Polls a virtual node (v-node) for immediate I/O.
int vn_select (vp, correl, e, re, notify, vinfo, crp) struct vnode *vp; int correl; int e; int re; int (*notify)(); caddr_t vinfo; struct ucred *crp;
| vp | Points to the v-node to be polled. |
| correl | Specifies the ID used for correlation in the selnotify kernel service. |
| e | Identifies the requested event. |
| re | Returns an events list. If the v-node is ready for immediate I/O, this field should be set to indicate the requested event is ready. |
| notify | Specifies the subroutine to call when the event occurs. This parameter is for nested polls. |
| vinfo | Is currently unused. |
| crp | Points to the cred structure. This structure contains data that the file system can use to validate access permission. |
The vn_select entry point is invoked by the logical file system to poll a v-node to determine if it is immediately ready for I/O. This entry point is used to implement the select and poll subroutines.
File system implementation can support constructs, such as devices or pipes, that support the select semantics. The fp_select kernel service provides more information about select and poll requests.
The vn_select entry point can be called from the process environment only.
| 0 | Indicates success. |
Nonzero return values are returned from the /usr/include/sys/errno.h file to indicate failure.
The poll subroutine, select subroutine.
The fp_select kernel service, selnotify kernel service.
Virtual File System Overview, Virtual File System Kernel Extensions Overview, Logical File System Overview, Understanding Virtual Nodes (V-nodes) in AIX Kernel Extensions and Device Support Programming Concepts.
List of Virtual File System Operations.