ocfs2: Abstract ocfs2_extent_tree in b-tree operations.

[pandora-kernel.git] / fs / ocfs2 / suballoc.c

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 2a817bc..b642c82 100644 (file)
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1894,3 +1894,85 @@ static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe)
                       (unsigned long long)fe->id2.i_chain.cl_recs[i].c_blkno);
        }
 }
+
+/*
+ * For a given allocation, determine which allocators will need to be
+ * accessed, and lock them, reserving the appropriate number of bits.
+ *
+ * Sparse file systems call this from ocfs2_write_begin_nolock()
+ * and ocfs2_allocate_unwritten_extents().
+ *
+ * File systems which don't support holes call this from
+ * ocfs2_extend_allocation().
+ */
+int ocfs2_lock_allocators(struct inode *inode, struct buffer_head *root_bh,
+                         struct ocfs2_extent_list *root_el,
+                         u32 clusters_to_add, u32 extents_to_split,
+                         struct ocfs2_alloc_context **data_ac,
+                         struct ocfs2_alloc_context **meta_ac)
+{
+       int ret = 0, num_free_extents;
+       unsigned int max_recs_needed = clusters_to_add + 2 * extents_to_split;
+       struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+       *meta_ac = NULL;
+       if (data_ac)
+               *data_ac = NULL;
+
+       BUG_ON(clusters_to_add != 0 && data_ac == NULL);
+
+       num_free_extents = ocfs2_num_free_extents(osb, inode, root_bh,
+                                                 OCFS2_DINODE_EXTENT);
+       if (num_free_extents < 0) {
+               ret = num_free_extents;
+               mlog_errno(ret);
+               goto out;
+       }
+
+       /*
+        * Sparse allocation file systems need to be more conservative
+        * with reserving room for expansion - the actual allocation
+        * happens while we've got a journal handle open so re-taking
+        * a cluster lock (because we ran out of room for another
+        * extent) will violate ordering rules.
+        *
+        * Most of the time we'll only be seeing this 1 cluster at a time
+        * anyway.
+        *
+        * Always lock for any unwritten extents - we might want to
+        * add blocks during a split.
+        */
+       if (!num_free_extents ||
+           (ocfs2_sparse_alloc(osb) && num_free_extents < max_recs_needed)) {
+               ret = ocfs2_reserve_new_metadata(osb, root_el, meta_ac);
+               if (ret < 0) {
+                       if (ret != -ENOSPC)
+                               mlog_errno(ret);
+                       goto out;
+               }
+       }
+
+       if (clusters_to_add == 0)
+               goto out;
+
+       ret = ocfs2_reserve_clusters(osb, clusters_to_add, data_ac);
+       if (ret < 0) {
+               if (ret != -ENOSPC)
+                       mlog_errno(ret);
+               goto out;
+       }
+
+out:
+       if (ret) {
+               if (*meta_ac) {
+                       ocfs2_free_alloc_context(*meta_ac);
+                       *meta_ac = NULL;
+               }
+
+               /*
+                * We cannot have an error and a non null *data_ac.
+                */
+       }
+
+       return ret;
+}