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From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@lists.01.org
Cc: jack@suse.cz, Matthew Wilcox <mawilcox@microsoft.com>,
	Dave Chinner <david@fromorbit.com>,
	linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: [PATCH v7 02/14] fs, dax: prepare for dax-specific address_space_operations
Date: Wed, 21 Mar 2018 15:57:21 -0700	[thread overview]
Message-ID: <152167304153.5268.5998667213622821211.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <152167302988.5268.4370226749268662682.stgit@dwillia2-desk3.amr.corp.intel.com>

In preparation for the dax implementation to start associating dax pages
to inodes via page->mapping, we need to provide a 'struct
address_space_operations' instance for dax. Define some generic VFS aops
helpers for dax. These noop implementations are there in the dax case to
prevent the VFS from falling back to operations with page-cache
assumptions, dax_writeback_mapping_range() may not be referenced in the
FS_DAX=n case.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Matthew Wilcox <mawilcox@microsoft.com>
Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/libfs.c          |   27 +++++++++++++++++++++++++++
 include/linux/dax.h |   12 +++++++++---
 include/linux/fs.h  |    3 +++
 3 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index 7ff3cb904acd..e49d0ac6f800 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1060,6 +1060,33 @@ int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 }
 EXPORT_SYMBOL(noop_fsync);
 
+int noop_set_page_dirty(struct page *page)
+{
+	/*
+	 * Unlike __set_page_dirty_no_writeback that handles dirty page
+	 * tracking in the page object, dax does all dirty tracking in
+	 * the inode address_space in response to mkwrite faults. In the
+	 * dax case we only need to worry about potentially dirty CPU
+	 * caches, not dirty page cache pages to write back.
+	 *
+	 * This callback is defined to prevent fallback to
+	 * __set_page_dirty_buffers() in set_page_dirty().
+	 */
+	return 0;
+}
+EXPORT_SYMBOL_GPL(noop_set_page_dirty);
+
+void noop_invalidatepage(struct page *page, unsigned int offset,
+		unsigned int length)
+{
+	/*
+	 * There is no page cache to invalidate in the dax case, however
+	 * we need this callback defined to prevent falling back to
+	 * block_invalidatepage() in do_invalidatepage().
+	 */
+}
+EXPORT_SYMBOL_GPL(noop_invalidatepage);
+
 /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
 void kfree_link(void *p)
 {
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 0185ecdae135..ae27a7efe7ab 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -38,6 +38,7 @@ static inline void put_dax(struct dax_device *dax_dev)
 }
 #endif
 
+struct writeback_control;
 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
 #if IS_ENABLED(CONFIG_FS_DAX)
 int __bdev_dax_supported(struct super_block *sb, int blocksize);
@@ -57,6 +58,8 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
 }
 
 struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
+int dax_writeback_mapping_range(struct address_space *mapping,
+		struct block_device *bdev, struct writeback_control *wbc);
 #else
 static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
 {
@@ -76,6 +79,12 @@ static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 {
 	return NULL;
 }
+
+static inline int dax_writeback_mapping_range(struct address_space *mapping,
+		struct block_device *bdev, struct writeback_control *wbc)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 int dax_read_lock(void);
@@ -121,7 +130,4 @@ static inline bool dax_mapping(struct address_space *mapping)
 	return mapping->host && IS_DAX(mapping->host);
 }
 
-struct writeback_control;
-int dax_writeback_mapping_range(struct address_space *mapping,
-		struct block_device *bdev, struct writeback_control *wbc);
 #endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 79c413985305..b57db31d294d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3129,6 +3129,9 @@ extern int simple_rmdir(struct inode *, struct dentry *);
 extern int simple_rename(struct inode *, struct dentry *,
 			 struct inode *, struct dentry *, unsigned int);
 extern int noop_fsync(struct file *, loff_t, loff_t, int);
+extern int noop_set_page_dirty(struct page *page);
+extern void noop_invalidatepage(struct page *page, unsigned int offset,
+		unsigned int length);
 extern int simple_empty(struct dentry *);
 extern int simple_readpage(struct file *file, struct page *page);
 extern int simple_write_begin(struct file *file, struct address_space *mapping,

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  parent reply	other threads:[~2018-03-21 22:59 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-21 22:57 [PATCH v7 00/14] dax: fix dma vs truncate/hole-punch Dan Williams
2018-03-21 22:57 ` [PATCH v7 01/14] dax: store pfns in the radix Dan Williams
2018-03-21 22:57 ` Dan Williams [this message]
2018-03-29 15:28   ` [PATCH v7 02/14] fs, dax: prepare for dax-specific address_space_operations Jan Kara
2018-03-21 22:57 ` [PATCH v7 03/14] block, dax: remove dead code in blkdev_writepages() Dan Williams
2018-03-29 15:29   ` Jan Kara
2018-03-21 22:57 ` [PATCH v7 04/14] xfs, dax: introduce xfs_dax_aops Dan Williams
2018-03-29 15:30   ` Jan Kara
2018-03-21 22:57 ` [PATCH v7 05/14] ext4, dax: introduce ext4_dax_aops Dan Williams
2018-03-29 15:40   ` Jan Kara
2018-03-29 18:09     ` Christoph Hellwig
2018-03-29 22:47       ` Dan Williams
2018-03-21 22:57 ` [PATCH v7 06/14] ext2, dax: introduce ext2_dax_aops Dan Williams
2018-03-29 15:44   ` Jan Kara
2018-03-21 22:57 ` [PATCH v7 07/14] fs, dax: use page->mapping to warn if truncate collides with a busy page Dan Williams
2018-03-29 16:02   ` Jan Kara
2018-03-29 19:02     ` Dan Williams
2018-03-29 23:02     ` Dan Williams
2018-03-30  8:22       ` Jan Kara
2018-03-21 22:57 ` [PATCH v7 08/14] mm, dax: enable filesystems to trigger dev_pagemap ->page_free callbacks Dan Williams
2018-03-29 16:36   ` Jan Kara
2018-03-21 22:57 ` [PATCH v7 09/14] mm, dev_pagemap: introduce CONFIG_DEV_PAGEMAP_OPS Dan Williams
2018-03-22  7:49   ` Christoph Hellwig
2018-03-30 10:37   ` Jan Kara
2018-03-21 22:58 ` [PATCH v7 10/14] memremap: mark devm_memremap_pages() EXPORT_SYMBOL_GPL Dan Williams
2018-03-22  7:51   ` Christoph Hellwig
2018-03-21 22:58 ` [PATCH v7 11/14] mm, fs, dax: handle layout changes to pinned dax mappings Dan Williams
2018-03-21 22:58 ` [PATCH v7 12/14] xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL Dan Williams
2018-03-22  7:25   ` Christoph Hellwig
2018-03-30 15:16   ` Darrick J. Wong
2018-03-21 22:58 ` [PATCH v7 13/14] xfs: prepare xfs_break_layouts() for another layout type Dan Williams
2018-03-22  7:27   ` Christoph Hellwig
2018-03-22 15:50     ` Dan Williams
2018-03-21 22:58 ` [PATCH v7 14/14] xfs, dax: introduce xfs_break_dax_layouts() Dan Williams
2018-03-22  7:43   ` Christoph Hellwig
2018-03-22 16:28     ` Dan Williams
2018-03-22 17:02       ` Christoph Hellwig

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