Re: [PATCH 07/12] fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info

[Jan Kara <jack@suse.cz>]

On Wed 14-01-15 10:42:36, Christoph Hellwig wrote:
> Now that we got rid of the bdi abuse on character devices we can always use
> sb->s_bdi to get at the backing_dev_info for a file, except for the block
> device special case.  Export inode_to_bdi and replace uses of
> mapping->backing_dev_info with it to prepare for the removal of
> mapping->backing_dev_info.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Tejun Heo <tj@kernel.org>
  Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/btrfs/file.c                  |  2 +-
>  fs/ceph/file.c                   |  2 +-
>  fs/ext2/ialloc.c                 |  2 +-
>  fs/ext4/super.c                  |  2 +-
>  fs/fs-writeback.c                |  3 ++-
>  fs/fuse/file.c                   | 10 +++++-----
>  fs/gfs2/aops.c                   |  2 +-
>  fs/gfs2/super.c                  |  2 +-
>  fs/nfs/filelayout/filelayout.c   |  2 +-
>  fs/nfs/write.c                   |  6 +++---
>  fs/ntfs/file.c                   |  3 ++-
>  fs/ocfs2/file.c                  |  2 +-
>  fs/xfs/xfs_file.c                |  2 +-
>  include/linux/backing-dev.h      |  6 ++++--
>  include/trace/events/writeback.h |  6 +++---
>  mm/fadvise.c                     |  4 ++--
>  mm/filemap.c                     |  4 ++--
>  mm/filemap_xip.c                 |  3 ++-
>  mm/page-writeback.c              | 29 +++++++++++++----------------
>  mm/readahead.c                   |  4 ++--
>  mm/truncate.c                    |  2 +-
>  mm/vmscan.c                      |  4 ++--
>  22 files changed, 52 insertions(+), 50 deletions(-)
> 
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index e409025..835c04a 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -1746,7 +1746,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
>  
>  	mutex_lock(&inode->i_mutex);
>  
> -	current->backing_dev_info = inode->i_mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
>  	if (err) {
>  		mutex_unlock(&inode->i_mutex);
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index ce74b39..905986d 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -945,7 +945,7 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	mutex_lock(&inode->i_mutex);
>  
>  	/* We can write back this queue in page reclaim */
> -	current->backing_dev_info = file->f_mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  
>  	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
>  	if (err)
> diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
> index 7d66fb0..6c14bb8 100644
> --- a/fs/ext2/ialloc.c
> +++ b/fs/ext2/ialloc.c
> @@ -170,7 +170,7 @@ static void ext2_preread_inode(struct inode *inode)
>  	struct ext2_group_desc * gdp;
>  	struct backing_dev_info *bdi;
>  
> -	bdi = inode->i_mapping->backing_dev_info;
> +	bdi = inode_to_bdi(inode);
>  	if (bdi_read_congested(bdi))
>  		return;
>  	if (bdi_write_congested(bdi))
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 74c5f53..ad88e60 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -334,7 +334,7 @@ static void save_error_info(struct super_block *sb, const char *func,
>  static int block_device_ejected(struct super_block *sb)
>  {
>  	struct inode *bd_inode = sb->s_bdev->bd_inode;
> -	struct backing_dev_info *bdi = bd_inode->i_mapping->backing_dev_info;
> +	struct backing_dev_info *bdi = inode_to_bdi(bd_inode);
>  
>  	return bdi->dev == NULL;
>  }
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index e8116a4..a20b114 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -66,7 +66,7 @@ int writeback_in_progress(struct backing_dev_info *bdi)
>  }
>  EXPORT_SYMBOL(writeback_in_progress);
>  
> -static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
> +struct backing_dev_info *inode_to_bdi(struct inode *inode)
>  {
>  	struct super_block *sb = inode->i_sb;
>  #ifdef CONFIG_BLOCK
> @@ -75,6 +75,7 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
>  #endif
>  	return sb->s_bdi;
>  }
> +EXPORT_SYMBOL_GPL(inode_to_bdi);
>  
>  static inline struct inode *wb_inode(struct list_head *head)
>  {
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 760b2c5..19d80b8 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -1159,7 +1159,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	mutex_lock(&inode->i_mutex);
>  
>  	/* We can write back this queue in page reclaim */
> -	current->backing_dev_info = mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  
>  	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
>  	if (err)
> @@ -1464,7 +1464,7 @@ static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
>  {
>  	struct inode *inode = req->inode;
>  	struct fuse_inode *fi = get_fuse_inode(inode);
> -	struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
> +	struct backing_dev_info *bdi = inode_to_bdi(inode);
>  	int i;
>  
>  	list_del(&req->writepages_entry);
> @@ -1658,7 +1658,7 @@ static int fuse_writepage_locked(struct page *page)
>  	req->end = fuse_writepage_end;
>  	req->inode = inode;
>  
> -	inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
> +	inc_bdi_stat(inode_to_bdi(inode), BDI_WRITEBACK);
>  	inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
>  
>  	spin_lock(&fc->lock);
> @@ -1768,7 +1768,7 @@ static bool fuse_writepage_in_flight(struct fuse_req *new_req,
>  
>  	if (old_req->num_pages == 1 && (old_req->state == FUSE_REQ_INIT ||
>  					old_req->state == FUSE_REQ_PENDING)) {
> -		struct backing_dev_info *bdi = page->mapping->backing_dev_info;
> +		struct backing_dev_info *bdi = inode_to_bdi(page->mapping->host);
>  
>  		copy_highpage(old_req->pages[0], page);
>  		spin_unlock(&fc->lock);
> @@ -1872,7 +1872,7 @@ static int fuse_writepages_fill(struct page *page,
>  	req->page_descs[req->num_pages].offset = 0;
>  	req->page_descs[req->num_pages].length = PAGE_SIZE;
>  
> -	inc_bdi_stat(page->mapping->backing_dev_info, BDI_WRITEBACK);
> +	inc_bdi_stat(inode_to_bdi(inode), BDI_WRITEBACK);
>  	inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
>  
>  	err = 0;
> diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
> index 805b37f..4ad4f94 100644
> --- a/fs/gfs2/aops.c
> +++ b/fs/gfs2/aops.c
> @@ -289,7 +289,7 @@ continue_unlock:
>  		if (!clear_page_dirty_for_io(page))
>  			goto continue_unlock;
>  
> -		trace_wbc_writepage(wbc, mapping->backing_dev_info);
> +		trace_wbc_writepage(wbc, inode_to_bdi(inode));
>  
>  		ret = __gfs2_jdata_writepage(page, wbc);
>  		if (unlikely(ret)) {
> diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
> index 5b327f8..1666382 100644
> --- a/fs/gfs2/super.c
> +++ b/fs/gfs2/super.c
> @@ -743,7 +743,7 @@ static int gfs2_write_inode(struct inode *inode, struct writeback_control *wbc)
>  	struct gfs2_inode *ip = GFS2_I(inode);
>  	struct gfs2_sbd *sdp = GFS2_SB(inode);
>  	struct address_space *metamapping = gfs2_glock2aspace(ip->i_gl);
> -	struct backing_dev_info *bdi = metamapping->backing_dev_info;
> +	struct backing_dev_info *bdi = inode_to_bdi(metamapping->host);
>  	int ret = 0;
>  
>  	if (wbc->sync_mode == WB_SYNC_ALL)
> diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
> index 7afb52f..51aa889 100644
> --- a/fs/nfs/filelayout/filelayout.c
> +++ b/fs/nfs/filelayout/filelayout.c
> @@ -1081,7 +1081,7 @@ mds_commit:
>  	spin_unlock(cinfo->lock);
>  	if (!cinfo->dreq) {
>  		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
> -		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
> +		inc_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
>  			     BDI_RECLAIMABLE);
>  		__mark_inode_dirty(req->wb_context->dentry->d_inode,
>  				   I_DIRTY_DATASYNC);
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index af3af68..298abcc 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -786,7 +786,7 @@ nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
>  	spin_unlock(cinfo->lock);
>  	if (!cinfo->dreq) {
>  		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
> -		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
> +		inc_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
>  			     BDI_RECLAIMABLE);
>  		__mark_inode_dirty(req->wb_context->dentry->d_inode,
>  				   I_DIRTY_DATASYNC);
> @@ -853,7 +853,7 @@ static void
>  nfs_clear_page_commit(struct page *page)
>  {
>  	dec_zone_page_state(page, NR_UNSTABLE_NFS);
> -	dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
> +	dec_bdi_stat(inode_to_bdi(page_file_mapping(page)->host), BDI_RECLAIMABLE);
>  }
>  
>  /* Called holding inode (/cinfo) lock */
> @@ -1564,7 +1564,7 @@ void nfs_retry_commit(struct list_head *page_list,
>  		nfs_mark_request_commit(req, lseg, cinfo);
>  		if (!cinfo->dreq) {
>  			dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
> -			dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
> +			dec_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
>  				     BDI_RECLAIMABLE);
>  		}
>  		nfs_unlock_and_release_request(req);
> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
> index 643faa4..1da9b2d 100644
> --- a/fs/ntfs/file.c
> +++ b/fs/ntfs/file.c
> @@ -19,6 +19,7 @@
>   * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
>   */
>  
> +#include <linux/backing-dev.h>
>  #include <linux/buffer_head.h>
>  #include <linux/gfp.h>
>  #include <linux/pagemap.h>
> @@ -2091,7 +2092,7 @@ static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
>  	count = iov_length(iov, nr_segs);
>  	pos = *ppos;
>  	/* We can write back this queue in page reclaim. */
> -	current->backing_dev_info = mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  	written = 0;
>  	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
>  	if (err)
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 3950693..abe7d98 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2363,7 +2363,7 @@ relock:
>  			goto out_dio;
>  		}
>  	} else {
> -		current->backing_dev_info = file->f_mapping->backing_dev_info;
> +		current->backing_dev_info = inode_to_bdi(inode);
>  		written = generic_perform_write(file, from, *ppos);
>  		if (likely(written >= 0))
>  			iocb->ki_pos = *ppos + written;
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 13e974e..5684ac3 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -699,7 +699,7 @@ xfs_file_buffered_aio_write(
>  
>  	iov_iter_truncate(from, count);
>  	/* We can write back this queue in page reclaim */
> -	current->backing_dev_info = mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  
>  write_retry:
>  	trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0);
> diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
> index 478f95d..ed59dee 100644
> --- a/include/linux/backing-dev.h
> +++ b/include/linux/backing-dev.h
> @@ -106,6 +106,8 @@ struct backing_dev_info {
>  #endif
>  };
>  
> +struct backing_dev_info *inode_to_bdi(struct inode *inode);
> +
>  int __must_check bdi_init(struct backing_dev_info *bdi);
>  void bdi_destroy(struct backing_dev_info *bdi);
>  
> @@ -303,12 +305,12 @@ static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
>  
>  static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
>  {
> -	return bdi_cap_writeback_dirty(mapping->backing_dev_info);
> +	return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
>  }
>  
>  static inline bool mapping_cap_account_dirty(struct address_space *mapping)
>  {
> -	return bdi_cap_account_dirty(mapping->backing_dev_info);
> +	return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
>  }
>  
>  static inline int bdi_sched_wait(void *word)
> diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
> index cee02d6..74f5207 100644
> --- a/include/trace/events/writeback.h
> +++ b/include/trace/events/writeback.h
> @@ -47,7 +47,7 @@ TRACE_EVENT(writeback_dirty_page,
>  
>  	TP_fast_assign(
>  		strncpy(__entry->name,
> -			mapping ? dev_name(mapping->backing_dev_info->dev) : "(unknown)", 32);
> +			mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32);
>  		__entry->ino = mapping ? mapping->host->i_ino : 0;
>  		__entry->index = page->index;
>  	),
> @@ -72,7 +72,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
>  	),
>  
>  	TP_fast_assign(
> -		struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
> +		struct backing_dev_info *bdi = inode_to_bdi(inode);
>  
>  		/* may be called for files on pseudo FSes w/ unregistered bdi */
>  		strncpy(__entry->name,
> @@ -116,7 +116,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
>  
>  	TP_fast_assign(
>  		strncpy(__entry->name,
> -			dev_name(inode->i_mapping->backing_dev_info->dev), 32);
> +			dev_name(inode_to_bdi(inode)->dev), 32);
>  		__entry->ino		= inode->i_ino;
>  		__entry->sync_mode	= wbc->sync_mode;
>  	),
> diff --git a/mm/fadvise.c b/mm/fadvise.c
> index 2ad7adf..fac23ec 100644
> --- a/mm/fadvise.c
> +++ b/mm/fadvise.c
> @@ -73,7 +73,7 @@ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
>  	else
>  		endbyte--;		/* inclusive */
>  
> -	bdi = mapping->backing_dev_info;
> +	bdi = inode_to_bdi(mapping->host);
>  
>  	switch (advice) {
>  	case POSIX_FADV_NORMAL:
> @@ -113,7 +113,7 @@ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
>  	case POSIX_FADV_NOREUSE:
>  		break;
>  	case POSIX_FADV_DONTNEED:
> -		if (!bdi_write_congested(mapping->backing_dev_info))
> +		if (!bdi_write_congested(bdi))
>  			__filemap_fdatawrite_range(mapping, offset, endbyte,
>  						   WB_SYNC_NONE);
>  
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 673e458..5d7c23c 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -211,7 +211,7 @@ void __delete_from_page_cache(struct page *page, void *shadow)
>  	 */
>  	if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
>  		dec_zone_page_state(page, NR_FILE_DIRTY);
> -		dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
> +		dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE);
>  	}
>  }
>  
> @@ -2565,7 +2565,7 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	size_t		count = iov_iter_count(from);
>  
>  	/* We can write back this queue in page reclaim */
> -	current->backing_dev_info = mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
>  	if (err)
>  		goto out;
> diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
> index 0d105ae..26897fb 100644
> --- a/mm/filemap_xip.c
> +++ b/mm/filemap_xip.c
> @@ -9,6 +9,7 @@
>   */
>  
>  #include <linux/fs.h>
> +#include <linux/backing-dev.h>
>  #include <linux/pagemap.h>
>  #include <linux/export.h>
>  #include <linux/uio.h>
> @@ -410,7 +411,7 @@ xip_file_write(struct file *filp, const char __user *buf, size_t len,
>  	count = len;
>  
>  	/* We can write back this queue in page reclaim */
> -	current->backing_dev_info = mapping->backing_dev_info;
> +	current->backing_dev_info = inode_to_bdi(inode);
>  
>  	ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
>  	if (ret)
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 6f43352..d4cbb4b 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -1351,7 +1351,7 @@ static void balance_dirty_pages(struct address_space *mapping,
>  	unsigned long task_ratelimit;
>  	unsigned long dirty_ratelimit;
>  	unsigned long pos_ratio;
> -	struct backing_dev_info *bdi = mapping->backing_dev_info;
> +	struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
>  	bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT;
>  	unsigned long start_time = jiffies;
>  
> @@ -1574,7 +1574,7 @@ DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0;
>   */
>  void balance_dirty_pages_ratelimited(struct address_space *mapping)
>  {
> -	struct backing_dev_info *bdi = mapping->backing_dev_info;
> +	struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
>  	int ratelimit;
>  	int *p;
>  
> @@ -1929,7 +1929,7 @@ continue_unlock:
>  			if (!clear_page_dirty_for_io(page))
>  				goto continue_unlock;
>  
> -			trace_wbc_writepage(wbc, mapping->backing_dev_info);
> +			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
>  			ret = (*writepage)(page, wbc, data);
>  			if (unlikely(ret)) {
>  				if (ret == AOP_WRITEPAGE_ACTIVATE) {
> @@ -2094,10 +2094,12 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)
>  	trace_writeback_dirty_page(page, mapping);
>  
>  	if (mapping_cap_account_dirty(mapping)) {
> +		struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
> +
>  		__inc_zone_page_state(page, NR_FILE_DIRTY);
>  		__inc_zone_page_state(page, NR_DIRTIED);
> -		__inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
> -		__inc_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED);
> +		__inc_bdi_stat(bdi, BDI_RECLAIMABLE);
> +		__inc_bdi_stat(bdi, BDI_DIRTIED);
>  		task_io_account_write(PAGE_CACHE_SIZE);
>  		current->nr_dirtied++;
>  		this_cpu_inc(bdp_ratelimits);
> @@ -2156,7 +2158,7 @@ void account_page_redirty(struct page *page)
>  	if (mapping && mapping_cap_account_dirty(mapping)) {
>  		current->nr_dirtied--;
>  		dec_zone_page_state(page, NR_DIRTIED);
> -		dec_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED);
> +		dec_bdi_stat(inode_to_bdi(mapping->host), BDI_DIRTIED);
>  	}
>  }
>  EXPORT_SYMBOL(account_page_redirty);
> @@ -2295,7 +2297,7 @@ int clear_page_dirty_for_io(struct page *page)
>  		 */
>  		if (TestClearPageDirty(page)) {
>  			dec_zone_page_state(page, NR_FILE_DIRTY);
> -			dec_bdi_stat(mapping->backing_dev_info,
> +			dec_bdi_stat(inode_to_bdi(mapping->host),
>  					BDI_RECLAIMABLE);
>  			return 1;
>  		}
> @@ -2315,7 +2317,7 @@ int test_clear_page_writeback(struct page *page)
>  
>  	memcg = mem_cgroup_begin_page_stat(page, &locked, &memcg_flags);
>  	if (mapping) {
> -		struct backing_dev_info *bdi = mapping->backing_dev_info;
> +		struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
>  		unsigned long flags;
>  
>  		spin_lock_irqsave(&mapping->tree_lock, flags);
> @@ -2352,7 +2354,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
>  
>  	memcg = mem_cgroup_begin_page_stat(page, &locked, &memcg_flags);
>  	if (mapping) {
> -		struct backing_dev_info *bdi = mapping->backing_dev_info;
> +		struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
>  		unsigned long flags;
>  
>  		spin_lock_irqsave(&mapping->tree_lock, flags);
> @@ -2406,12 +2408,7 @@ EXPORT_SYMBOL(mapping_tagged);
>   */
>  void wait_for_stable_page(struct page *page)
>  {
> -	struct address_space *mapping = page_mapping(page);
> -	struct backing_dev_info *bdi = mapping->backing_dev_info;
> -
> -	if (!bdi_cap_stable_pages_required(bdi))
> -		return;
> -
> -	wait_on_page_writeback(page);
> +	if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host)))
> +		wait_on_page_writeback(page);
>  }
>  EXPORT_SYMBOL_GPL(wait_for_stable_page);
> diff --git a/mm/readahead.c b/mm/readahead.c
> index 17b9172..9356758 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -27,7 +27,7 @@
>  void
>  file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
>  {
> -	ra->ra_pages = mapping->backing_dev_info->ra_pages;
> +	ra->ra_pages = inode_to_bdi(mapping->host)->ra_pages;
>  	ra->prev_pos = -1;
>  }
>  EXPORT_SYMBOL_GPL(file_ra_state_init);
> @@ -541,7 +541,7 @@ page_cache_async_readahead(struct address_space *mapping,
>  	/*
>  	 * Defer asynchronous read-ahead on IO congestion.
>  	 */
> -	if (bdi_read_congested(mapping->backing_dev_info))
> +	if (bdi_read_congested(inode_to_bdi(mapping->host)))
>  		return;
>  
>  	/* do read-ahead */
> diff --git a/mm/truncate.c b/mm/truncate.c
> index f1e4d60..ddec5a5 100644
> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -112,7 +112,7 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
>  		struct address_space *mapping = page->mapping;
>  		if (mapping && mapping_cap_account_dirty(mapping)) {
>  			dec_zone_page_state(page, NR_FILE_DIRTY);
> -			dec_bdi_stat(mapping->backing_dev_info,
> +			dec_bdi_stat(inode_to_bdi(mapping->host),
>  					BDI_RECLAIMABLE);
>  			if (account_size)
>  				task_io_account_cancelled_write(account_size);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index ab2505c..e00a163 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -497,7 +497,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
>  	}
>  	if (mapping->a_ops->writepage == NULL)
>  		return PAGE_ACTIVATE;
> -	if (!may_write_to_queue(mapping->backing_dev_info, sc))
> +	if (!may_write_to_queue(inode_to_bdi(mapping->host), sc))
>  		return PAGE_KEEP;
>  
>  	if (clear_page_dirty_for_io(page)) {
> @@ -876,7 +876,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
>  		 */
>  		mapping = page_mapping(page);
>  		if (((dirty || writeback) && mapping &&
> -		     bdi_write_congested(mapping->backing_dev_info)) ||
> +		     bdi_write_congested(inode_to_bdi(mapping->host))) ||
>  		    (writeback && PageReclaim(page)))
>  			nr_congested++;
>  
> -- 
> 1.9.1
> 
> --
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-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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