btrfs: get device pointer from device_list_add()

Instead of pointer to btrfs_fs_devices as an arg in device_list_add()
better to get pointer to btrfs_device as return value, then we have
both, pointer to btrfs_device and btrfs_fs_devices. btrfs_device is
needed to handle reappearing missing device.

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

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4224a735493b2b200cd0951c814818f0dc742072..34c889a66240f331fc1edafb49129b1897007c24 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -724,12 +724,11 @@ error_brelse:
  * Add new device to list of registered devices
  *
  * Returns:
- * 0   - device already known or newly added
- * < 0 - error
+ * device pointer which was just added or updated when successful
+ * error pointer when failed
  */
-static noinline int device_list_add(const char *path,
-                          struct btrfs_super_block *disk_super,
-                          u64 devid, struct btrfs_fs_devices **fs_devices_ret)
+static noinline struct btrfs_device *device_list_add(const char *path,
+                          struct btrfs_super_block *disk_super, u64 devid)
 {
        struct btrfs_device *device;
        struct btrfs_fs_devices *fs_devices;
@@ -740,7 +739,7 @@ static noinline int device_list_add(const char *path,
        if (!fs_devices) {
                fs_devices = alloc_fs_devices(disk_super->fsid);
                if (IS_ERR(fs_devices))
-                       return PTR_ERR(fs_devices);
+                       return ERR_CAST(fs_devices);
 
                list_add(&fs_devices->list, &fs_uuids);
 
@@ -752,19 +751,19 @@ static noinline int device_list_add(const char *path,
 
        if (!device) {
                if (fs_devices->opened)
-                       return -EBUSY;
+                       return ERR_PTR(-EBUSY);
 
                device = btrfs_alloc_device(NULL, &devid,
                                            disk_super->dev_item.uuid);
                if (IS_ERR(device)) {
                        /* we can safely leave the fs_devices entry around */
-                       return PTR_ERR(device);
+                       return device;
                }
 
                name = rcu_string_strdup(path, GFP_NOFS);
                if (!name) {
                        free_device(device);
-                       return -ENOMEM;
+                       return ERR_PTR(-ENOMEM);
                }
                rcu_assign_pointer(device->name, name);
 
@@ -818,12 +817,12 @@ static noinline int device_list_add(const char *path,
                         * with larger generation number or the last-in if
                         * generation are equal.
                         */
-                       return -EEXIST;
+                       return ERR_PTR(-EEXIST);
                }
 
                name = rcu_string_strdup(path, GFP_NOFS);
                if (!name)
-                       return -ENOMEM;
+                       return ERR_PTR(-ENOMEM);
                rcu_string_free(device->name);
                rcu_assign_pointer(device->name, name);
                if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
@@ -843,9 +842,7 @@ static noinline int device_list_add(const char *path,
 
        fs_devices->total_devices = btrfs_super_num_devices(disk_super);
 
-       *fs_devices_ret = fs_devices;
-
-       return 0;
+       return device;
 }
 
 static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
@@ -1180,9 +1177,10 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
                          struct btrfs_fs_devices **fs_devices_ret)
 {
        struct btrfs_super_block *disk_super;
+       struct btrfs_device *device;
        struct block_device *bdev;
        struct page *page;
-       int ret;
+       int ret = 0;
        u64 devid;
        u64 bytenr;
 
@@ -1209,7 +1207,11 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 
        devid = btrfs_stack_device_id(&disk_super->dev_item);
 
-       ret = device_list_add(path, disk_super, devid, fs_devices_ret);
+       device = device_list_add(path, disk_super, devid);
+       if (IS_ERR(device))
+               ret = PTR_ERR(device);
+       else
+               *fs_devices_ret = device->fs_devices;
 
        btrfs_release_disk_super(page);