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<p class="MsoNormal">FID is packed after ext4_dir_entry.name, you can refer to osd_ldiskfs_filldir() to see how it’s unpacked.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Cheers,<o:p></o:p></p>
<p class="MsoNormal">Lai<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">lustre-devel <lustre-devel-bounces@lists.lustre.org> on behalf of Saisha Kamat via lustre-devel <lustre-devel@lists.lustre.org><br>
<b>Reply-To: </b>Saisha Kamat <skamat1@uncc.edu><br>
<b>Date: </b>Thursday, August 5, 2021 at 10:30 AM<br>
<b>To: </b>"lustre-devel@lists.lustre.org" <lustre-devel@lists.lustre.org><br>
<b>Subject: </b>[lustre-devel] Locating FID-in-Dirent.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm;box-sizing:inherit;font-variant-ligatures:none;white-space:pre-wrap;border-radius:4px;font-variant-caps:normal;text-decoration-style:initial;text-decoration-color:initial;word-spacing:0px"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">Hi all, <o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"><o:p> </o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">I am a Ph.D student at UNCC. I am currently trying to retrieve lustre metadata from ldiskfs. <o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"><o:p> </o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">The Lustre Document for LFSCK Phase 1.5 suggests that there is a FID-in-Dirent (File Identifier for each sub-directories and child files) stored in the Directory Entry of the Parent Directory. But we could not find such FID while reading the directory entry of ldiskfs.<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"><o:p> </o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">We use the following data struct ext4_dir_entry{} to access the directory entry information (after checking the ldiskfs patches, we do not notice any change to this data structure in ldiskfs).<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"><o:p> </o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">struct ext4_dir_entry {<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"> __le32 inode; /* Inode number */<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"> __le16 rec_len; /* Directory entry length */<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"> __le16 name_len; /* Name length */<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"> char name[EXT4_NAME_LEN]; /* File name */<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">}; <o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"> <br><br><o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">Applying it to a ldiskfs image, we are able to read each directory entry's inode number and name correctly. But, we can not find its File Identifier.<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"> <o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">Can you let us know where to locate the FID-in-Dirent information?<o:p></o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D"><o:p> </o:p></span></pre>
<pre style="mso-margin-top-alt:3.0pt;margin-right:0cm;margin-bottom:3.0pt;margin-left:0cm"><span style="font-size:9.0pt;font-family:Monaco;color:#1D1C1D">Thanks,<br>Saisha Kamat<o:p></o:p></span></pre>
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