The commit is pushed to "branch-rh7-3.10.0-327.18.2.vz7.15.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.18.2.vz7.14.27
------>
commit 28150e9b63d016913a70e044ac405a2e356ddf1b
Author: Maxim Patlasov <[email protected]>
Date: Tue Jul 19 16:32:47 2016 +0400
ploop: fix freeze/thaw ioctls
Current implementation suffers from several problems:
1) If someone, e.g. another instance of push-backup tool, mistakenly
attempts to freeze ploop while its thawing is in progress, we can
end up in double freeze.
2) After initiating thawing, no way to find out it by sysctl or /sys.
3) Handling PLOOP_S_FROZEN bit is not synchronized with ploop STOP/CLEAR
ioctls. It's not nice if ploop releases bdev keeping it in frozen state.
The patch fixes the above in straightforward way: more descriptive
plo->freeze_state, visible via /sys/block/ploopN/pstate/freeze_state, and
special checks in ioctl-s to ensure that freeze/thaw is allowed only on
running ploops and that thaw must preceed ploop STOP.
https://jira.sw.ru/browse/PSBM-49699
Signed-off-by: Maxim Patlasov <[email protected]>
Acked-by: Dmitry Monakhov <[email protected]>
---
drivers/block/ploop/dev.c | 34 ++++++++++++++++++++++++++++++----
drivers/block/ploop/sysfs.c | 6 ++++++
include/linux/ploop/ploop.h | 8 +++++++-
3 files changed, 43 insertions(+), 5 deletions(-)
diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 9b7a764..98fae18 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -3979,6 +3979,13 @@ static int ploop_stop(struct ploop_device * plo, struct
block_device *bdev)
return -EBUSY;
}
+ if (plo->freeze_state != PLOOP_F_NORMAL) {
+ if (printk_ratelimit())
+ printk(KERN_INFO "stop ploop%d failed
(freeze_state=%d)\n",
+ plo->index, plo->freeze_state);
+ return -EBUSY;
+ }
+
clear_bit(PLOOP_S_PUSH_BACKUP, &plo->state);
ploop_pb_stop(plo->pbd, true);
@@ -4896,15 +4903,21 @@ static int ploop_freeze(struct ploop_device *plo,
struct block_device *bdev)
{
struct super_block *sb = plo->sb;
- if (test_bit(PLOOP_S_FROZEN, &plo->state))
+ if (!test_bit(PLOOP_S_RUNNING, &plo->state))
+ return -EINVAL;
+
+ if (plo->freeze_state == PLOOP_F_FROZEN)
return 0;
+ if (plo->freeze_state == PLOOP_F_THAWING)
+ return -EBUSY;
+
sb = freeze_bdev(bdev);
if (sb && IS_ERR(sb))
return PTR_ERR(sb);
plo->sb = sb;
- set_bit(PLOOP_S_FROZEN, &plo->state);
+ plo->freeze_state = PLOOP_F_FROZEN;
return 0;
}
@@ -4913,16 +4926,29 @@ static int ploop_thaw(struct ploop_device *plo, struct
block_device *bdev)
struct super_block *sb = plo->sb;
int err;
- if (!test_bit(PLOOP_S_FROZEN, &plo->state))
+ if (!test_bit(PLOOP_S_RUNNING, &plo->state))
+ return -EINVAL;
+
+ if (plo->freeze_state == PLOOP_F_NORMAL)
return 0;
+ if (plo->freeze_state == PLOOP_F_THAWING)
+ return -EBUSY;
+
plo->sb = NULL;
- clear_bit(PLOOP_S_FROZEN, &plo->state);
+ plo->freeze_state = PLOOP_F_THAWING;
mutex_unlock(&plo->ctl_mutex);
err = thaw_bdev(bdev, sb);
mutex_lock(&plo->ctl_mutex);
+ BUG_ON(plo->freeze_state != PLOOP_F_THAWING);
+
+ if (!err)
+ plo->freeze_state = PLOOP_F_NORMAL;
+ else
+ plo->freeze_state = PLOOP_F_FROZEN;
+
return err;
}
diff --git a/drivers/block/ploop/sysfs.c b/drivers/block/ploop/sysfs.c
index 9e4c9ab..55f5d58 100644
--- a/drivers/block/ploop/sysfs.c
+++ b/drivers/block/ploop/sysfs.c
@@ -445,6 +445,11 @@ static u32 show_blocked_bios(struct ploop_device * plo)
return plo->blocked_bios;
}
+static u32 show_freeze_state(struct ploop_device * plo)
+{
+ return plo->freeze_state;
+}
+
#define _TUNE_U32(_name) \
static u32 show_##_name(struct ploop_device * plo) \
{ \
@@ -531,6 +536,7 @@ static struct attribute *state_attributes[] = {
_A(free_qmax),
_A(blockable_reqs),
_A(blocked_bios),
+ _A(freeze_state),
NULL
};
diff --git a/include/linux/ploop/ploop.h b/include/linux/ploop/ploop.h
index 7ce2ca8..9d3410b 100644
--- a/include/linux/ploop/ploop.h
+++ b/include/linux/ploop/ploop.h
@@ -61,7 +61,12 @@ enum {
(for minor mgmt only) */
PLOOP_S_ONCE, /* An event (e.g. printk once) happened */
PLOOP_S_PUSH_BACKUP, /* Push_backup is in progress */
- PLOOP_S_FROZEN /* Frozen PLOOP_IOC_FREEZE */
+};
+
+enum {
+ PLOOP_F_NORMAL, /* Default: not yet freezed or unfrozen */
+ PLOOP_F_FROZEN, /* Frozen PLOOP_IOC_FREEZE */
+ PLOOP_F_THAWING, /* thaw_bdev is in progress */
};
struct ploop_snapdata
@@ -415,6 +420,7 @@ struct ploop_device
struct request_queue *queue;
struct task_struct *thread;
struct super_block *sb;
+ int freeze_state;
struct rb_node link;
/* someone who wants to quiesce state-machine waits
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