[PATCH] fs: fix iversion handling

[Christoph Hellwig]

Currently notify_change directly updates i_version for size updates,
which not only is counter to how all other fields are updated through
struct iattr, but also breaks XFS, which need inode updates to happen
under its own lock, and synchronized to the structure that gets written
to the log.

Remove the update in the common code, and it to btrfs and ext4,
XFS already does a proper updaste internally and currently gets a
double update with the existing code.

IMHO this is 3.13 and -stable material and should go in through the XFS
tree.

Signed-off-by: Christoph Hellwig <hch at lst.de>

Index: xfs/fs/attr.c
===================================================================
--- xfs.orig/fs/attr.c	2013-11-19 16:08:42.275415189 +0100
+++ xfs/fs/attr.c	2013-11-19 16:08:51.803414994 +0100
@@ -182,11 +182,6 @@ int notify_change(struct dentry * dentry
 			return -EPERM;
 	}
 
-	if ((ia_valid & ATTR_SIZE) && IS_I_VERSION(inode)) {
-		if (attr->ia_size != inode->i_size)
-			inode_inc_iversion(inode);
-	}
-
 	if ((ia_valid & ATTR_MODE)) {
 		umode_t amode = attr->ia_mode;
 		/* Flag setting protected by i_mutex */
Index: xfs/fs/btrfs/inode.c
===================================================================
--- xfs.orig/fs/btrfs/inode.c	2013-11-19 16:08:42.275415189 +0100
+++ xfs/fs/btrfs/inode.c	2013-11-19 16:08:51.803414994 +0100
@@ -4345,8 +4345,12 @@ static int btrfs_setsize(struct inode *i
 	 * these flags set.  For all other operations the VFS set these flags
 	 * explicitly if it wants a timestamp update.
 	 */
-	if (newsize != oldsize && (!(mask & (ATTR_CTIME | ATTR_MTIME))))
-		inode->i_ctime = inode->i_mtime = current_fs_time(inode->i_sb);
+	if (newsize != oldsize) {
+		inode_inc_iversion(inode);
+		if (!(mask & (ATTR_CTIME | ATTR_MTIME)))
+			inode->i_ctime = inode->i_mtime =
+				current_fs_time(inode->i_sb);
+	}
 
 	if (newsize > oldsize) {
 		truncate_pagecache(inode, newsize);
Index: xfs/fs/ext4/inode.c
===================================================================
--- xfs.orig/fs/ext4/inode.c	2013-11-19 16:08:42.275415189 +0100
+++ xfs/fs/ext4/inode.c	2013-11-19 16:08:51.803414994 +0100
@@ -4594,6 +4594,10 @@ int ext4_setattr(struct dentry *dentry,
 			if (attr->ia_size > sbi->s_bitmap_maxbytes)
 				return -EFBIG;
 		}
+
+		if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
+			inode_inc_iversion(inode);
+
 		if (S_ISREG(inode->i_mode) &&
 		    (attr->ia_size < inode->i_size)) {
 			if (ext4_should_order_data(inode)) {