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authorMark Brown <broonie@linaro.org>2014-02-14 12:15:57 +0000
committerMark Brown <broonie@linaro.org>2014-02-14 12:15:57 +0000
commit6a7fe00e1f5a2e77b777b6e3b90c924c95bfa866 (patch)
tree1446c710e4a76d79fe11b1fa01ccb508f0d12d67 /drivers/md
parentccf1801b089f5575144c4346e4d7d3883a6c9163 (diff)
parent8415e604452966f981f20cb4d8a8a30e38a772dd (diff)
downloadlinaro-lsk-linux-linaro-lsk-v3.10-android.tar.gz
Merge branch 'linux-linaro-lsk' into linux-linaro-lsk-androidlinux-linaro-lsk-v3.10-androidlinux-linaro-lsk-android
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/Kconfig4
-rw-r--r--drivers/md/Makefile1
-rw-r--r--drivers/md/dm-builtin.c48
-rw-r--r--drivers/md/dm-sysfs.c5
-rw-r--r--drivers/md/dm-thin-metadata.c20
-rw-r--r--drivers/md/dm-thin-metadata.h2
-rw-r--r--drivers/md/dm-thin.c31
-rw-r--r--drivers/md/dm.c15
-rw-r--r--drivers/md/dm.h17
-rw-r--r--drivers/md/persistent-data/dm-space-map-common.c6
-rw-r--r--drivers/md/persistent-data/dm-space-map-metadata.c28
11 files changed, 147 insertions, 30 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 3bfc8f1da9f..29cff90096a 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -176,8 +176,12 @@ config MD_FAULTY
source "drivers/md/bcache/Kconfig"
+config BLK_DEV_DM_BUILTIN
+ boolean
+
config BLK_DEV_DM
tristate "Device mapper support"
+ select BLK_DEV_DM_BUILTIN
---help---
Device-mapper is a low level volume manager. It works by allowing
people to specify mappings for ranges of logical sectors. Various
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 1439fd4ad9b..3591a729238 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_MD_FAULTY) += faulty.o
obj-$(CONFIG_BCACHE) += bcache/
obj-$(CONFIG_BLK_DEV_MD) += md-mod.o
obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
+obj-$(CONFIG_BLK_DEV_DM_BUILTIN) += dm-builtin.o
obj-$(CONFIG_DM_BUFIO) += dm-bufio.o
obj-$(CONFIG_DM_BIO_PRISON) += dm-bio-prison.o
obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
diff --git a/drivers/md/dm-builtin.c b/drivers/md/dm-builtin.c
new file mode 100644
index 00000000000..6c9049c51b2
--- /dev/null
+++ b/drivers/md/dm-builtin.c
@@ -0,0 +1,48 @@
+#include "dm.h"
+
+/*
+ * The kobject release method must not be placed in the module itself,
+ * otherwise we are subject to module unload races.
+ *
+ * The release method is called when the last reference to the kobject is
+ * dropped. It may be called by any other kernel code that drops the last
+ * reference.
+ *
+ * The release method suffers from module unload race. We may prevent the
+ * module from being unloaded at the start of the release method (using
+ * increased module reference count or synchronizing against the release
+ * method), however there is no way to prevent the module from being
+ * unloaded at the end of the release method.
+ *
+ * If this code were placed in the dm module, the following race may
+ * happen:
+ * 1. Some other process takes a reference to dm kobject
+ * 2. The user issues ioctl function to unload the dm device
+ * 3. dm_sysfs_exit calls kobject_put, however the object is not released
+ * because of the other reference taken at step 1
+ * 4. dm_sysfs_exit waits on the completion
+ * 5. The other process that took the reference in step 1 drops it,
+ * dm_kobject_release is called from this process
+ * 6. dm_kobject_release calls complete()
+ * 7. a reschedule happens before dm_kobject_release returns
+ * 8. dm_sysfs_exit continues, the dm device is unloaded, module reference
+ * count is decremented
+ * 9. The user unloads the dm module
+ * 10. The other process that was rescheduled in step 7 continues to run,
+ * it is now executing code in unloaded module, so it crashes
+ *
+ * Note that if the process that takes the foreign reference to dm kobject
+ * has a low priority and the system is sufficiently loaded with
+ * higher-priority processes that prevent the low-priority process from
+ * being scheduled long enough, this bug may really happen.
+ *
+ * In order to fix this module unload race, we place the release method
+ * into a helper code that is compiled directly into the kernel.
+ */
+
+void dm_kobject_release(struct kobject *kobj)
+{
+ complete(dm_get_completion_from_kobject(kobj));
+}
+
+EXPORT_SYMBOL(dm_kobject_release);
diff --git a/drivers/md/dm-sysfs.c b/drivers/md/dm-sysfs.c
index 84d2b91e4ef..c62c5ab6aed 100644
--- a/drivers/md/dm-sysfs.c
+++ b/drivers/md/dm-sysfs.c
@@ -86,6 +86,7 @@ static const struct sysfs_ops dm_sysfs_ops = {
static struct kobj_type dm_ktype = {
.sysfs_ops = &dm_sysfs_ops,
.default_attrs = dm_attrs,
+ .release = dm_kobject_release,
};
/*
@@ -104,5 +105,7 @@ int dm_sysfs_init(struct mapped_device *md)
*/
void dm_sysfs_exit(struct mapped_device *md)
{
- kobject_put(dm_kobject(md));
+ struct kobject *kobj = dm_kobject(md);
+ kobject_put(kobj);
+ wait_for_completion(dm_get_completion_from_kobject(kobj));
}
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 60bce435f4f..33ac3be2e83 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1349,6 +1349,12 @@ dm_thin_id dm_thin_dev_id(struct dm_thin_device *td)
return td->id;
}
+/*
+ * Check whether @time (of block creation) is older than @td's last snapshot.
+ * If so then the associated block is shared with the last snapshot device.
+ * Any block on a device created *after* the device last got snapshotted is
+ * necessarily not shared.
+ */
static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
{
return td->snapshotted_time > time;
@@ -1458,6 +1464,20 @@ int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block)
return r;
}
+int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result)
+{
+ int r;
+ uint32_t ref_count;
+
+ down_read(&pmd->root_lock);
+ r = dm_sm_get_count(pmd->data_sm, b, &ref_count);
+ if (!r)
+ *result = (ref_count != 0);
+ up_read(&pmd->root_lock);
+
+ return r;
+}
+
bool dm_thin_changed_this_transaction(struct dm_thin_device *td)
{
int r;
diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h
index 845ebbe589a..125c0944401 100644
--- a/drivers/md/dm-thin-metadata.h
+++ b/drivers/md/dm-thin-metadata.h
@@ -181,6 +181,8 @@ int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
+int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
+
/*
* Returns -ENOSPC if the new size is too small and already allocated
* blocks would be lost.
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index e36f81e282e..73c76c565a4 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -512,6 +512,7 @@ struct dm_thin_new_mapping {
unsigned quiesced:1;
unsigned prepared:1;
unsigned pass_discard:1;
+ unsigned definitely_not_shared:1;
struct thin_c *tc;
dm_block_t virt_block;
@@ -683,7 +684,15 @@ static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m)
cell_defer_no_holder(tc, m->cell2);
if (m->pass_discard)
- remap_and_issue(tc, m->bio, m->data_block);
+ if (m->definitely_not_shared)
+ remap_and_issue(tc, m->bio, m->data_block);
+ else {
+ bool used = false;
+ if (dm_pool_block_is_used(tc->pool->pmd, m->data_block, &used) || used)
+ bio_endio(m->bio, 0);
+ else
+ remap_and_issue(tc, m->bio, m->data_block);
+ }
else
bio_endio(m->bio, 0);
@@ -751,13 +760,17 @@ static int ensure_next_mapping(struct pool *pool)
static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool)
{
- struct dm_thin_new_mapping *r = pool->next_mapping;
+ struct dm_thin_new_mapping *m = pool->next_mapping;
BUG_ON(!pool->next_mapping);
+ memset(m, 0, sizeof(struct dm_thin_new_mapping));
+ INIT_LIST_HEAD(&m->list);
+ m->bio = NULL;
+
pool->next_mapping = NULL;
- return r;
+ return m;
}
static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
@@ -769,15 +782,10 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
struct pool *pool = tc->pool;
struct dm_thin_new_mapping *m = get_next_mapping(pool);
- INIT_LIST_HEAD(&m->list);
- m->quiesced = 0;
- m->prepared = 0;
m->tc = tc;
m->virt_block = virt_block;
m->data_block = data_dest;
m->cell = cell;
- m->err = 0;
- m->bio = NULL;
if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
m->quiesced = 1;
@@ -840,15 +848,12 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
struct pool *pool = tc->pool;
struct dm_thin_new_mapping *m = get_next_mapping(pool);
- INIT_LIST_HEAD(&m->list);
m->quiesced = 1;
m->prepared = 0;
m->tc = tc;
m->virt_block = virt_block;
m->data_block = data_block;
m->cell = cell;
- m->err = 0;
- m->bio = NULL;
/*
* If the whole block of data is being overwritten or we are not
@@ -1032,12 +1037,12 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
*/
m = get_next_mapping(pool);
m->tc = tc;
- m->pass_discard = (!lookup_result.shared) && pool->pf.discard_passdown;
+ m->pass_discard = pool->pf.discard_passdown;
+ m->definitely_not_shared = !lookup_result.shared;
m->virt_block = block;
m->data_block = lookup_result.block;
m->cell = cell;
m->cell2 = cell2;
- m->err = 0;
m->bio = bio;
if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) {
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1c13071a81b..204a59fd872 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -184,8 +184,8 @@ struct mapped_device {
/* forced geometry settings */
struct hd_geometry geometry;
- /* sysfs handle */
- struct kobject kobj;
+ /* kobject and completion */
+ struct dm_kobject_holder kobj_holder;
/* zero-length flush that will be cloned and submitted to targets */
struct bio flush_bio;
@@ -1904,6 +1904,7 @@ static struct mapped_device *alloc_dev(int minor)
init_waitqueue_head(&md->wait);
INIT_WORK(&md->work, dm_wq_work);
init_waitqueue_head(&md->eventq);
+ init_completion(&md->kobj_holder.completion);
md->disk->major = _major;
md->disk->first_minor = minor;
@@ -2735,20 +2736,14 @@ struct gendisk *dm_disk(struct mapped_device *md)
struct kobject *dm_kobject(struct mapped_device *md)
{
- return &md->kobj;
+ return &md->kobj_holder.kobj;
}
-/*
- * struct mapped_device should not be exported outside of dm.c
- * so use this check to verify that kobj is part of md structure
- */
struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
{
struct mapped_device *md;
- md = container_of(kobj, struct mapped_device, kobj);
- if (&md->kobj != kobj)
- return NULL;
+ md = container_of(kobj, struct mapped_device, kobj_holder.kobj);
if (test_bit(DMF_FREEING, &md->flags) ||
dm_deleting_md(md))
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 45b97da1bd0..9b3222f4483 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -15,6 +15,8 @@
#include <linux/list.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
+#include <linux/completion.h>
+#include <linux/kobject.h>
/*
* Suspend feature flags
@@ -125,12 +127,27 @@ void dm_interface_exit(void);
/*
* sysfs interface
*/
+struct dm_kobject_holder {
+ struct kobject kobj;
+ struct completion completion;
+};
+
+static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
+{
+ return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
+}
+
int dm_sysfs_init(struct mapped_device *md);
void dm_sysfs_exit(struct mapped_device *md);
struct kobject *dm_kobject(struct mapped_device *md);
struct mapped_device *dm_get_from_kobject(struct kobject *kobj);
/*
+ * The kobject helper
+ */
+void dm_kobject_release(struct kobject *kobj);
+
+/*
* Targets for linear and striped mappings
*/
int dm_linear_init(void);
diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c
index 3e7a88d99eb..0d240373ffa 100644
--- a/drivers/md/persistent-data/dm-space-map-common.c
+++ b/drivers/md/persistent-data/dm-space-map-common.c
@@ -245,6 +245,10 @@ int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
return -EINVAL;
}
+ /*
+ * We need to set this before the dm_tm_new_block() call below.
+ */
+ ll->nr_blocks = nr_blocks;
for (i = old_blocks; i < blocks; i++) {
struct dm_block *b;
struct disk_index_entry idx;
@@ -252,6 +256,7 @@ int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
r = dm_tm_new_block(ll->tm, &dm_sm_bitmap_validator, &b);
if (r < 0)
return r;
+
idx.blocknr = cpu_to_le64(dm_block_location(b));
r = dm_tm_unlock(ll->tm, b);
@@ -266,7 +271,6 @@ int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
return r;
}
- ll->nr_blocks = nr_blocks;
return 0;
}
diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c
index 58fc1eef749..afb419e514b 100644
--- a/drivers/md/persistent-data/dm-space-map-metadata.c
+++ b/drivers/md/persistent-data/dm-space-map-metadata.c
@@ -608,20 +608,38 @@ static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
* Flick into a mode where all blocks get allocated in the new area.
*/
smm->begin = old_len;
- memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
+ memcpy(sm, &bootstrap_ops, sizeof(*sm));
/*
* Extend.
*/
r = sm_ll_extend(&smm->ll, extra_blocks);
+ if (r)
+ goto out;
/*
- * Switch back to normal behaviour.
+ * We repeatedly increment then commit until the commit doesn't
+ * allocate any new blocks.
*/
- memcpy(&smm->sm, &ops, sizeof(smm->sm));
- for (i = old_len; !r && i < smm->begin; i++)
- r = sm_ll_inc(&smm->ll, i, &ev);
+ do {
+ for (i = old_len; !r && i < smm->begin; i++) {
+ r = sm_ll_inc(&smm->ll, i, &ev);
+ if (r)
+ goto out;
+ }
+ old_len = smm->begin;
+
+ r = sm_ll_commit(&smm->ll);
+ if (r)
+ goto out;
+
+ } while (old_len != smm->begin);
+out:
+ /*
+ * Switch back to normal behaviour.
+ */
+ memcpy(sm, &ops, sizeof(*sm));
return r;
}