif	
+}
+
+static inline struct fscache_cookie *v9fs_session_cache(struct v9fs_session_info *v9ses)
+{
+#ifdef CONFIG_9P_FSCACHE
+	return v9ses->fscache;
+#else
+	return NULL;
+#endif	
+}
+
+
 extern int v9fs_show_options(struct seq_file *m, struct dentry *root);
 
 struct p9_fid *v9fs_session_init(struct v9fs_session_info *, const char *,
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index cce9ace651a2..c0882ad0f3bb 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -19,7 +19,7 @@
 #include <linux/idr.h>
 #include <linux/sched.h>
 #include <linux/uio.h>
-#include <linux/bvec.h>
+#include <linux/netfs.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -29,89 +29,88 @@
 #include "fid.h"
 
 /**
- * v9fs_fid_readpage - read an entire page in from 9P
- *
- * @fid: fid being read
- * @page: structure to page
- *
+ * v9fs_req_issue_op - Issue a read from 9P
+ * @subreq: The read to make
  */
-static int v9fs_fid_readpage(void *data, struct page *page)
+static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq)
 {
-	struct p9_fid *fid = data;
-	struct inode *inode = page->mapping->host;
-	struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
+	struct netfs_read_request *rreq = subreq->rreq;
+	struct p9_fid *fid = rreq->netfs_priv;
 	struct iov_iter to;
+	loff_t pos = subreq->start + subreq->transferred;
+	size_t len = subreq->len   - subreq->transferred;
 	int retval, err;
 
-	p9_debug(P9_DEBUG_VFS, "\n");
+	iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len);
 
-	BUG_ON(!PageLocked(page));
+	retval = p9_client_read(fid, pos, &to, &err);
+	if (retval)
+		subreq->error = retval;
+}
 
-	retval = v9fs_readpage_from_fscache(inode, page);
-	if (retval == 0)
-		return retval;
+/**
+ * v9fs_init_rreq - Initialise a read request
+ * @rreq: The read request
+ * @file: The file being read from
+ */
+static void v9fs_init_rreq(struct netfs_read_request *rreq, struct file *file)
+{
+	struct v9fs_inode *v9inode = V9FS_I(rreq->inode);
 
-	iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE);
+	rreq->netfs_priv = file->private_data;
+	if (v9fs_inode_cookie(v9inode))
+		rreq->cookie_debug_id = v9fs_inode_cookie(v9inode)->debug_id;
+}
 
-	retval = p9_client_read(fid, page_offset(page), &to, &err);
-	if (err) {
-		v9fs_uncache_page(inode, page);
-		retval = err;
-		goto done;
-	}
+/**
+ * v9fs_is_cache_enabled - Determine if caching is enabled for an inode
+ * @inode: The inode to check
+ */
+static bool v9fs_is_cache_enabled(struct inode *inode)
+{
+	struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(inode));
 
-	zero_user(page, retval, PAGE_SIZE - retval);
-	flush_dcache_page(page);
-	SetPageUptodate(page);
+	return fscache_cookie_enabled(cookie) && !hlist_empty(&cookie->backing_objects);
+}
 
-	v9fs_readpage_to_fscache(inode, page);
-	retval = 0;
+/**
+ * v9fs_begin_cache_operation - Begin a cache operation for a read
+ * @rreq: The read request
+ */
+static int v9fs_begin_cache_operation(struct netfs_read_request *rreq)
+{
+	struct v9fs_inode *v9inode = V9FS_I(rreq->inode);
 
-done:
-	unlock_page(page);
-	return retval;
+	return fscache_begin_operation(v9fs_inode_cookie(v9inode),
+				       &rreq->cache_resources,
+				       FSCACHE_WANT_PARAMS);
 }
 
+static const struct netfs_read_request_ops v9fs_req_ops = {
+	.init_rreq		= v9fs_init_rreq,
+	.is_cache_enabled	= v9fs_is_cache_enabled,
+	.begin_cache_operation	= v9fs_begin_cache_operation,
+	.issue_op		= v9fs_req_issue_op,
+};
+
 /**
  * v9fs_vfs_readpage - read an entire page in from 9P
- *
  * @filp: file being read
  * @page: structure to page
  *
  */
-
-static int v9fs_vfs_readpage(struct file *filp, struct page *page)
+static int v9fs_vfs_readpage(struct file *file, struct page *page)
 {
-	return v9fs_fid_readpage(filp->private_data, page);
+	return netfs_readpage(file, page, &v9fs_req_ops, NULL);
 }
 
 /**
- * v9fs_vfs_readpages - read a set of pages from 9P
- *
- * @filp: file being read
- * @mapping: the address space
- * @pages: list of pages to read
- * @nr_pages: count of pages to read
- *
+ * v9fs_vfs_readahead - read a set of pages from 9P
+ * @ractl: The readahead parameters
  */
-
-static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
-			     struct list_head *pages, unsigned nr_pages)
+static void v9fs_vfs_readahead(struct readahead_control *ractl)
 {
-	int ret = 0;
-	struct inode *inode;
-
-	inode = mapping->host;
-	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
-
-	ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
-	if (ret == 0)
-		return ret;
-
-	ret = read_cache_pages(mapping, pages, v9fs_fid_readpage,
-			filp->private_data);
-	p9_debug(P9_DEBUG_VFS, "  = %d\n", ret);
-	return ret;
+	netfs_readahead(ractl, &v9fs_req_ops, NULL);
 }
 
 /**
@@ -124,7 +123,14 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 {
 	if (PagePrivate(page))
 		return 0;
-	return v9fs_fscache_release_page(page, gfp);
+#ifdef CONFIG_AFS_FSCACHE
+	if (PageFsCache(page)) {
+		if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS))
+			return 0;
+		wait_on_page_fscache(page);
+	}
+#endif
+	return 1;
 }
 
 /**
@@ -137,21 +143,27 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 static void v9fs_invalidate_page(struct page *page, unsigned int offset,
 				 unsigned int length)
 {
-	/*
-	 * If called with zero offset, we should release
-	 * the private state assocated with the page
-	 */
-	if (offset == 0 && length == PAGE_SIZE)
-		v9fs_fscache_invalidate_page(page);
+	wait_on_page_fscache(page);
+}
+
+static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error)
+{
+	struct v9fs_inode *v9inode = priv;
+
+	if (IS_ERR_VALUE(transferred_or_error) &&
+	    transferred_or_error != -ENOBUFS)
+		fscache_invalidate(v9fs_inode_cookie(v9inode),
+				   &v9inode->qid.version,
+				   i_size_read(&v9inode->vfs_inode), 0);
 }
 
 static int v9fs_vfs_writepage_locked(struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct v9fs_inode *v9inode = V9FS_I(inode);
+	loff_t start = page_offset(page);
 	loff_t size = i_size_read(inode);
 	struct iov_iter from;
-	struct bio_vec bvec;
 	int err, len;
 
 	if (page->index == size >> PAGE_SHIFT)
@@ -159,17 +171,22 @@ static int v9fs_vfs_writepage_locked(struct page *page)
 	else
 		len = PAGE_SIZE;
 
-	bvec.bv_page = page;
-	bvec.bv_offset = 0;
-	bvec.bv_len = len;
-	iov_iter_bvec(&from, WRITE, &bvec, 1, len);
+	iov_iter_xarray(&from, WRITE, &page->mapping->i_pages, start, len);
 
 	/* We should have writeback_fid always set */
 	BUG_ON(!v9inode->writeback_fid);
 
 	set_page_writeback(page);
 
-	p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);
+	p9_client_write(v9inode->writeback_fid, start, &from, &err);
+
+	if (err == 0 &&
+	    fscache_cookie_enabled(v9fs_inode_cookie(v9inode)) &&
+	    TestSetPageFsCache(page)) {
+		fscache_write_to_cache(v9fs_inode_cookie(v9inode),
+				       page->mapping, start, len, size,
+				       v9fs_write_to_cache_done, v9inode);
+	}
 
 	end_page_writeback(page);
 	return err;
@@ -205,14 +222,13 @@ static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
 static int v9fs_launder_page(struct page *page)
 {
 	int retval;
-	struct inode *inode = page->mapping->host;
 
-	v9fs_fscache_wait_on_page_write(inode, page);
 	if (clear_page_dirty_for_io(page)) {
 		retval = v9fs_vfs_writepage_locked(page);
 		if (retval)
 			return retval;
 	}
+	wait_on_page_fscache(page);
 	return 0;
 }
 
@@ -256,44 +272,35 @@ static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
 			    loff_t pos, unsigned len, unsigned flags,
 			    struct page **pagep, void **fsdata)
 {
-	int retval = 0;
+	int retval;
 	struct page *page;
-	struct v9fs_inode *v9inode;
-	pgoff_t index = pos >> PAGE_SHIFT;
-	struct inode *inode = mapping->host;
-
+	struct v9fs_inode *v9inode = V9FS_I(mapping->host);
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
-	v9inode = V9FS_I(inode);
-start:
-	page = grab_cache_page_write_begin(mapping, index, flags);
-	if (!page) {
-		retval = -ENOMEM;
-		goto out;
-	}
 	BUG_ON(!v9inode->writeback_fid);
-	if (PageUptodate(page))
-		goto out;
 
-	if (len == PAGE_SIZE)
-		goto out;
+	/* Prefetch area to be written into the cache if we're caching this
+	 * file.  We need to do this before we get a lock on the page in case
+	 * there's more than one writer competing for the same cache block.
+	 */
+	retval = netfs_write_begin(filp, mapping, pos, len, flags, &page, fsdata,
+				   &v9fs_req_ops, NULL);
+	if (retval < 0)
+		return retval;
 
-	retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
-	put_page(page);
-	if (!retval)
-		goto start;
-out:
-	*pagep = page;
+	*pagep = find_subpage(page, pos / PAGE_SIZE);
 	return retval;
 }
 
 static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 			  loff_t pos, unsigned len, unsigned copied,
-			  struct page *page, void *fsdata)
+			  struct page *subpage, void *fsdata)
 {
+	struct page *page = thp_head(subpage);
 	loff_t last_pos = pos + copied;
-	struct inode *inode = page->mapping->host;
+	struct inode *inode = mapping->host;
+	struct v9fs_inode *v9inode = V9FS_I(inode);
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
@@ -301,7 +308,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 		if (unlikely(copied < len)) {
 			copied = 0;
 			goto out;
-		} else if (len == PAGE_SIZE) {
+		} else if (len == thp_size(page)) {
 			SetPageUptodate(page);
 		}
 	}
@@ -312,6 +319,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 	if (last_pos > inode->i_size) {
 		inode_add_bytes(inode, last_pos - inode->i_size);
 		i_size_write(inode, last_pos);
+		fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos);
 	}
 	set_page_dirty(page);
 out:
@@ -324,7 +332,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 
 const struct address_space_operations v9fs_addr_operations = {
 	.readpage = v9fs_vfs_readpage,
-	.readpages = v9fs_vfs_readpages,
+	.readahead = v9fs_vfs_readahead,
 	.set_page_dirty = __set_page_dirty_nobuffers,
 	.writepage = v9fs_vfs_writepage,
 	.write_begin = v9fs_write_begin,
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 674d22bf4f6f..eade5091654a 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -19,6 +19,7 @@
 #include <linux/idr.h>
 #include <linux/slab.h>
 #include <linux/uio.h>
+#include <linux/fscache.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -205,13 +206,23 @@ static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 
 int v9fs_dir_release(struct inode *inode, struct file *filp)
 {
+	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct p9_fid *fid;
-
+	loff_t i_size;
+	
 	fid = filp->private_data;
 	p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 		 inode, filp, fid ? fid->fid : -1);
 	if (fid)
 		p9_client_clunk(fid);
+
+	if ((filp->f_mode & FMODE_WRITE)) {
+		i_size = i_size_read(inode);
+		fscache_unuse_cookie(v9fs_inode_cookie(v9inode),
+				     &v9inode->qid.version, &i_size);
+	} else {
+		fscache_unuse_cookie(v9fs_inode_cookie(v9inode), NULL, NULL);
+	}
 	return 0;
 }
 
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index b177fd3b1eb3..d6b393c223b6 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -94,8 +94,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 		v9inode->writeback_fid = (void *) fid;
 	}
 	mutex_unlock(&v9inode->v_mutex);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-		v9fs_cache_inode_set_cookie(inode, file);
+	fscache_use_cookie(v9fs_inode_cookie(v9inode), file->f_mode & FMODE_WRITE);
 	return 0;
 out_error:
 	p9_client_clunk(file->private_data);
@@ -554,14 +553,27 @@ v9fs_vm_page_mkwrite(struct vm_fault *vmf)
 	p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n",
 		 page, (unsigned long)filp->private_data);
 
+	v9inode = V9FS_I(inode);
+
+	/* Wait for the page to be written to the cache before we allow it to
+	 * be modified.  We then assume the entire page will need writing back.
+	 */
+#ifdef CONFIG_V9FS_FSCACHE
+	if (PageFsCache(page) &&
+	    wait_on_page_bit_killable(page, PG_fscache) < 0)
+		return VM_FAULT_RETRY;
+#endif
+
+	if (PageWriteback(page) &&
+	    wait_on_page_bit_killable(page, PG_writeback) < 0)
+		return VM_FAULT_RETRY;
+
 	/* Update file times before taking page lock */
 	file_update_time(filp);
 
-	v9inode = V9FS_I(inode);
-	/* make sure the cache has finished storing the page */
-	v9fs_fscache_wait_on_page_write(inode, page);
 	BUG_ON(!v9inode->writeback_fid);
-	lock_page(page);
+	if (lock_page_killable(page) < 0)
+		return VM_FAULT_RETRY;
 	if (page->mapping != inode->i_mapping)
 		goto out_unlock;
 	wait_for_stable_page(page);
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index ae0c38ad1fcb..4cdf4660d7c2 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -228,7 +228,6 @@ struct inode *v9fs_alloc_inode(struct super_block *sb)
 		return NULL;
 #ifdef CONFIG_9P_FSCACHE
 	v9inode->fscache = NULL;
-	mutex_init(&v9inode->fscache_lock);
 #endif
 	v9inode->writeback_fid = NULL;
 	v9inode->cache_validity = 0;
@@ -377,10 +376,12 @@ void v9fs_evict_inode(struct inode *inode)
 	struct v9fs_inode *v9inode = V9FS_I(inode);
 
 	truncate_inode_pages_final(&inode->i_data);
+	fscache_clear_inode_writeback(v9fs_inode_cookie(v9inode), inode,
+				      &v9inode->qid.version);
 	clear_inode(inode);
 	filemap_fdatawrite(&inode->i_data);
 
-	v9fs_cache_inode_put_cookie(inode);
+	fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
 	/* clunk the fid stashed in writeback_fid */
 	if (v9inode->writeback_fid) {
 		p9_client_clunk(v9inode->writeback_fid);
@@ -846,8 +847,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		goto error;
 
 	file->private_data = fid;
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-		v9fs_cache_inode_set_cookie(d_inode(dentry), file);
+	fscache_use_cookie(v9fs_inode_cookie(v9inode), file->f_mode & FMODE_WRITE);
 
 	file->f_mode |= FMODE_CREATED;
 out:
@@ -1035,6 +1035,8 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	int retval;
+	struct inode *inode = d_inode(dentry);
+	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid = NULL;
 	struct p9_wstat wstat;
@@ -1078,20 +1080,22 @@ static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 
 	/* Write all dirty data */
 	if (d_is_reg(dentry))
-		filemap_write_and_wait(d_inode(dentry)->i_mapping);
+		filemap_write_and_wait(inode->i_mapping);
 
 	retval = p9_client_wstat(fid, &wstat);
 	if (retval < 0)
 		return retval;
 
 	if ((iattr->ia_valid & ATTR_SIZE) &&
-	    iattr->ia_size != i_size_read(d_inode(dentry)))
-		truncate_setsize(d_inode(dentry), iattr->ia_size);
+	    iattr->ia_size != i_size_read(inode)) {
+		truncate_setsize(inode, iattr->ia_size);
+		fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+	}
 
-	v9fs_invalidate_inode_attr(d_inode(dentry));
+	v9fs_invalidate_inode_attr(inode);
 
-	setattr_copy(d_inode(dentry), iattr);
-	mark_inode_dirty(d_inode(dentry));
+	setattr_copy(inode, iattr);
+	mark_inode_dirty(inode);
 	return 0;
 }
 
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 0028eccb665a..773ec75eefbe 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -340,8 +340,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	if (err)
 		goto err_clunk_old_fid;
 	file->private_data = ofid;
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-		v9fs_cache_inode_set_cookie(inode, file);
+	fscache_use_cookie(v9fs_inode_cookie(v9inode), file->f_mode & FMODE_WRITE);
 	file->f_mode |= FMODE_CREATED;
 out:
 	v9fs_put_acl(dacl, pacl);
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 10ef9c0f32ac..068e5c8e7586 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -786,6 +786,7 @@ int afs_drop_inode(struct inode *inode)
  */
 void afs_evict_inode(struct inode *inode)
 {
+	struct afs_vnode_cache_aux aux;
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 
 	_enter("{%llx:%llu.%d}",
@@ -799,12 +800,8 @@ void afs_evict_inode(struct inode *inode)
 
 	truncate_inode_pages_final(&inode->i_data);
 
-	if (inode->i_state & I_PINNING_FSCACHE_WB) {
-		struct afs_vnode_cache_aux aux;
-		loff_t i_size = i_size_read(&vnode->vfs_inode);
-		aux.data_version = vnode->status.data_version;
-		fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
-	}
+	aux.data_version = vnode->status.data_version;
+	fscache_clear_inode_writeback(afs_vnode_cache(vnode), inode, &aux);
 	clear_inode(inode);
 
 	while (!list_empty(&vnode->wb_keys)) {
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 0613ccea88c1..f129c159e1c1 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -682,4 +682,24 @@ static inline void fscache_unpin_writeback(struct writeback_control *wbc,
 		fscache_unuse_cookie(cookie, NULL, NULL);
 }
 
+/**
+ * fscache_clear_inode_writeback - Clear writeback resources pinned by an inode
+ * @cookie: The cookie referring to the cache object
+ * @inode: The inode to clean up
+ * @aux: Auxiliary data to apply to the inode
+ *
+ * Clear any writeback resources held by an inode when the inode is evicted.
+ * This must be called before clear_inode() is called.
+ */
+static inline void fscache_clear_inode_writeback(struct fscache_cookie *cookie,
+						 struct inode *inode,
+						 const void *aux)
+{
+	if (inode->i_state & I_PINNING_FSCACHE_WB) {
+		loff_t i_size = i_size_read(inode);
+		fscache_unuse_cookie(cookie, aux, &i_size);
+	}
+
+}
+
 #endif /* _LINUX_FSCACHE_H */


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 11:02 [PATCH] 9p: Convert to new fscache API David Howells
  2020-11-18 11:43 ` David Howells
@ 2020-11-18 12:00 ` David Howells
  2020-11-18 12:48 ` Dominique Martinet
                   ` (2 subsequent siblings)
  4 siblings, 0 replies; 8+ messages in thread
From: David Howells @ 2020-11-18 12:00 UTC (permalink / raw)
  To: Dominique Martinet
  Cc: dhowells, Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

David Howells <dhowells@redhat.com> wrote:

> +static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq)
>  {
> +	struct netfs_read_request *rreq = subreq->rreq;
> +	struct p9_fid *fid = rreq->netfs_priv;
>  	struct iov_iter to;
> +	loff_t pos = subreq->start + subreq->transferred;
> +	size_t len = subreq->len   - subreq->transferred;
>  	int retval, err;
>  
> +	iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len);
>  
> +	retval = p9_client_read(fid, pos, &to, &err);
> +	if (retval)
> +		subreq->error = retval;

I forgot something: netfs_subreq_terminated() needs to be called when the read
is complete.  If p9_client_read() is synchronous, then that would be here,
probably something like:

	retval = p9_client_read(fid, pos, &to, &err);
	netfs_subreq_terminated(subreq, retval);

is what's required.  Manually setting subreq->error can then be removed.

David


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 11:02 [PATCH] 9p: Convert to new fscache API David Howells
  2020-11-18 11:43 ` David Howells
  2020-11-18 12:00 ` David Howells
@ 2020-11-18 12:48 ` Dominique Martinet
  2020-11-18 13:38 ` David Howells
  2020-11-18 14:59 ` David Howells
  4 siblings, 0 replies; 8+ messages in thread
From: Dominique Martinet @ 2020-11-18 12:48 UTC (permalink / raw)
  To: David Howells
  Cc: Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

David Howells wrote on Wed, Nov 18, 2020:
> Here's a rough draft of a patch to convert 9P to use the rewritten fscache
> API.  It compiles, but I've no way to test it.  This is built on top of my
> fscache-iter branch:
> 
> 	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-iter

Thanks, I'm ashamed I hadn't found time to work on this it's a great
help.
I can get some test running with this.

What's the current schedule/plan for the fscache branch merging? Will
you be trying this merge window next month?

Couple more questions below

> Notes:
> 
>  (*) I've switched to use ITER_XATTR rather than ITER_BVEC in some places.
> 
>  (*) I've added a pair of helper functions to get the cookie:
> 
> 	v9fs_inode_cookie()
> 	v9fs_session_cache()
> 
>      These return NULL if CONFIG_9P_FSCACHE=n.
> 
>  (*) I've moved some of the fscache accesses inline.  Using the above helper
>      functions, it all compiles away due to NULL pointer checks in the header
>      file if fscache is disabled.
> 
>  (*) 9P's readpage and readpages now just jump into the netfs helpers, as does
>      write_begin.  v9fs_req_issue_op() initiates the I/O on behalf of the
>      helpers.
> 
>  (*) v9fs_write_begin() now returns the subpage and v9fs_write_end() goes back
>      out to the head page.  thp_size() is also used.  This should mean you
>      handle transparent huge pages (THPs) and can turn that on.
> 
>  (*) I have made an assumption that 9p_client_read() and write can handle I/Os
>      larger than a page.  If this is not the case, v9fs_req_ops will need
>      clamp_length() implementing.

There's a max driven by the client's msize (client->msize - P9_IOHDRSZ ;
unfortunately msize is just guaranted to be >= 4k so that means the
actual IO size would be smaller in that case even if that's not intended
to be common)

>  (*) The expand_readahead() and clamp_length() ops should perhaps be
>      implemented to align and trim with respect to maximum I/O size.
> 
>  (*) iget and evict acquire and relinquish a cookie.
> 
>  (*) open and release use and unuse that cookie.
> 
>  (*) writepage writes the dirty data to the cache.
> 
>  (*) setattr resizes the cache if necessary.
> 
>  (*) The cache needs to be invalidated if a 3rd-party change happens, but I
>      haven't done that.

There's no concurrent access logic in 9p as far as I'm aware (like NFS
does if the mtime changes for example), so I assume we can keep ignoring
this.

>  (*) With these changes, 9p should cache local changes too, not just data
>      read.
> 
>  (*) If 9p supports DIO writes, it should invalidate a cache object with
>      FSCACHE_INVAL_DIO_WRITE when one happens - thereby stopping caching for
>      that file until all file handles on it are closed.

Not 100% sure actually there is some code about it but comment says it's
disabled when cache is active; I'll check just found another problem
with some queued patch that need fixing first...

> I forgot something: netfs_subreq_terminated() needs to be called when
> the read is complete.  If p9_client_read() is synchronous, then that
> would be here,

(it is synchronous; I'll add that suggestion)

-- 
Dominique

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 11:02 [PATCH] 9p: Convert to new fscache API David Howells
                   ` (2 preceding siblings ...)
  2020-11-18 12:48 ` Dominique Martinet
@ 2020-11-18 13:38 ` David Howells
  2020-11-18 14:16   ` Dominique Martinet
  2020-11-18 15:02   ` David Howells
  2020-11-18 14:59 ` David Howells
  4 siblings, 2 replies; 8+ messages in thread
From: David Howells @ 2020-11-18 13:38 UTC (permalink / raw)
  To: Dominique Martinet
  Cc: dhowells, Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

Dominique Martinet <asmadeus@codewreck.org> wrote:

> What's the current schedule/plan for the fscache branch merging? Will
> you be trying this merge window next month?

That's the aim.  We have afs, ceph and nfs are about ready; I've had a go at
doing the 9p conversion, which I'll have to leave to you now, I think, and am
having a poke at cifs.

> >  (*) I have made an assumption that 9p_client_read() and write can handle I/Os
> >      larger than a page.  If this is not the case, v9fs_req_ops will need
> >      clamp_length() implementing.
> 
> There's a max driven by the client's msize

The netfs read helpers provide you with a couple of options here:

 (1) You can use ->clamp_length() to do multiple slices of at least 1 byte
     each.  The assumption being that these represent parallel operations.  A
     new subreq will be generated for each slice.

 (2) You can go with large slices that are larger than msize, and just read
     part of it with each read.  After reading, the netfs helper will keep
     calling you again to read some more of it, provided you didn't return an
     error and you at least read something.

> (client->msize - P9_IOHDRSZ ; unfortunately msize is just guaranted to be >=
> 4k so that means the actual IO size would be smaller in that case even if
> that's not intended to be common)

Does that mean you might be limited to reads of less than PAGE_SIZE on some
systems (ppc64 for example)?  This isn't a problem for the read helper, but
might be an issue for writing from THPs.

> >  (*) The cache needs to be invalidated if a 3rd-party change happens, but I
> >      haven't done that.
> 
> There's no concurrent access logic in 9p as far as I'm aware (like NFS
> does if the mtime changes for example), so I assume we can keep ignoring
> this.

By that, I presume you mean concurrent accesses are just not permitted?

> >  (*) If 9p supports DIO writes, it should invalidate a cache object with
> >      FSCACHE_INVAL_DIO_WRITE when one happens - thereby stopping caching for
> >      that file until all file handles on it are closed.
> 
> Not 100% sure actually there is some code about it but comment says it's
> disabled when cache is active; I'll check just found another problem
> with some queued patch that need fixing first...

Ok.

> > I forgot something: netfs_subreq_terminated() needs to be called when
> > the read is complete.  If p9_client_read() is synchronous, then that
> > would be here,
> 
> (it is synchronous; I'll add that suggestion)

Thanks.

David


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 13:38 ` David Howells
@ 2020-11-18 14:16   ` Dominique Martinet
  2020-11-18 15:02   ` David Howells
  1 sibling, 0 replies; 8+ messages in thread
From: Dominique Martinet @ 2020-11-18 14:16 UTC (permalink / raw)
  To: David Howells
  Cc: Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

David Howells wrote on Wed, Nov 18, 2020:
> > What's the current schedule/plan for the fscache branch merging? Will
> > you be trying this merge window next month?
> 
> That's the aim.  We have afs, ceph and nfs are about ready; I've had a go at
> doing the 9p conversion, which I'll have to leave to you now, I think, and am
> having a poke at cifs.

Ok, will try to polish it up by then.
Worst case as discussed is to have fscache be an alias for cache=loose
until it's ready but with the first version you gave me it hopefully
won't be needed.

> > >  (*) I have made an assumption that 9p_client_read() and write can handle I/Os
> > >      larger than a page.  If this is not the case, v9fs_req_ops will need
> > >      clamp_length() implementing.
> > 
> > There's a max driven by the client's msize
> 
> The netfs read helpers provide you with a couple of options here:
> 
>  (1) You can use ->clamp_length() to do multiple slices of at least 1 byte
>      each.  The assumption being that these represent parallel operations.  A
>      new subreq will be generated for each slice.
> 
>  (2) You can go with large slices that are larger than msize, and just read
>      part of it with each read.  After reading, the netfs helper will keep
>      calling you again to read some more of it, provided you didn't return an
>      error and you at least read something.

clamp_length looks good for that, if we can get parallel requests out
it'll all come back faster.

> > (client->msize - P9_IOHDRSZ ; unfortunately msize is just guaranted to be >=
> > 4k so that means the actual IO size would be smaller in that case even if
> > that's not intended to be common)
> 
> Does that mean you might be limited to reads of less than PAGE_SIZE on some
> systems (ppc64 for example)?  This isn't a problem for the read helper, but
> might be an issue for writing from THPs.

Quite likely, the actual used size varies depending on the backend (64k
for tcp, 500k for virtio) but can definietly be less than PAGE_SIZE.

I take it the read helper would just iterate as long as there's data
still required to read, writing from THPs wouldn't do that?


> > >  (*) The cache needs to be invalidated if a 3rd-party change happens, but I
> > >      haven't done that.
> > 
> > There's no concurrent access logic in 9p as far as I'm aware (like NFS
> > does if the mtime changes for example), so I assume we can keep ignoring
> > this.
> 
> By that, I presume you mean concurrent accesses are just not permitted?

Sorry - I meant coherency if files are modified on multiple clients
isn't guaranted - there are voluntary locks but that's about it, nothing
will detect e.g. remote file size modifications.
Concurrency on a given client works fine and should be used if possible.

-- 
Dominique

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 11:02 [PATCH] 9p: Convert to new fscache API David Howells
                   ` (3 preceding siblings ...)
  2020-11-18 13:38 ` David Howells
@ 2020-11-18 14:59 ` David Howells
  4 siblings, 0 replies; 8+ messages in thread
From: David Howells @ 2020-11-18 14:59 UTC (permalink / raw)
  To: Dominique Martinet
  Cc: dhowells, Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

Another bit I forgot: you need something like:

int afs_set_page_dirty(struct page *page)
{
	return fscache_set_page_dirty(page, afs_vnode_cache(AFS_FS_I(page->mapping->host)));
}

and point the set_page_dirty address space op at it.

David


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] 9p: Convert to new fscache API
  2020-11-18 13:38 ` David Howells
  2020-11-18 14:16   ` Dominique Martinet
@ 2020-11-18 15:02   ` David Howells
  1 sibling, 0 replies; 8+ messages in thread
From: David Howells @ 2020-11-18 15:02 UTC (permalink / raw)
  To: Dominique Martinet
  Cc: dhowells, Eric Van Hensbergen, Latchesar Ionkov, v9fs-developer,
	linux-cachefs, linux-fsdevel

Dominique Martinet <asmadeus@codewreck.org> wrote:

> I take it the read helper would just iterate as long as there's data
> still required to read, writing from THPs wouldn't do that?

Yep.  As long as you read some data, the helper will call you again if you
didn't read everything.  subreq->transferred keeps track of what has been read
so far.  You can also tell the helper just to clear the rest by setting
NETFS_SREQ_CLEAR_TAIL.

The helper tries to hide the pages from you as far as possible.  Using
ITER_XARRAY hides that even more.

David


^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2020-11-18 15:03 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-18 11:02 [PATCH] 9p: Convert to new fscache API David Howells
2020-11-18 11:43 ` David Howells
2020-11-18 12:00 ` David Howells
2020-11-18 12:48 ` Dominique Martinet
2020-11-18 13:38 ` David Howells
2020-11-18 14:16   ` Dominique Martinet
2020-11-18 15:02   ` David Howells
2020-11-18 14:59 ` David Howells

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).