Btrfs: improve forever loop when doing balance relocation

[sfrench/cifs-2.6.git] / fs / btrfs / relocation.c

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 429c73c374b84f9bcd468067221bf99e0b9f67db..63708f77c8e06e1b2d75040e9c5aa58cbc212f87 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -94,6 +94,7 @@ struct backref_edge {
 
 #define LOWER  0
 #define UPPER  1
+#define RELOCATION_RESERVED_NODES      256
 
 struct backref_cache {
        /* red black tree of all backref nodes in the cache */
@@ -176,6 +177,8 @@ struct reloc_control {
        u64 merging_rsv_size;
        /* size of relocated tree nodes */
        u64 nodes_relocated;
+       /* reserved size for block group relocation*/
+       u64 reserved_bytes;
 
        u64 search_start;
        u64 extents_found;
@@ -184,7 +187,6 @@ struct reloc_control {
        unsigned int create_reloc_tree:1;
        unsigned int merge_reloc_tree:1;
        unsigned int found_file_extent:1;
-       unsigned int commit_transaction:1;
 };
 
 /* stages of data relocation */
@@ -2590,28 +2592,36 @@ static int reserve_metadata_space(struct btrfs_trans_handle *trans,
        struct btrfs_root *root = rc->extent_root;
        u64 num_bytes;
        int ret;
+       u64 tmp;
 
        num_bytes = calcu_metadata_size(rc, node, 1) * 2;
 
        trans->block_rsv = rc->block_rsv;
-       ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
-                                 BTRFS_RESERVE_FLUSH_ALL);
+       rc->reserved_bytes += num_bytes;
+       ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
+                               BTRFS_RESERVE_FLUSH_ALL);
        if (ret) {
-               if (ret == -EAGAIN)
-                       rc->commit_transaction = 1;
+               if (ret == -EAGAIN) {
+                       tmp = rc->extent_root->nodesize *
+                               RELOCATION_RESERVED_NODES;
+                       while (tmp <= rc->reserved_bytes)
+                               tmp <<= 1;
+                       /*
+                        * only one thread can access block_rsv at this point,
+                        * so we don't need hold lock to protect block_rsv.
+                        * we expand more reservation size here to allow enough
+                        * space for relocation and we will return eailer in
+                        * enospc case.
+                        */
+                       rc->block_rsv->size = tmp + rc->extent_root->nodesize *
+                                             RELOCATION_RESERVED_NODES;
+               }
                return ret;
        }
 
        return 0;
 }
 
-static void release_metadata_space(struct reloc_control *rc,
-                                  struct backref_node *node)
-{
-       u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
-       btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
-}
-
 /*
  * relocate a block tree, and then update pointers in upper level
  * blocks that reference the block to point to the new location.
@@ -2898,7 +2908,6 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
                                struct btrfs_path *path)
 {
        struct btrfs_root *root;
-       int release = 0;
        int ret = 0;
 
        if (!node)
@@ -2915,7 +2924,6 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
                ret = reserve_metadata_space(trans, rc, node);
                if (ret)
                        goto out;
-               release = 1;
        }
 
        if (root) {
@@ -2940,11 +2948,8 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
                ret = do_relocation(trans, rc, node, key, path, 1);
        }
 out:
-       if (ret || node->level == 0 || node->cowonly) {
-               if (release)
-                       release_metadata_space(rc, node);
+       if (ret || node->level == 0 || node->cowonly)
                remove_backref_node(&rc->backref_cache, node);
-       }
        return ret;
 }
 
@@ -3867,29 +3872,20 @@ static noinline_for_stack
 int prepare_to_relocate(struct reloc_control *rc)
 {
        struct btrfs_trans_handle *trans;
-       int ret;
 
        rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
                                              BTRFS_BLOCK_RSV_TEMP);
        if (!rc->block_rsv)
                return -ENOMEM;
 
-       /*
-        * reserve some space for creating reloc trees.
-        * btrfs_init_reloc_root will use them when there
-        * is no reservation in transaction handle.
-        */
-       ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
-                                 rc->extent_root->nodesize * 256,
-                                 BTRFS_RESERVE_FLUSH_ALL);
-       if (ret)
-               return ret;
-
        memset(&rc->cluster, 0, sizeof(rc->cluster));
        rc->search_start = rc->block_group->key.objectid;
        rc->extents_found = 0;
        rc->nodes_relocated = 0;
        rc->merging_rsv_size = 0;
+       rc->reserved_bytes = 0;
+       rc->block_rsv->size = rc->extent_root->nodesize *
+                             RELOCATION_RESERVED_NODES;
 
        rc->create_reloc_tree = 1;
        set_reloc_control(rc);
@@ -3933,6 +3929,14 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
        }
 
        while (1) {
+               rc->reserved_bytes = 0;
+               ret = btrfs_block_rsv_refill(rc->extent_root,
+                                       rc->block_rsv, rc->block_rsv->size,
+                                       BTRFS_RESERVE_FLUSH_ALL);
+               if (ret) {
+                       err = ret;
+                       break;
+               }
                progress++;
                trans = btrfs_start_transaction(rc->extent_root, 0);
                if (IS_ERR(trans)) {
@@ -4020,14 +4024,8 @@ restart:
                        }
                }
 
-               if (rc->commit_transaction) {
-                       rc->commit_transaction = 0;
-                       ret = btrfs_commit_transaction(trans, rc->extent_root);
-                       BUG_ON(ret);
-               } else {
-                       btrfs_end_transaction_throttle(trans, rc->extent_root);
-                       btrfs_btree_balance_dirty(rc->extent_root);
-               }
+               btrfs_end_transaction_throttle(trans, rc->extent_root);
+               btrfs_btree_balance_dirty(rc->extent_root);
                trans = NULL;
 
                if (rc->stage == MOVE_DATA_EXTENTS &&