From 53a08cb9b8bccfe58f1228c7c27baf34a83da78b Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@suse.cz>
Date: Sat, 13 Dec 2014 00:59:51 +0100
Subject: [PATCH] ovl: make upperdir optional
Make "upperdir=" mount option optional. If "upperdir=" is not given, then
the "workdir=" option is also optional (and ignored if given).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
fs/overlayfs/super.c | 83 +++++++++++++++++++++++++-------------------
1 file changed, 47 insertions(+), 36 deletions(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 592370ff453a..35bb0adf10cf 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -516,8 +516,10 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
struct ovl_fs *ufs = sb->s_fs_info;
seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
- seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
- seq_printf(m, ",workdir=%s", ufs->config.workdir);
+ if (ufs->config.upperdir) {
+ seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
+ seq_printf(m, ",workdir=%s", ufs->config.workdir);
+ }
return 0;
}
@@ -768,8 +770,8 @@ static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
static int ovl_fill_super(struct super_block *sb, void *data, int silent)
{
struct path lowerpath;
- struct path upperpath;
- struct path workpath;
+ struct path upperpath = { NULL, NULL };
+ struct path workpath = { NULL, NULL };
struct dentry *root_dentry;
struct ovl_entry *oe;
struct ovl_fs *ufs;
@@ -786,31 +788,38 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (err)
goto out_free_config;
- /* FIXME: workdir is not needed for a R/O mount */
err = -EINVAL;
- if (!ufs->config.upperdir || !ufs->config.lowerdir ||
- !ufs->config.workdir) {
- pr_err("overlayfs: missing upperdir or lowerdir or workdir\n");
+ if (!ufs->config.lowerdir) {
+ pr_err("overlayfs: missing 'lowerdir'\n");
goto out_free_config;
}
- err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
- if (err)
- goto out_free_config;
+ sb->s_stack_depth = 0;
+ if (ufs->config.upperdir) {
+ /* FIXME: workdir is not needed for a R/O mount */
+ if (!ufs->config.workdir) {
+ pr_err("overlayfs: missing 'workdir'\n");
+ goto out_free_config;
+ }
- err = ovl_mount_dir(ufs->config.workdir, &workpath);
- if (err)
- goto out_put_upperpath;
+ err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
+ if (err)
+ goto out_free_config;
- if (upperpath.mnt != workpath.mnt) {
- pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
- goto out_put_workpath;
- }
- if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
- pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
- goto out_put_workpath;
+ err = ovl_mount_dir(ufs->config.workdir, &workpath);
+ if (err)
+ goto out_put_upperpath;
+
+ if (upperpath.mnt != workpath.mnt) {
+ pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
+ goto out_put_workpath;
+ }
+ if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
+ pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
+ goto out_put_workpath;
+ }
+ sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
}
- sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
err = ovl_lower_dir(ufs->config.lowerdir, &lowerpath,
&ufs->lower_namelen, &sb->s_stack_depth);
@@ -824,19 +833,21 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
goto out_put_lowerpath;
}
- ufs->upper_mnt = clone_private_mount(&upperpath);
- err = PTR_ERR(ufs->upper_mnt);
- if (IS_ERR(ufs->upper_mnt)) {
- pr_err("overlayfs: failed to clone upperpath\n");
- goto out_put_lowerpath;
- }
+ if (ufs->config.upperdir) {
+ ufs->upper_mnt = clone_private_mount(&upperpath);
+ err = PTR_ERR(ufs->upper_mnt);
+ if (IS_ERR(ufs->upper_mnt)) {
+ pr_err("overlayfs: failed to clone upperpath\n");
+ goto out_put_lowerpath;
+ }
- ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
- err = PTR_ERR(ufs->workdir);
- if (IS_ERR(ufs->workdir)) {
- pr_err("overlayfs: failed to create directory %s/%s\n",
- ufs->config.workdir, OVL_WORKDIR_NAME);
- goto out_put_upper_mnt;
+ ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
+ err = PTR_ERR(ufs->workdir);
+ if (IS_ERR(ufs->workdir)) {
+ pr_err("overlayfs: failed to create directory %s/%s\n",
+ ufs->config.workdir, OVL_WORKDIR_NAME);
+ goto out_put_upper_mnt;
+ }
}
ufs->lower_mnt = kcalloc(1, sizeof(struct vfsmount *), GFP_KERNEL);
@@ -858,8 +869,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ufs->lower_mnt[0] = mnt;
ufs->numlower = 1;
- /* If the upper fs is r/o, we mark overlayfs r/o too */
- if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
+ /* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */
+ if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))
sb->s_flags |= MS_RDONLY;
sb->s_d_op = &ovl_dentry_operations;
--
2.30.9