On Tue, Aug 25, 2015 at 11:33 PM, Peng Tao <tao.peng@xxxxxxxxxxxxxxx> 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.
>
> 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@xxxxxxxxxxxxxxx
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Signed-off-by: Peng Tao <tao.peng@xxxxxxxxxxxxxxx>
> ---
> 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);
One question to btrfs guys... I wanted to add the .clone_range
operation explicit semantics such that it does not allow partial
success, and returns either 0 for success or a negative failure code,
because we don't not expect CLONE to succeed partially. Does btrfs
CLONE have the same semantics? It looks like so by going over
btrfs_clone() but it would be great if someone working on btrfs can
confirm it.
Thanks,
Tao
> #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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