[PATCH 4/9] ovl: Copy up only metadata during copy up where it makes sense

[Vivek Goyal <vgoyal@redhat.com>]

If it makes sense to copy up only metadata during copy up, do it. This
is done for regular files which are not opened for WRITE and have origin
being saved.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 fs/overlayfs/copy_up.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index b626584bb7b4..ebd404629c6d 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -306,11 +306,8 @@ static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 			return PTR_ERR(fh);
 	}
 
-	/*
-	 * Do not fail when upper doesn't support xattrs.
-	 */
 	err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
-				 fh ? fh->len : 0, 0);
+				 fh ? fh->len : 0, -EOPNOTSUPP);
 	kfree(fh);
 
 	return err;
@@ -328,6 +325,7 @@ struct ovl_copy_up_ctx {
 	struct dentry *workdir;
 	bool tmpfile;
 	bool origin;
+	bool metadata_only;
 };
 
 static int ovl_link_up(struct ovl_copy_up_ctx *c)
@@ -458,11 +456,15 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 	 */
 	if (c->origin) {
 		err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
-		if (err)
-			return err;
+		if (err) {
+			if (err != -EOPNOTSUPP)
+				return err;
+			/* Upper does not support xattr. Copy up data as well */
+			c->metadata_only = false;
+		}
 	}
 
-	if (S_ISREG(c->stat.mode)) {
+	if (S_ISREG(c->stat.mode) && !c->metadata_only) {
 		struct path upperpath;
 
 		ovl_path_upper(c->dentry, &upperpath);
@@ -592,10 +594,12 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
 	int err;
 	DEFINE_DELAYED_CALL(done);
 	struct path parentpath;
+	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 	struct ovl_copy_up_ctx ctx = {
 		.parent = parent,
 		.dentry = dentry,
 		.workdir = ovl_workdir(dentry),
+		.metadata_only = ofs->config.metacopy,
 	};
 
 	if (WARN_ON(!ctx.workdir))
@@ -616,9 +620,17 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
 	if (err)
 		return err;
 
+	if (!S_ISREG(ctx.stat.mode))
+		ctx.metadata_only = false;
+
 	/* maybe truncate regular file. this has no effect on dirs */
-	if (flags & O_TRUNC)
+	if (flags & O_TRUNC) {
 		ctx.stat.size = 0;
+		ctx.metadata_only = false;
+	}
+
+	if (flags & (OPEN_FMODE(flags) & FMODE_WRITE))
+		ctx.metadata_only = false;
 
 	if (S_ISLNK(ctx.stat.mode)) {
 		ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
-- 
2.13.5