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drbd: device->ldev is not guaranteed on an D_ATTACHING disk

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Some parts of the code assumed that get_ldev_if_state(device, D_ATTACHING)
is sufficient to access the ldev member of the device object. That was
wrong. ldev may not be there or might be freed at any time if the device
has a disk state of D_ATTACHING.

bm_rw()
  Documented that drbd_bm_read() is only called from drbd_adm_attach.
  drbd_bm_write() is only called when a reference is held, and it is
  documented that a caller has to hold a reference before calling
  drbd_bm_write()

drbd_bm_write_page()
  Use get_ldev() instead of get_ldev_if_state(device, D_ATTACHING)

drbd_bmio_set_n_write()
  No longer use get_ldev_if_state(device, D_ATTACHING). All callers
  hold a reference to ldev now.

drbd_bmio_clear_n_write()
  All callers where holding a reference of ldev anyways. Remove the
  misleading get_ldev_if_state(device, D_ATTACHING)

drbd_reconsider_max_bio_size()
  Removed the get_ldev_if_state(device, D_ATTACHING). All callers
  now pass a struct drbd_backing_dev* when they have a proper
  reference, or a NULL pointer.
  Before this fix, the receiver could trigger a NULL pointer
  deref when in drbd_reconsider_max_bio_size()

drbd_bump_write_ordering()
  Used get_ldev_if_state(device, D_ATTACHING) with the wrong assumption.
  Remove it, and allow the caller to pass in a struct drbd_backing_dev*
  when the caller knows that accessing this bdev is safe.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Philipp Reisner
2013-11-22 13:22:13 +01:00
parent e952658020
commit 8fe39aac05
6 changed files with 80 additions and 57 deletions
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2
include/linux/drbd.h
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@@ -245,7 +245,7 @@ enum drbd_disk_state {
D_DISKLESS,
D_ATTACHING, /* In the process of reading the meta-data */
D_FAILED, /* Becomes D_DISKLESS as soon as we told it the peer */
/* when >= D_FAILED it is legal to access mdev->bc */
/* when >= D_FAILED it is legal to access mdev->ldev */
D_NEGOTIATING, /* Late attaching state, we need to talk to the peer */
D_INCONSISTENT,
D_OUTDATED,