Messages in this thread | | | Date | Sun, 25 May 2008 15:32:11 -0400 | From | Christoph Hellwig <> | Subject | Re: [RFC PATCH 1/3] Implement generic freeze feature |
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> + if (test_and_set_bit(BD_FREEZE_OP, &bdev->bd_state)) > + return ERR_PTR(-EBUSY); > + > + sb = get_super_without_lock(bdev); > + > + /* If super_block has been already frozen, return. */ > + if (sb && sb->s_frozen != SB_UNFROZEN) { > + put_super(sb); > + clear_bit(BD_FREEZE_OP, &bdev->bd_state); > + return sb; > + }
The BD_FREEZE_OP flag in the block_device already prevents multiple freezes for a singe block device, so there is no need for this additional check and the get_super_without_lock helper.
> down(&bdev->bd_mount_sem);
And with that flag bd_mount_sem is also obsolete for preventing the multiple freeze operations. We still need investigate what synchronization we need vs unmount which also takes bd_mount_sem without every having document what it exactly protects.
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