US 12,248,376 B2
Maintaining and recomputing reference counts in a persistent memory file system
Ananthan Subramanian, San Ramon, CA (US); Matthew Fontaine Curtis-Maury, Apex, NC (US); and Vinay Devadas, Apex, NC (US)
Assigned to NetApp, Inc., San Jose, CA (US)
Filed by NetApp Inc., San Jose, CA (US)
Filed on Apr. 1, 2024, as Appl. No. 18/623,387.
Application 18/623,387 is a continuation of application No. 17/892,175, filed on Aug. 22, 2022, granted, now 11,947,430.
Application 17/892,175 is a continuation of application No. 16/944,001, filed on Jul. 30, 2020, granted, now 11,422,903, issued on Aug. 23, 2022.
Prior Publication US 2024/0241801 A1, Jul. 18, 2024
Int. Cl. G06F 11/00 (2006.01); G06F 11/07 (2006.01); G06F 11/14 (2006.01); G06F 11/30 (2006.01); G06F 12/02 (2006.01); G06F 12/0817 (2016.01); G06F 12/0882 (2016.01)
CPC G06F 11/1471 (2013.01) [G06F 11/0772 (2013.01); G06F 11/3037 (2013.01); G06F 12/0246 (2013.01); G06F 12/0824 (2013.01); G06F 12/0882 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A method comprising:
receiving, by a persistent memory file system of a node, a copy operation targeting a parent page stored within a persistent memory of the node;
executing the copy operation to create a copy of the parent page as a copied page within the persistent memory;
creating a visited flag for the copied page;
setting the visited flag to inherit a parent visited flag of the parent page;
setting a shadow reference count for the copied page to a value based upon a visited field of the parent page indicating that the parent page was encountered by a traversal of the persistent memory file system; and
utilizing the shadow reference count to correct a primary reference count for the copied page.