ovl: Provide a mount option metacopy=on/off for metadata copyup
By default metadata only copy up is disabled. Provide a mount option so
that users can choose one way or other.
Also provide a kernel config and module option to enable/disable metacopy
feature.
metacopy feature requires redirect_dir=on when upper is present.
Otherwise, it requires redirect_dir=follow atleast.
As of now, metacopy does not work with nfs_export=on. So if both
metacopy=on and nfs_export=on then nfs_export is disabled.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 0e84593..d4caeee 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -64,6 +64,11 @@ static void ovl_entry_stack_free(struct ovl_entry *oe)
dput(oe->lowerstack[i].dentry);
}
+static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
+module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
+MODULE_PARM_DESC(ovl_metacopy_def,
+ "Default to on or off for the metadata only copy up feature");
+
static void ovl_dentry_release(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
@@ -347,6 +352,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
"on" : "off");
if (ofs->config.xino != ovl_xino_def())
seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
+ if (ofs->config.metacopy != ovl_metacopy_def)
+ seq_printf(m, ",metacopy=%s",
+ ofs->config.metacopy ? "on" : "off");
return 0;
}
@@ -384,6 +392,8 @@ enum {
OPT_XINO_ON,
OPT_XINO_OFF,
OPT_XINO_AUTO,
+ OPT_METACOPY_ON,
+ OPT_METACOPY_OFF,
OPT_ERR,
};
@@ -400,6 +410,8 @@ static const match_table_t ovl_tokens = {
{OPT_XINO_ON, "xino=on"},
{OPT_XINO_OFF, "xino=off"},
{OPT_XINO_AUTO, "xino=auto"},
+ {OPT_METACOPY_ON, "metacopy=on"},
+ {OPT_METACOPY_OFF, "metacopy=off"},
{OPT_ERR, NULL}
};
@@ -452,6 +464,7 @@ static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
static int ovl_parse_opt(char *opt, struct ovl_config *config)
{
char *p;
+ int err;
config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
if (!config->redirect_mode)
@@ -526,6 +539,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
config->xino = OVL_XINO_AUTO;
break;
+ case OPT_METACOPY_ON:
+ config->metacopy = true;
+ break;
+
+ case OPT_METACOPY_OFF:
+ config->metacopy = false;
+ break;
+
default:
pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
return -EINVAL;
@@ -540,7 +561,20 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
config->workdir = NULL;
}
- return ovl_parse_redirect_mode(config, config->redirect_mode);
+ err = ovl_parse_redirect_mode(config, config->redirect_mode);
+ if (err)
+ return err;
+
+ /* metacopy feature with upper requires redirect_dir=on */
+ if (config->upperdir && config->metacopy && !config->redirect_dir) {
+ pr_warn("overlayfs: metadata only copy up requires \"redirect_dir=on\", falling back to metacopy=off.\n");
+ config->metacopy = false;
+ } else if (config->metacopy && !config->redirect_follow) {
+ pr_warn("overlayfs: metadata only copy up requires \"redirect_dir=follow\" on non-upper mount, falling back to metacopy=off.\n");
+ config->metacopy = false;
+ }
+
+ return 0;
}
#define OVL_WORKDIR_NAME "work"
@@ -1013,7 +1047,8 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
if (err) {
ofs->noxattr = true;
ofs->config.index = false;
- pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off.\n");
+ ofs->config.metacopy = false;
+ pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
err = 0;
} else {
vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
@@ -1035,7 +1070,6 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
ofs->config.nfs_export = false;
}
-
out:
mnt_drop_write(mnt);
return err;
@@ -1346,6 +1380,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ofs->config.index = ovl_index_def;
ofs->config.nfs_export = ovl_nfs_export_def;
ofs->config.xino = ovl_xino_def();
+ ofs->config.metacopy = ovl_metacopy_def;
err = ovl_parse_opt((char *) data, &ofs->config);
if (err)
goto out_err;
@@ -1416,6 +1451,11 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
}
+ if (ofs->config.metacopy && ofs->config.nfs_export) {
+ pr_warn("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+
if (ofs->config.nfs_export)
sb->s_export_op = &ovl_export_operations;