freeze_bdev

Langue: en

Version: May 2009 (fedora - 06/07/09)

Section: 9 (Appels noyau Linux)

NAME

freeze_bdev - - lock a filesystem and force it into a consistent state

SYNOPSIS

struct super_block * freeze_bdev(struct block_device * bdev);

ARGUMENTS

bdev

blockdevice to lock

DESCRIPTION

This takes the block device bd_mount_sem to make sure no new mounts happen on bdev until thaw_bdev is called. If a superblock is found on this device, we take the s_umount semaphore on it to make sure nobody unmounts until the snapshot creation is done. The reference counter (bd_fsfreeze_count) guarantees that only the last unfreeze process can unfreeze the frozen filesystem actually when multiple freeze requests arrive simultaneously. It counts up in freeze_bdev and count down in thaw_bdev. When it becomes 0, thaw_bdev will unfreeze actually.