1 files changed, 83 insertions, 1 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 4921b4ee9431..6ee20e82bcc5 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -59,6 +59,7 @@
 #include "xattr.h"
 #include "acl.h"
 #include "quota.h"
+#include "refcounttree.h"
 
 #include "buffer_head_io.h"
 
@@ -1656,6 +1657,70 @@ static long ocfs2_fallocate(struct inode *inode, int mode, loff_t offset,
                                          OCFS2_IOC_RESVSP64, &sr, change_size);
 }
 
+int ocfs2_check_range_for_refcount(struct inode *inode, loff_t pos,
+                                   size_t count)
+{
+        int ret = 0;
+        unsigned int extent_flags;
+        u32 cpos, clusters, extent_len, phys_cpos;
+        struct super_block *sb = inode->i_sb;
+
+        if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb)) ||
+            !(OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL))
+                return 0;
+
+        cpos = pos >> OCFS2_SB(sb)->s_clustersize_bits;
+        clusters = ocfs2_clusters_for_bytes(sb, pos + count) - cpos;
+
+        while (clusters) {
+                ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &extent_len,
+                                         &extent_flags);
+                if (ret < 0) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                if (phys_cpos && (extent_flags & OCFS2_EXT_REFCOUNTED)) {
+                        ret = 1;
+                        break;
+                }
+
+                if (extent_len > clusters)
+                        extent_len = clusters;
+
+                clusters -= extent_len;
+                cpos += extent_len;
+        }
+out:
+        return ret;
+}
+
+static int ocfs2_prepare_inode_for_refcount(struct inode *inode,
+                                            loff_t pos, size_t count,
+                                            int *meta_level)
+{
+        int ret;
+        struct buffer_head *di_bh = NULL;
+        u32 cpos = pos >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
+        u32 clusters =
+                ocfs2_clusters_for_bytes(inode->i_sb, pos + count) - cpos;
+
+        ret = ocfs2_inode_lock(inode, &di_bh, 1);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        *meta_level = 1;
+
+        ret = ocfs2_refcount_cow(inode, di_bh, cpos, clusters);
+        if (ret)
+                mlog_errno(ret);
+out:
+        brelse(di_bh);
+        return ret;
+}
+
 static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
                                          loff_t *ppos,
                                          size_t count,
@@ -1712,6 +1777,22 @@ static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
 
                 end = saved_pos + count;
 
+                ret = ocfs2_check_range_for_refcount(inode, saved_pos, count);
+                if (ret == 1) {
+                        ocfs2_inode_unlock(inode, meta_level);
+                        meta_level = -1;
+
+                        ret = ocfs2_prepare_inode_for_refcount(inode,
+                                                               saved_pos,
+                                                               count,
+                                                               &meta_level);
+                }
+
+                if (ret < 0) {
+                        mlog_errno(ret);
+                        goto out_unlock;
+                }
+
                 /*
                  * Skip the O_DIRECT checks if we don't need
                  * them.
@@ -1758,7 +1839,8 @@ static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
                 *ppos = saved_pos;
 
 out_unlock:
-        ocfs2_inode_unlock(inode, meta_level);
+        if (meta_level >= 0)
+                ocfs2_inode_unlock(inode, meta_level);
 
 out:
         return ret;