freeze_bdev (9) Linux Manual Page
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.