On Tue, May 29, 2018 at 01:51:01PM -0600, Ross Zwisler wrote:
> From: Dave Jiang <dave.ji...@intel.com>
> 
> The function return values are confusing with the way the function is
> named. We expect a true or false return value but it actually returns
> 0/-errno.  This makes the code very confusing. Changing the return values
> to return a bool where if DAX is supported then return true and no DAX
> support returns false.
> 
> Signed-off-by: Dave Jiang <dave.ji...@intel.com>
> Signed-off-by: Ross Zwisler <ross.zwis...@linux.intel.com>

Looks ok, do you want me to pull the first two patches through the xfs
tree?

Reviewed-by: Darrick J. Wong <darrick.w...@oracle.com>

--D

> ---
>  drivers/dax/super.c | 16 ++++++++--------
>  fs/ext2/super.c     |  3 +--
>  fs/ext4/super.c     |  3 +--
>  fs/xfs/xfs_ioctl.c  |  4 ++--
>  fs/xfs/xfs_super.c  | 12 ++++++------
>  include/linux/dax.h |  8 ++++----
>  6 files changed, 22 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 3943feb9a090..1d7bd96511f0 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -80,9 +80,9 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
>   * This is a library function for filesystems to check if the block device
>   * can be mounted with dax option.
>   *
> - * Return: negative errno if unsupported, 0 if supported.
> + * Return: true if supported, false if unsupported
>   */
> -int __bdev_dax_supported(struct block_device *bdev, int blocksize)
> +bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
>  {
>       struct dax_device *dax_dev;
>       pgoff_t pgoff;
> @@ -95,21 +95,21 @@ int __bdev_dax_supported(struct block_device *bdev, int 
> blocksize)
>       if (blocksize != PAGE_SIZE) {
>               pr_debug("%s: error: unsupported blocksize for dax\n",
>                               bdevname(bdev, buf));
> -             return -EINVAL;
> +             return false;
>       }
>  
>       err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
>       if (err) {
>               pr_debug("%s: error: unaligned partition for dax\n",
>                               bdevname(bdev, buf));
> -             return err;
> +             return false;
>       }
>  
>       dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
>       if (!dax_dev) {
>               pr_debug("%s: error: device does not support dax\n",
>                               bdevname(bdev, buf));
> -             return -EOPNOTSUPP;
> +             return false;
>       }
>  
>       id = dax_read_lock();
> @@ -121,7 +121,7 @@ int __bdev_dax_supported(struct block_device *bdev, int 
> blocksize)
>       if (len < 1) {
>               pr_debug("%s: error: dax access failed (%ld)\n",
>                               bdevname(bdev, buf), len);
> -             return len < 0 ? len : -EIO;
> +             return false;
>       }
>  
>       if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) {
> @@ -139,10 +139,10 @@ int __bdev_dax_supported(struct block_device *bdev, int 
> blocksize)
>       } else {
>               pr_debug("%s: error: dax support not enabled\n",
>                               bdevname(bdev, buf));
> -             return -EOPNOTSUPP;
> +             return false;
>       }
>  
> -     return 0;
> +     return true;
>  }
>  EXPORT_SYMBOL_GPL(__bdev_dax_supported);
>  #endif
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 9627c3054b5c..c09289a42dc5 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -961,8 +961,7 @@ 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 (sbi->s_mount_opt & EXT2_MOUNT_DAX) {
> -             err = bdev_dax_supported(sb->s_bdev, blocksize);
> -             if (err) {
> +             if (!bdev_dax_supported(sb->s_bdev, blocksize)) {
>                       ext2_msg(sb, KERN_ERR,
>                               "DAX unsupported by block device. Turning off 
> DAX.");
>                       sbi->s_mount_opt &= ~EXT2_MOUNT_DAX;
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 089170e99895..2e1622907f4a 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3732,8 +3732,7 @@ static int ext4_fill_super(struct super_block *sb, void 
> *data, int silent)
>                                       " that may contain inline data");
>                       sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
>               }
> -             err = bdev_dax_supported(sb->s_bdev, blocksize);
> -             if (err) {
> +             if (!bdev_dax_supported(sb->s_bdev, blocksize)) {
>                       ext4_msg(sb, KERN_ERR,
>                               "DAX unsupported by block device. Turning off 
> DAX.");
>                       sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 0effd46b965f..2c70a0a4f59f 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1103,8 +1103,8 @@ xfs_ioctl_setattr_dax_invalidate(
>       if (fa->fsx_xflags & FS_XFLAG_DAX) {
>               if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
>                       return -EINVAL;
> -             if (bdev_dax_supported(xfs_find_bdev_for_inode(VFS_I(ip)),
> -                             sb->s_blocksize) < 0)
> +             if (!bdev_dax_supported(xfs_find_bdev_for_inode(VFS_I(ip)),
> +                             sb->s_blocksize))
>                       return -EINVAL;
>       }
>  
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 62188c2a4c36..86915dc40eed 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1690,17 +1690,17 @@ xfs_fs_fill_super(
>               sb->s_flags |= SB_I_VERSION;
>  
>       if (mp->m_flags & XFS_MOUNT_DAX) {
> -             int     error2 = 0;
> +             bool rtdev_is_dax = false, datadev_is_dax;
>  
>               xfs_warn(mp,
>               "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
>  
> -             error = bdev_dax_supported(mp->m_ddev_targp->bt_bdev,
> -                             sb->s_blocksize);
> +             datadev_is_dax = bdev_dax_supported(mp->m_ddev_targp->bt_bdev,
> +                     sb->s_blocksize);
>               if (mp->m_rtdev_targp)
> -                     error2 = bdev_dax_supported(mp->m_rtdev_targp->bt_bdev,
> -                                     sb->s_blocksize);
> -             if (error && error2) {
> +                     rtdev_is_dax = bdev_dax_supported(
> +                             mp->m_rtdev_targp->bt_bdev, sb->s_blocksize);
> +             if (!rtdev_is_dax && !datadev_is_dax) {
>                       xfs_alert(mp,
>                       "DAX unsupported by block device. Turning off DAX.");
>                       mp->m_flags &= ~XFS_MOUNT_DAX;
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 2a4f7295c12b..c99692ddd4b5 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -64,8 +64,8 @@ static inline bool dax_write_cache_enabled(struct 
> dax_device *dax_dev)
>  struct writeback_control;
>  int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
>  #if IS_ENABLED(CONFIG_FS_DAX)
> -int __bdev_dax_supported(struct block_device *bdev, int blocksize);
> -static inline int bdev_dax_supported(struct block_device *bdev, int 
> blocksize)
> +bool __bdev_dax_supported(struct block_device *bdev, int blocksize);
> +static inline bool bdev_dax_supported(struct block_device *bdev, int 
> blocksize)
>  {
>       return __bdev_dax_supported(bdev, blocksize);
>  }
> @@ -84,10 +84,10 @@ 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);
>  #else
> -static inline int bdev_dax_supported(struct block_device *bdev,
> +static inline bool bdev_dax_supported(struct block_device *bdev,
>               int blocksize)
>  {
> -     return -EOPNOTSUPP;
> +     return false;
>  }
>  
>  static inline struct dax_device *fs_dax_get_by_host(const char *host)
> -- 
> 2.14.3
> 
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