ext4: move common truncate functions to header file

Move two functions that will be needed by the indirect functions to be
moved to indirect.c as well as inode.c to truncate.h as inline
functions, so that we can avoid having duplicate copies of the
function (which can be a maintenance problem) without having to expose
them as globally functions.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -47,6 +47,7 @@
 #include "xattr.h"
 #include "acl.h"
 #include "ext4_extents.h"
+#include "truncate.h"
 
 #include <trace/events/ext4.h>
 
@@ -88,33 +89,6 @@ static int ext4_inode_is_fast_symlink(struct inode *inode)
 	return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
 }
 
-/*
- * Work out how many blocks we need to proceed with the next chunk of a
- * truncate transaction.
- */
-static unsigned long 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;
-}
-
 /*
  * Truncate transactions can be complex and absolutely huge.  So we need to
  * be able to restart the transaction at a conventient checkpoint to make
@@ -129,7 +103,7 @@ static handle_t *start_transaction(struct inode *inode)
 {
 	handle_t *result;
 
-	result = ext4_journal_start(inode, blocks_for_truncate(inode));
+	result = ext4_journal_start(inode, ext4_blocks_for_truncate(inode));
 	if (!IS_ERR(result))
 		return result;
 
@@ -149,7 +123,7 @@ static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
 		return 0;
 	if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
 		return 0;
-	if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
+	if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
 		return 0;
 	return 1;
 }
@@ -204,7 +178,7 @@ void ext4_evict_inode(struct inode *inode)
 	if (is_bad_inode(inode))
 		goto no_delete;
 
-	handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
+	handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3);
 	if (IS_ERR(handle)) {
 		ext4_std_error(inode->i_sb, PTR_ERR(handle));
 		/*
@@ -1555,16 +1529,6 @@ static int do_journal_get_write_access(handle_t *handle,
 	return ret;
 }
 
-/*
- * Truncate blocks that were not used by write. We have to truncate the
- * pagecache as well so that corresponding buffers get properly unmapped.
- */
-static void ext4_truncate_failed_write(struct inode *inode)
-{
-	truncate_inode_pages(inode->i_mapping, inode->i_size);
-	ext4_truncate(inode);
-}
-
 static int ext4_get_block_write(struct inode *inode, sector_t iblock,
 		   struct buffer_head *bh_result, int create);
 static int ext4_write_begin(struct file *file, struct address_space *mapping,
@@ -4134,7 +4098,7 @@ static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
 		if (unlikely(err))
 			goto out_err;
 		err = ext4_truncate_restart_trans(handle, inode,
-						  blocks_for_truncate(inode));
+					ext4_blocks_for_truncate(inode));
 		if (unlikely(err))
 			goto out_err;
 		if (bh) {
@@ -4329,7 +4293,7 @@ static void ext4_free_branches(handle_t *handle, struct inode *inode,
 			if (try_to_extend_transaction(handle, inode)) {
 				ext4_mark_inode_dirty(handle, inode);
 				ext4_truncate_restart_trans(handle, inode,
-					    blocks_for_truncate(inode));
+					    ext4_blocks_for_truncate(inode));
 			}
 
 			/*

fs/ext4/truncate.h

+/*
+ * 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;
+}
+