<p dir="ltr"><br>
On 30-Aug-2014 10:49 AM, "Joshi" <<a href="mailto:joshiiitr@gmail.com">joshiiitr@gmail.com</a>> wrote:<br>
><br>
> I am trying to obtain file name at block layer level (above IO scheduler).<br>
> At this level I receive bio structure, within which page pointers are kept.<br>
><br>
> Thereby I do following to obtain the inode and dentry -<br>
><br>
> struct inode *inode_ptr = page->mapping->host;<br>
> if (inode_ptr != NULL)<br>
> /* Access dentry i.e. i_dentry in the inode */<br>
></p>
<p dir="ltr">Are you doing this in readpage(s) or writepage(s) callback? If that's the case your page would be locked and dentry/inode wouldn't go away.</p>
<p dir="ltr">If you are doing something else then first make sure you do lock_page and proceed only if you get that page lock.</p>
<p dir="ltr">Second you can try dget and dput before you start working with dentry. </p>
<p dir="ltr">><br>
> This works usually. But problem is, inode and dentry may get released<br>
> from inode and dentry cache at any time.<br>
> While accessing inode/dentry I need to ensure that till the time I am<br>
> accessing'em these structure remain valid in memory.<br>
> Is it possible to ensure that? Which structures/locks I need to check<br>
> for the purpose.</p>
<p dir="ltr">is this your observation from your test case? Can you explain your test case a bit.<br>
><br>
> Appreciate any help.<br>
><br>
> Thanks!<br>
><br>
> --<br>
> Joshi<br>
><br>
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</p>