Btrfs: Add a special device list for chunk allocations

This allows other code that needs to walk every device in the FS to do so
without locking against allocations.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 107fc74c3ab8..5619e50583e3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -111,6 +111,7 @@ static int device_list_add(const char *path,
                 if (!fs_devices)
                         return -ENOMEM;
                 INIT_LIST_HEAD(&fs_devices->devices);
+                INIT_LIST_HEAD(&fs_devices->alloc_list);
                 list_add(&fs_devices->list, &fs_uuids);
                 memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
                 fs_devices->latest_devid = devid;
@@ -139,6 +140,7 @@ static int device_list_add(const char *path,
                         return -ENOMEM;
                 }
                 list_add(&device->dev_list, &fs_devices->devices);
+                list_add(&device->dev_alloc_list, &fs_devices->alloc_list);
                 fs_devices->num_devices++;
         }
 
@@ -660,7 +662,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         struct btrfs_device *device = NULL;
         struct btrfs_chunk *chunk;
         struct list_head private_devs;
-        struct list_head *dev_list = &extent_root->fs_info->fs_devices->devices;
+        struct list_head *dev_list;
         struct list_head *cur;
         struct extent_map_tree *em_tree;
         struct map_lookup *map;
@@ -682,6 +684,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         int stripe_len = 64 * 1024;
         struct btrfs_key key;
 
+        dev_list = &extent_root->fs_info->fs_devices->alloc_list;
         if (list_empty(dev_list))
                 return -ENOSPC;
 
@@ -752,12 +755,12 @@ again:
 
         /* build a private list of devices we will allocate from */
         while(index < num_stripes) {
-                device = list_entry(cur, struct btrfs_device, dev_list);
+                device = list_entry(cur, struct btrfs_device, dev_alloc_list);
 
                 avail = device->total_bytes - device->bytes_used;
                 cur = cur->next;
                 if (avail >= min_free) {
-                        list_move_tail(&device->dev_list, &private_devs);
+                        list_move_tail(&device->dev_alloc_list, &private_devs);
                         index++;
                         if (type & BTRFS_BLOCK_GROUP_DUP)
                                 index++;
@@ -812,12 +815,12 @@ printk("new chunk type %Lu start %Lu size %Lu\n", type, key.offset, *num_bytes);
                 struct btrfs_stripe *stripe;
                 BUG_ON(list_empty(&private_devs));
                 cur = private_devs.next;
-                device = list_entry(cur, struct btrfs_device, dev_list);
+                device = list_entry(cur, struct btrfs_device, dev_alloc_list);
 
                 /* loop over this device again if we're doing a dup group */
                 if (!(type & BTRFS_BLOCK_GROUP_DUP) ||
                     (index == num_stripes - 1))
-                        list_move_tail(&device->dev_list, dev_list);
+                        list_move_tail(&device->dev_alloc_list, dev_list);
 
                 ret = btrfs_alloc_dev_extent(trans, device,
                              info->chunk_root->root_key.objectid,
@@ -1329,6 +1332,8 @@ static int read_one_dev(struct btrfs_root *root,
                         return -ENOMEM;
                 list_add(&device->dev_list,
                          &root->fs_info->fs_devices->devices);
+                list_add(&device->dev_alloc_list,
+                         &root->fs_info->fs_devices->alloc_list);
                 device->barriers = 1;
                 spin_lock_init(&device->io_lock);
         }