FREEZE_BDEV(9)                            The Linux VFS                            FREEZE_BDEV(9)



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
       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.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                            FREEZE_BDEV(9)