NFS: Remove size hack in nfs_inode_attrs_need_update()

Prior to this patch, we used to always OK attribute updates that extended
the file size on the assumption that we might be performing writeback.
Now that we have attribute barriers to protect the writeback related updates,
we should remove this hack, as it can cause truncate() operations to
apparently be reverted if/when a readahead or getattr RPC call races
with our on-the-wire SETATTR.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Tested-by: NChuck Lever <chuck.lever@oracle.com>

fs/nfs/inode.c

@@ -1238,13 +1238,6 @@ static int nfs_ctime_need_update(const struct inode *inode, const struct nfs_fat
 	return timespec_compare(&fattr->ctime, &inode->i_ctime) > 0;
 }
 
-static int nfs_size_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
-{
-	if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
-		return 0;
-	return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
-}
-
 static atomic_long_t nfs_attr_generation_counter;
 
 static unsigned long nfs_read_attr_generation_counter(void)
@@ -1393,7 +1386,6 @@ static int nfs_inode_attrs_need_update(const struct inode *inode, const struct n
 
 	return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||
 		nfs_ctime_need_update(inode, fattr) ||
-		nfs_size_need_update(inode, fattr) ||
 		((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);
 }