<table><tr><td style="">chinmoyr added a comment.
</td><a style="text-decoration: none; padding: 4px 8px; margin: 0 8px 8px; float: right; color: #464C5C; font-weight: bold; border-radius: 3px; background-color: #F7F7F9; background-image: linear-gradient(to bottom,#fff,#f1f0f1); display: inline-block; border: 1px solid rgba(71,87,120,.2);" href="https://phabricator.kde.org/D17737">View Revision</a></tr></table><br /><div><div><blockquote style="border-left: 3px solid #8C98B8;
color: #6B748C;
font-style: italic;
margin: 4px 0 12px 0;
padding: 8px 12px;
background-color: #F8F9FC;">
<div style="font-style: normal;
padding-bottom: 4px;">In <a href="https://phabricator.kde.org/D17737#381029" style="background-color: #e7e7e7;
border-color: #e7e7e7;
border-radius: 3px;
padding: 0 4px;
font-weight: bold;
color: black;text-decoration: none;">D17737#381029</a>, <a href="https://phabricator.kde.org/p/bruns/" style="
border-color: #f1f7ff;
color: #19558d;
background-color: #f1f7ff;
border: 1px solid transparent;
border-radius: 3px;
font-weight: bold;
padding: 0 4px;">@bruns</a> wrote:</div>
<div style="margin: 0;
padding: 0;
border: 0;
color: rgb(107, 116, 140);"><p>I think it would be much simpler if you just tried to do the the FICLONE iotctl in the job, without any prior checking:</p>
<ul class="remarkup-list">
<li class="remarkup-list-item">no possibility for races</li>
<li class="remarkup-list-item">less syscals</li>
<li class="remarkup-list-item">less code</li>
</ul></div>
</blockquote>
<p>I am not sure I followed you here. To me ioctl seems to naturally fit in FileProtocol::copy(). Can I ask you to elaborate a bit?</p></div></div><br /><div><strong>INLINE COMMENTS</strong><div><div style="margin: 6px 0 12px 0;"><div style="border: 1px solid #C7CCD9; border-radius: 3px;"><div style="padding: 0; background: #F7F7F7; border-color: #e3e4e8; border-style: solid; border-width: 0 0 1px 0; margin: 0;"><div style="color: #74777d; background: #eff2f4; padding: 6px 8px; overflow: hidden;"><a style="float: right; text-decoration: none;" href="https://phabricator.kde.org/D17737#inline-97540">View Inline</a><span style="color: #4b4d51; font-weight: bold;">bruns</span> wrote in <span style="color: #4b4d51; font-weight: bold;">copyjob.cpp:742</span></div>
<div style="margin: 8px 0; padding: 0 12px; color: #74777D;"><p style="padding: 0; margin: 8px;">it is *much* cheaper to compare the st_dev fields from stat for the source file and the destination directory.</p></div></div>
<div style="margin: 8px 0; padding: 0 12px;"><p style="padding: 0; margin: 8px;">I agree but in case of KIO::copy() the destination can be a non-existent file resulting in lstat to fail. However, I did considered using st_dev for source but couldn't find a way to map it to a block device. Maybe we can use st_dev by default and fallback to KMountPoint upon encountering this particular case?</p></div></div><br /><div style="border: 1px solid #C7CCD9; border-radius: 3px;"><div style="padding: 0; background: #F7F7F7; border-color: #e3e4e8; border-style: solid; border-width: 0 0 1px 0; margin: 0;"><div style="color: #74777d; background: #eff2f4; padding: 6px 8px; overflow: hidden;"><a style="float: right; text-decoration: none;" href="https://phabricator.kde.org/D17737#inline-97542">View Inline</a><span style="color: #4b4d51; font-weight: bold;">bruns</span> wrote in <span style="color: #4b4d51; font-weight: bold;">kmountpoint.cpp:471</span></div>
<div style="margin: 8px 0; padding: 0 12px; color: #74777D;"><p style="padding: 0; margin: 8px;">This is not correct, xfs <strong>may</strong> support reflinks, but it is a feature only recently added, and has to be enabled at file system creation time.</p></div></div>
<div style="margin: 8px 0; padding: 0 12px;"><p style="padding: 0; margin: 8px;">Here by 'support' I meant support in its implementation. Meaning aside, unlike btrfs' "nodatacow" option which we can get using KMountPoint I couldn't find any API to get the "reflink" option set during file system creation time. How do you suggest I proceed from here?</p></div></div><br /><div style="border: 1px solid #C7CCD9; border-radius: 3px;"><div style="padding: 0; background: #F7F7F7; border-color: #e3e4e8; border-style: solid; border-width: 0 0 1px 0; margin: 0;"><div style="color: #74777d; background: #eff2f4; padding: 6px 8px; overflow: hidden;"><a style="float: right; text-decoration: none;" href="https://phabricator.kde.org/D17737#inline-97541">View Inline</a><span style="color: #4b4d51; font-weight: bold;">bruns</span> wrote in <span style="color: #4b4d51; font-weight: bold;">kmountpoint.h:145</span></div>
<div style="margin: 8px 0; padding: 0 12px; color: #74777D;"><p style="padding: 0; margin: 8px;">The correct term here is "reflink", not CoW.</p></div></div>
<div style="margin: 8px 0; padding: 0 12px;"><p style="padding: 0; margin: 8px;">Some documents I read on btrfs and xfs described copy-on-write as a 'feature'. So I felt the enum should contain 'Supports' followed by the feature name.<br />
But reflink or clone fits here better. I will make the change in next update.</p></div></div></div></div></div><br /><div><strong>REPOSITORY</strong><div><div>R241 KIO</div></div></div><br /><div><strong>REVISION DETAIL</strong><div><a href="https://phabricator.kde.org/D17737">https://phabricator.kde.org/D17737</a></div></div><br /><div><strong>To: </strong>chinmoyr, dfaure, davidedmundson<br /><strong>Cc: </strong>bruns, kde-frameworks-devel, michaelh, ngraham<br /></div>