On Thu, Sep 08, 2016 at 06:29:54PM +0300, Amir Goldstein wrote:
> When copying up within the same fs, try to use f_op->copy_file_range().
> This becomes very efficient when lower and upper are on the same fs
> with file reflink support.
>
> Tested correct behavior when lower and upper are on:
> 1. same ext4 (copy)
> 2. same xfs + reflink patches + mkfs.xfs (copy)
> 3. same xfs + reflink patches + mkfs.xfs -m reflink=1 (clone)
> 4. different xfs + reflink patches + mkfs.xfs -m reflink=1 (copy)
>
> Verified that all the overlay xfstests pass in the 'same xfs+reflink'
> setup.
>
> For comparison, on my laptop, xfstest overlay/001 (copy up of large
> sparse files) takes less than 1 second in the xfs reflink setup vs.
> 25 seconds on the rest of the setups.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/copy_up.c | 28 +++++++++++++++++++++++++---
> 1 file changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index 43fdc27..400567b 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -121,6 +121,7 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
> struct file *new_file;
> loff_t old_pos = 0;
> loff_t new_pos = 0;
> + int try_copy_file = 0;
> int error = 0;
>
> if (len == 0)
> @@ -136,6 +137,13 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
> goto out_fput;
> }
>
> + /*
> + * When copying up within the same fs, try to use fs's copy_file_range
> + */
> + if (file_inode(old_file)->i_sb == file_inode(new_file)->i_sb) {
> + try_copy_file = (new_file->f_op->copy_file_range != NULL);
> + }
You don't need this. .copy_file_range() should return -EXDEV when
you try to use it to copy files across different mount points or
superblocks.
i.e. you should probably be calling vfs_copy_file_range() here to do
the copy up, and if that fails (for whatever reason) then fall back
to the existing data copying code.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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