Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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
+7
-18
+7
-18
drivers/block/rbd.c
+7
-18
drivers/block/rbd.c
···
2098
2098
* If an image has a non-zero parent overlap, get a reference to its
2099
2099
* parent.
2100
2100
*
2101
-
* We must get the reference before checking for the overlap to
2102
-
* coordinate properly with zeroing the parent overlap in
2103
-
* rbd_dev_v2_parent_info() when an image gets flattened. We
2104
-
* drop it again if there is no overlap.
2105
-
*
2106
2101
* Returns true if the rbd device has a parent with a non-zero
2107
2102
* overlap and a reference for it was successfully taken, or
2108
2103
* false otherwise.
2109
2104
*/
2110
2105
static bool rbd_dev_parent_get(struct rbd_device *rbd_dev)
2111
2106
{
2112
-
int counter;
2107
+
int counter = 0;
2113
2108
2114
2109
if (!rbd_dev->parent_spec)
2115
2110
return false;
2116
2111
2117
-
counter = atomic_inc_return_safe(&rbd_dev->parent_ref);
2118
-
if (counter > 0 && rbd_dev->parent_overlap)
2119
-
return true;
2120
-
2121
-
/* Image was flattened, but parent is not yet torn down */
2112
+
down_read(&rbd_dev->header_rwsem);
2113
+
if (rbd_dev->parent_overlap)
2114
+
counter = atomic_inc_return_safe(&rbd_dev->parent_ref);
2115
+
up_read(&rbd_dev->header_rwsem);
2122
2116
2123
2117
if (counter < 0)
2124
2118
rbd_warn(rbd_dev, "parent reference overflow");
2125
2119
2126
-
return false;
2120
+
return counter > 0;
2127
2121
}
2128
2122
2129
2123
/*
···
4233
4239
*/
4234
4240
if (rbd_dev->parent_overlap) {
4235
4241
rbd_dev->parent_overlap = 0;
4236
-
smp_mb();
4237
4242
rbd_dev_parent_put(rbd_dev);
4238
4243
pr_info("%s: clone image has been flattened\n",
4239
4244
rbd_dev->disk->disk_name);
···
4278
4285
* treat it specially.
4279
4286
*/
4280
4287
rbd_dev->parent_overlap = overlap;
4281
-
smp_mb();
4282
4288
if (!overlap) {
4283
4289
4284
4290
/* A null parent_spec indicates it's the initial probe */
···
5106
5114
{
5107
5115
struct rbd_image_header *header;
5108
5116
5109
-
/* Drop parent reference unless it's already been done (or none) */
5110
-
5111
-
if (rbd_dev->parent_overlap)
5112
-
rbd_dev_parent_put(rbd_dev);
5117
+
rbd_dev_parent_put(rbd_dev);
5113
5118
5114
5119
/* Free dynamic fields from the header, then zero it out */
5115
5120