Implements control operations for a file system.
Item | Description |
---|---|
vfsp | Points to the file system for which the control operation is to be issued. |
cmd | Specifies which control operation to perform. |
arg | Identifies data specific to the control operation. |
argsize | Identifies the length of the data specified by the arg parameter. |
crp | Points to the cred structure. This structure contains data that the file system can use to validate access permission. |
The vfs_cntl entry point is invoked by the logical file system to request various control operations on the underlying file system. A file system implementation can define file system-specific cmd parameter values and corresponding control functions. The cmd parameter for these functions should have a minimum value of 32768. These control operations can be issued with the fscntl subroutine.
The vfs_cntl entry point can be called from the process environment only.
Item | Description |
---|---|
0 | Indicates success. |
Non-zero return values are returned from the /usr/include/sys/errno.h file to indicate failure. Typical values include:
Item | Description |
---|---|
EINVAL | Indicates that the cmd parameter is not a supported control, or the arg parameter is not a valid argument for the command. |
EACCES | Indicates that the cmd parameter requires a privilege that the current process does not have. |