Btrfs: add two more find_device() methods
Stefan Behrens [Mon, 5 Nov 2012 13:42:30 +0000 (14:42 +0100)]
The new function btrfs_find_device_missing_or_by_path() will be
used for the device replace procedure. This function itself calls
the second new function btrfs_find_device_by_path().
Unfortunately, it is not possible to currently make the rest of the
code use these functions as well, since all functions that look
similar at first view are all a little bit different in what they
are doing. But in the future, new code could benefit from these
two new functions, and currently, device replace uses them.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/volumes.c
fs/btrfs/volumes.h

index 4def1fd..1483041 100644 (file)
@@ -1522,6 +1522,65 @@ error_undo:
        goto error_brelse;
 }
 
+int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
+                             struct btrfs_device **device)
+{
+       int ret = 0;
+       struct btrfs_super_block *disk_super;
+       u64 devid;
+       u8 *dev_uuid;
+       struct block_device *bdev;
+       struct buffer_head *bh;
+
+       *device = NULL;
+       ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ,
+                                   root->fs_info->bdev_holder, 0, &bdev, &bh);
+       if (ret)
+               return ret;
+       disk_super = (struct btrfs_super_block *)bh->b_data;
+       devid = btrfs_stack_device_id(&disk_super->dev_item);
+       dev_uuid = disk_super->dev_item.uuid;
+       *device = btrfs_find_device(root, devid, dev_uuid,
+                                   disk_super->fsid);
+       brelse(bh);
+       if (!*device)
+               ret = -ENOENT;
+       blkdev_put(bdev, FMODE_READ);
+       return ret;
+}
+
+int btrfs_find_device_missing_or_by_path(struct btrfs_root *root,
+                                        char *device_path,
+                                        struct btrfs_device **device)
+{
+       *device = NULL;
+       if (strcmp(device_path, "missing") == 0) {
+               struct list_head *devices;
+               struct btrfs_device *tmp;
+
+               devices = &root->fs_info->fs_devices->devices;
+               /*
+                * It is safe to read the devices since the volume_mutex
+                * is held by the caller.
+                */
+               list_for_each_entry(tmp, devices, dev_list) {
+                       if (tmp->in_fs_metadata && !tmp->bdev) {
+                               *device = tmp;
+                               break;
+                       }
+               }
+
+               if (!*device) {
+                       pr_err("btrfs: no missing device found\n");
+                       return -ENOENT;
+               }
+
+               return 0;
+       } else {
+               return btrfs_find_device_by_path(root, device_path, device);
+       }
+}
+
 /*
  * does all the dirty work required for changing file system's UUID.
  */
index 1789cda..657bb12 100644 (file)
@@ -268,6 +268,11 @@ 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 btrfs_find_device_missing_or_by_path(struct btrfs_root *root,
+                                        char *device_path,
+                                        struct btrfs_device **device);
+int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
+                             struct btrfs_device **device);
 int btrfs_add_device(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root,
                     struct btrfs_device *device);