When ext4_ext_insert_extent() fails to insert new blocks

[linux-2.6] / fs / ext4 / extents.c

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ffe7cb6c4c0077b80a76fbcfa50c7739a5299eec..b9ce24129070bff5cee547a333139d9a4645d2c7 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1127,6 +1127,55 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
        return 0;
 }
 
+/*
+ * check if a portion of the "newext" extent overlaps with an
+ * existing extent.
+ *
+ * If there is an overlap discovered, it updates the length of the newext
+ * such that there will be no overlap, and then returns 1.
+ * If there is no overlap found, it returns 0.
+ */
+unsigned int ext4_ext_check_overlap(struct inode *inode,
+                                   struct ext4_extent *newext,
+                                   struct ext4_ext_path *path)
+{
+       unsigned long b1, b2;
+       unsigned int depth, len1;
+       unsigned int ret = 0;
+
+       b1 = le32_to_cpu(newext->ee_block);
+       len1 = le16_to_cpu(newext->ee_len);
+       depth = ext_depth(inode);
+       if (!path[depth].p_ext)
+               goto out;
+       b2 = le32_to_cpu(path[depth].p_ext->ee_block);
+
+       /*
+        * get the next allocated block if the extent in the path
+        * is before the requested block(s) 
+        */
+       if (b2 < b1) {
+               b2 = ext4_ext_next_allocated_block(path);
+               if (b2 == EXT_MAX_BLOCK)
+                       goto out;
+       }
+
+       /* check for wrap through zero */
+       if (b1 + len1 < b1) {
+               len1 = EXT_MAX_BLOCK - b1;
+               newext->ee_len = cpu_to_le16(len1);
+               ret = 1;
+       }
+
+       /* check for overlap */
+       if (b1 + len1 > b2) {
+               newext->ee_len = cpu_to_le16(b2 - b1);
+               ret = 1;
+       }
+out:
+       return ret;
+}
+
 /*
  * ext4_ext_insert_extent:
  * tries to merge requsted extent into the existing extent or
@@ -2031,7 +2080,15 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
 
        /* allocate new block */
        goal = ext4_ext_find_goal(inode, path, iblock);
-       allocated = max_blocks;
+
+       /* Check if we can really insert (iblock)::(iblock+max_blocks) extent */
+       newex.ee_block = cpu_to_le32(iblock);
+       newex.ee_len = cpu_to_le16(max_blocks);
+       err = ext4_ext_check_overlap(inode, &newex, path);
+       if (err)
+               allocated = le16_to_cpu(newex.ee_len);
+       else
+               allocated = max_blocks;
        newblock = ext4_new_blocks(handle, inode, goal, &allocated, &err);
        if (!newblock)
                goto out2;
@@ -2039,12 +2096,15 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
                        goal, newblock, allocated);
 
        /* try to insert new extent into found leaf and return */
-       newex.ee_block = cpu_to_le32(iblock);
        ext4_ext_store_pblock(&newex, newblock);
        newex.ee_len = cpu_to_le16(allocated);
        err = ext4_ext_insert_extent(handle, inode, path, &newex);
-       if (err)
+       if (err) {
+               /* free data blocks we just allocated */
+               ext4_free_blocks(handle, inode, ext_pblock(&newex),
+                                       le16_to_cpu(newex.ee_len));
                goto out2;
+       }
 
        if (extend_disksize && inode->i_size > EXT4_I(inode)->i_disksize)
                EXT4_I(inode)->i_disksize = inode->i_size;
@@ -2157,11 +2217,3 @@ int ext4_ext_writepage_trans_blocks(struct inode *inode, int num)
 
        return needed;
 }
-
-EXPORT_SYMBOL(ext4_mark_inode_dirty);
-EXPORT_SYMBOL(ext4_ext_invalidate_cache);
-EXPORT_SYMBOL(ext4_ext_insert_extent);
-EXPORT_SYMBOL(ext4_ext_walk_space);
-EXPORT_SYMBOL(ext4_ext_find_goal);
-EXPORT_SYMBOL(ext4_ext_calc_credits_for_insert);
-