fs, dax: prepare for dax-specific address_space_operations
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>
Reviewed-by: Jan Kara <jack@suse.cz>
Suggested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 0185ecda..ae27a7e 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -38,6 +38,7 @@
}
#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 @@
}
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 @@
{
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 @@
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