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From: David Howells <dhowells@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
	linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
	ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH 54/76] fscache: Provide resize operation
Date: Fri, 20 Nov 2020 15:14:07 +0000
Message-ID: <160588524777.3465195.17942558956161670737.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <160588455242.3465195.3214733858273019178.stgit@warthog.procyon.org.uk>

Provide a cache operation to resize an object.  This is intended to be run
synchronously rather than being deferred as it really needs to run inside
the inode lock on the netfs inode from ->setattr() to correctly order with
respect to other truncates and writes.

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

 fs/cachefiles/interface.c      |   31 +++++++++++++++++++++++++++++++
 fs/fscache/internal.h          |    3 +++
 fs/fscache/io.c                |   28 ++++++++++++++++++++++++++++
 fs/fscache/stats.c             |    9 +++++++--
 include/linux/fscache-cache.h  |    2 ++
 include/linux/fscache.h        |   18 ++++++++++++++++++
 include/trace/events/fscache.h |   26 ++++++++++++++++++++++++++
 7 files changed, 115 insertions(+), 2 deletions(-)

diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 56ae8d956174..aca08e4227b9 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -249,6 +249,36 @@ static bool cachefiles_shorten_object(struct cachefiles_object *object, loff_t n
 	return true;
 }
 
+/*
+ * Resize the backing object.
+ */
+static void cachefiles_resize_object(struct fscache_object *_object, loff_t new_size)
+{
+	struct cachefiles_object *object =
+		container_of(_object, struct cachefiles_object, fscache);
+	struct cachefiles_cache *cache =
+		container_of(object->fscache.cache, struct cachefiles_cache, cache);
+	const struct cred *saved_cred;
+	loff_t old_size = object->fscache.cookie->object_size;
+
+	_enter("%llu->%llu", old_size, new_size);
+
+	if (new_size < old_size) {
+		cachefiles_begin_secure(cache, &saved_cred);
+		cachefiles_shorten_content_map(object, new_size);
+		cachefiles_shorten_object(object, new_size);
+		cachefiles_end_secure(cache, saved_cred);
+		object->fscache.cookie->object_size = new_size;
+		return;
+	}
+
+	/* The file is being expanded.  We don't need to do anything
+	 * particularly.  cookie->initial_size doesn't change and so the point
+	 * at which we have to download before doesn't change.
+	 */
+	object->fscache.cookie->object_size = new_size;
+}
+
 /*
  * Trim excess stored data off of an object.
  */
@@ -652,6 +682,7 @@ const struct fscache_cache_ops cachefiles_cache_ops = {
 	.free_lookup_data	= cachefiles_free_lookup_data,
 	.grab_object		= cachefiles_grab_object,
 	.update_object		= cachefiles_update_object,
+	.resize_object		= cachefiles_resize_object,
 	.invalidate_object	= cachefiles_invalidate_object,
 	.drop_object		= cachefiles_drop_object,
 	.put_object		= cachefiles_put_object,
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 3c408da2c837..ff193f61a4c5 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -194,6 +194,9 @@ extern atomic_t fscache_n_updates_run;
 extern atomic_t fscache_n_relinquishes;
 extern atomic_t fscache_n_relinquishes_retire;
 
+extern atomic_t fscache_n_resizes;
+extern atomic_t fscache_n_resizes_null;
+
 extern atomic_t fscache_n_cookie_index;
 extern atomic_t fscache_n_cookie_data;
 extern atomic_t fscache_n_cookie_special;
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
index f13a7729bad3..5401c9ed347b 100644
--- a/fs/fscache/io.c
+++ b/fs/fscache/io.c
@@ -232,3 +232,31 @@ void fscache_put_super(struct super_block *sb,
 	}
 }
 EXPORT_SYMBOL(fscache_put_super);
+
+/*
+ * Change the size of a backing object.
+ */
+void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
+{
+	struct fscache_op_resources opr;
+
+	ASSERT(cookie->type != FSCACHE_COOKIE_TYPE_INDEX);
+
+	trace_fscache_resize(cookie, new_size);
+	if (fscache_begin_operation(cookie, &opr, FSCACHE_WANT_WRITE) != -ENOBUFS) {
+		struct fscache_object *object = opr.object;
+
+		fscache_stat(&fscache_n_resizes);
+		set_bit(FSCACHE_OBJECT_NEEDS_UPDATE, &object->flags);
+
+		/* We cannot defer a resize as we need to do it inside the
+		 * netfs's inode lock so that we're serialised with respect to
+		 * writes.
+		 */
+		object->cache->ops->resize_object(object, new_size);
+		fscache_end_operation(&opr);
+	} else {
+		fscache_stat(&fscache_n_resizes_null);
+	}
+}
+EXPORT_SYMBOL(__fscache_resize_cookie);
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index 952214305853..2a2df9d1649e 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -28,6 +28,9 @@ atomic_t fscache_n_updates_run;
 atomic_t fscache_n_relinquishes;
 atomic_t fscache_n_relinquishes_retire;
 
+atomic_t fscache_n_resizes;
+atomic_t fscache_n_resizes_null;
+
 atomic_t fscache_n_cookie_index;
 atomic_t fscache_n_cookie_data;
 atomic_t fscache_n_cookie_special;
@@ -99,9 +102,11 @@ static int fscache_stats_show(struct seq_file *m, void *v)
 	seq_printf(m, "Invals : n=%u\n",
 		   atomic_read(&fscache_n_invalidates));
 
-	seq_printf(m, "Updates: n=%u run=%u\n",
+	seq_printf(m, "Updates: n=%u nul=%u rsz=%u rsn=%u\n",
 		   atomic_read(&fscache_n_updates),
-		   atomic_read(&fscache_n_updates_run));
+		   atomic_read(&fscache_n_updates_run),
+		   atomic_read(&fscache_n_resizes),
+		   atomic_read(&fscache_n_resizes_null));
 
 	seq_printf(m, "Relinqs: n=%u rtr=%u\n",
 		   atomic_read(&fscache_n_relinquishes),
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index eb303deb39c1..958fa899917d 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -117,6 +117,8 @@ struct fscache_cache_ops {
 
 	/* store the updated auxiliary data on an object */
 	void (*update_object)(struct fscache_object *object);
+	/* Change the size of a data object */
+	void (*resize_object)(struct fscache_object *object, loff_t new_size);
 
 	/* Invalidate an object */
 	bool (*invalidate_object)(struct fscache_object *object,
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 3c173fb660a6..1c1ea3558421 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -221,6 +221,7 @@ extern int __fscache_begin_operation(struct fscache_cookie *, struct fscache_op_
 				     enum fscache_want_stage);
 extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
 extern void __fscache_update_cookie(struct fscache_cookie *, const void *, const loff_t *);
+extern void __fscache_resize_cookie(struct fscache_cookie *, loff_t);
 extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t, unsigned int);
 extern void fscache_put_super(struct super_block *,
 			      struct fscache_cookie *(*get_cookie)(struct inode *));
@@ -417,6 +418,23 @@ void fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data,
 		__fscache_update_cookie(cookie, aux_data, object_size);
 }
 
+/**
+ * fscache_resize_cookie - Request that a cache object be resized
+ * @cookie: The cookie representing the cache object
+ * @new_size: The new size of the object (may be NULL)
+ *
+ * Request that the size of an object be changed.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
+{
+	if (fscache_cookie_enabled(cookie))
+		__fscache_resize_cookie(cookie, new_size);
+}
+
 /**
  * fscache_pin_cookie - Pin a data-storage cache object in its cache
  * @cookie: The cookie representing the cache object
diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
index adb5618ce0c1..20bf21d12d0c 100644
--- a/include/trace/events/fscache.h
+++ b/include/trace/events/fscache.h
@@ -219,6 +219,32 @@ TRACE_EVENT(fscache_invalidate,
 		      __entry->cookie, __entry->new_size)
 	    );
 
+TRACE_EVENT(fscache_resize,
+	    TP_PROTO(struct fscache_cookie *cookie, loff_t new_size),
+
+	    TP_ARGS(cookie, new_size),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,		cookie		)
+		    __field(loff_t,			old_size	)
+		    __field(loff_t,			zero_point	)
+		    __field(loff_t,			new_size	)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->cookie	= cookie->debug_id;
+		    __entry->old_size	= cookie->object_size;
+		    __entry->zero_point	= cookie->zero_point;
+		    __entry->new_size	= new_size;
+			   ),
+
+	    TP_printk("c=%08x os=%08llx zp=%08llx sz=%08llx",
+		      __entry->cookie,
+		      __entry->old_size,
+		      __entry->zero_point,
+		      __entry->new_size)
+	    );
+
 #endif /* _TRACE_FSCACHE_H */
 
 /* This part must be outside protection */



  parent reply index

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-20 15:02 [RFC PATCH 00/76] fscache: Modernisation David Howells
2020-11-20 15:02 ` [RFC PATCH 01/76] nfs, cifs, ceph, 9p: Disable use of fscache prior to its rewrite David Howells
2020-11-20 15:02 ` [RFC PATCH 02/76] afs: Disable use of the fscache I/O routines David Howells
2020-11-20 15:03 ` [RFC PATCH 03/76] fscache: Add a cookie debug ID and use that in traces David Howells
2020-11-20 15:03 ` [RFC PATCH 04/76] fscache: Procfile to display cookies David Howells
2020-11-20 15:03 ` [RFC PATCH 05/76] fscache: Remove the old I/O API David Howells
2020-11-20 15:03 ` [RFC PATCH 06/76] fscache: Remove the netfs data from the cookie David Howells
2020-11-20 15:04 ` [RFC PATCH 07/76] fscache: Remove struct fscache_cookie_def David Howells
2020-11-20 15:04 ` [RFC PATCH 08/76] fscache: Remove store_limit* from struct fscache_object David Howells
2020-11-20 15:04 ` [RFC PATCH 09/76] fscache: Remove fscache_check_consistency() David Howells
2020-11-20 15:04 ` [RFC PATCH 10/76] fscache: Remove fscache_attr_changed() David Howells
2020-11-20 15:04 ` [RFC PATCH 11/76] fscache: Remove obsolete stats David Howells
2020-11-20 15:05 ` [RFC PATCH 12/76] fscache: Remove old I/O tracepoints David Howells
2020-11-20 15:05 ` [RFC PATCH 13/76] fscache: Temporarily disable fscache_invalidate() David Howells
2020-11-20 15:05 ` [RFC PATCH 14/76] fscache: Remove the I/O operation manager David Howells
2020-11-20 15:05 ` [RFC PATCH 15/76] fscache: Change %p in format strings to something else David Howells
2020-11-20 15:06 ` [RFC PATCH 16/76] cachefiles: " David Howells
2020-11-20 15:06 ` [RFC PATCH 17/76] iov_iter: Add ITER_XARRAY David Howells
2020-11-20 15:06 ` [RFC PATCH 18/76] vm: Add wait/unlock functions for PG_fscache David Howells
2020-11-20 15:06 ` [RFC PATCH 19/76] mm: Implement readahead_control pageset expansion David Howells
2020-11-20 15:06 ` [RFC PATCH 20/76] mm: Stop generic_file_buffered_read() from grabbing a superfluous page David Howells
2020-11-20 15:07 ` [RFC PATCH 21/76] vfs: Export rw_verify_area() for use by cachefiles David Howells
2020-11-20 15:07 ` [RFC PATCH 22/76] vfs: Provide S_CACHE_FILE inode flag David Howells
2020-11-20 15:07 ` [RFC PATCH 23/76] cachefiles: Remove tree of active files and use " David Howells
2020-11-20 15:07 ` [RFC PATCH 24/76] fscache: Provide a simple thread pool for running ops asynchronously David Howells
2020-11-20 15:08 ` [RFC PATCH 26/76] fscache: Rewrite the I/O API based on iov_iter David Howells
2020-11-20 15:08 ` [RFC PATCH 27/76] fscache: Keep track of size of a file last set independently on the server David Howells
2020-11-20 15:08 ` [RFC PATCH 28/76] fscache, cachefiles: Fix disabled histogram warnings David Howells
2020-11-20 15:08 ` [RFC PATCH 29/76] fscache: Recast assertion in terms of cookie not being an index David Howells
2020-11-20 15:08 ` [RFC PATCH 30/76] vfs, fscache: Force ->write_inode() to occur if cookie pinned for writeback David Howells
2020-11-20 15:09 ` [RFC PATCH 31/76] fscache: Allow ->put_super() to be used to wait for cache operations David Howells
2020-11-20 15:09 ` [RFC PATCH 32/76] netfs: Make a netfs helper module David Howells
2020-11-20 15:09 ` [RFC PATCH 33/76] netfs: Provide readahead and readpage netfs helpers David Howells
2020-11-20 15:09 ` [RFC PATCH 34/76] netfs: Use the cache David Howells
2020-11-20 15:10 ` [RFC PATCH 35/76] fscache: read-helper: Add tracepoints David Howells
2020-11-20 15:10 ` [RFC PATCH 36/76] cachefiles: Remove some redundant checks on unsigned values David Howells
2020-11-20 15:10 ` [RFC PATCH 37/76] cachefiles: trace: Log coherency checks David Howells
2020-11-20 15:10 ` [RFC PATCH 38/76] cachefiles: Split cachefiles_drop_object() up a bit David Howells
2020-11-20 15:11 ` [RFC PATCH 39/76] cachefiles: Implement new fscache I/O backend API David Howells
2020-11-20 15:11 ` [RFC PATCH 40/76] cachefiles: Merge object->backer into object->dentry David Howells
2020-11-20 15:11 ` [RFC PATCH 41/76] cachefiles: Implement a content-present indicator and bitmap David Howells
2020-11-20 15:11 ` [RFC PATCH 42/76] cachefiles: Shape requests from the fscache read helper David Howells
2020-11-20 15:11 ` [RFC PATCH 43/76] cachefiles: Round the cachefile size up to DIO block size David Howells
2020-11-20 15:12 ` [RFC PATCH 44/76] cachefiles: Implement read and write parts of new I/O API David Howells
2020-11-20 15:12 ` [RFC PATCH 45/76] cachefiles: Add I/O tracepoints David Howells
2020-11-20 15:12 ` [RFC PATCH 46/76] fscache: Display cache-specific data in /proc/fs/fscache/objects David Howells
2020-11-20 15:12 ` [RFC PATCH 47/76] fscache: Remove more obsolete stats David Howells
2020-11-20 15:12 ` [RFC PATCH 48/76] fscache: Always create /proc/fs/fscache/stats if configured David Howells
2020-11-20 15:13 ` [RFC PATCH 49/76] netfs: Stats David Howells
2020-11-20 15:13 ` [RFC PATCH 50/76] fscache: New stats David Howells
2020-11-20 15:13 ` [RFC PATCH 51/76] fscache, cachefiles: Rewrite invalidation David Howells
2020-11-20 15:13 ` [RFC PATCH 52/76] fscache: disable cookie when doing an invalidation for DIO write David Howells
2020-11-20 15:13 ` [RFC PATCH 53/76] fscache: Implement "will_modify" parameter on fscache_use_cookie() David Howells
2020-11-20 15:14 ` David Howells [this message]
2020-11-20 15:14 ` [RFC PATCH 55/76] fscache: Remove the update operation David Howells
2020-11-20 15:14 ` [RFC PATCH 56/76] afs: Pass page into dirty region helpers to provide THP size David Howells
2020-11-20 15:14 ` [RFC PATCH 57/76] afs: Print the operation debug_id when logging an unexpected data version David Howells
2020-11-20 15:14 ` [RFC PATCH 58/76] afs: Move key to afs_read struct David Howells
2020-11-20 15:15 ` [RFC PATCH 59/76] afs: Don't truncate iter during data fetch David Howells
2020-11-20 15:15 ` [RFC PATCH 60/76] afs: Log remote unmarshalling errors David Howells
2020-11-20 15:15 ` [RFC PATCH 61/76] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2020-11-20 15:15 ` [RFC PATCH 62/76] afs: Use ITER_XARRAY for writing David Howells
2020-11-20 15:16 ` [RFC PATCH 63/76] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2020-11-20 15:16 ` [RFC PATCH 64/76] afs: Extract writeback extension into its own function David Howells
2020-11-20 15:16 ` [RFC PATCH 65/76] afs: Prepare for use of THPs David Howells
2020-11-20 15:16 ` [RFC PATCH 66/76] afs: Use the fs operation ops to handle FetchData completion David Howells
2020-11-20 15:17 ` [RFC PATCH 67/76] afs: Use new fscache read helper API David Howells
2020-11-20 15:17 ` [RFC PATCH 68/76] netfs: Add write_begin helper David Howells
2020-11-20 15:17 ` [RFC PATCH 69/76] fscache: Add support for writing to the cache David Howells
2020-11-20 15:17 ` [RFC PATCH 70/76] afs: Use the fscache_write_begin() helper David Howells
2020-11-20 15:18 ` [RFC PATCH 71/76] afs: Copy local writes to the cache when writing to the server David Howells
2020-11-20 15:18 ` [RFC PATCH 72/76] afs: Invoke fscache_resize_cookie() when handling ATTR_SIZE for setattr David Howells
2020-11-20 15:18 ` [RFC PATCH 73/76] afs: Add O_DIRECT read support David Howells
2020-11-20 15:18 ` [RFC PATCH 74/76] afs: Skip truncation on the server of data we haven't written yet David Howells
2020-11-20 15:19 ` [RFC PATCH 75/76] afs: Make afs_write_begin() return the THP subpage David Howells
2020-11-20 15:19 ` [RFC PATCH 76/76] afs: Fix speculative status fetch going out of order wrt to modifications David Howells

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