btrfs: cleanup assigning next active device with a check

Creates helper fucntion as needed by the device delete
and replace operations. Also now it checks if the next
device being assigned is an active device.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index c93eec9..1f193f7 100644 (file)
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -569,11 +569,9 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
        ASSERT(list_empty(&src_device->resized_list));
        tgt_device->commit_total_bytes = src_device->commit_total_bytes;
        tgt_device->commit_bytes_used = src_device->bytes_used;
-       if (fs_info->sb->s_bdev &&
-               (fs_info->sb->s_bdev == src_device->bdev))
-               fs_info->sb->s_bdev = tgt_device->bdev;
-       if (fs_info->fs_devices->latest_bdev == src_device->bdev)
-               fs_info->fs_devices->latest_bdev = tgt_device->bdev;
+
+       btrfs_assign_next_active_device(fs_info, src_device, tgt_device);
+
        list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
        fs_info->fs_devices->rw_devices++;
 

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 41bc384..3fb0786 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1756,10 +1756,49 @@ static int btrfs_check_raid_min_devices(struct btrfs_fs_info *fs_info,
        return 0;
 }
 
+struct btrfs_device *btrfs_find_next_active_device(struct btrfs_fs_devices *fs_devs,
+                                       struct btrfs_device *device)
+{
+       struct btrfs_device *next_device;
+
+       list_for_each_entry(next_device, &fs_devs->devices, dev_list) {
+               if (next_device != device &&
+                       !next_device->missing && next_device->bdev)
+                       return next_device;
+       }
+
+       return NULL;
+}
+
+/*
+ * Helper function to check if the given device is part of s_bdev / latest_bdev
+ * and replace it with the provided or the next active device, in the context
+ * where this function called, there should be always be another device (or
+ * this_dev) which is active.
+ */
+void btrfs_assign_next_active_device(struct btrfs_fs_info *fs_info,
+               struct btrfs_device *device, struct btrfs_device *this_dev)
+{
+       struct btrfs_device *next_device;
+
+       if (this_dev)
+               next_device = this_dev;
+       else
+               next_device = btrfs_find_next_active_device(fs_info->fs_devices,
+                                                               device);
+       ASSERT(next_device);
+
+       if (fs_info->sb->s_bdev &&
+                       (fs_info->sb->s_bdev == device->bdev))
+               fs_info->sb->s_bdev = next_device->bdev;
+
+       if (fs_info->fs_devices->latest_bdev == device->bdev)
+               fs_info->fs_devices->latest_bdev = next_device->bdev;
+}
+
 int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
 {
        struct btrfs_device *device;
-       struct btrfs_device *next_device;
        struct btrfs_fs_devices *cur_devices;
        u64 num_devices;
        int ret = 0;
@@ -1846,13 +1885,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
        if (device->missing)
                device->fs_devices->missing_devices--;
 
-       next_device = list_entry(root->fs_info->fs_devices->devices.next,
-                                struct btrfs_device, dev_list);
-       if (root->fs_info->sb->s_bdev &&
-               (root->fs_info->sb->s_bdev == device->bdev))
-               root->fs_info->sb->s_bdev = next_device->bdev;
-       if (device->bdev == root->fs_info->fs_devices->latest_bdev)
-               root->fs_info->fs_devices->latest_bdev = next_device->bdev;
+       btrfs_assign_next_active_device(root->fs_info, device, NULL);
 
        if (device->bdev) {
                device->fs_devices->open_devices--;
@@ -1981,8 +2014,6 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_fs_info *fs_info,
 void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
                                      struct btrfs_device *tgtdev)
 {
-       struct btrfs_device *next_device;
-
        mutex_lock(&uuid_mutex);
        WARN_ON(!tgtdev);
        mutex_lock(&fs_info->fs_devices->device_list_mutex);
@@ -1995,13 +2026,8 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
        }
        fs_info->fs_devices->num_devices--;
 
-       next_device = list_entry(fs_info->fs_devices->devices.next,
-                                struct btrfs_device, dev_list);
-       if (fs_info->sb->s_bdev &&
-               (tgtdev->bdev == fs_info->sb->s_bdev))
-               fs_info->sb->s_bdev = next_device->bdev;
-       if (tgtdev->bdev == fs_info->fs_devices->latest_bdev)
-               fs_info->fs_devices->latest_bdev = next_device->bdev;
+       btrfs_assign_next_active_device(fs_info, tgtdev, NULL);
+
        list_del_rcu(&tgtdev->dev_list);
 
        call_rcu(&tgtdev->rcu, free_device);

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index febdb7b..7038017 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -445,6 +445,8 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
                          struct btrfs_fs_devices **fs_devices_ret);
 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
 void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices, int step);
+void btrfs_assign_next_active_device(struct btrfs_fs_info *fs_info,
+               struct btrfs_device *device, struct btrfs_device *this_dev);
 int btrfs_find_device_missing_or_by_path(struct btrfs_root *root,
                                         char *device_path,
                                         struct btrfs_device **device);