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AIX Version 4.3 Kernel and Subsystems Technical Reference, Volume 1

vn_rdwr_attr Entry Point


Reads or writes data to or from a file.


vn_rdwr_attr (vp, rw, fflags, uiop, vinfo, prevap, postvap, crp)
struct vnode *vp;
enum uio_rw rw;
int fflags;
struct uio *uiop;
int ext;
caddr_t vinfo;
struct vattr*prevap;
struct vattr*postvap;
struct ucred *crp;


vp Points to the vnode to be read or written.
rw Specifies a flag indicating read or write.
fflags Specifies the file flags.
uiop Points to the uiop structure describing the operation.
ext Specifies the extension parameter passed to readx or writex.
vinfo Specifies the vinfo parameter from the file table entry.
prevap Points to an attributes structure for pre-operation attributes.
postvap Points to an attributes structure for post-operation attributes.
crp Specifies user's credentials.


The vn_rdwr_attr entry point is used to read and write files. The arguments are identical to the vn_rdwr entry point. The prevap and postvap pointers are used to return file attributes before and after the operation.

File systems that do not define GFS_VERSION421 in their gfs flags do not need to supply a vn_rdwr_attr entry point.

Execution Environment

The vn_rdwr_attr entry point can be called from the process environment only.

Return Values

Zero Indicates a successful operation.
Nonzero Indicates that the operation failed; return values should be chosen from the /usr/include/sys/errno.h file.

Related Information

Virtual File System Overview, Logical File System Overview, Understanding Virtual Nodes (V-nodes), and Virtual File System Kernel Extensions Overview.

List of Virtual File System Operations.

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