1 files changed, 43 insertions, 0 deletions

diff --git a/fs/ext4/truncate.h b/fs/ext4/truncate.h
new file mode 100644
index 000000000000..011ba6670d99
--- /dev/null
+++ b/fs/ext4/truncate.h
@@ -0,0 +1,43 @@
+/*
+ * linux/fs/ext4/truncate.h
+ *
+ * Common inline functions needed for truncate support
+ */
+
+/*
+ * Truncate blocks that were not used by write. We have to truncate the
+ * pagecache as well so that corresponding buffers get properly unmapped.
+ */
+static inline void ext4_truncate_failed_write(struct inode *inode)
+{
+        truncate_inode_pages(inode->i_mapping, inode->i_size);
+        ext4_truncate(inode);
+}
+
+/*
+ * Work out how many blocks we need to proceed with the next chunk of a
+ * truncate transaction.
+ */
+static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
+{
+        ext4_lblk_t needed;
+
+        needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
+
+        /* Give ourselves just enough room to cope with inodes in which
+         * i_blocks is corrupt: we've seen disk corruptions in the past
+         * which resulted in random data in an inode which looked enough
+         * like a regular file for ext4 to try to delete it.  Things
+         * will go a bit crazy if that happens, but at least we should
+         * try not to panic the whole kernel. */
+        if (needed < 2)
+                needed = 2;
+
+        /* But we need to bound the transaction so we don't overflow the
+         * journal. */
+        if (needed > EXT4_MAX_TRANS_DATA)
+                needed = EXT4_MAX_TRANS_DATA;
+
+        return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
+}
+