This will call FITRIM within guest. The API has 4 arguments, however, only 2 will be used for now (@dom and @minumum). The rest two are there if in future qemu guest agent learns them.
s/in future/in the future/
+/** + * virDomainFSTrim: + * @dom: a domain object + * @mountPoint: which mount point trim
s/trim/to trim/
+ * @minimum: Minimum contiguous free range to discard in bytes + * @flags: extra flags, not used yet, so callers should always pass 0 + * + * Calls FITRIM within the guest (hence guest agent may be + * required depending on hypervisor used). Either call it on each + * mounted filesystem (@mountPoint is NULL) or just on specified + * @mountPoint. @minimum tell that free ranges smaller than this
s/tell/hints/
+ * may be ignored (this is a hint and the guest may not respect + * it). By increasing this value, the fstrim operation will + * complete more quickly for filesystems with badly fragmented + * free space, although not all blocks will be discarded.
Maybe mention that the command may fail if @minimum is not 0.