Hi Sachin,
Sachin Prabhu <sprabhu@xxxxxxxxxx> writes:
> The patch introduces the file_operations helper cifs_copy_file_range().
>
> The vfs helper vfs_copy_file_range() first calls clone_file_range
> which for cifs uses
> SMB2_ioctl(.., FSCTL_DUPLICATE_EXTENTS_TO_FILE, ..)
> to do a server side copy of the file. This ioctl is only supported on
> SMB3 and later versions.
>
> Once this call fails, vfs_copy_file_range() calls copy_file_range()
> corresponding to the cifs filesystem which is introduced by this patch.
> This calls the more widely available
> SMB2_ioctl(.., FSCTL_SRV_COPYCHUNK_WRITE, ..)
Sounds good.
> The upstream changes in this area was first made by the commit
> 04b38d601239 ("vfs: pull btrfs clone API to vfs layer")
> This commit also introduces the ioctls FICLONE and FICLONERANGE which
IIUC it also allows the copy_file_range syscall defined in
fs/read_write.c to take advantage of the dup extents fsctl, if
available, nice!
Now, I wonder if there is a way to implement the FIDEDUPERANGE ioctl in
SMB3, which does the same thing as a clone but it exits early if the
destination does not already match the source.
> removes the need for separate cifs ioctls to perform server side copies
> and hence can be removed.
Isn't this breaking userspace? I understand it was a private ioctl only
availaible in SMB3 so it's not a big issue but
> @@ -250,9 +146,6 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
> cifs_dbg(FYI, "set compress flag rc %d\n", rc);
> }
> break;
> - case CIFS_IOC_COPYCHUNK_FILE:
> - rc = cifs_ioctl_clone(xid, filep, arg);
> - break;
> case CIFS_IOC_SET_INTEGRITY:
> if (pSMBFile == NULL)
> break;
I believe the ioctl will return -ENOTTY now. I remember this story when
an error code was changed: https://lkml.org/lkml/2012/12/23/75 *gulp*
Maybe I'm overthinking this.
Cheers,
--
Aurélien Aptel / SUSE Labs Samba Team
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SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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