Commit 884e00f3 authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

Pull Ceph fixes from Sage Weil:
 "These paches from Ilya finally squash a race condition with layered
  images that he's been chasing for a while"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  rbd: drop parent_ref in rbd_dev_unprobe() unconditionally
  rbd: fix rbd_dev_parent_get() when parent_overlap == 0
parents a2ae004a e69b8d41
...@@ -2098,32 +2098,26 @@ static void rbd_dev_parent_put(struct rbd_device *rbd_dev) ...@@ -2098,32 +2098,26 @@ static void rbd_dev_parent_put(struct rbd_device *rbd_dev)
* If an image has a non-zero parent overlap, get a reference to its * If an image has a non-zero parent overlap, get a reference to its
* parent. * parent.
* *
* We must get the reference before checking for the overlap to
* coordinate properly with zeroing the parent overlap in
* rbd_dev_v2_parent_info() when an image gets flattened. We
* drop it again if there is no overlap.
*
* Returns true if the rbd device has a parent with a non-zero * Returns true if the rbd device has a parent with a non-zero
* overlap and a reference for it was successfully taken, or * overlap and a reference for it was successfully taken, or
* false otherwise. * false otherwise.
*/ */
static bool rbd_dev_parent_get(struct rbd_device *rbd_dev) static bool rbd_dev_parent_get(struct rbd_device *rbd_dev)
{ {
int counter; int counter = 0;
if (!rbd_dev->parent_spec) if (!rbd_dev->parent_spec)
return false; return false;
down_read(&rbd_dev->header_rwsem);
if (rbd_dev->parent_overlap)
counter = atomic_inc_return_safe(&rbd_dev->parent_ref); counter = atomic_inc_return_safe(&rbd_dev->parent_ref);
if (counter > 0 && rbd_dev->parent_overlap) up_read(&rbd_dev->header_rwsem);
return true;
/* Image was flattened, but parent is not yet torn down */
if (counter < 0) if (counter < 0)
rbd_warn(rbd_dev, "parent reference overflow"); rbd_warn(rbd_dev, "parent reference overflow");
return false; return counter > 0;
} }
/* /*
...@@ -4239,7 +4233,6 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev) ...@@ -4239,7 +4233,6 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
*/ */
if (rbd_dev->parent_overlap) { if (rbd_dev->parent_overlap) {
rbd_dev->parent_overlap = 0; rbd_dev->parent_overlap = 0;
smp_mb();
rbd_dev_parent_put(rbd_dev); rbd_dev_parent_put(rbd_dev);
pr_info("%s: clone image has been flattened\n", pr_info("%s: clone image has been flattened\n",
rbd_dev->disk->disk_name); rbd_dev->disk->disk_name);
...@@ -4285,7 +4278,6 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev) ...@@ -4285,7 +4278,6 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
* treat it specially. * treat it specially.
*/ */
rbd_dev->parent_overlap = overlap; rbd_dev->parent_overlap = overlap;
smp_mb();
if (!overlap) { if (!overlap) {
/* A null parent_spec indicates it's the initial probe */ /* A null parent_spec indicates it's the initial probe */
...@@ -5114,9 +5106,6 @@ static void rbd_dev_unprobe(struct rbd_device *rbd_dev) ...@@ -5114,9 +5106,6 @@ static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
{ {
struct rbd_image_header *header; struct rbd_image_header *header;
/* Drop parent reference unless it's already been done (or none) */
if (rbd_dev->parent_overlap)
rbd_dev_parent_put(rbd_dev); rbd_dev_parent_put(rbd_dev);
/* Free dynamic fields from the header, then zero it out */ /* Free dynamic fields from the header, then zero it out */
......
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