On Mon 26-08-19 16:33:26, Vivek Goyal wrote: > On Mon, Aug 26, 2019 at 04:53:16AM -0700, Christoph Hellwig wrote: > > On Wed, Aug 21, 2019 at 01:57:03PM -0400, Vivek Goyal wrote: > > > Right now dax_writeback_mapping_range() is passed a bdev and dax_dev > > > is searched from that bdev name. > > > > > > virtio-fs does not have a bdev. So pass in dax_dev also to > > > dax_writeback_mapping_range(). If dax_dev is passed in, bdev is not > > > used otherwise dax_dev is searched using bdev. > > > > Please just pass in only the dax_device and get rid of the block device. > > The callers should have one at hand easily, e.g. for XFS just call > > xfs_find_daxdev_for_inode instead of xfs_find_bdev_for_inode. > > Sure. Here is the updated patch. > > This patch can probably go upstream independently. If you are fine with > the patch, I can post it separately for inclusion. > > > Subject: dax: Pass dax_dev instead of bdev to dax_writeback_mapping_range() > > As of now dax_writeback_mapping_range() takes "struct block_device" as a > parameter and dax_dev is searched from bdev name. This also involves taking > a fresh reference on dax_dev and putting that reference at the end of > function. > > We are developing a new filesystem virtio-fs and using dax to access host > page cache directly. But there is no block device. IOW, we want to make > use of dax but want to get rid of this assumption that there is always > a block device associated with dax_dev. > > So pass in "struct dax_device" as parameter instead of bdev. > > ext2/ext4/xfs are current users and they already have a reference on > dax_device. So there is no need to take reference and drop reference to > dax_device on each call of this function. > > Suggested-by: Christoph Hellwig <[email protected]> > Signed-off-by: Vivek Goyal <[email protected]>
Looks good to me. You can add: Reviewed-by: Jan Kara <[email protected]> Honza > --- > fs/dax.c | 8 +------- > fs/ext2/inode.c | 5 +++-- > fs/ext4/inode.c | 2 +- > fs/xfs/xfs_aops.c | 2 +- > include/linux/dax.h | 2 +- > 5 files changed, 7 insertions(+), 12 deletions(-) > > Index: rhvgoyal-linux-fuse/fs/dax.c > =================================================================== > --- rhvgoyal-linux-fuse.orig/fs/dax.c 2019-08-26 11:20:36.545009968 -0400 > +++ rhvgoyal-linux-fuse/fs/dax.c 2019-08-26 11:24:43.973009968 -0400 > @@ -936,12 +936,11 @@ static int dax_writeback_one(struct xa_s > * on persistent storage prior to completion of the operation. > */ > int dax_writeback_mapping_range(struct address_space *mapping, > - struct block_device *bdev, struct writeback_control *wbc) > + struct dax_device *dax_dev, struct writeback_control *wbc) > { > XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT); > struct inode *inode = mapping->host; > pgoff_t end_index = wbc->range_end >> PAGE_SHIFT; > - struct dax_device *dax_dev; > void *entry; > int ret = 0; > unsigned int scanned = 0; > @@ -952,10 +951,6 @@ int dax_writeback_mapping_range(struct a > if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) > return 0; > > - dax_dev = dax_get_by_host(bdev->bd_disk->disk_name); > - if (!dax_dev) > - return -EIO; > - > trace_dax_writeback_range(inode, xas.xa_index, end_index); > > tag_pages_for_writeback(mapping, xas.xa_index, end_index); > @@ -976,7 +971,6 @@ int dax_writeback_mapping_range(struct a > xas_lock_irq(&xas); > } > xas_unlock_irq(&xas); > - put_dax(dax_dev); > trace_dax_writeback_range_done(inode, xas.xa_index, end_index); > return ret; > } > Index: rhvgoyal-linux-fuse/include/linux/dax.h > =================================================================== > --- rhvgoyal-linux-fuse.orig/include/linux/dax.h 2019-08-26 > 11:20:36.545009968 -0400 > +++ rhvgoyal-linux-fuse/include/linux/dax.h 2019-08-26 11:26:08.384009968 > -0400 > @@ -141,7 +141,7 @@ static inline void fs_put_dax(struct dax > > 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); > + struct dax_device *dax_dev, struct writeback_control *wbc); > > struct page *dax_layout_busy_page(struct address_space *mapping); > dax_entry_t dax_lock_page(struct page *page); > Index: rhvgoyal-linux-fuse/fs/xfs/xfs_aops.c > =================================================================== > --- rhvgoyal-linux-fuse.orig/fs/xfs/xfs_aops.c 2019-08-26 > 11:20:36.545009968 -0400 > +++ rhvgoyal-linux-fuse/fs/xfs/xfs_aops.c 2019-08-26 11:34:51.085009968 > -0400 > @@ -1120,7 +1120,7 @@ xfs_dax_writepages( > { > xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); > return dax_writeback_mapping_range(mapping, > - xfs_find_bdev_for_inode(mapping->host), wbc); > + xfs_find_daxdev_for_inode(mapping->host), wbc); > } > > STATIC int > Index: rhvgoyal-linux-fuse/fs/ext4/inode.c > =================================================================== > --- rhvgoyal-linux-fuse.orig/fs/ext4/inode.c 2019-08-26 11:20:36.545009968 > -0400 > +++ rhvgoyal-linux-fuse/fs/ext4/inode.c 2019-08-26 11:39:56.828009968 > -0400 > @@ -2992,7 +2992,7 @@ static int ext4_dax_writepages(struct ad > percpu_down_read(&sbi->s_journal_flag_rwsem); > trace_ext4_writepages(inode, wbc); > > - ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc); > + ret = dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc); > trace_ext4_writepages_result(inode, wbc, ret, > nr_to_write - wbc->nr_to_write); > percpu_up_read(&sbi->s_journal_flag_rwsem); > Index: rhvgoyal-linux-fuse/fs/ext2/inode.c > =================================================================== > --- rhvgoyal-linux-fuse.orig/fs/ext2/inode.c 2019-08-26 11:20:36.545009968 > -0400 > +++ rhvgoyal-linux-fuse/fs/ext2/inode.c 2019-08-26 11:43:04.842009968 > -0400 > @@ -957,8 +957,9 @@ ext2_writepages(struct address_space *ma > static int > ext2_dax_writepages(struct address_space *mapping, struct writeback_control > *wbc) > { > - return dax_writeback_mapping_range(mapping, > - mapping->host->i_sb->s_bdev, wbc); > + struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb); > + > + return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc); > } > > const struct address_space_operations ext2_aops = { -- Jan Kara <[email protected]> SUSE Labs, CR
