diff mbox series

[v5,5/7] fsdax: Dedup file range to use a compare function

Message ID 20210511030933.3080921-6-ruansy.fnst@fujitsu.com (mailing list archive)
State New
Headers show
Series fsdax,xfs: Add reflink&dedupe support for fsdax | expand

Commit Message

ruansy.fnst@fujitsu.com May 11, 2021, 3:09 a.m. UTC
With dax we cannot deal with readpage() etc. So, we create a dax
comparison funciton which is similar with
vfs_dedupe_file_range_compare().
And introduce dax_remap_file_range_prep() for filesystem use.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
 fs/dax.c             | 56 +++++++++++++++++++++++++++++++++++++++++++
 fs/remap_range.c     | 57 +++++++++++++++++++++++++++++++++++++-------
 fs/xfs/xfs_reflink.c |  8 +++++--
 include/linux/dax.h  |  4 ++++
 include/linux/fs.h   | 12 ++++++----
 5 files changed, 123 insertions(+), 14 deletions(-)

Comments

Darrick J. Wong May 12, 2021, 1:23 a.m. UTC | #1
On Tue, May 11, 2021 at 11:09:31AM +0800, Shiyang Ruan wrote:
> With dax we cannot deal with readpage() etc. So, we create a dax
> comparison funciton which is similar with
> vfs_dedupe_file_range_compare().
> And introduce dax_remap_file_range_prep() for filesystem use.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> ---
>  fs/dax.c             | 56 +++++++++++++++++++++++++++++++++++++++++++
>  fs/remap_range.c     | 57 +++++++++++++++++++++++++++++++++++++-------
>  fs/xfs/xfs_reflink.c |  8 +++++--
>  include/linux/dax.h  |  4 ++++
>  include/linux/fs.h   | 12 ++++++----
>  5 files changed, 123 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index ee9d28a79bfb..dedf1be0155c 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1853,3 +1853,59 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
>  	return dax_insert_pfn_mkwrite(vmf, pfn, order);
>  }
>  EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
> +
> +static loff_t dax_range_compare_actor(struct inode *ino1, loff_t pos1,
> +		struct inode *ino2, loff_t pos2, loff_t len, void *data,
> +		struct iomap *smap, struct iomap *dmap)
> +{
> +	void *saddr, *daddr;
> +	bool *same = data;
> +	int ret;
> +
> +	if (smap->type == IOMAP_HOLE && dmap->type == IOMAP_HOLE) {
> +		*same = true;
> +		return len;
> +	}
> +
> +	if (smap->type == IOMAP_HOLE || dmap->type == IOMAP_HOLE) {
> +		*same = false;
> +		return 0;
> +	}
> +
> +	ret = dax_iomap_direct_access(smap, pos1, ALIGN(pos1 + len, PAGE_SIZE),
> +				      &saddr, NULL);
> +	if (ret < 0)
> +		return -EIO;
> +
> +	ret = dax_iomap_direct_access(dmap, pos2, ALIGN(pos2 + len, PAGE_SIZE),
> +				      &daddr, NULL);
> +	if (ret < 0)
> +		return -EIO;
> +
> +	*same = !memcmp(saddr, daddr, len);
> +	return len;
> +}
> +
> +int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> +		struct inode *dest, loff_t destoff, loff_t len, bool *is_same,
> +		const struct iomap_ops *ops)
> +{
> +	int id, ret = 0;
> +
> +	id = dax_read_lock();
> +	while (len) {
> +		ret = iomap_apply2(src, srcoff, dest, destoff, len, 0, ops,
> +				   is_same, dax_range_compare_actor);
> +		if (ret < 0 || !*is_same)
> +			goto out;
> +
> +		len -= ret;
> +		srcoff += ret;
> +		destoff += ret;
> +	}
> +	ret = 0;
> +out:
> +	dax_read_unlock(id);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dax_dedupe_file_range_compare);
> diff --git a/fs/remap_range.c b/fs/remap_range.c
> index e4a5fdd7ad7b..7bc4c8e3aa9f 100644
> --- a/fs/remap_range.c
> +++ b/fs/remap_range.c
> @@ -14,6 +14,7 @@
>  #include <linux/compat.h>
>  #include <linux/mount.h>
>  #include <linux/fs.h>
> +#include <linux/dax.h>
>  #include "internal.h"
>  
>  #include <linux/uaccess.h>
> @@ -199,9 +200,9 @@ static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
>   * Compare extents of two files to see if they are the same.
>   * Caller must have locked both inodes to prevent write races.
>   */
> -static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> -					 struct inode *dest, loff_t destoff,
> -					 loff_t len, bool *is_same)
> +int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> +				  struct inode *dest, loff_t destoff,
> +				  loff_t len, bool *is_same)
>  {
>  	loff_t src_poff;
>  	loff_t dest_poff;
> @@ -280,6 +281,7 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
>  out_error:
>  	return error;
>  }
> +EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
>  
>  /*
>   * Check that the two inodes are eligible for cloning, the ranges make
> @@ -289,9 +291,11 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
>   * If there's an error, then the usual negative error code is returned.
>   * Otherwise returns 0 with *len set to the request length.
>   */
> -int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> -				  struct file *file_out, loff_t pos_out,
> -				  loff_t *len, unsigned int remap_flags)
> +static int
> +__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> +				struct file *file_out, loff_t pos_out,
> +				loff_t *len, unsigned int remap_flags,
> +				const struct iomap_ops *dax_read_ops)
>  {
>  	struct inode *inode_in = file_inode(file_in);
>  	struct inode *inode_out = file_inode(file_out);
> @@ -351,8 +355,17 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
>  	if (remap_flags & REMAP_FILE_DEDUP) {
>  		bool		is_same = false;
>  
> -		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> -				inode_out, pos_out, *len, &is_same);
> +		if (!IS_DAX(inode_in))
> +			ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> +					inode_out, pos_out, *len, &is_same);
> +#ifdef CONFIG_FS_DAX
> +		else if (dax_read_ops)
> +			ret = dax_dedupe_file_range_compare(inode_in, pos_in,
> +					inode_out, pos_out, *len, &is_same,
> +					dax_read_ops);
> +#endif /* CONFIG_FS_DAX */

Hmm, can you add an entry to the !IS_ENABLED(CONFIG_DAX) part of dax.h
that defines dax_dedupe_file_range_compare as a dummy function that
returns -EOPNOTSUPP?  We try not to sprinkle preprocessor directives
into the middle of functions, per Linus rules.

> +		else
> +			return -EINVAL;
>  		if (ret)
>  			return ret;
>  		if (!is_same)
> @@ -370,6 +383,34 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
>  
>  	return ret;
>  }
> +
> +#ifdef CONFIG_FS_DAX
> +int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> +			      struct file *file_out, loff_t pos_out,
> +			      loff_t *len, unsigned int remap_flags,
> +			      const struct iomap_ops *ops)
> +{
> +	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
> +					       pos_out, len, remap_flags, ops);
> +}
> +#else
> +int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> +			      struct file *file_out, loff_t pos_out,
> +			      loff_t *len, unsigned int remap_flags,
> +			      const struct iomap_ops *ops)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif /* CONFIG_FS_DAX */
> +EXPORT_SYMBOL(dax_remap_file_range_prep);

I think this symbol belongs in fs/dax.c and the declaration in dax.h?

--D

> +int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> +				  struct file *file_out, loff_t pos_out,
> +				  loff_t *len, unsigned int remap_flags)
> +{
> +	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
> +					       pos_out, len, remap_flags, NULL);
> +}
>  EXPORT_SYMBOL(generic_remap_file_range_prep);
>  
>  loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 060695d6d56a..d25434f93235 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1329,8 +1329,12 @@ xfs_reflink_remap_prep(
>  	if (IS_DAX(inode_in) || IS_DAX(inode_out))
>  		goto out_unlock;
>  
> -	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> -			len, remap_flags);
> +	if (!IS_DAX(inode_in))
> +		ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
> +				pos_out, len, remap_flags);
> +	else
> +		ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
> +				pos_out, len, remap_flags, &xfs_read_iomap_ops);
>  	if (ret || *len == 0)
>  		goto out_unlock;
>  
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 3275e01ed33d..32e1c34349f2 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -239,6 +239,10 @@ int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
>  				      pgoff_t index);
>  s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
>  		struct iomap *srcmap);
> +int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> +				  struct inode *dest, loff_t destoff,
> +				  loff_t len, bool *is_same,
> +				  const struct iomap_ops *ops);
>  static inline bool dax_mapping(struct address_space *mapping)
>  {
>  	return mapping->host && IS_DAX(mapping->host);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index c3c88fdb9b2a..e2c348553d87 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -71,6 +71,7 @@ struct fsverity_operations;
>  struct fs_context;
>  struct fs_parameter_spec;
>  struct fileattr;
> +struct iomap_ops;
>  
>  extern void __init inode_init(void);
>  extern void __init inode_init_early(void);
> @@ -2126,10 +2127,13 @@ extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
>  extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
>  				       struct file *file_out, loff_t pos_out,
>  				       size_t len, unsigned int flags);
> -extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> -					 struct file *file_out, loff_t pos_out,
> -					 loff_t *count,
> -					 unsigned int remap_flags);
> +int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> +				  struct file *file_out, loff_t pos_out,
> +				  loff_t *count, unsigned int remap_flags);
> +int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> +			      struct file *file_out, loff_t pos_out,
> +			      loff_t *len, unsigned int remap_flags,
> +			      const struct iomap_ops *ops);
>  extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
>  				  struct file *file_out, loff_t pos_out,
>  				  loff_t len, unsigned int remap_flags);
> -- 
> 2.31.1
> 
> 
>
ruansy.fnst@fujitsu.com May 14, 2021, 8:35 a.m. UTC | #2
> -----Original Message-----
> From: Darrick J. Wong <djwong@kernel.org>
> Subject: Re: [PATCH v5 5/7] fsdax: Dedup file range to use a compare function
> 
> On Tue, May 11, 2021 at 11:09:31AM +0800, Shiyang Ruan wrote:
> > With dax we cannot deal with readpage() etc. So, we create a dax
> > comparison funciton which is similar with
> > vfs_dedupe_file_range_compare().
> > And introduce dax_remap_file_range_prep() for filesystem use.
> >
> > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> > ---
> >  fs/dax.c             | 56
> +++++++++++++++++++++++++++++++++++++++++++
> >  fs/remap_range.c     | 57
> +++++++++++++++++++++++++++++++++++++-------
> >  fs/xfs/xfs_reflink.c |  8 +++++--
> >  include/linux/dax.h  |  4 ++++
> >  include/linux/fs.h   | 12 ++++++----
> >  5 files changed, 123 insertions(+), 14 deletions(-)
> >
> > diff --git a/fs/dax.c b/fs/dax.c
> > index ee9d28a79bfb..dedf1be0155c 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -1853,3 +1853,59 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault
> *vmf,
> >  	return dax_insert_pfn_mkwrite(vmf, pfn, order);  }
> > EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
> > +
> > +static loff_t dax_range_compare_actor(struct inode *ino1, loff_t pos1,
> > +		struct inode *ino2, loff_t pos2, loff_t len, void *data,
> > +		struct iomap *smap, struct iomap *dmap) {
> > +	void *saddr, *daddr;
> > +	bool *same = data;
> > +	int ret;
> > +
> > +	if (smap->type == IOMAP_HOLE && dmap->type == IOMAP_HOLE) {
> > +		*same = true;
> > +		return len;
> > +	}
> > +
> > +	if (smap->type == IOMAP_HOLE || dmap->type == IOMAP_HOLE) {
> > +		*same = false;
> > +		return 0;
> > +	}
> > +
> > +	ret = dax_iomap_direct_access(smap, pos1, ALIGN(pos1 + len, PAGE_SIZE),
> > +				      &saddr, NULL);
> > +	if (ret < 0)
> > +		return -EIO;
> > +
> > +	ret = dax_iomap_direct_access(dmap, pos2, ALIGN(pos2 + len, PAGE_SIZE),
> > +				      &daddr, NULL);
> > +	if (ret < 0)
> > +		return -EIO;
> > +
> > +	*same = !memcmp(saddr, daddr, len);
> > +	return len;
> > +}
> > +
> > +int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > +		struct inode *dest, loff_t destoff, loff_t len, bool *is_same,
> > +		const struct iomap_ops *ops)
> > +{
> > +	int id, ret = 0;
> > +
> > +	id = dax_read_lock();
> > +	while (len) {
> > +		ret = iomap_apply2(src, srcoff, dest, destoff, len, 0, ops,
> > +				   is_same, dax_range_compare_actor);
> > +		if (ret < 0 || !*is_same)
> > +			goto out;
> > +
> > +		len -= ret;
> > +		srcoff += ret;
> > +		destoff += ret;
> > +	}
> > +	ret = 0;
> > +out:
> > +	dax_read_unlock(id);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dax_dedupe_file_range_compare);
> > diff --git a/fs/remap_range.c b/fs/remap_range.c index
> > e4a5fdd7ad7b..7bc4c8e3aa9f 100644
> > --- a/fs/remap_range.c
> > +++ b/fs/remap_range.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/compat.h>
> >  #include <linux/mount.h>
> >  #include <linux/fs.h>
> > +#include <linux/dax.h>
> >  #include "internal.h"
> >
> >  #include <linux/uaccess.h>
> > @@ -199,9 +200,9 @@ static void vfs_unlock_two_pages(struct page *page1,
> struct page *page2)
> >   * Compare extents of two files to see if they are the same.
> >   * Caller must have locked both inodes to prevent write races.
> >   */
> > -static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > -					 struct inode *dest, loff_t destoff,
> > -					 loff_t len, bool *is_same)
> > +int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > +				  struct inode *dest, loff_t destoff,
> > +				  loff_t len, bool *is_same)
> >  {
> >  	loff_t src_poff;
> >  	loff_t dest_poff;
> > @@ -280,6 +281,7 @@ static int vfs_dedupe_file_range_compare(struct
> > inode *src, loff_t srcoff,
> >  out_error:
> >  	return error;
> >  }
> > +EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
> >
> >  /*
> >   * Check that the two inodes are eligible for cloning, the ranges
> > make @@ -289,9 +291,11 @@ static int
> vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> >   * If there's an error, then the usual negative error code is returned.
> >   * Otherwise returns 0 with *len set to the request length.
> >   */
> > -int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > -				  struct file *file_out, loff_t pos_out,
> > -				  loff_t *len, unsigned int remap_flags)
> > +static int
> > +__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > +				struct file *file_out, loff_t pos_out,
> > +				loff_t *len, unsigned int remap_flags,
> > +				const struct iomap_ops *dax_read_ops)
> >  {
> >  	struct inode *inode_in = file_inode(file_in);
> >  	struct inode *inode_out = file_inode(file_out); @@ -351,8 +355,17 @@
> > int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> >  	if (remap_flags & REMAP_FILE_DEDUP) {
> >  		bool		is_same = false;
> >
> > -		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> > -				inode_out, pos_out, *len, &is_same);
> > +		if (!IS_DAX(inode_in))
> > +			ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> > +					inode_out, pos_out, *len, &is_same); #ifdef
> CONFIG_FS_DAX
> > +		else if (dax_read_ops)
> > +			ret = dax_dedupe_file_range_compare(inode_in, pos_in,
> > +					inode_out, pos_out, *len, &is_same,
> > +					dax_read_ops);
> > +#endif /* CONFIG_FS_DAX */
> 
> Hmm, can you add an entry to the !IS_ENABLED(CONFIG_DAX) part of dax.h
> that defines dax_dedupe_file_range_compare as a dummy function that returns
> -EOPNOTSUPP?  We try not to sprinkle preprocessor directives into the middle
> of functions, per Linus rules.

I found that it's ok to build without the #ifdef and #endif here, even though CONFIG_FS_DAX is disabled.
And like other dax functions in fs/dax.c, such as dax_iomap_rw(), it is declared in include/linux/dax.h without IS_ENABLED() or #ifdef wrapped.  And xfs calls it directly and it won't cause build error.  So, I think I could just remove the #ifdef here, but I am not sure if this obeys the rule.

> 
> > +		else
> > +			return -EINVAL;
> >  		if (ret)
> >  			return ret;
> >  		if (!is_same)
> > @@ -370,6 +383,34 @@ int generic_remap_file_range_prep(struct file
> > *file_in, loff_t pos_in,
> >
> >  	return ret;
> >  }
> > +
> > +#ifdef CONFIG_FS_DAX
> > +int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > +			      struct file *file_out, loff_t pos_out,
> > +			      loff_t *len, unsigned int remap_flags,
> > +			      const struct iomap_ops *ops) {
> > +	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
> > +					       pos_out, len, remap_flags, ops); } #else int
> > +dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > +			      struct file *file_out, loff_t pos_out,
> > +			      loff_t *len, unsigned int remap_flags,
> > +			      const struct iomap_ops *ops) {
> > +	return -EOPNOTSUPP;
> > +}
> > +#endif /* CONFIG_FS_DAX */
> > +EXPORT_SYMBOL(dax_remap_file_range_prep);
> 
> I think this symbol belongs in fs/dax.c and the declaration in dax.h?

For the function name, it does should belong to fs/dax.  But if so, __generic_remap_file_range_prep() needs to be called in fs/dax.  I don't think this is good.


--
Thanks,
Ruan Shiyang.

> 
> --D
> 
> > +int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > +				  struct file *file_out, loff_t pos_out,
> > +				  loff_t *len, unsigned int remap_flags) {
> > +	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
> > +					       pos_out, len, remap_flags, NULL); }
> >  EXPORT_SYMBOL(generic_remap_file_range_prep);
> >
> >  loff_t do_clone_file_range(struct file *file_in, loff_t pos_in, diff
> > --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index
> > 060695d6d56a..d25434f93235 100644
> > --- a/fs/xfs/xfs_reflink.c
> > +++ b/fs/xfs/xfs_reflink.c
> > @@ -1329,8 +1329,12 @@ xfs_reflink_remap_prep(
> >  	if (IS_DAX(inode_in) || IS_DAX(inode_out))
> >  		goto out_unlock;
> >
> > -	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> > -			len, remap_flags);
> > +	if (!IS_DAX(inode_in))
> > +		ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
> > +				pos_out, len, remap_flags);
> > +	else
> > +		ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
> > +				pos_out, len, remap_flags, &xfs_read_iomap_ops);
> >  	if (ret || *len == 0)
> >  		goto out_unlock;
> >
> > diff --git a/include/linux/dax.h b/include/linux/dax.h index
> > 3275e01ed33d..32e1c34349f2 100644
> > --- a/include/linux/dax.h
> > +++ b/include/linux/dax.h
> > @@ -239,6 +239,10 @@ int dax_invalidate_mapping_entry_sync(struct
> address_space *mapping,
> >  				      pgoff_t index);
> >  s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
> >  		struct iomap *srcmap);
> > +int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > +				  struct inode *dest, loff_t destoff,
> > +				  loff_t len, bool *is_same,
> > +				  const struct iomap_ops *ops);
> >  static inline bool dax_mapping(struct address_space *mapping)  {
> >  	return mapping->host && IS_DAX(mapping->host); diff --git
> > a/include/linux/fs.h b/include/linux/fs.h index
> > c3c88fdb9b2a..e2c348553d87 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -71,6 +71,7 @@ struct fsverity_operations;  struct fs_context;
> > struct fs_parameter_spec;  struct fileattr;
> > +struct iomap_ops;
> >
> >  extern void __init inode_init(void);
> >  extern void __init inode_init_early(void); @@ -2126,10 +2127,13 @@
> > extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file
> > *,  extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
> >  				       struct file *file_out, loff_t pos_out,
> >  				       size_t len, unsigned int flags); -extern int
> > generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > -					 struct file *file_out, loff_t pos_out,
> > -					 loff_t *count,
> > -					 unsigned int remap_flags);
> > +int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > +				  struct file *file_out, loff_t pos_out,
> > +				  loff_t *count, unsigned int remap_flags); int
> > +dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > +			      struct file *file_out, loff_t pos_out,
> > +			      loff_t *len, unsigned int remap_flags,
> > +			      const struct iomap_ops *ops);
> >  extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
> >  				  struct file *file_out, loff_t pos_out,
> >  				  loff_t len, unsigned int remap_flags);
> > --
> > 2.31.1
> >
> >
> >
Darrick J. Wong May 14, 2021, 4:03 p.m. UTC | #3
On Fri, May 14, 2021 at 08:35:44AM +0000, ruansy.fnst@fujitsu.com wrote:
> 
> 
> > -----Original Message-----
> > From: Darrick J. Wong <djwong@kernel.org>
> > Subject: Re: [PATCH v5 5/7] fsdax: Dedup file range to use a compare function
> > 
> > On Tue, May 11, 2021 at 11:09:31AM +0800, Shiyang Ruan wrote:
> > > With dax we cannot deal with readpage() etc. So, we create a dax
> > > comparison funciton which is similar with
> > > vfs_dedupe_file_range_compare().
> > > And introduce dax_remap_file_range_prep() for filesystem use.
> > >
> > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> > > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> > > ---
> > >  fs/dax.c             | 56
> > +++++++++++++++++++++++++++++++++++++++++++
> > >  fs/remap_range.c     | 57
> > +++++++++++++++++++++++++++++++++++++-------
> > >  fs/xfs/xfs_reflink.c |  8 +++++--
> > >  include/linux/dax.h  |  4 ++++
> > >  include/linux/fs.h   | 12 ++++++----
> > >  5 files changed, 123 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/fs/dax.c b/fs/dax.c
> > > index ee9d28a79bfb..dedf1be0155c 100644
> > > --- a/fs/dax.c
> > > +++ b/fs/dax.c
> > > @@ -1853,3 +1853,59 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault
> > *vmf,
> > >  	return dax_insert_pfn_mkwrite(vmf, pfn, order);  }
> > > EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
> > > +
> > > +static loff_t dax_range_compare_actor(struct inode *ino1, loff_t pos1,
> > > +		struct inode *ino2, loff_t pos2, loff_t len, void *data,
> > > +		struct iomap *smap, struct iomap *dmap) {
> > > +	void *saddr, *daddr;
> > > +	bool *same = data;
> > > +	int ret;
> > > +
> > > +	if (smap->type == IOMAP_HOLE && dmap->type == IOMAP_HOLE) {
> > > +		*same = true;
> > > +		return len;
> > > +	}
> > > +
> > > +	if (smap->type == IOMAP_HOLE || dmap->type == IOMAP_HOLE) {
> > > +		*same = false;
> > > +		return 0;
> > > +	}
> > > +
> > > +	ret = dax_iomap_direct_access(smap, pos1, ALIGN(pos1 + len, PAGE_SIZE),
> > > +				      &saddr, NULL);
> > > +	if (ret < 0)
> > > +		return -EIO;
> > > +
> > > +	ret = dax_iomap_direct_access(dmap, pos2, ALIGN(pos2 + len, PAGE_SIZE),
> > > +				      &daddr, NULL);
> > > +	if (ret < 0)
> > > +		return -EIO;
> > > +
> > > +	*same = !memcmp(saddr, daddr, len);
> > > +	return len;
> > > +}
> > > +
> > > +int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > > +		struct inode *dest, loff_t destoff, loff_t len, bool *is_same,
> > > +		const struct iomap_ops *ops)
> > > +{
> > > +	int id, ret = 0;
> > > +
> > > +	id = dax_read_lock();
> > > +	while (len) {
> > > +		ret = iomap_apply2(src, srcoff, dest, destoff, len, 0, ops,
> > > +				   is_same, dax_range_compare_actor);
> > > +		if (ret < 0 || !*is_same)
> > > +			goto out;
> > > +
> > > +		len -= ret;
> > > +		srcoff += ret;
> > > +		destoff += ret;
> > > +	}
> > > +	ret = 0;
> > > +out:
> > > +	dax_read_unlock(id);
> > > +	return ret;
> > > +}
> > > +EXPORT_SYMBOL_GPL(dax_dedupe_file_range_compare);
> > > diff --git a/fs/remap_range.c b/fs/remap_range.c index
> > > e4a5fdd7ad7b..7bc4c8e3aa9f 100644
> > > --- a/fs/remap_range.c
> > > +++ b/fs/remap_range.c
> > > @@ -14,6 +14,7 @@
> > >  #include <linux/compat.h>
> > >  #include <linux/mount.h>
> > >  #include <linux/fs.h>
> > > +#include <linux/dax.h>
> > >  #include "internal.h"
> > >
> > >  #include <linux/uaccess.h>
> > > @@ -199,9 +200,9 @@ static void vfs_unlock_two_pages(struct page *page1,
> > struct page *page2)
> > >   * Compare extents of two files to see if they are the same.
> > >   * Caller must have locked both inodes to prevent write races.
> > >   */
> > > -static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > > -					 struct inode *dest, loff_t destoff,
> > > -					 loff_t len, bool *is_same)
> > > +int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > > +				  struct inode *dest, loff_t destoff,
> > > +				  loff_t len, bool *is_same)
> > >  {
> > >  	loff_t src_poff;
> > >  	loff_t dest_poff;
> > > @@ -280,6 +281,7 @@ static int vfs_dedupe_file_range_compare(struct
> > > inode *src, loff_t srcoff,
> > >  out_error:
> > >  	return error;
> > >  }
> > > +EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
> > >
> > >  /*
> > >   * Check that the two inodes are eligible for cloning, the ranges
> > > make @@ -289,9 +291,11 @@ static int
> > vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > >   * If there's an error, then the usual negative error code is returned.
> > >   * Otherwise returns 0 with *len set to the request length.
> > >   */
> > > -int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > -				  struct file *file_out, loff_t pos_out,
> > > -				  loff_t *len, unsigned int remap_flags)
> > > +static int
> > > +__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > +				struct file *file_out, loff_t pos_out,
> > > +				loff_t *len, unsigned int remap_flags,
> > > +				const struct iomap_ops *dax_read_ops)
> > >  {
> > >  	struct inode *inode_in = file_inode(file_in);
> > >  	struct inode *inode_out = file_inode(file_out); @@ -351,8 +355,17 @@
> > > int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > >  	if (remap_flags & REMAP_FILE_DEDUP) {
> > >  		bool		is_same = false;
> > >
> > > -		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> > > -				inode_out, pos_out, *len, &is_same);
> > > +		if (!IS_DAX(inode_in))
> > > +			ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> > > +					inode_out, pos_out, *len, &is_same); #ifdef
> > CONFIG_FS_DAX
> > > +		else if (dax_read_ops)
> > > +			ret = dax_dedupe_file_range_compare(inode_in, pos_in,
> > > +					inode_out, pos_out, *len, &is_same,
> > > +					dax_read_ops);
> > > +#endif /* CONFIG_FS_DAX */
> > 
> > Hmm, can you add an entry to the !IS_ENABLED(CONFIG_DAX) part of dax.h
> > that defines dax_dedupe_file_range_compare as a dummy function that returns
> > -EOPNOTSUPP?  We try not to sprinkle preprocessor directives into the middle
> > of functions, per Linus rules.
> 
> I found that it's ok to build without the #ifdef and #endif here, even
> though CONFIG_FS_DAX is disabled.
> And like other dax functions in fs/dax.c, such as dax_iomap_rw(), it
> is declared in include/linux/dax.h without IS_ENABLED() or #ifdef
> wrapped.  And xfs calls it directly and it won't cause build error.
> So, I think I could just remove the #ifdef here, but I am not sure if
> this obeys the rule.

If it doesn't break the build (yay kbuild robot!) then it's probably
ok.

> > 
> > > +		else
> > > +			return -EINVAL;
> > >  		if (ret)
> > >  			return ret;
> > >  		if (!is_same)
> > > @@ -370,6 +383,34 @@ int generic_remap_file_range_prep(struct file
> > > *file_in, loff_t pos_in,
> > >
> > >  	return ret;
> > >  }
> > > +
> > > +#ifdef CONFIG_FS_DAX
> > > +int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > +			      struct file *file_out, loff_t pos_out,
> > > +			      loff_t *len, unsigned int remap_flags,
> > > +			      const struct iomap_ops *ops) {
> > > +	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
> > > +					       pos_out, len, remap_flags, ops); } #else int
> > > +dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > +			      struct file *file_out, loff_t pos_out,
> > > +			      loff_t *len, unsigned int remap_flags,
> > > +			      const struct iomap_ops *ops) {
> > > +	return -EOPNOTSUPP;
> > > +}
> > > +#endif /* CONFIG_FS_DAX */
> > > +EXPORT_SYMBOL(dax_remap_file_range_prep);
> > 
> > I think this symbol belongs in fs/dax.c and the declaration in dax.h?
> 
> For the function name, it does should belong to fs/dax.  But if so,
> __generic_remap_file_range_prep() needs to be called in fs/dax.  I
> don't think this is good.

Why not?  FS_DAX is a boolean, so fs/dax.o will get linked into the same
vmlinux file as fs/remap_range.o.

--D

> 
> 
> --
> Thanks,
> Ruan Shiyang.
> 
> > 
> > --D
> > 
> > > +int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > +				  struct file *file_out, loff_t pos_out,
> > > +				  loff_t *len, unsigned int remap_flags) {
> > > +	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
> > > +					       pos_out, len, remap_flags, NULL); }
> > >  EXPORT_SYMBOL(generic_remap_file_range_prep);
> > >
> > >  loff_t do_clone_file_range(struct file *file_in, loff_t pos_in, diff
> > > --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index
> > > 060695d6d56a..d25434f93235 100644
> > > --- a/fs/xfs/xfs_reflink.c
> > > +++ b/fs/xfs/xfs_reflink.c
> > > @@ -1329,8 +1329,12 @@ xfs_reflink_remap_prep(
> > >  	if (IS_DAX(inode_in) || IS_DAX(inode_out))
> > >  		goto out_unlock;
> > >
> > > -	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> > > -			len, remap_flags);
> > > +	if (!IS_DAX(inode_in))
> > > +		ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
> > > +				pos_out, len, remap_flags);
> > > +	else
> > > +		ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
> > > +				pos_out, len, remap_flags, &xfs_read_iomap_ops);
> > >  	if (ret || *len == 0)
> > >  		goto out_unlock;
> > >
> > > diff --git a/include/linux/dax.h b/include/linux/dax.h index
> > > 3275e01ed33d..32e1c34349f2 100644
> > > --- a/include/linux/dax.h
> > > +++ b/include/linux/dax.h
> > > @@ -239,6 +239,10 @@ int dax_invalidate_mapping_entry_sync(struct
> > address_space *mapping,
> > >  				      pgoff_t index);
> > >  s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
> > >  		struct iomap *srcmap);
> > > +int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > > +				  struct inode *dest, loff_t destoff,
> > > +				  loff_t len, bool *is_same,
> > > +				  const struct iomap_ops *ops);
> > >  static inline bool dax_mapping(struct address_space *mapping)  {
> > >  	return mapping->host && IS_DAX(mapping->host); diff --git
> > > a/include/linux/fs.h b/include/linux/fs.h index
> > > c3c88fdb9b2a..e2c348553d87 100644
> > > --- a/include/linux/fs.h
> > > +++ b/include/linux/fs.h
> > > @@ -71,6 +71,7 @@ struct fsverity_operations;  struct fs_context;
> > > struct fs_parameter_spec;  struct fileattr;
> > > +struct iomap_ops;
> > >
> > >  extern void __init inode_init(void);
> > >  extern void __init inode_init_early(void); @@ -2126,10 +2127,13 @@
> > > extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file
> > > *,  extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
> > >  				       struct file *file_out, loff_t pos_out,
> > >  				       size_t len, unsigned int flags); -extern int
> > > generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > -					 struct file *file_out, loff_t pos_out,
> > > -					 loff_t *count,
> > > -					 unsigned int remap_flags);
> > > +int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > +				  struct file *file_out, loff_t pos_out,
> > > +				  loff_t *count, unsigned int remap_flags); int
> > > +dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> > > +			      struct file *file_out, loff_t pos_out,
> > > +			      loff_t *len, unsigned int remap_flags,
> > > +			      const struct iomap_ops *ops);
> > >  extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
> > >  				  struct file *file_out, loff_t pos_out,
> > >  				  loff_t len, unsigned int remap_flags);
> > > --
> > > 2.31.1
> > >
> > >
> > >
diff mbox series

Patch

diff --git a/fs/dax.c b/fs/dax.c
index ee9d28a79bfb..dedf1be0155c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1853,3 +1853,59 @@  vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
 	return dax_insert_pfn_mkwrite(vmf, pfn, order);
 }
 EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
+
+static loff_t dax_range_compare_actor(struct inode *ino1, loff_t pos1,
+		struct inode *ino2, loff_t pos2, loff_t len, void *data,
+		struct iomap *smap, struct iomap *dmap)
+{
+	void *saddr, *daddr;
+	bool *same = data;
+	int ret;
+
+	if (smap->type == IOMAP_HOLE && dmap->type == IOMAP_HOLE) {
+		*same = true;
+		return len;
+	}
+
+	if (smap->type == IOMAP_HOLE || dmap->type == IOMAP_HOLE) {
+		*same = false;
+		return 0;
+	}
+
+	ret = dax_iomap_direct_access(smap, pos1, ALIGN(pos1 + len, PAGE_SIZE),
+				      &saddr, NULL);
+	if (ret < 0)
+		return -EIO;
+
+	ret = dax_iomap_direct_access(dmap, pos2, ALIGN(pos2 + len, PAGE_SIZE),
+				      &daddr, NULL);
+	if (ret < 0)
+		return -EIO;
+
+	*same = !memcmp(saddr, daddr, len);
+	return len;
+}
+
+int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
+		struct inode *dest, loff_t destoff, loff_t len, bool *is_same,
+		const struct iomap_ops *ops)
+{
+	int id, ret = 0;
+
+	id = dax_read_lock();
+	while (len) {
+		ret = iomap_apply2(src, srcoff, dest, destoff, len, 0, ops,
+				   is_same, dax_range_compare_actor);
+		if (ret < 0 || !*is_same)
+			goto out;
+
+		len -= ret;
+		srcoff += ret;
+		destoff += ret;
+	}
+	ret = 0;
+out:
+	dax_read_unlock(id);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dax_dedupe_file_range_compare);
diff --git a/fs/remap_range.c b/fs/remap_range.c
index e4a5fdd7ad7b..7bc4c8e3aa9f 100644
--- a/fs/remap_range.c
+++ b/fs/remap_range.c
@@ -14,6 +14,7 @@ 
 #include <linux/compat.h>
 #include <linux/mount.h>
 #include <linux/fs.h>
+#include <linux/dax.h>
 #include "internal.h"
 
 #include <linux/uaccess.h>
@@ -199,9 +200,9 @@  static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
  * Compare extents of two files to see if they are the same.
  * Caller must have locked both inodes to prevent write races.
  */
-static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
-					 struct inode *dest, loff_t destoff,
-					 loff_t len, bool *is_same)
+int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
+				  struct inode *dest, loff_t destoff,
+				  loff_t len, bool *is_same)
 {
 	loff_t src_poff;
 	loff_t dest_poff;
@@ -280,6 +281,7 @@  static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
 out_error:
 	return error;
 }
+EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
 
 /*
  * Check that the two inodes are eligible for cloning, the ranges make
@@ -289,9 +291,11 @@  static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
  * If there's an error, then the usual negative error code is returned.
  * Otherwise returns 0 with *len set to the request length.
  */
-int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
-				  struct file *file_out, loff_t pos_out,
-				  loff_t *len, unsigned int remap_flags)
+static int
+__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				loff_t *len, unsigned int remap_flags,
+				const struct iomap_ops *dax_read_ops)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
@@ -351,8 +355,17 @@  int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 	if (remap_flags & REMAP_FILE_DEDUP) {
 		bool		is_same = false;
 
-		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
-				inode_out, pos_out, *len, &is_same);
+		if (!IS_DAX(inode_in))
+			ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
+					inode_out, pos_out, *len, &is_same);
+#ifdef CONFIG_FS_DAX
+		else if (dax_read_ops)
+			ret = dax_dedupe_file_range_compare(inode_in, pos_in,
+					inode_out, pos_out, *len, &is_same,
+					dax_read_ops);
+#endif /* CONFIG_FS_DAX */
+		else
+			return -EINVAL;
 		if (ret)
 			return ret;
 		if (!is_same)
@@ -370,6 +383,34 @@  int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 
 	return ret;
 }
+
+#ifdef CONFIG_FS_DAX
+int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+			      struct file *file_out, loff_t pos_out,
+			      loff_t *len, unsigned int remap_flags,
+			      const struct iomap_ops *ops)
+{
+	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
+					       pos_out, len, remap_flags, ops);
+}
+#else
+int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+			      struct file *file_out, loff_t pos_out,
+			      loff_t *len, unsigned int remap_flags,
+			      const struct iomap_ops *ops)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_FS_DAX */
+EXPORT_SYMBOL(dax_remap_file_range_prep);
+
+int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+				  struct file *file_out, loff_t pos_out,
+				  loff_t *len, unsigned int remap_flags)
+{
+	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
+					       pos_out, len, remap_flags, NULL);
+}
 EXPORT_SYMBOL(generic_remap_file_range_prep);
 
 loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 060695d6d56a..d25434f93235 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1329,8 +1329,12 @@  xfs_reflink_remap_prep(
 	if (IS_DAX(inode_in) || IS_DAX(inode_out))
 		goto out_unlock;
 
-	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
-			len, remap_flags);
+	if (!IS_DAX(inode_in))
+		ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
+				pos_out, len, remap_flags);
+	else
+		ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
+				pos_out, len, remap_flags, &xfs_read_iomap_ops);
 	if (ret || *len == 0)
 		goto out_unlock;
 
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 3275e01ed33d..32e1c34349f2 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -239,6 +239,10 @@  int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 				      pgoff_t index);
 s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
 		struct iomap *srcmap);
+int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
+				  struct inode *dest, loff_t destoff,
+				  loff_t len, bool *is_same,
+				  const struct iomap_ops *ops);
 static inline bool dax_mapping(struct address_space *mapping)
 {
 	return mapping->host && IS_DAX(mapping->host);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c3c88fdb9b2a..e2c348553d87 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -71,6 +71,7 @@  struct fsverity_operations;
 struct fs_context;
 struct fs_parameter_spec;
 struct fileattr;
+struct iomap_ops;
 
 extern void __init inode_init(void);
 extern void __init inode_init_early(void);
@@ -2126,10 +2127,13 @@  extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
 extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
 				       struct file *file_out, loff_t pos_out,
 				       size_t len, unsigned int flags);
-extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
-					 struct file *file_out, loff_t pos_out,
-					 loff_t *count,
-					 unsigned int remap_flags);
+int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+				  struct file *file_out, loff_t pos_out,
+				  loff_t *count, unsigned int remap_flags);
+int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+			      struct file *file_out, loff_t pos_out,
+			      loff_t *len, unsigned int remap_flags,
+			      const struct iomap_ops *ops);
 extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
 				  struct file *file_out, loff_t pos_out,
 				  loff_t len, unsigned int remap_flags);