From: Anand Jain <anand.j...@oracle.com>
At the end of unmount/dev-delete, if the device exclusive open is not
actually closed, then there might be a race with another program in
the userland who is trying to open the device in exclusive mode and
it may fail for eg:
unmount /btrfs; fsck /dev/x
btrfs dev del /dev/x /btrfs; fsck /dev/x
so here background blkdev_put() is not a choice
---
This patch depends on the patch 2/2 as below,
[PATCH 1/2] btrfs: reorg btrfs_close_one_device()
[PATCH v3 2/2] btrfs: make sure device is synced before return
RFC->PATCH:
Collage sync and put to a function and use it
fs/btrfs/volumes.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f741ade130a4..1ce584893d1b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -834,10 +834,6 @@ static void __free_device(struct work_struct *work)
struct btrfs_device *device;
device = container_of(work, struct btrfs_device, rcu_work);
-
- if (device->bdev)
- blkdev_put(device->bdev, device->mode);
-
rcu_string_free(device->name);
kfree(device);
}
@@ -852,6 +848,17 @@ static void free_device(struct rcu_head *head)
schedule_work(&device->rcu_work);
}
+static void btrfs_close_bdev(struct btrfs_device *device)
+{
+ if (device->bdev && device->writeable) {
+ sync_blockdev(device->bdev);
+ invalidate_bdev(device->bdev);
+ }
+
+ if (device->bdev)
+ blkdev_put(device->bdev, device->mode);
+}
+
static void btrfs_close_one_device(struct btrfs_device *device)
{
struct btrfs_fs_devices *fs_devices = device->fs_devices;
@@ -870,10 +877,7 @@ static void btrfs_close_one_device(struct btrfs_device
*device)
if (device->missing)
fs_devices->missing_devices--;
- if (device->bdev && device->writeable) {
- sync_blockdev(device->bdev);
- invalidate_bdev(device->bdev);
- }
+ btrfs_close_bdev(device);
new_device = btrfs_alloc_device(NULL, &device->devid,
device->uuid);
@@ -1932,6 +1936,8 @@ int btrfs_rm_device(struct btrfs_root *root, char
*device_path, u64 devid)
btrfs_sysfs_rm_device_link(root->fs_info->fs_devices, device);
}
+ btrfs_close_bdev(device);
+
call_rcu(&device->rcu, free_device);
num_devices = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
@@ -2025,6 +2031,9 @@ void btrfs_rm_dev_replace_free_srcdev(struct
btrfs_fs_info *fs_info,
/* zero out the old super if it is writable */
btrfs_scratch_superblocks(srcdev->bdev, srcdev->name->str);
}
+
+ btrfs_close_bdev(srcdev);
+
call_rcu(&srcdev->rcu, free_device);
/*
@@ -2080,6 +2089,8 @@ void btrfs_destroy_dev_replace_tgtdev(struct
btrfs_fs_info *fs_info,
* the device_list_mutex lock.
*/
btrfs_scratch_superblocks(tgtdev->bdev, tgtdev->name->str);
+
+ btrfs_close_bdev(tgtdev);
call_rcu(&tgtdev->rcu, free_device);
}
--
2.7.0
--
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