On Thu, Dec 22, 2016 at 12:25 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> Add support for extra rename flags that can be passed to
> vfs_rename() from kernel code.
>
> Define a new internal vfs flag RENAME_VFS_DTYPE.
> This flag indicates that caller would like fs to set the dtype
> of the target entry to a specified value. The dtype value to use
> is specified on the S_IFMT mask bits (12..15) of the rename flags.
>
> For example, code can call vfs_rename(..., RENAME_DT_WHT) to set
> the target dir entry type to DT_WHT, regardless of the value
> of inode->i_mode.
>
> File systems that supports the new RENAME_VFS_DTYPE flag would
> check for (flags & RENAME_VFS_DTYPE) and use RENAME_DT_MODE(flags)
> instead of inode->i_mode to determine the value of dtype to store
> in the directory entry.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Ted,
My bad. I posted this thing on the overlayfs list only.
That's the VFS API part.
I'll also post the XFS POC.
> ---
> include/linux/fs.h | 30 ++++++++++++++++++++++++++++++
> include/uapi/linux/fs.h | 4 ++++
> 2 files changed, 34 insertions(+)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 8f1580d..82ce8ca 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1559,6 +1559,36 @@ extern int vfs_symlink(struct inode *, struct dentry *, const char *);
> extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
> extern int vfs_rmdir(struct inode *, struct dentry *);
> extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
> +
> +/* vfs_rename() extra flags */
> +#define RENAME_VFS_FLAG(i) (1 << (RENAME_UAPI_BITS + (i)))
> +#define RENAME_VFS_DTYPE RENAME_VFS_FLAG(0) /* Set dest dtype */
> +
> +#define RENAME_VFS_FLAG_BITS 1
> +
> +#define RENAME_FLAGS_BITS (RENAME_UAPI_BITS + RENAME_VFS_FLAG_BITS)
> +#define RENAME_FLAGS_MASK ((1 << RENAME_FLAGS_BITS) - 1)
> +
> +/*
> + * S_IFMT bits (12..15) carry the dtype value to set for RENAME_VFS_DTYPE.
> + *
> + * For example, code can call vfs_rename(..., RENAME_DT_WHT) to set the
> + * target dir entry type to DT_WHT, regardless of inode->i_mode.
> + * file systems that supports the new RENAME_VFS_DTYPE flag, would check
> + * for (flags & RENAME_VFS_DTYPE) and use RENAME_DT_MODE(flags) instead
> + * of inode->i_mode to determine the dtype to store in the directory entry.
> + */
> +#define RENAME_DT_BITS 4
> +#define RENAME_DT_SHIFT 12
> +#define RENAME_DT_MASK S_IFMT
> +#define RENAME_DT(dt) (((dt) << RENAME_DT_SHIFT) | RENAME_VFS_DTYPE)
> +#define RENAME_DT_UNKNOWN RENAME_DT(DT_UNKNOWN)
> +#define RENAME_DT_WHT RENAME_DT(DT_WHT)
> +/* mode to use instead of i_mode when setting dtype */
> +#define RENAME_DT_MODE(f) ((f) & RENAME_DT_MASK)
> +
> +#define RENAME_VFS_MASK (RENAME_FLAGS_MASK | RENAME_DT_MASK)
> +
> extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
> extern int vfs_whiteout(struct inode *, struct dentry *);
>
> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 36da93f..11f0c6b 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h
> @@ -38,10 +38,14 @@
> #define SEEK_HOLE 4 /* seek to the next hole */
> #define SEEK_MAX SEEK_HOLE
>
> +/* renameat2(2) user api flags */
> #define RENAME_NOREPLACE (1 << 0) /* Don't overwrite target */
> #define RENAME_EXCHANGE (1 << 1) /* Exchange source and dest */
> #define RENAME_WHITEOUT (1 << 2) /* Whiteout source */
>
> +#define RENAME_UAPI_BITS 3
> +#define RENAME_UAPI_MASK ((1 << RENAME_UAPI_BITS) - 1)
> +
> struct file_clone_range {
> __s64 src_fd;
> __u64 src_offset;
> --
> 2.7.4
>
