1 files changed, 77 insertions, 27 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index edc0b617f409..3bcf3629265e 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -480,13 +480,86 @@ leave:
         return status;
 }
 
+/*
+ * For a given allocation, determine which allocators will need to be
+ * accessed, and lock them, reserving the appropriate number of bits.
+ *
+ * Called from ocfs2_extend_allocation() for file systems which don't
+ * support holes, and from ocfs2_prepare_write() for file systems
+ * which understand sparse inodes.
+ */
+static int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_dinode *di,
+                                 u32 clusters_to_add,
+                                 struct ocfs2_alloc_context **data_ac,
+                                 struct ocfs2_alloc_context **meta_ac)
+{
+        int ret, num_free_extents;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        *meta_ac = NULL;
+        *data_ac = NULL;
+
+        mlog(0, "extend inode %llu, i_size = %lld, di->i_clusters = %u, "
+             "clusters_to_add = %u\n",
+             (unsigned long long)OCFS2_I(inode)->ip_blkno, i_size_read(inode),
+             le32_to_cpu(di->i_clusters), clusters_to_add);
+
+        num_free_extents = ocfs2_num_free_extents(osb, inode, di);
+        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 page at a time
+         * anyway.
+         */
+        if (!num_free_extents ||
+            (ocfs2_sparse_alloc(osb) && num_free_extents < clusters_to_add)) {
+                ret = ocfs2_reserve_new_metadata(osb, di, meta_ac);
+                if (ret < 0) {
+                        if (ret != -ENOSPC)
+                                mlog_errno(ret);
+                        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;
+}
+
 static int ocfs2_extend_allocation(struct inode *inode,
                                    u32 clusters_to_add)
 {
         int status = 0;
         int restart_func = 0;
         int drop_alloc_sem = 0;
-        int credits, num_free_extents;
+        int credits;
         u32 prev_clusters, logical_start;
         struct buffer_head *bh = NULL;
         struct ocfs2_dinode *fe = NULL;
@@ -523,36 +596,13 @@ static int ocfs2_extend_allocation(struct inode *inode,
 restart_all:
         BUG_ON(le32_to_cpu(fe->i_clusters) != OCFS2_I(inode)->ip_clusters);
 
-        mlog(0, "extend inode %llu, i_size = %lld, fe->i_clusters = %u, "
-             "clusters_to_add = %u\n",
-             (unsigned long long)OCFS2_I(inode)->ip_blkno, i_size_read(inode),
-             fe->i_clusters, clusters_to_add);
-
-        num_free_extents = ocfs2_num_free_extents(osb,
-                                                  inode,
-                                                  fe);
-        if (num_free_extents < 0) {
-                status = num_free_extents;
+        status = ocfs2_lock_allocators(inode, fe, clusters_to_add, &data_ac,
+                                       &meta_ac);
+        if (status) {
                 mlog_errno(status);
                 goto leave;
         }
 
-        if (!num_free_extents) {
-                status = ocfs2_reserve_new_metadata(osb, fe, &meta_ac);
-                if (status < 0) {
-                        if (status != -ENOSPC)
-                                mlog_errno(status);
-                        goto leave;
-                }
-        }
-
-        status = ocfs2_reserve_clusters(osb, clusters_to_add, &data_ac);
-        if (status < 0) {
-                if (status != -ENOSPC)
-                        mlog_errno(status);
-                goto leave;
-        }
-
         /* blocks peope in read/write from reading our allocation
          * until we're done changing it. We depend on i_mutex to block
          * other extend/truncate calls while we're here. Ordering wrt