Re: filefrag and reflink

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Jul 18, 2018 at 12:41:27PM -0600, Chris Murphy wrote:
> xfsprogs 4.17.0 mkfs with reflink=1
> kernel 4.17.6
> 
> $ fallocate -l 1g tmp2
> $ cp --reflink tmp2 tmp3
> $ filefrag -v *
> Filesystem type is: 58465342
> File size of tmp2 is 1073741824 (262144 blocks of 4096 bytes)
>  ext:     logical_offset:        physical_offset: length:   expected: flags:
>    0:        0..  130136:         24..    130160: 130137:             unwritten
>    1:   130137..  260280:     131082..    261225: 130144:     130161: unwritten
>    2:   260281..  262143:     264714..    266576:   1863:     261226:
> last,unwritten,eof
> tmp2: 3 extents found
> File size of tmp3 is 1073741824 (262144 blocks of 4096 bytes)
> tmp3: 0 extents found
> [chris@f28s xfs]$
> 
> 
> Is this expected? When I do it on Btrfs, I see identical information
> for the two files after reflink copy, with flags "unwritten,shared".

Yes.  xfs doesn't share unwritten extents; what would be the point?

--D

> Regular files behave as expected, I'm only seeing this on reflink
> copies of fallocated files.
> 
> 
> 
> 
> -- 
> Chris Murphy
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html