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[78.151.217.120]) by smtp.gmail.com with ESMTPSA id n4sm18547625wrp.61.2019.06.05.05.21.49 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Wed, 05 Jun 2019 05:21:50 -0700 (PDT) From: Alan Jenkins Subject: Re: [PATCH 25/25] fsinfo: Add API documentation [ver #13] To: David Howells Cc: viro@zeniv.linux.org.uk, raven@themaw.net, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mszeredi@redhat.com References: <155905626142.1662.18430571708534506785.stgit@warthog.procyon.org.uk> <155905647369.1662.10806818386998503329.stgit@warthog.procyon.org.uk> Message-ID: Date: Wed, 5 Jun 2019 13:21:48 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <155905647369.1662.10806818386998503329.stgit@warthog.procyon.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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