On Fri, Jan 27, 2017 at 1:50 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> On Fri, Jan 27, 2017 at 1:09 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>> On Mon, Jan 23, 2017 at 8:43 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>>> Before calling write f_ops, call file_start_write() instead
>>> of sb_start_write().
>>>
>>> This ensures freeze protection for both overlay and upper fs
>>> when file is open from an overlayfs mount.
>>>
>>> Replace {sb,file}_start_write() for {copy,clone}_file_range() and
>>> for fallocate().
>>>
>>> For dedup_file_range() there is no need for mnt_want_write_file().
>>> File is already open for write, so we already have mnt_want_write()
>>> and we only need file_start_write().
>>
>> Being opened for write is not verified if capable(CAP_SYS_ADMIN).
>> Ugly special case, don't ask me why it's done...
>>
>
> Christoph, Darrick, is that by design?
Anyway, whether is makes sense or not, that's a legacy from
BTRFS_IOC_FILE_EXTENT_SAME, we probably have to live with.
Michael, I recon man page needs updating.
I'll remove this hunk from the patch.
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