1 files changed, 60 insertions, 5 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6cb82f62cb7c..340a92d08e84 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -508,6 +508,44 @@ static noinline int device_list_add(const char *path,
                 ret = 1;
                 device->fs_devices = fs_devices;
         } else if (!device->name || strcmp(device->name->str, path)) {
+                /*
+                 * When FS is already mounted.
+                 * 1. If you are here and if the device->name is NULL that
+                 *    means this device was missing at time of FS mount.
+                 * 2. If you are here and if the device->name is different
+                 *    from 'path' that means either
+                 *      a. The same device disappeared and reappeared with
+                 *         different name. or
+                 *      b. The missing-disk-which-was-replaced, has
+                 *         reappeared now.
+                 *
+                 * We must allow 1 and 2a above. But 2b would be a spurious
+                 * and unintentional.
+                 *
+                 * Further in case of 1 and 2a above, the disk at 'path'
+                 * would have missed some transaction when it was away and
+                 * in case of 2a the stale bdev has to be updated as well.
+                 * 2b must not be allowed at all time.
+                 */
+
+                /*
+                 * As of now don't allow update to btrfs_fs_device through
+                 * the btrfs dev scan cli, after FS has been mounted.
+                 */
+                if (fs_devices->opened) {
+                        return -EBUSY;
+                } else {
+                        /*
+                         * That is if the FS is _not_ mounted and if you
+                         * are here, that means there is more than one
+                         * disk with same uuid and devid.We keep the one
+                         * with larger generation number or the last-in if
+                         * generation are equal.
+                         */
+                        if (found_transid < device->generation)
+                                return -EEXIST;
+                }
+
                 name = rcu_string_strdup(path, GFP_NOFS);
                 if (!name)
                         return -ENOMEM;
@@ -519,6 +557,15 @@ static noinline int device_list_add(const char *path,
                 }
         }
 
+        /*
+         * Unmount does not free the btrfs_device struct but would zero
+         * generation along with most of the other members. So just update
+         * it back. We need it to pick the disk with largest generation
+         * (as above).
+         */
+        if (!fs_devices->opened)
+                device->generation = found_transid;
+
         if (found_transid > fs_devices->latest_trans) {
                 fs_devices->latest_devid = devid;
                 fs_devices->latest_trans = found_transid;
@@ -1436,7 +1483,7 @@ static int btrfs_add_device(struct btrfs_trans_handle *trans,
         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
-        btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
+        btrfs_set_device_total_bytes(leaf, dev_item, device->disk_total_bytes);
         btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
         btrfs_set_device_group(leaf, dev_item, 0);
         btrfs_set_device_seek_speed(leaf, dev_item, 0);
@@ -1671,7 +1718,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
         device->fs_devices->total_devices--;
 
         if (device->missing)
-                root->fs_info->fs_devices->missing_devices--;
+                device->fs_devices->missing_devices--;
 
         next_device = list_entry(root->fs_info->fs_devices->devices.next,
                                  struct btrfs_device, dev_list);
@@ -1801,8 +1848,12 @@ void btrfs_rm_dev_replace_srcdev(struct btrfs_fs_info *fs_info,
         if (srcdev->bdev) {
                 fs_info->fs_devices->open_devices--;
 
-                /* zero out the old super */
-                btrfs_scratch_superblock(srcdev);
+                /*
+                 * zero out the old super if it is not writable
+                 * (e.g. seed device)
+                 */
+                if (srcdev->writeable)
+                        btrfs_scratch_superblock(srcdev);
         }
 
         call_rcu(&srcdev->rcu, free_device);
@@ -1941,6 +1992,9 @@ static int btrfs_prepare_sprout(struct btrfs_root *root)
         fs_devices->seeding = 0;
         fs_devices->num_devices = 0;
         fs_devices->open_devices = 0;
+        fs_devices->missing_devices = 0;
+        fs_devices->num_can_discard = 0;
+        fs_devices->rotating = 0;
         fs_devices->seed = seed_devices;
 
         generate_random_uuid(fs_devices->fsid);
@@ -5800,7 +5854,8 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
         else
                 generate_random_uuid(dev->uuid);
 
-        btrfs_init_work(&dev->work, pending_bios_fn, NULL, NULL);
+        btrfs_init_work(&dev->work, btrfs_submit_helper,
+                        pending_bios_fn, NULL, NULL);
 
         return dev;
 }