IFS - FS Service Routines

Installable File Systems for OS/2
Installable File System Mechanism Installable File System Overview Extended Attributes FSD File Image FSD Initialization IFS Commands File System Function Calls FSD System Interfaces FSD Calling Conventions and Requirements FS Service Routines FS Helper Functions Remote IPL / Bootable IFS mini-FDS Entry Points mini-FDS Helper Routines

Reprint Courtesy of International Business Machines Corporation, © International Business Machines Corporation

The following table summarizes the entry points that make up the interface between the kernel and the FSD.

Note

Names must be in all upper case, as required by OS/2 naming conventions.

FS Entry Point	Description	FSDs Required to export
FS_ALLOCATEPAGESPACE	Adjust the size of paging file	PAGE I/O
FS_ATTACH	Attach to an FSD	ALL
FS_CANCELLOCKREQUEST	Cancel file record lock request	FILE I/O
FS_CHDIR	Change/Verify directory path	ALL
FS_CHGFILEPTR	Move a file's position pointer	ALL
FS_CLOSE	Release a file handle	ALL
FS_COMMIT	Flush a file's buffer to disk	ALL
FS_COPY	Copy a file	ALL
FS_DELETE	Delete a file	ALL
FS_DOPAGEIO	Perform paging I/O operations	PAGE I/O
FS_EXIT	End of a process cleanup	ALL
FS_FILEATTRIBUTE	Query/Set file's attributes	ALL
FS_FILEINFO	Query/Set file's information	ALL
FS_FILEIO	Multi-function file I/O	ALL
FS_FILELOCKS	Request a file record lock/unlock	FILE I/O
FS_FINDCLOSE	Directory search close	ALL
FS_FINDFIRST	Find first matching filename	ALL
FS_FINDFROMNAME	Find matching filename from name	ALL
FS_FINDNEXT	Find next matching filename	ALL
FS_FINDNOTIFYCLOSE	Close FindNotify handle	ALL
FS_FINDNOTIFYFIRST	Monitor a directory for changes	ALL
FS_FINDNOTIFYNEXT	Resume reporting directory changes	ALL
FS_FLUSHBUF	Commit file buffers to disk	ALL
FS_FSCTL	File system control	ALL
FS_FSINFO	Query/Set file system information	ALL
FS_INIT	FSD initialization	ALL
FS_IOCTL	I/O device control	ALL
FS_MKDIR	Make a directory	ALL
FS_MOUNT	Mount/unmount volumes	ALL
FS_MOVE	Move a file or subdirectory	ALL
FS_NEWSIZE	Change a file's logical size	ALL
FS_NMPIPE	Do a named pipe operation	ALL
FS_OPENCREATE	Open/create/replace files	ALL
FS_OPENPAGEFILE	Create paging file and handle	PAGE I/O
FS_PATHINFO	Query/Set a file's information	ALL
FS_PROCESSNAME	FSD unique name canonicalization	ALL
FS_READ	Read data from a file	ALL
FS_RMDIR	Remove a subdirectory	ALL
FS_SETSWAP	Notification of swapfile ownership	ALL
FS_SHUTDOWN	Shutdown file system	ALL
FS_VERIFYUNCNAME	Verify UNC server ownership	UNC
FS_WRITE	Write data to a file	ALL

Each FS entry point has a distinct parameter list composed of those parameters needed by that particular entry. Parameters include:

• File pathname
• Current disk/directory information
• Open file information
• Application data buffers
• Descriptions of file extended attributes
• Other parameters specific to an individual call

Most of the FS entry points have a level parameter for specifying the level of information they are provided or have to supply. FSDs must provide for additional levels which may be added in future versions of OS/2 by returning ERROR_NOT_SUPPORTED for any level they do not recognize.

File system drivers which support hierarchical directory structures must use '\' and '/' as path name component separators. File system drivers which do not support hierarchical directory structures must reject as illegal any use of '\' or '/' in path names. The file names '.' and '..' are reserved for use in hierarchical directory structures for the current directory and the parent of the current directory, respectively.

Unless otherwise specified in the descriptions below, data buffers may be accessed without concern for the accessibility of the data. OS/2 will either check buffers for accessibility and lock them, or transfer them into locally accessible data areas.

Simple parameters will be verified by the IFS router before the FS service routine is called.

Note

New with 2.0, some entry points need only be exported and supported by those FSDs which desire to service the pager (PAGE I/0), UNC servers (UNC) and/or file locking (FILE I/O). With these new entry point groups, a FSD must export all or none of the entry points within a particular group.

These optional entry points are:

FS_ALLOCATEPAGESPACE    (PAGE I/O)
FS_CANCELLOCKREQUEST    (FILE I/O)
FS_DOPAGEIO             (PAGE I/O)
FS_FILELOCKS            (FILE I/O)
FS_OPENPAGEFILE         (PAGE I/O)
FS_VERIFYUNCNAME        (UNC)