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authorXiao Guangrong <xiaoguangrong@cn.fujitsu.com>2011-04-20 10:07:30 +0000
committerChris Mason <chris.mason@oracle.com>2011-05-23 13:24:42 -0400
commitc9513edb0079f97749c2ac00c887a22c4ba44792 (patch)
tree6b34bd7cdf5dcd882e61bf4912ae10b4de3b87dd
parent4f6c9328c6c0d8558907f16579a9d47815abef80 (diff)
Btrfs: fix the race between reading and updating devices
On btrfs_congested_fn and __unplug_io_fn paths, we should hold device_list_mutex to avoid remove/add device path to update fs_devices->devices On __btrfs_close_devices and btrfs_prepare_sprout paths, the devices in fs_devices->devices or fs_devices->devices is updated, so we should hold the mutex to avoid the reader side to reach them Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/disk-io.c2
-rw-r--r--fs/btrfs/volumes.c7
2 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 64b289690f9..4e53a4fc467 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1410,6 +1410,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
struct btrfs_device *device;
struct backing_dev_info *bdi;
+ mutex_lock(&info->fs_devices->device_list_mutex);
list_for_each_entry(device, &info->fs_devices->devices, dev_list) {
if (!device->bdev)
continue;
@@ -1419,6 +1420,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
break;
}
}
+ mutex_unlock(&info->fs_devices->device_list_mutex);
return ret;
}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 290100fc47b..43c4f09e441 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -481,6 +481,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
if (--fs_devices->opened > 0)
return 0;
+ mutex_lock(&fs_devices->device_list_mutex);
list_for_each_entry(device, &fs_devices->devices, dev_list) {
if (device->bdev) {
blkdev_put(device->bdev, device->mode);
@@ -495,6 +496,8 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
device->writeable = 0;
device->in_fs_metadata = 0;
}
+ mutex_unlock(&fs_devices->device_list_mutex);
+
WARN_ON(fs_devices->open_devices);
WARN_ON(fs_devices->rw_devices);
fs_devices->opened = 0;
@@ -1415,7 +1418,11 @@ static int btrfs_prepare_sprout(struct btrfs_trans_handle *trans,
INIT_LIST_HEAD(&seed_devices->devices);
INIT_LIST_HEAD(&seed_devices->alloc_list);
mutex_init(&seed_devices->device_list_mutex);
+
+ mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
list_splice_init(&fs_devices->devices, &seed_devices->devices);
+ mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+
list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);
list_for_each_entry(device, &seed_devices->devices, dev_list) {
device->fs_devices = seed_devices;