Re: [PATCH RFC 01/11] vfs: pull btrfs clone API to vfs layer

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Aug 25, 2015 at 11:33:39PM +0800, Peng Tao wrote:
> Now that a few file systems are adding clone functionality, namingly
> btrfs, NFS (later in the series) and XFS
> (ttp://oss.sgi.com/archives/xfs/2015-06/msg00407.html), it makes sense
> to pull the ioctl to common code.

Please cc me on future postings of this entire patchset, seeing as you're
referencing an email I sent and am still actively working on. :)

I agree with what Dave said, please also cc the entire set to fsdevel.

--D

> 
> Add vfs_file_clone_range() helper and .clone_range file operation interface
> to allow underlying filesystems to clone between regular files.
> 
> The change in do_vfs_ioctl() is defered to next patch where btrfs
> .clone_range is added, just so that we don't break btrfs CLONE ioctl
> with this patch.
> 
> Cc: linux-btrfs@vger.kernel.org
> Cc: linux-fsdevel@vger.kernel.org
> Signed-off-by: Peng Tao <tao.peng@primarydata.com>
> ---
>  fs/ioctl.c              | 24 ++++++++++++++++++++++++
>  fs/read_write.c         | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/fs.h      |  4 ++++
>  include/uapi/linux/fs.h |  9 +++++++++
>  4 files changed, 82 insertions(+)
> 
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 5d01d26..726c5d7 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -215,6 +215,30 @@ static int ioctl_fiemap(struct file *filp, unsigned long arg)
>  	return error;
>  }
>  
> +static long ioctl_file_clone(struct file *dst_file, unsigned long srcfd,
> +			     u64 off, u64 olen, u64 destoff)
> +{
> +	struct fd src_file = fdget(srcfd);
> +	int ret;
> +
> +	if (!src_file.file)
> +		return -EBADF;
> +	ret = vfs_file_clone_range(src_file.file, dst_file, off, olen, destoff);
> +
> +	fdput(src_file);
> +	return ret;
> +}
> +
> +static long ioctl_file_clone_range(struct file *file, void __user *argp)
> +{
> +	struct file_clone_range args;
> +
> +	if (copy_from_user(&args, argp, sizeof(args)))
> +		return -EFAULT;
> +	return ioctl_file_clone(file, args.src_fd, args.src_offset,
> +				args.src_length, args.dest_offset);
> +}
> +
>  #ifdef CONFIG_BLOCK
>  
>  static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 819ef3f..beaad2c 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -16,6 +16,7 @@
>  #include <linux/pagemap.h>
>  #include <linux/splice.h>
>  #include <linux/compat.h>
> +#include <linux/mount.h>
>  #include "internal.h"
>  
>  #include <asm/uaccess.h>
> @@ -1327,3 +1328,47 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
>  	return do_sendfile(out_fd, in_fd, NULL, count, 0);
>  }
>  #endif
> +
> +int vfs_file_clone_range(struct file *src_file, struct file *dst_file,
> +			 loff_t off, size_t len, loff_t dstoff)
> +{
> +	struct inode *src_ino;
> +	struct inode *dst_ino;
> +	ssize_t ret;
> +
> +	if (!(src_file->f_mode & FMODE_READ) ||
> +	    !(dst_file->f_mode & FMODE_WRITE) ||
> +	    (dst_file->f_flags & O_APPEND) ||
> +	    !src_file->f_op || !src_file->f_op->clone_range)
> +		return -EINVAL;
> +
> +	src_ino = file_inode(src_file);
> +	dst_ino = file_inode(dst_file);
> +
> +        if (S_ISDIR(src_ino->i_mode) || S_ISDIR(dst_ino->i_mode))
> +                return -EISDIR;
> +
> +	/* sanity check on offsets and length */
> +	if (off + len < off || dstoff + len < dstoff ||
> +	    off + len > i_size_read(src_ino))
> +		return -EINVAL;
> +
> +	if (src_ino->i_sb != dst_ino->i_sb ||
> +	    src_file->f_path.mnt != dst_file->f_path.mnt)
> +		return -EXDEV;
> +
> +	ret = mnt_want_write_file(dst_file);
> +	if (ret)
> +		return ret;
> +
> +	ret = src_file->f_op->clone_range(src_file, dst_file, off, len, dstoff);
> +	if (!ret) {
> +		fsnotify_access(src_file);
> +		fsnotify_modify(dst_file);
> +	}
> +
> +	mnt_drop_write_file(dst_file);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(vfs_file_clone_range);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index cc008c3..612d7f4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1628,6 +1628,8 @@ struct file_operations {
>  	long (*fallocate)(struct file *file, int mode, loff_t offset,
>  			  loff_t len);
>  	void (*show_fdinfo)(struct seq_file *m, struct file *f);
> +	int (*clone_range)(struct file *src_file, struct file *dst_file,
> +			   loff_t off, size_t len, loff_t dstoff);
>  #ifndef CONFIG_MMU
>  	unsigned (*mmap_capabilities)(struct file *);
>  #endif
> @@ -2678,6 +2680,8 @@ int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t,
>  int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *);
>  #define dax_mkwrite(vma, vmf, gb, iod)		dax_fault(vma, vmf, gb, iod)
>  #define __dax_mkwrite(vma, vmf, gb, iod)	__dax_fault(vma, vmf, gb, iod)
> +int vfs_file_clone_range(struct file *src_file, struct file *dst_file,
> +			 loff_t off, size_t len, loff_t dstoff);
>  
>  #ifdef CONFIG_BLOCK
>  typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode,
> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 9b964a5..ac7f1c5 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h
> @@ -39,6 +39,13 @@
>  #define RENAME_EXCHANGE		(1 << 1)	/* Exchange source and dest */
>  #define RENAME_WHITEOUT		(1 << 2)	/* Whiteout source */
>  
> +struct file_clone_range {
> +	__s64 src_fd;
> +	__u64 src_offset;
> +	__u64 src_length;
> +	__u64 dest_offset;
> +};
> +
>  struct fstrim_range {
>  	__u64 start;
>  	__u64 len;
> @@ -159,6 +166,8 @@ struct inodes_stat_t {
>  #define FIFREEZE	_IOWR('X', 119, int)	/* Freeze */
>  #define FITHAW		_IOWR('X', 120, int)	/* Thaw */
>  #define FITRIM		_IOWR('X', 121, struct fstrim_range)	/* Trim */
> +#define FICLONE		_IOW(0x94, 9, int)	/* Clone */
> +#define FICLONERANGE	_IOW(0x94, 13, struct file_clone_range)	/* Clone range */
>  
>  #define	FS_IOC_GETFLAGS			_IOR('f', 1, long)
>  #define	FS_IOC_SETFLAGS			_IOW('f', 2, long)
> -- 
> 1.8.3.1
> 
> --
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