Re: [dm-devel] [PATCH 07/11] dax: remove dax_capable

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Oct 18, 2021 at 06:40:50AM +0200, Christoph Hellwig wrote:
> Just open code the block size and dax_dev == NULL checks in the callers.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/dax/super.c          | 36 ------------------------------------
>  drivers/md/dm-table.c        | 22 +++++++++++-----------
>  drivers/md/dm.c              | 21 ---------------------
>  drivers/md/dm.h              |  4 ----
>  drivers/nvdimm/pmem.c        |  1 -
>  drivers/s390/block/dcssblk.c |  1 -
>  fs/erofs/super.c             | 11 +++++++----
>  fs/ext2/super.c              |  6 ++++--
>  fs/ext4/super.c              |  9 ++++++---
>  fs/xfs/xfs_super.c           | 21 ++++++++-------------
>  include/linux/dax.h          | 14 --------------
>  11 files changed, 36 insertions(+), 110 deletions(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 482fe775324a4..803942586d1b6 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -108,42 +108,6 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
>  	return dax_dev;
>  }
>  EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> -
> -bool generic_fsdax_supported(struct dax_device *dax_dev,
> -		struct block_device *bdev, int blocksize, sector_t start,
> -		sector_t sectors)
> -{
> -	if (blocksize != PAGE_SIZE) {
> -		pr_info("%pg: error: unsupported blocksize for dax\n", bdev);
> -		return false;
> -	}
> -
> -	if (!dax_dev) {
> -		pr_debug("%pg: error: dax unsupported by block device\n", bdev);
> -		return false;
> -	}
> -
> -	return true;
> -}
> -EXPORT_SYMBOL_GPL(generic_fsdax_supported);
> -
> -bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> -		int blocksize, sector_t start, sector_t len)
> -{
> -	bool ret = false;
> -	int id;
> -
> -	if (!dax_dev)
> -		return false;
> -
> -	id = dax_read_lock();
> -	if (dax_alive(dax_dev) && dax_dev->ops->dax_supported)
> -		ret = dax_dev->ops->dax_supported(dax_dev, bdev, blocksize,
> -						  start, len);
> -	dax_read_unlock(id);
> -	return ret;
> -}
> -EXPORT_SYMBOL_GPL(dax_supported);
>  #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
>  
>  enum dax_device_flags {
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 1fa4d5582dca5..4ae671c2168ea 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -807,12 +807,14 @@ void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type)
>  EXPORT_SYMBOL_GPL(dm_table_set_type);
>  
>  /* validate the dax capability of the target device span */
> -int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
> +static int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
>  			sector_t start, sector_t len, void *data)
>  {
> -	int blocksize = *(int *) data;
> +	if (dev->dax_dev)
> +		return false;
>  
> -	return !dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
> +	pr_debug("%pg: error: dax unsupported by block device\n", dev->bdev);
> +	return true;
>  }
>  
>  /* Check devices support synchronous DAX */
> @@ -822,8 +824,8 @@ static int device_not_dax_synchronous_capable(struct dm_target *ti, struct dm_de
>  	return !dev->dax_dev || !dax_synchronous(dev->dax_dev);
>  }
>  
> -bool dm_table_supports_dax(struct dm_table *t,
> -			   iterate_devices_callout_fn iterate_fn, int *blocksize)
> +static bool dm_table_supports_dax(struct dm_table *t,
> +			   iterate_devices_callout_fn iterate_fn)
>  {
>  	struct dm_target *ti;
>  	unsigned i;
> @@ -836,7 +838,7 @@ bool dm_table_supports_dax(struct dm_table *t,
>  			return false;
>  
>  		if (!ti->type->iterate_devices ||
> -		    ti->type->iterate_devices(ti, iterate_fn, blocksize))
> +		    ti->type->iterate_devices(ti, iterate_fn, NULL))
>  			return false;
>  	}
>  
> @@ -863,7 +865,6 @@ static int dm_table_determine_type(struct dm_table *t)
>  	struct dm_target *tgt;
>  	struct list_head *devices = dm_table_get_devices(t);
>  	enum dm_queue_mode live_md_type = dm_get_md_type(t->md);
> -	int page_size = PAGE_SIZE;
>  
>  	if (t->type != DM_TYPE_NONE) {
>  		/* target already set the table's type */
> @@ -907,7 +908,7 @@ static int dm_table_determine_type(struct dm_table *t)
>  verify_bio_based:
>  		/* We must use this table as bio-based */
>  		t->type = DM_TYPE_BIO_BASED;
> -		if (dm_table_supports_dax(t, device_not_dax_capable, &page_size) ||
> +		if (dm_table_supports_dax(t, device_not_dax_capable) ||
>  		    (list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED)) {
>  			t->type = DM_TYPE_DAX_BIO_BASED;
>  		}
> @@ -1981,7 +1982,6 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
>  			      struct queue_limits *limits)
>  {
>  	bool wc = false, fua = false;
> -	int page_size = PAGE_SIZE;
>  	int r;
>  
>  	/*
> @@ -2015,9 +2015,9 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
>  	}
>  	blk_queue_write_cache(q, wc, fua);
>  
> -	if (dm_table_supports_dax(t, device_not_dax_capable, &page_size)) {
> +	if (dm_table_supports_dax(t, device_not_dax_capable)) {
>  		blk_queue_flag_set(QUEUE_FLAG_DAX, q);
> -		if (dm_table_supports_dax(t, device_not_dax_synchronous_capable, NULL))
> +		if (dm_table_supports_dax(t, device_not_dax_synchronous_capable))
>  			set_dax_synchronous(t->md->dax_dev);
>  	}
>  	else
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index a0a4703620650..f896ad29a67a7 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1027,26 +1027,6 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
>  	return ret;
>  }
>  
> -static bool dm_dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> -		int blocksize, sector_t start, sector_t len)
> -{
> -	struct mapped_device *md = dax_get_private(dax_dev);
> -	struct dm_table *map;
> -	bool ret = false;
> -	int srcu_idx;
> -
> -	map = dm_get_live_table(md, &srcu_idx);
> -	if (!map)
> -		goto out;
> -
> -	ret = dm_table_supports_dax(map, device_not_dax_capable, &blocksize);
> -
> -out:
> -	dm_put_live_table(md, srcu_idx);
> -
> -	return ret;
> -}
> -
>  static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
>  				    void *addr, size_t bytes, struct iov_iter *i)
>  {
> @@ -3050,7 +3030,6 @@ static const struct block_device_operations dm_rq_blk_dops = {
>  
>  static const struct dax_operations dm_dax_ops = {
>  	.direct_access = dm_dax_direct_access,
> -	.dax_supported = dm_dax_supported,
>  	.copy_from_iter = dm_dax_copy_from_iter,
>  	.copy_to_iter = dm_dax_copy_to_iter,
>  	.zero_page_range = dm_dax_zero_page_range,
> diff --git a/drivers/md/dm.h b/drivers/md/dm.h
> index 742d9c80efe19..9013dc1a7b002 100644
> --- a/drivers/md/dm.h
> +++ b/drivers/md/dm.h
> @@ -73,10 +73,6 @@ bool dm_table_bio_based(struct dm_table *t);
>  bool dm_table_request_based(struct dm_table *t);
>  void dm_table_free_md_mempools(struct dm_table *t);
>  struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
> -bool dm_table_supports_dax(struct dm_table *t, iterate_devices_callout_fn fn,
> -			   int *blocksize);
> -int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
> -			   sector_t start, sector_t len, void *data);
>  
>  void dm_lock_md_type(struct mapped_device *md);
>  void dm_unlock_md_type(struct mapped_device *md);
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 5628afb808f41..428a485800058 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -321,7 +321,6 @@ static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
>  
>  static const struct dax_operations pmem_dax_ops = {
>  	.direct_access = pmem_dax_direct_access,
> -	.dax_supported = generic_fsdax_supported,
>  	.copy_from_iter = pmem_copy_from_iter,
>  	.copy_to_iter = pmem_copy_to_iter,
>  	.zero_page_range = pmem_dax_zero_page_range,
> diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
> index 657e492f2bc26..e65e83764d1ce 100644
> --- a/drivers/s390/block/dcssblk.c
> +++ b/drivers/s390/block/dcssblk.c
> @@ -72,7 +72,6 @@ static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,
>  
>  static const struct dax_operations dcssblk_dax_ops = {
>  	.direct_access = dcssblk_dax_direct_access,
> -	.dax_supported = generic_fsdax_supported,
>  	.copy_from_iter = dcssblk_dax_copy_from_iter,
>  	.copy_to_iter = dcssblk_dax_copy_to_iter,
>  	.zero_page_range = dcssblk_dax_zero_page_range,
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index b8f042c3e7e67..530d7b1e0f138 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -649,10 +649,13 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>  	if (err)
>  		return err;
>  
> -	if (test_opt(&sbi->opt, DAX_ALWAYS) &&
> -	    !dax_supported(sbi->dax_dev, sb->s_bdev, EROFS_BLKSIZ, 0, bdev_nr_sectors(sb->s_bdev))) {
> -		errorfc(fc, "DAX unsupported by block device. Turning off DAX.");
> -		clear_opt(&sbi->opt, DAX_ALWAYS);
> +	if (test_opt(&sbi->opt, DAX_ALWAYS)) {
> +		BUILD_BUG_ON(EROFS_BLKSIZ != PAGE_SIZE);
> +
> +		if (!sbi->dax_dev) {
> +			errorfc(fc, "DAX unsupported by block device. Turning off DAX.");
> +			clear_opt(&sbi->opt, DAX_ALWAYS);
> +		}
>  	}
>  	sb->s_flags |= SB_RDONLY | SB_NOATIME;
>  	sb->s_maxbytes = MAX_LFS_FILESIZE;
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index d8d580b609baa..a964066a80aa7 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -946,11 +946,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
>  	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
>  
>  	if (test_opt(sb, DAX)) {
> -		if (!dax_supported(dax_dev, sb->s_bdev, blocksize, 0,
> -				bdev_nr_sectors(sb->s_bdev))) {
> +		if (!dax_dev) {
>  			ext2_msg(sb, KERN_ERR,
>  				"DAX unsupported by block device. Turning off DAX.");
>  			clear_opt(sbi->s_mount_opt, DAX);
> +		} else if (blocksize != PAGE_SIZE) {
> +			ext2_msg(sb, KERN_ERR, "unsupported blocksize for DAX\n");
> +			clear_opt(sbi->s_mount_opt, DAX);
>  		}
>  	}
>  
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 6361ea1f97bc5..f571be3a6252b 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4291,9 +4291,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  		goto failed_mount;
>  	}
>  
> -	if (dax_supported(dax_dev, sb->s_bdev, blocksize, 0,
> -			bdev_nr_sectors(sb->s_bdev)))
> -		set_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags);
> +	if (dax_dev) {
> +		if (blocksize == PAGE_SIZE)
> +			set_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags);
> +		else
> +			ext4_msg(sb, KERN_ERR, "unsupported blocksize for DAX\n");
> +	}
>  
>  	if (sbi->s_mount_opt & EXT4_MOUNT_DAX_ALWAYS) {
>  		if (ext4_has_feature_inline_data(sb)) {
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index d07020a8eb9e3..163ceafbd8fd2 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -330,28 +330,23 @@ xfs_set_inode_alloc(
>  	return xfs_is_inode32(mp) ? maxagi : agcount;
>  }
>  
> -static bool
> -xfs_buftarg_is_dax(
> -	struct super_block	*sb,
> -	struct xfs_buftarg	*bt)
> -{
> -	return dax_supported(bt->bt_daxdev, bt->bt_bdev, sb->s_blocksize, 0,
> -			bdev_nr_sectors(bt->bt_bdev));
> -}
> -
>  static int
>  xfs_setup_dax(
>  	struct xfs_mount	*mp)
>  {
> -	struct super_block	*sb = mp->m_super;
> -
> -	if (!xfs_buftarg_is_dax(sb, mp->m_ddev_targp) &&
> -	   (!mp->m_rtdev_targp || !xfs_buftarg_is_dax(sb, mp->m_rtdev_targp))) {
> +	if (!mp->m_ddev_targp->bt_daxdev &&
> +	   (!mp->m_rtdev_targp || !mp->m_rtdev_targp->bt_daxdev)) {
>  		xfs_alert(mp,
>  			"DAX unsupported by block device. Turning off DAX.");
>  		goto disable_dax;
>  	}
>  
> +	if (mp->m_super->s_blocksize != PAGE_SIZE) {
> +		xfs_alert(mp,
> +			"DAX not supported for blocksize. Turning off DAX.\n");

Newlines aren't needed at the end of extX_msg/xfs_alert format strings.

Aside from that, the fs/dax/pmem changes look good to me.  I didn't look
as carefully at the dm parts, though as an fs developer, nothing bad
stood out to me.

With the format strings fixed,

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

(Sorry I didn't notice this patch had fs changes in it until I saw that
Gao replied to it...)

--D

> +		goto disable_dax;
> +	}
> +
>  	if (xfs_has_reflink(mp)) {
>  		xfs_alert(mp, "DAX and reflink cannot be used together!");
>  		return -EINVAL;
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index e2e9a67004cbd..439c3c70e347b 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -111,12 +111,6 @@ int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
>  #if IS_ENABLED(CONFIG_FS_DAX)
>  int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk);
>  void dax_remove_host(struct gendisk *disk);
> -bool generic_fsdax_supported(struct dax_device *dax_dev,
> -		struct block_device *bdev, int blocksize, sector_t start,
> -		sector_t sectors);
> -
> -bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> -		int blocksize, sector_t start, sector_t len);
>  
>  static inline void fs_put_dax(struct dax_device *dax_dev)
>  {
> @@ -139,14 +133,6 @@ static inline int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk)
>  static inline void dax_remove_host(struct gendisk *disk)
>  {
>  }
> -#define generic_fsdax_supported		NULL
> -
> -static inline bool dax_supported(struct dax_device *dax_dev,
> -		struct block_device *bdev, int blocksize, sector_t start,
> -		sector_t len)
> -{
> -	return false;
> -}
>  
>  static inline void fs_put_dax(struct dax_device *dax_dev)
>  {
> -- 
> 2.30.2
> 
> --
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>