Commit bb6aa6f0 authored Oct 13, 2017 by Rakesh Pandit Committed by Jens Axboe Oct 13, 2017

lightnvm: prevent bd removal if busy



When a virtual block device is formatted and mounted after creating
with "nvme lnvm create... -t pblk", a removal from "nvm lnvm remove"
would result in this:

446416.309757] bdi-block not registered
[446416.309773] ------------[ cut here ]------------
[446416.309780] WARNING: CPU: 3 PID: 4319 at fs/fs-writeback.c:2159
  __mark_inode_dirty+0x268/0x340

Ideally removal should return -EBUSY as block device is mounted after
formatting.  This patch tries to address this checking if whole device
or any partition of it already mounted or not before removal.

Whole device is checked using "bd_super" member of block device.  This
member is always set once block device has been mounted using a
filesystem.  Another member "bd_part_count" takes care of checking any
if any partitions are under use.  "bd_part_count" is only updated
under locks when partitions are opened or closed (first open and last
release).  This at least does take care sending -EBUSY if removal is
being attempted while whole block device or any partition is mounted.

Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 90014829

drivers/lightnvm/core.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -373,6 +373,7 @@ static void __nvm_remove_target(struct nvm_target *t)
		static int nvm_remove_tgt(struct nvm_dev dev, struct nvm_ioctl_remove remove)
		{
		struct nvm_target *t;
		struct block_device *bdev;

		mutex_lock(&dev->mlock);
		t = nvm_find_target(dev, remove->tgtname);
		@@ -380,6 +381,19 @@ static int nvm_remove_tgt(struct nvm_dev dev, struct nvm_ioctl_remove remove)
		mutex_unlock(&dev->mlock);
		return 1;
		}
		bdev = bdget_disk(t->disk, 0);
		if (!bdev) {
		pr_err("nvm: removal failed, allocating bd failed\n");
		mutex_unlock(&dev->mlock);
		return -ENOMEM;
		}
		if (bdev->bd_super \|\| bdev->bd_part_count) {
		pr_err("nvm: removal failed, block device busy\n");
		bdput(bdev);
		mutex_unlock(&dev->mlock);
		return -EBUSY;
		}
		bdput(bdev);
		__nvm_remove_target(t);
		mutex_unlock(&dev->mlock);

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