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NAME

Filesys::POSIX::Mount - Exposes VFS mounting functionality to Filesys::POSIX

DESCRIPTION

Filesys::POSIX::Mount is a mixin module imported into the Filesys::POSIX namespace by said module that provides a frontend to the internal VFS. Rather than dealing in terms of mount point vnodes as Filesys::POSIX::VFS does, the system calls provided in this module deal in terms of pathnames.

SYSTEM CALLS

$fs->mount($dev, $path, %opts)

Attach the filesystem device, $dev, to the directory inode specified by $path. The %opts hash can be used to pass mount options to the initialization routines for the device object to be mounted; these options are passed to the $dev->init() routine that said filesystem device implements.

The filesystem mount record is kept in an ordered list by the VFS, and can be retrieved later using the $fs->statfs, or $fs->mountlist system calls.

$fs->unmount($path)

Attempts to unmount a filesystem mounted at the directory pointed to by $path, performing a number of sanity checks to ensure the safety of the current operation. The following checks are made:

The directory inode is retrieved using $fs->stat.
Using Filesys::POSIX::VFS->statfs, with the directory inode passed, the VFS is queried to determine if the location given has a filesystem mounted at all. If so, the mount record is kept for reference for the next series of checks.
The file descriptor table is scanned for open files whose inodes exist on the device found for the mount record queried in the previous step by the VFS. An EBUSY exception is thrown when matching file descriptors are found.
The current working directory is checked to ensure it is not a reference to a directory inode associated with the mounted device. An EBUSY exception is thrown if the current directory is on the same device that is to be unmounted.
$fs->statfs($path)

Returns the mount record for the device associated with the inode specified by $path. The inode is found using $fs->stat, then queried for by Filesys::POSIX::VFS->statfs.

$fs->fstatfs($fd)

Returns the mount record for the device associated with the inode referenced by the open file descriptor, $fd. The inode is found using $fs->fstat, then queried for by Filesys::POSIX::VFS->statfs.

$fs->mountlist

Returns a list of records for each filesystem currently mounted, in the order in which they were mounted.

ANATOMY OF A MOUNT RECORD

Mount records are created internally by Filesys::POSIX::VFS->mount, and are stored as anonymous HASHes. They contain the following attributes:

mountpoint

Reference to the directory inode (or vnode in the case of multiple filesystems mounted in the same logical location) the filesystem is mounted to.

root

Reference to the mounted filesystem's root directory inode. This is never a vnode.

special

The value of the special flag specified in a call to $fs->mount. When no value is specified, the value stored is equal to ref $dev.

dev

A reference to the filesystem device object that was mounted by $fs->mount.

type

A lowercase string formed by chopping all but the last item in a Perl fully qualified package name corresponding to the type of the device mounted. For instance, an instance of Filesys::POSIX::Mem mounted will result in a value of 'mem'.

path

The true, original, and sanitized path of the mount point specified by $fs->mount.

vnode

A VFS inode created by Filesys::POSIX::VFS::Inode->new, containing most attributes of the mounted device's root inode, but with a parent pointing to the mount point inode's parent.

flags

A copy of the options passed to $fs->mount, minus the special option.

AUTHOR

Written by Xan Tronix <xan@cpan.org>

CONTRIBUTORS

Rikus Goodell <rikus.goodell@cpanel.net>
Brian Carlson <brian.carlson@cpanel.net>

COPYRIGHT

Copyright (c) 2014, cPanel, Inc. Distributed under the terms of the Perl Artistic license.