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From: David Howells <dhowells@redhat.com>
To: Trond.Myklebust@netapp.com, chuck.lever@oracle.com,
	casey@schaufler-ca.com
Cc: nfsv4@linux-nfs.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, selinux@tycho.nsa.gov,
	linux-security-module@vger.kernel.org, dhowells@redhat.com
Subject: [PATCH 17/37] CacheFiles: Add a hook to write a single page of data to an inode [ver #34]
Date: Fri, 29 Feb 2008 00:45:04 +0000	[thread overview]
Message-ID: <20080229004504.4142.51681.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <20080229004332.4142.51771.stgit@warthog.procyon.org.uk>

Add an address space operation to write one single page of data to an inode at
a page-aligned location (thus permitting the implementation to be highly
optimised).  The data source is a single page.

This is used by CacheFiles to store the contents of netfs pages into their
backing file pages.

Supply a generic implementation for this that uses the write_begin() and
write_end() address_space operations to bind a copy directly into the page
cache.

Hook the Ext2 and Ext3 operations to the generic implementation.

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

 fs/ext2/inode.c    |    2 ++
 fs/ext3/inode.c    |    3 +++
 include/linux/fs.h |    7 ++++++
 mm/filemap.c       |   61 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 0 deletions(-)


diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index c620068..f483014 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -792,6 +792,7 @@ const struct address_space_operations ext2_aops = {
 	.direct_IO		= ext2_direct_IO,
 	.writepages		= ext2_writepages,
 	.migratepage		= buffer_migrate_page,
+	.write_one_page		= generic_file_buffered_write_one_page,
 };
 
 const struct address_space_operations ext2_aops_xip = {
@@ -810,6 +811,7 @@ const struct address_space_operations ext2_nobh_aops = {
 	.direct_IO		= ext2_direct_IO,
 	.writepages		= ext2_writepages,
 	.migratepage		= buffer_migrate_page,
+	.write_one_page		= generic_file_buffered_write_one_page,
 };
 
 /*
diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index c976123..0209f3b 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1776,6 +1776,7 @@ static const struct address_space_operations ext3_ordered_aops = {
 	.releasepage	= ext3_releasepage,
 	.direct_IO	= ext3_direct_IO,
 	.migratepage	= buffer_migrate_page,
+	.write_one_page	= generic_file_buffered_write_one_page,
 };
 
 static const struct address_space_operations ext3_writeback_aops = {
@@ -1790,6 +1791,7 @@ static const struct address_space_operations ext3_writeback_aops = {
 	.releasepage	= ext3_releasepage,
 	.direct_IO	= ext3_direct_IO,
 	.migratepage	= buffer_migrate_page,
+	.write_one_page	= generic_file_buffered_write_one_page,
 };
 
 static const struct address_space_operations ext3_journalled_aops = {
@@ -1803,6 +1805,7 @@ static const struct address_space_operations ext3_journalled_aops = {
 	.bmap		= ext3_bmap,
 	.invalidatepage	= ext3_invalidatepage,
 	.releasepage	= ext3_releasepage,
+	.write_one_page	= generic_file_buffered_write_one_page,
 };
 
 void ext3_set_aops(struct inode *inode)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d218ef5..dd6c3d1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -481,6 +481,11 @@ struct address_space_operations {
 	int (*migratepage) (struct address_space *,
 			struct page *, struct page *);
 	int (*launder_page) (struct page *);
+	/* write the contents of the source page over the page at the specified
+	 * index in the target address space (the source page does not need to
+	 * be related to the target address space) */
+	int (*write_one_page)(struct address_space *, pgoff_t, struct page *);
+
 };
 
 /*
@@ -1811,6 +1816,8 @@ extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
 		unsigned long *, loff_t, loff_t *, size_t, size_t);
 extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
 		unsigned long, loff_t, loff_t *, size_t, ssize_t);
+extern int generic_file_buffered_write_one_page(struct address_space *,
+						pgoff_t, struct page *);
 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
 extern int generic_segment_checks(const struct iovec *iov,
diff --git a/mm/filemap.c b/mm/filemap.c
index df1e149..a583f44 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2359,6 +2359,67 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
 }
 EXPORT_SYMBOL(generic_file_buffered_write);
 
+/**
+ * generic_file_buffered_write_one_page - Write a single page of data to an
+ *	inode
+ * @mapping - The address space of the target inode
+ * @index - The target page in the target inode to fill
+ * @source - The data to write into the target page
+ *
+ * Write the data from the source page to the page in the nominated address
+ * space at the @index specified.  Note that the file will not be extended if
+ * the page crosses the EOF marker, in which case only the first part of the
+ * page will be written.
+ *
+ * The @source page does not need to have any association with the file or the
+ * target page offset.
+ */
+int generic_file_buffered_write_one_page(struct address_space *mapping,
+					 pgoff_t index,
+					 struct page *source)
+{
+	const struct address_space_operations *a_ops = mapping->a_ops;
+	struct page *page;
+	unsigned len;
+	loff_t isize, pos;
+	void *fsdata;
+	int ret;
+
+	pos = index;
+	pos <<= PAGE_CACHE_SHIFT;
+
+	len = PAGE_CACHE_SIZE;
+	isize = i_size_read(mapping->host);
+	if ((isize >> PAGE_CACHE_SHIFT) == index)
+		len = isize & (PAGE_CACHE_SIZE - 1);
+
+	ret = pagecache_write_begin(NULL, mapping, pos, len,
+				    AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
+	if (ret < 0)
+		goto sync;
+
+	copy_highpage(page, source);
+
+	ret = pagecache_write_end(NULL, mapping, pos, len, len, page, fsdata);
+	if (ret < 0)
+		goto sync;
+
+	balance_dirty_pages_ratelimited(mapping);
+	cond_resched();
+
+sync:
+	/* the caller must handle O_SYNC themselves, but we handle S_SYNC and
+	 * MS_SYNCHRONOUS here */
+	if (unlikely(IS_SYNC(mapping->host)) && !a_ops->writepage)
+		ret = generic_osync_inode(mapping->host, mapping,
+					     OSYNC_METADATA | OSYNC_DATA);
+
+	/* the caller must handle O_DIRECT for themselves */
+
+	return ret;
+}
+EXPORT_SYMBOL(generic_file_buffered_write_one_page);
+
 static ssize_t
 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
 				unsigned long nr_segs, loff_t *ppos)


  parent reply	other threads:[~2008-02-29  0:54 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-29  0:43 [PATCH 00/37] Permit filesystem local caching " David Howells
2008-02-29  0:43 ` [PATCH 01/37] KEYS: Increase the payload size when instantiating a key " David Howells
2008-02-29  0:43 ` [PATCH 02/37] KEYS: Check starting keyring as part of search " David Howells
2008-02-29  0:43 ` [PATCH 03/37] KEYS: Allow the callout data to be passed as a blob rather than a string " David Howells
2008-02-29  0:43 ` [PATCH 04/37] KEYS: Add keyctl function to get a security label " David Howells
2008-02-29  0:44 ` [PATCH 05/37] Security: Change current->fs[ug]id to current_fs[ug]id() " David Howells
2008-02-29  0:44 ` [PATCH 06/37] Security: Separate task security context from task_struct " David Howells
2008-02-29  0:44 ` [PATCH 07/37] Security: De-embed task security record from task and use refcounting " David Howells
2008-02-29  0:44 ` [PATCH 08/37] Security: Add a kernel_service object class to SELinux " David Howells
2008-02-29  0:44 ` [PATCH 09/37] Security: Allow kernel services to override LSM settings for task actions " David Howells
2008-02-29  0:44 ` [PATCH 10/37] Security: Make NFSD work with detached security " David Howells
2008-02-29  0:44 ` [PATCH 11/37] FS-Cache: Release page->private after failed readahead " David Howells
2008-02-29  0:44 ` [PATCH 12/37] FS-Cache: Recruit a couple of page flags for cache management " David Howells
2008-02-29  0:44 ` [PATCH 13/37] FS-Cache: Provide an add_wait_queue_tail() function " David Howells
2008-02-29  0:44 ` [PATCH 14/37] FS-Cache: Generic filesystem caching facility " David Howells
2008-02-29  0:44 ` [PATCH 15/37] CacheFiles: Add missing copy_page export for ia64 " David Howells
2008-02-29  0:44 ` [PATCH 16/37] CacheFiles: Be consistent about the use of mapping vs file->f_mapping in Ext3 " David Howells
2008-02-29  0:45 ` David Howells [this message]
2008-02-29  0:45 ` [PATCH 18/37] CacheFiles: Permit the page lock state to be monitored " David Howells
2008-02-29  0:45 ` [PATCH 19/37] CacheFiles: Export things for CacheFiles " David Howells
2008-02-29  0:45 ` [PATCH 20/37] CacheFiles: A cache that backs onto a mounted filesystem " David Howells
2008-02-29  0:45 ` [PATCH 21/37] NFS: Add comment banners to some NFS functions " David Howells
2008-02-29  0:45 ` [PATCH 22/37] NFS: Add FS-Cache option bit and debug bit " David Howells
2008-02-29  0:45 ` [PATCH 23/37] NFS: Permit local filesystem caching to be enabled for NFS " David Howells
2008-02-29  0:45 ` [PATCH 24/37] NFS: Register NFS for caching and retrieve the top-level index " David Howells
2008-02-29  0:45 ` [PATCH 25/37] NFS: Define and create server-level objects " David Howells
2008-02-29  0:45 ` [PATCH 26/37] NFS: Define and create superblock-level " David Howells
2008-02-29  0:45 ` [PATCH 27/37] NFS: Define and create inode-level cache " David Howells
2008-02-29  0:46 ` [PATCH 28/37] NFS: Use local disk inode cache " David Howells
2008-02-29  0:46 ` [PATCH 29/37] NFS: Invalidate FsCache page flags when cache removed " David Howells
2008-02-29  0:46 ` [PATCH 30/37] NFS: Add some new I/O event counters for FS-Cache events " David Howells
2008-02-29  0:46 ` [PATCH 31/37] NFS: FS-Cache page management " David Howells
2008-02-29  0:46 ` [PATCH 32/37] NFS: Add read context retention for FS-Cache to call back with " David Howells
2008-02-29  0:46 ` [PATCH 33/37] NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching " David Howells
2008-02-29  0:46 ` [PATCH 34/37] NFS: Read pages from FS-Cache into an NFS inode " David Howells
2008-02-29  0:46 ` [PATCH 35/37] NFS: Store pages from an NFS inode into a local cache " David Howells
2008-02-29  0:46 ` [PATCH 36/37] NFS: Display local caching state " David Howells
2008-02-29  0:46 ` [PATCH 37/37] NFS: Add mount options to enable local caching on NFS " David Howells
2008-03-19 17:12 ` Performance degradation measurement [was Re: [PATCH 06/37] Security: Separate task security context from task_struct [ver #34]] David Howells
2008-03-23  5:17   ` Valdis.Kletnieks
2008-03-23 12:40   ` David Howells

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