Re: [PATCH 25/25] fsinfo: Add API documentation [ver #13]

From: Alan Jenkins
Date: Wed Jun 05 2019 - 08:25:54 EST


On 28/05/2019 16:14, David Howells wrote:
+Then there are attributes that convey information about the mount topology:
+
+ * ``FSINFO_ATTR_MOUNT_INFO``
+
+ This struct-type attribute conveys information about a mount topology node
+ rather than a superblock. This includes the ID of the superblock mounted
+ there and the ID of the mount node, its parent, group, master and
+ propagation source. It also contains the attribute flags for the mount and
+ a change notification counter so that it can be quickly determined if that
+ node changed.
+
+ * ``FSINFO_ATTR_MOUNT_DEVNAME``
+
+ This string-type attribute returns the "device name" that was supplied when
+ the mount object was created.
+
+ * ``FSINFO_ATTR_MOUNT_CHILDREN``
+
+ This is an array-type attribute that conveys a set of structs, each of
+ which indicates the mount ID of a child and the change counter for that
+ child. The kernel also tags an extra element on the end that indicates the
+ ID and change counter of the queried object. This allows a conflicting
+ change to be quickly detected by comparing the before and after counters.
+
+ * ``FSINFO_ATTR_MOUNT_SUBMOUNT``
+
+ This is a string-type attribute that conveys the pathname of the Nth
+ mountpoint under the target mount, relative to the mount root or the
+ chroot, whichever is closer. These correspond on a 1:1 basis with the
+ eleemnts in the FSINFO_ATTR_MOUNT_CHROOT list.

FSINFO_ATTR_MOUNT_CHROOT -> FSINFO_ATTR_MOUNT_CHILDREN