Btrfs: Dynamic chunk and block group allocation

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

1 files changed, 53 insertions, 34 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 90a8d45dc6d7..a52a13f365d6 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -131,7 +131,7 @@ check_pending:
         btrfs_release_path(root, path);
         BUG_ON(*start < search_start);
 
-        if (*start + num_bytes >= search_end) {
+        if (*start + num_bytes > search_end) {
                 ret = -ENOSPC;
                 goto error;
         }
@@ -159,8 +159,9 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
                 return -ENOMEM;
 
         ret = find_free_dev_extent(trans, device, path, num_bytes, start);
-        if (ret)
+        if (ret) {
                 goto err;
+        }
 
         key.objectid = device->devid;
         key.offset = *start;
@@ -214,22 +215,6 @@ error:
         return ret;
 }
 
-static struct btrfs_device *next_device(struct list_head *head,
-                                        struct list_head *last)
-{
-        struct list_head *next = last->next;
-        struct btrfs_device *dev;
-
-        if (list_empty(head))
-                return NULL;
-
-        if (next == head)
-                next = next->next;
-
-        dev = list_entry(next, struct btrfs_device, dev_list);
-        return dev;
-}
-
 static int find_next_devid(struct btrfs_root *root, struct btrfs_path *path,
                            u64 *objectid)
 {
@@ -397,31 +382,63 @@ int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
 
 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                       struct btrfs_root *extent_root, u64 *start,
-                      u64 *num_bytes, u32 type)
+                      u64 *num_bytes, u64 type)
 {
         u64 dev_offset;
         struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
         struct btrfs_stripe *stripes;
         struct btrfs_device *device = NULL;
         struct btrfs_chunk *chunk;
+        struct list_head private_devs;
         struct list_head *dev_list = &extent_root->fs_info->devices;
-        struct list_head *last_dev = extent_root->fs_info->last_device;
+        struct list_head *cur;
         struct extent_map_tree *em_tree;
         struct map_lookup *map;
         struct extent_map *em;
         u64 physical;
         u64 calc_size = 1024 * 1024 * 1024;
-        int num_stripes;
+        u64 avail;
+        u64 max_avail = 0;
+        int num_stripes = 1;
+        int looped = 0;
         int ret;
-        int index = 0;
+        int index;
         struct btrfs_key key;
 
+        if (list_empty(dev_list))
+                return -ENOSPC;
+again:
+        INIT_LIST_HEAD(&private_devs);
+        cur = dev_list->next;
+        index = 0;
+        /* build a private list of devices we will allocate from */
+        while(index < num_stripes) {
+                device = list_entry(cur, struct btrfs_device, dev_list);
+                avail = device->total_bytes - device->bytes_used;
+                cur = cur->next;
+                if (avail > max_avail)
+                        max_avail = avail;
+                if (avail >= calc_size) {
+                        list_move_tail(&device->dev_list, &private_devs);
+                        index++;
+                }
+                if (cur == dev_list)
+                        break;
+        }
+        if (index < num_stripes) {
+                list_splice(&private_devs, dev_list);
+                if (!looped && max_avail > 0) {
+                        looped = 1;
+                        calc_size = max_avail;
+                        goto again;
+                }
+                return -ENOSPC;
+        }
 
         ret = find_next_chunk(chunk_root, &key.objectid);
         if (ret)
                 return ret;
 
-        num_stripes = 1;
         chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
         if (!chunk)
                 return -ENOMEM;
@@ -429,11 +446,12 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         stripes = &chunk->stripe;
 
         *num_bytes = calc_size;
+        index = 0;
         while(index < num_stripes) {
-                device = next_device(dev_list, last_dev);
-                BUG_ON(!device);
-                last_dev = &device->dev_list;
-                extent_root->fs_info->last_device = last_dev;
+                BUG_ON(list_empty(&private_devs));
+                cur = private_devs.next;
+                device = list_entry(cur, struct btrfs_device, dev_list);
+                list_move_tail(&device->dev_list, dev_list);
 
                 ret = btrfs_alloc_dev_extent(trans, device,
                                              key.objectid,
@@ -449,6 +467,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                 physical = dev_offset;
                 index++;
         }
+        BUG_ON(!list_empty(&private_devs));
 
         /* key.objectid was set above */
         key.offset = *num_bytes;
@@ -692,17 +711,17 @@ static int read_one_dev(struct btrfs_root *root, struct btrfs_key *key,
         int ret;
 
         devid = btrfs_device_id(leaf, dev_item);
-        if (btrfs_find_device(root, devid))
-                return 0;
-
-        device = kmalloc(sizeof(*device), GFP_NOFS);
-        if (!device)
-                return -ENOMEM;
+        device = btrfs_find_device(root, devid);
+        if (!device) {
+                device = kmalloc(sizeof(*device), GFP_NOFS);
+                if (!device)
+                        return -ENOMEM;
+                list_add(&device->dev_list, &root->fs_info->devices);
+        }
 
         fill_device_from_item(leaf, dev_item, device);
         device->dev_root = root->fs_info->dev_root;
         device->bdev = root->fs_info->sb->s_bdev;
-        list_add(&device->dev_list, &root->fs_info->devices);
         memcpy(&device->dev_key, key, sizeof(*key));
         ret = 0;
 #if 0