On Thu, Apr 08, 2021 at 08:04:31PM +0800, Shiyang Ruan wrote:
> In fsdax mode, WRITE and ZERO on a shared extent need CoW performed. After
> CoW, new allocated extents needs to be remapped to the file.  So, add an
> iomap_end for dax write ops to do the remapping work.
> 
> Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com>
> ---
>  fs/xfs/xfs_bmap_util.c |  3 +--
>  fs/xfs/xfs_file.c      |  9 +++----
>  fs/xfs/xfs_iomap.c     | 58 +++++++++++++++++++++++++++++++++++++++++-
>  fs/xfs/xfs_iomap.h     |  4 +++
>  fs/xfs/xfs_iops.c      |  7 +++--
>  fs/xfs/xfs_reflink.c   |  3 +--
>  6 files changed, 69 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index e7d68318e6a5..9fcea33dd2c9 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -954,8 +954,7 @@ xfs_free_file_space(
>               return 0;
>       if (offset + len > XFS_ISIZE(ip))
>               len = XFS_ISIZE(ip) - offset;
> -     error = iomap_zero_range(VFS_I(ip), offset, len, NULL,
> -                     &xfs_buffered_write_iomap_ops);
> +     error = xfs_iomap_zero_range(VFS_I(ip), offset, len, NULL);
>       if (error)
>               return error;
>  
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index a007ca0711d9..5795d5d6f869 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -684,11 +684,8 @@ xfs_file_dax_write(
>       pos = iocb->ki_pos;
>  
>       trace_xfs_file_dax_write(iocb, from);
> -     ret = dax_iomap_rw(iocb, from, &xfs_direct_write_iomap_ops);
> -     if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
> -             i_size_write(inode, iocb->ki_pos);
> -             error = xfs_setfilesize(ip, pos, ret);
> -     }
> +     ret = dax_iomap_rw(iocb, from, &xfs_dax_write_iomap_ops);
> +
>  out:
>       if (iolock)
>               xfs_iunlock(ip, iolock);
> @@ -1309,7 +1306,7 @@ __xfs_filemap_fault(
>  
>               ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL,
>                               (write_fault && !vmf->cow_page) ?
> -                              &xfs_direct_write_iomap_ops :
> +                              &xfs_dax_write_iomap_ops :
>                                &xfs_read_iomap_ops);
>               if (ret & VM_FAULT_NEEDDSYNC)
>                       ret = dax_finish_sync_fault(vmf, pe_size, pfn);
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index e17ab7f42928..f818f989687b 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -760,7 +760,8 @@ xfs_direct_write_iomap_begin(
>  
>               /* may drop and re-acquire the ilock */
>               error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
> -                             &lockmode, flags & IOMAP_DIRECT);
> +                             &lockmode,
> +                             flags & IOMAP_DIRECT || IS_DAX(inode));

Parentheses, please:
                                (flags & IOMAP_DIRECT) || IS_DAX(inode));

>               if (error)
>                       goto out_unlock;
>               if (shared)
> @@ -853,6 +854,38 @@ const struct iomap_ops xfs_direct_write_iomap_ops = {
>       .iomap_begin            = xfs_direct_write_iomap_begin,
>  };
>  
> +static int
> +xfs_dax_write_iomap_end(
> +     struct inode            *inode,
> +     loff_t                  pos,
> +     loff_t                  length,
> +     ssize_t                 written,
> +     unsigned int            flags,
> +     struct iomap            *iomap)
> +{
> +     int                     error = 0;
> +     xfs_inode_t             *ip = XFS_I(inode);

Please don't use typedefs:

        struct xfs_inode        *ip = XFS_I(inode);

> +     bool                    cow = xfs_is_cow_inode(ip);
> +
> +     if (pos + written > i_size_read(inode)) {

What if we wrote zero bytes?  Usually that means error, right?

> +             i_size_write(inode, pos + written);
> +             error = xfs_setfilesize(ip, pos, written);
> +             if (error && cow) {
> +                     xfs_reflink_cancel_cow_range(ip, pos, written, true);
> +                     return error;
> +             }
> +     }
> +     if (cow)
> +             error = xfs_reflink_end_cow(ip, pos, written);
> +
> +     return error;
> +}
> +
> +const struct iomap_ops xfs_dax_write_iomap_ops = {
> +     .iomap_begin            = xfs_direct_write_iomap_begin,
> +     .iomap_end              = xfs_dax_write_iomap_end,
> +};
> +
>  static int
>  xfs_buffered_write_iomap_begin(
>       struct inode            *inode,
> @@ -1314,3 +1347,26 @@ xfs_xattr_iomap_begin(
>  const struct iomap_ops xfs_xattr_iomap_ops = {
>       .iomap_begin            = xfs_xattr_iomap_begin,
>  };
> +
> +int
> +xfs_iomap_zero_range(
> +     struct inode            *inode,

Might as well pass the xfs_inode pointers directly into these two functions.

--D

> +     loff_t                  offset,
> +     loff_t                  len,
> +     bool                    *did_zero)
> +{
> +     return iomap_zero_range(inode, offset, len, did_zero,
> +                     IS_DAX(inode) ? &xfs_dax_write_iomap_ops :
> +                                     &xfs_buffered_write_iomap_ops);
> +}
> +
> +int
> +xfs_iomap_truncate_page(
> +     struct inode            *inode,
> +     loff_t                  pos,
> +     bool                    *did_zero)
> +{
> +     return iomap_truncate_page(inode, pos, did_zero,
> +                     IS_DAX(inode) ? &xfs_dax_write_iomap_ops :
> +                                     &xfs_buffered_write_iomap_ops);
> +}
> diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h
> index 7d3703556d0e..8adb2bf78a5a 100644
> --- a/fs/xfs/xfs_iomap.h
> +++ b/fs/xfs/xfs_iomap.h
> @@ -14,6 +14,9 @@ struct xfs_bmbt_irec;
>  int xfs_iomap_write_direct(struct xfs_inode *ip, xfs_fileoff_t offset_fsb,
>               xfs_fileoff_t count_fsb, struct xfs_bmbt_irec *imap);
>  int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, xfs_off_t, 
> bool);
> +int xfs_iomap_zero_range(struct inode *inode, loff_t offset, loff_t len,
> +             bool *did_zero);
> +int xfs_iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero);
>  xfs_fileoff_t xfs_iomap_eof_align_last_fsb(struct xfs_inode *ip,
>               xfs_fileoff_t end_fsb);
>  
> @@ -42,6 +45,7 @@ xfs_aligned_fsb_count(
>  
>  extern const struct iomap_ops xfs_buffered_write_iomap_ops;
>  extern const struct iomap_ops xfs_direct_write_iomap_ops;
> +extern const struct iomap_ops xfs_dax_write_iomap_ops;
>  extern const struct iomap_ops xfs_read_iomap_ops;
>  extern const struct iomap_ops xfs_seek_iomap_ops;
>  extern const struct iomap_ops xfs_xattr_iomap_ops;
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 66ebccb5a6ff..db8eeaa8a773 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -879,8 +879,8 @@ xfs_setattr_size(
>        */
>       if (newsize > oldsize) {
>               trace_xfs_zero_eof(ip, oldsize, newsize - oldsize);
> -             error = iomap_zero_range(inode, oldsize, newsize - oldsize,
> -                             &did_zeroing, &xfs_buffered_write_iomap_ops);
> +             error = xfs_iomap_zero_range(inode, oldsize, newsize - oldsize,
> +                             &did_zeroing);
>       } else {
>               /*
>                * iomap won't detect a dirty page over an unwritten block (or a
> @@ -892,8 +892,7 @@ xfs_setattr_size(
>                                                    newsize);
>               if (error)
>                       return error;
> -             error = iomap_truncate_page(inode, newsize, &did_zeroing,
> -                             &xfs_buffered_write_iomap_ops);
> +             error = xfs_iomap_truncate_page(inode, newsize, &did_zeroing);
>       }
>  
>       if (error)
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 9ef9f98725a2..a4cd6e8a7aa0 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1266,8 +1266,7 @@ xfs_reflink_zero_posteof(
>               return 0;
>  
>       trace_xfs_zero_eof(ip, isize, pos - isize);
> -     return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL,
> -                     &xfs_buffered_write_iomap_ops);
> +     return xfs_iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL);
>  }
>  
>  /*
> -- 
> 2.31.0
> 
> 
> 

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