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-rw-r--r--Documentation/filesystems/overlayfs.rst16
-rw-r--r--fs/overlayfs/copy_up.c2
-rw-r--r--fs/overlayfs/namei.c5
-rw-r--r--fs/overlayfs/overlayfs.h16
-rw-r--r--fs/overlayfs/ovl_entry.h2
-rw-r--r--fs/overlayfs/params.c25
-rw-r--r--fs/overlayfs/super.c16
7 files changed, 69 insertions, 13 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index b63e0db03631..d55381d3fa0f 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -657,6 +657,22 @@ can be useful in case the underlying disk is copied and the UUID of this copy
is changed. This is only applicable if all lower/upper/work directories are on
the same filesystem, otherwise it will fallback to normal behaviour.
+
+UUID and fsid
+-------------
+
+The UUID of overlayfs instance itself and the fsid reported by statfs(2) are
+controlled by the "uuid" mount option, which supports these values:
+
+- "null": (default)
+ UUID of overlayfs is null. fsid is taken from upper most filesystem.
+- "off":
+ UUID of overlayfs is null. fsid is taken from upper most filesystem.
+ UUID of underlying layers is ignored.
+- "on":
+ UUID of overlayfs is generated and used to report a unique fsid.
+
+
Volatile mount
--------------
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 2ead7c9a7748..618651b54818 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -416,7 +416,7 @@ struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
if (is_upper)
fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER;
fh->fb.len = sizeof(fh->fb) + buflen;
- if (ofs->config.uuid)
+ if (ovl_origin_uuid(ofs))
fh->fb.uuid = *uuid;
return fh;
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index d00ec43f2376..84c06512fb71 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -171,8 +171,9 @@ struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
* layer where file handle will be decoded.
* In case of uuid=off option just make sure that stored uuid is null.
*/
- if (ofs->config.uuid ? !uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
- !uuid_is_null(&fh->fb.uuid))
+ if (ovl_origin_uuid(ofs) ?
+ !uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
+ !uuid_is_null(&fh->fb.uuid))
return NULL;
bytes = (fh->fb.len - offsetof(struct ovl_fb, fid));
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 453610fb9bf9..000dd89fe319 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -68,6 +68,12 @@ enum {
};
enum {
+ OVL_UUID_OFF,
+ OVL_UUID_NULL,
+ OVL_UUID_ON,
+};
+
+enum {
OVL_XINO_OFF,
OVL_XINO_AUTO,
OVL_XINO_ON,
@@ -534,6 +540,16 @@ static inline bool ovl_redirect_dir(struct ovl_fs *ofs)
return ofs->config.redirect_mode == OVL_REDIRECT_ON;
}
+static inline bool ovl_origin_uuid(struct ovl_fs *ofs)
+{
+ return ofs->config.uuid != OVL_UUID_OFF;
+}
+
+static inline bool ovl_has_fsid(struct ovl_fs *ofs)
+{
+ return ofs->config.uuid == OVL_UUID_ON;
+}
+
/*
* With xino=auto, we do best effort to keep all inodes on same st_dev and
* d_ino consistent with st_ino.
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 7a5196c94d75..5d03f449adb1 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -12,7 +12,7 @@ struct ovl_config {
int redirect_mode;
int verity_mode;
bool index;
- bool uuid;
+ int uuid;
bool nfs_export;
int xino;
bool metacopy;
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index 575a60b76a6c..1ff93467e793 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -65,6 +65,23 @@ static const struct constant_table ovl_parameter_bool[] = {
{}
};
+static const struct constant_table ovl_parameter_uuid[] = {
+ { "off", OVL_UUID_OFF },
+ { "null", OVL_UUID_NULL },
+ { "on", OVL_UUID_ON },
+ {}
+};
+
+static const char *ovl_uuid_mode(struct ovl_config *config)
+{
+ return ovl_parameter_uuid[config->uuid].name;
+}
+
+static int ovl_uuid_def(void)
+{
+ return OVL_UUID_NULL;
+}
+
static const struct constant_table ovl_parameter_xino[] = {
{ "off", OVL_XINO_OFF },
{ "auto", OVL_XINO_AUTO },
@@ -129,7 +146,7 @@ const struct fs_parameter_spec ovl_parameter_spec[] = {
fsparam_flag("default_permissions", Opt_default_permissions),
fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_redirect_dir),
fsparam_enum("index", Opt_index, ovl_parameter_bool),
- fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool),
+ fsparam_enum("uuid", Opt_uuid, ovl_parameter_uuid),
fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool),
fsparam_flag("userxattr", Opt_userxattr),
fsparam_enum("xino", Opt_xino, ovl_parameter_xino),
@@ -701,7 +718,7 @@ int ovl_init_fs_context(struct fs_context *fc)
ofs->config.redirect_mode = ovl_redirect_mode_def();
ofs->config.index = ovl_index_def;
- ofs->config.uuid = true;
+ ofs->config.uuid = ovl_uuid_def();
ofs->config.nfs_export = ovl_nfs_export_def;
ofs->config.xino = ovl_xino_def();
ofs->config.metacopy = ovl_metacopy_def;
@@ -947,8 +964,8 @@ int ovl_show_options(struct seq_file *m, struct dentry *dentry)
ovl_redirect_mode(&ofs->config));
if (ofs->config.index != ovl_index_def)
seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
- if (!ofs->config.uuid)
- seq_puts(m, ",uuid=off");
+ if (ofs->config.uuid != ovl_uuid_def())
+ seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config));
if (ofs->config.nfs_export != ovl_nfs_export_def)
seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
"on" : "off");
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index e56108ffe8aa..c2bab6106e98 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -242,8 +242,9 @@ static int ovl_sync_fs(struct super_block *sb, int wait)
*/
static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
{
- struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
- struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct super_block *sb = dentry->d_sb;
+ struct ovl_fs *ofs = OVL_FS(sb);
+ struct dentry *root_dentry = sb->s_root;
struct path path;
int err;
@@ -253,6 +254,8 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
if (!err) {
buf->f_namelen = ofs->namelen;
buf->f_type = OVERLAYFS_SUPER_MAGIC;
+ if (ovl_has_fsid(ofs))
+ buf->f_fsid = uuid_to_fsid(sb->s_uuid.b);
}
return err;
@@ -1421,9 +1424,12 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
if (!ovl_upper_mnt(ofs))
sb->s_flags |= SB_RDONLY;
- if (!ofs->config.uuid && ofs->numfs > 1) {
- pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n");
- ofs->config.uuid = true;
+ if (!ovl_origin_uuid(ofs) && ofs->numfs > 1) {
+ pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=null.\n");
+ ofs->config.uuid = OVL_UUID_NULL;
+ } else if (ovl_has_fsid(ofs)) {
+ /* Use per instance uuid/fsid */
+ uuid_gen(&sb->s_uuid);
}
if (!ovl_force_readonly(ofs) && ofs->config.index) {
generated by cgit v1.2.3 (git 2.39.0) at 2024-07-27 00:40:29 +0300