The objective of this patch is to cleanup barrier_all_devices()
so that the error checking is in a separate loop independent of
of the loop which submits and waits on the device flush requests.
By doing this it helps to further develop patches which would tune
the error-actions as needed.
Here functions such as btrfs_dev_stats_dirty() couldn't be used
because it doesn't monitor the flush errors BTRFS_DEV_STAT_FLUSH_ERRS.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
v2: Address Qu review comments viz..
Add meaningful names, like cp_list (for checkpoint_list head).
(And actually it does not need a new struct type just to hold
the head pointer, list node is already named as device_checkpoint).
Check return value of add_device_checkpoint()
Check if the device is already added at add_device_checkpoint()
Rename fini_devices_checkpoint() to rel_devices_checkpoint()
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5719e036048b..d0c401884643 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3566,6 +3566,86 @@ static int write_dev_flush(struct btrfs_device *device,
int wait)
return 0;
}
+struct device_checkpoint {
+ struct list_head cp_node;
+ struct btrfs_device *device;
+ int stat_value_checkpoint;
+};
+
+static int add_device_checkpoint(struct btrfs_device *device,
+ struct list_head *cp_list)
+{
+ struct device_checkpoint *cdev;
+
+ list_for_each_entry(cdev, cp_list, cp_node) {
+ if (cdev->device == device) {
+ cdev->stat_value_checkpoint =
+ btrfs_dev_stat_read(device,
+ BTRFS_DEV_STAT_FLUSH_ERRS);
+ return 0;
+ }
+ }
+
+ cdev = kzalloc(sizeof(struct device_checkpoint), GFP_KERNEL);
+ if (!cdev)
+ return -ENOMEM;
+
+ list_add(&cdev->cp_node, cp_list);
+
+ cdev->device = device;
+ cdev->stat_value_checkpoint =
+ btrfs_dev_stat_read(device, BTRFS_DEV_STAT_FLUSH_ERRS);
+
+ return 0;
+}
+
+static void rel_devices_checkpoint(struct list_head *cp_list)
+{
+ struct device_checkpoint *cdev;
+
+ while(!list_empty(cp_list)) {
+ cdev = list_entry(cp_list->next,
+ struct device_checkpoint, cp_node);
+ list_del(&cdev->cp_node);
+ kfree(cdev);
+ }
+}
+
+static int check_stat_flush(struct btrfs_device *dev,
+ struct list_head *cp_list)
+{
+ int val;
+ struct device_checkpoint *cdev;
+
+ list_for_each_entry(cdev, cp_list, cp_node) {
+ if (cdev->device == dev) {
+ val = btrfs_dev_stat_read(dev,
+ BTRFS_DEV_STAT_FLUSH_ERRS);
+ if (cdev->stat_value_checkpoint != val)
+ return 1;
+ }
+ }
+ return 0;
+}
+
+static int check_barrier_error(struct btrfs_fs_devices *fsdevs,
+ struct list_head *cp_list)
+{
+ int dropouts = 0;
+ struct btrfs_device *dev;
+
+ list_for_each_entry_rcu(dev, &fsdevs->devices, dev_list) {
+ if (!dev->bdev || check_stat_flush(dev, cp_list))
+ dropouts++;
+ }
+
+ if (dropouts >
+ fsdevs->fs_info->num_tolerated_disk_barrier_failures)
+ return -EIO;
+
+ return 0;
+}
+
/*
* send an empty flush down to each device in parallel,
* then wait for them
@@ -3574,8 +3654,8 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
{
struct list_head *head;
struct btrfs_device *dev;
- int dropouts = 0;
int ret;
+ static LIST_HEAD(cp_list);
/* send down all the barriers */
head = &info->fs_devices->devices;
@@ -3587,29 +3667,35 @@ static int barrier_all_devices(struct btrfs_fs_info
*info)
if (!dev->in_fs_metadata || !dev->writeable)
continue;
+ ret = add_device_checkpoint(dev, &cp_list);
+ if (ret) {
+ rel_devices_checkpoint(&cp_list);
+ return ret;
+ }
ret = write_dev_flush(dev, 0);
- if (ret)
+ if (ret) {
+ rel_devices_checkpoint(&cp_list);
return ret;
+ }
}
/* wait for all the barriers */
list_for_each_entry_rcu(dev, head, dev_list) {
if (dev->missing)
continue;
- if (!dev->bdev) {
- dropouts++;
+ if (!dev->bdev)
continue;
- }
if (!dev->in_fs_metadata || !dev->writeable)
continue;
- ret = write_dev_flush(dev, 1);
- if (ret)
- dropouts++;
+ write_dev_flush(dev, 1);
}
- if (dropouts > info->num_tolerated_disk_barrier_failures)
- return -EIO;
- return 0;
+
+ ret = check_barrier_error(info->fs_devices, &cp_list);
+
+ rel_devices_checkpoint(&cp_list);
+
+ return ret;
}
int btrfs_get_num_tolerated_disk_barrier_failures(u64 flags)
--
2.10.0
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