| Message ID | 20230605-fs-overlayfs-mount_api-v2-1-3da91c97e0c0@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ovl: port to new mount api & updated layer parsing | expand |
Cool work. It will be interesting to do some performance testing on what does it actually look like to create ~500 or whatever overlayfs layers now that we can. On Fri, Jun 9, 2023, at 11:41 AM, Christian Brauner wrote: > > +static int ovl_init_fs_context(struct fs_context *fc) > +{ > + struct ovl_fs_context *ctx = NULL; > + struct ovl_fs *ofs = NULL; > + > + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); > + if (!ctx) > + goto out_err; It looks to me like in this case, ofs will be NULL, then: > +out_err: > + ovl_fs_context_free(ctx); > + ovl_free_fs(ofs); And then we'll jump here and `ovl_free_fs` is not NULL safe. I think the previous code was correct here as it just jumped directly to "out:". (I've always wondered why there's no usage of __attribute__((cleanup)) in kernel code and in our userspace code doing that we have the free functions be no-ops on NULL which systematically avoids these bugs, but then again maybe the real fix is Rust ;) )
On Fri, Jun 9, 2023 at 6:42 PM Christian Brauner <brauner@kernel.org> wrote: > > We recently ported util-linux to the new mount api. Now the mount(8) > tool will by default use the new mount api. While trying hard to fall > back to the old mount api gracefully there are still cases where we run > into issues that are difficult to handle nicely. > > Now with mount(8) and libmount supporting the new mount api I expect an > increase in the number of bug reports and issues we're going to see with > filesystems that don't yet support the new mount api. So it's time we > rectify this. > > Signed-off-by: Christian Brauner <brauner@kernel.org> > --- > fs/overlayfs/super.c | 515 ++++++++++++++++++++++++++++----------------------- > 1 file changed, 279 insertions(+), 236 deletions(-) > > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c > index f97ad8b40dbb..ceaf05743f45 100644 > --- a/fs/overlayfs/super.c > +++ b/fs/overlayfs/super.c > @@ -16,6 +16,8 @@ > #include <linux/posix_acl_xattr.h> > #include <linux/exportfs.h> > #include <linux/file.h> > +#include <linux/fs_context.h> > +#include <linux/fs_parser.h> > #include "overlayfs.h" > > MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); > @@ -67,6 +69,59 @@ module_param_named(metacopy, ovl_metacopy_def, bool, 0644); > MODULE_PARM_DESC(metacopy, > "Default to on or off for the metadata only copy up feature"); > > +enum { > + Opt_lowerdir, > + Opt_upperdir, > + Opt_workdir, > + Opt_default_permissions, > + Opt_redirect_dir, > + Opt_index, > + Opt_uuid, > + Opt_nfs_export, > + Opt_userxattr, > + Opt_xino, > + Opt_metacopy, > + Opt_volatile, > +}; > + > +static const struct constant_table ovl_parameter_bool[] = { > + { "on", true }, > + { "off", false }, > + {} > +}; > + > +static const struct constant_table ovl_parameter_xino[] = { > + { "on", OVL_XINO_ON }, > + { "off", OVL_XINO_OFF }, > + { "auto", OVL_XINO_AUTO }, > + {} > +}; > + > +static const struct fs_parameter_spec ovl_parameter_spec[] = { > + fsparam_string("lowerdir", Opt_lowerdir), > + fsparam_string("upperdir", Opt_upperdir), > + fsparam_string("workdir", Opt_workdir), > + fsparam_flag("default_permissions", Opt_default_permissions), > + fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_bool), > + fsparam_enum("index", Opt_index, ovl_parameter_bool), > + fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool), > + fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool), > + fsparam_flag("userxattr", Opt_userxattr), > + fsparam_enum("xino", Opt_xino, ovl_parameter_xino), > + fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool), > + fsparam_flag("volatile", Opt_volatile), > + {} > +}; > + > +#define OVL_METACOPY_SET BIT(0) > +#define OVL_REDIRECT_SET BIT(1) > +#define OVL_NFS_EXPORT_SET BIT(2) > +#define OVL_INDEX_SET BIT(3) > + > +struct ovl_fs_context { > + u8 set; > +}; > + > static void ovl_dentry_release(struct dentry *dentry) > { > struct ovl_entry *oe = dentry->d_fsdata; > @@ -394,27 +449,6 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) > return 0; > } > > -static int ovl_remount(struct super_block *sb, int *flags, char *data) > -{ > - struct ovl_fs *ofs = sb->s_fs_info; > - struct super_block *upper_sb; > - int ret = 0; > - > - if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) > - return -EROFS; > - > - if (*flags & SB_RDONLY && !sb_rdonly(sb)) { > - upper_sb = ovl_upper_mnt(ofs)->mnt_sb; > - if (ovl_should_sync(ofs)) { > - down_read(&upper_sb->s_umount); > - ret = sync_filesystem(upper_sb); > - up_read(&upper_sb->s_umount); > - } > - } > - > - return ret; > -} > - > static const struct super_operations ovl_super_operations = { > .alloc_inode = ovl_alloc_inode, > .free_inode = ovl_free_inode, > @@ -424,76 +458,8 @@ static const struct super_operations ovl_super_operations = { > .sync_fs = ovl_sync_fs, > .statfs = ovl_statfs, > .show_options = ovl_show_options, > - .remount_fs = ovl_remount, > -}; > - > -enum { > - OPT_LOWERDIR, > - OPT_UPPERDIR, > - OPT_WORKDIR, > - OPT_DEFAULT_PERMISSIONS, > - OPT_REDIRECT_DIR, > - OPT_INDEX_ON, > - OPT_INDEX_OFF, > - OPT_UUID_ON, > - OPT_UUID_OFF, > - OPT_NFS_EXPORT_ON, > - OPT_USERXATTR, > - OPT_NFS_EXPORT_OFF, > - OPT_XINO_ON, > - OPT_XINO_OFF, > - OPT_XINO_AUTO, > - OPT_METACOPY_ON, > - OPT_METACOPY_OFF, > - OPT_VOLATILE, > - OPT_ERR, > -}; > - > -static const match_table_t ovl_tokens = { > - {OPT_LOWERDIR, "lowerdir=%s"}, > - {OPT_UPPERDIR, "upperdir=%s"}, > - {OPT_WORKDIR, "workdir=%s"}, > - {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, > - {OPT_REDIRECT_DIR, "redirect_dir=%s"}, > - {OPT_INDEX_ON, "index=on"}, > - {OPT_INDEX_OFF, "index=off"}, > - {OPT_USERXATTR, "userxattr"}, > - {OPT_UUID_ON, "uuid=on"}, > - {OPT_UUID_OFF, "uuid=off"}, > - {OPT_NFS_EXPORT_ON, "nfs_export=on"}, > - {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, > - {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_VOLATILE, "volatile"}, > - {OPT_ERR, NULL} > }; > > -static char *ovl_next_opt(char **s) > -{ > - char *sbegin = *s; > - char *p; > - > - if (sbegin == NULL) > - return NULL; > - > - for (p = sbegin; *p; p++) { > - if (*p == '\\') { > - p++; > - if (!*p) > - break; > - } else if (*p == ',') { > - *p = '\0'; > - *s = p + 1; > - return sbegin; > - } > - } > - *s = NULL; > - return sbegin; > -} > - > static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) > { > if (strcmp(mode, "on") == 0) { > @@ -517,123 +483,14 @@ static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) > return 0; > } > > -static int ovl_parse_opt(char *opt, struct ovl_config *config) > +static int ovl_fs_params_verify(const struct ovl_fs_context *ctx, > + struct ovl_config *config) > { > - char *p; > int err; > - bool metacopy_opt = false, redirect_opt = false; > - bool nfs_export_opt = false, index_opt = false; > - > - config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); > - if (!config->redirect_mode) > - return -ENOMEM; > - > - while ((p = ovl_next_opt(&opt)) != NULL) { > - int token; > - substring_t args[MAX_OPT_ARGS]; > - > - if (!*p) > - continue; > - > - token = match_token(p, ovl_tokens, args); > - switch (token) { > - case OPT_UPPERDIR: > - kfree(config->upperdir); > - config->upperdir = match_strdup(&args[0]); > - if (!config->upperdir) > - return -ENOMEM; > - break; > - > - case OPT_LOWERDIR: > - kfree(config->lowerdir); > - config->lowerdir = match_strdup(&args[0]); > - if (!config->lowerdir) > - return -ENOMEM; > - break; > - > - case OPT_WORKDIR: > - kfree(config->workdir); > - config->workdir = match_strdup(&args[0]); > - if (!config->workdir) > - return -ENOMEM; > - break; > - > - case OPT_DEFAULT_PERMISSIONS: > - config->default_permissions = true; > - break; > - > - case OPT_REDIRECT_DIR: > - kfree(config->redirect_mode); > - config->redirect_mode = match_strdup(&args[0]); > - if (!config->redirect_mode) > - return -ENOMEM; > - redirect_opt = true; > - break; > - > - case OPT_INDEX_ON: > - config->index = true; > - index_opt = true; > - break; > - > - case OPT_INDEX_OFF: > - config->index = false; > - index_opt = true; > - break; > - > - case OPT_UUID_ON: > - config->uuid = true; > - break; > - > - case OPT_UUID_OFF: > - config->uuid = false; > - break; > - > - case OPT_NFS_EXPORT_ON: > - config->nfs_export = true; > - nfs_export_opt = true; > - break; > - > - case OPT_NFS_EXPORT_OFF: > - config->nfs_export = false; > - nfs_export_opt = true; > - break; > - > - case OPT_XINO_ON: > - config->xino = OVL_XINO_ON; > - break; > - > - case OPT_XINO_OFF: > - config->xino = OVL_XINO_OFF; > - break; > - > - case OPT_XINO_AUTO: > - config->xino = OVL_XINO_AUTO; > - break; > - > - case OPT_METACOPY_ON: > - config->metacopy = true; > - metacopy_opt = true; > - break; > - > - case OPT_METACOPY_OFF: > - config->metacopy = false; > - metacopy_opt = true; > - break; > - > - case OPT_VOLATILE: > - config->ovl_volatile = true; > - break; > - > - case OPT_USERXATTR: > - config->userxattr = true; > - break; > - > - default: > - pr_err("unrecognized mount option \"%s\" or missing value\n", > - p); > - return -EINVAL; > - } > - } > + bool metacopy_opt = ctx->set & OVL_METACOPY_SET, > + redirect_opt = ctx->set & OVL_REDIRECT_SET; > + bool nfs_export_opt = ctx->set & OVL_NFS_EXPORT_SET, > + index_opt = ctx->set & OVL_INDEX_SET; Nit: please split lines here. > > /* Workdir/index are useless in non-upper mount */ > if (!config->upperdir) { > @@ -1882,12 +1739,143 @@ static struct dentry *ovl_get_root(struct super_block *sb, > return root; > } > > -static int ovl_fill_super(struct super_block *sb, void *data, int silent) > +static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) > { > - struct path upperpath = { }; > + int err = 0; > + struct fs_parse_result result; > + struct ovl_fs *ofs = fc->s_fs_info; > + struct ovl_config *config = &ofs->config; > + struct ovl_fs_context *ctx = fc->fs_private; > + struct path path; > + char *dup; > + int opt; > + char *sval; > + > + /* > + * On remount overlayfs has always ignored all mount options no > + * matter if malformed or not so for backwards compatibility we > + * do the same here. > + */ > + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) > + return 0; > + > + opt = fs_parse(fc, ovl_parameter_spec, param, &result); > + if (opt < 0) > + return opt; > + > + switch (opt) { > + case Opt_lowerdir: > + dup = kstrdup(param->string, GFP_KERNEL); > + if (!dup) { > + path_put(&path); > + err = -ENOMEM; > + break; > + } > + > + kfree(config->lowerdir); > + config->lowerdir = dup; > + break; > + case Opt_upperdir: > + dup = kstrdup(param->string, GFP_KERNEL); > + if (!dup) { > + path_put(&path); > + err = -ENOMEM; > + break; > + } > + > + kfree(config->upperdir); > + config->upperdir = dup; > + break; > + case Opt_workdir: > + dup = kstrdup(param->string, GFP_KERNEL); > + if (!dup) { > + path_put(&path); > + err = -ENOMEM; > + break; > + } > + > + kfree(config->workdir); > + config->workdir = dup; > + break; > + case Opt_default_permissions: > + config->default_permissions = true; > + break; > + case Opt_index: > + config->index = result.uint_32; > + ctx->set |= OVL_INDEX_SET; > + break; > + case Opt_uuid: > + config->uuid = result.uint_32; > + break; > + case Opt_nfs_export: > + config->nfs_export = result.uint_32; > + ctx->set |= OVL_NFS_EXPORT_SET; > + break; > + case Opt_metacopy: > + config->metacopy = result.uint_32; > + ctx->set |= OVL_METACOPY_SET; > + break; > + case Opt_userxattr: > + config->userxattr = true; > + break; > + case Opt_volatile: > + config->ovl_volatile = true; > + break; > + case Opt_xino: > + config->xino = result.uint_32; > + break; > + case Opt_redirect_dir: > + if (result.uint_32 == true) > + sval = kstrdup("on", GFP_KERNEL); > + else > + sval = kstrdup("off", GFP_KERNEL); > + if (!sval) { > + err = -ENOMEM; > + break; > + } > + > + kfree(config->redirect_mode); > + config->redirect_mode = sval; > + ctx->set |= OVL_REDIRECT_SET; > + break; > + default: > + pr_err("unrecognized mount option \"%s\" or missing value\n", param->key); > + return -EINVAL; > + } > + > + return err; > +} For the end result, all these functions above should be in params.c I don't mind if you move it with an extra patch at the beginning Probably easier at the end. Just as long as you do not move ovl_fs_params_verify() in the same patch that changes half of it. Thanks, Amir.
On Fri, Jun 09, 2023 at 10:25:21PM +0300, Amir Goldstein wrote: > On Fri, Jun 9, 2023 at 6:42 PM Christian Brauner <brauner@kernel.org> wrote: > > > > We recently ported util-linux to the new mount api. Now the mount(8) > > tool will by default use the new mount api. While trying hard to fall > > back to the old mount api gracefully there are still cases where we run > > into issues that are difficult to handle nicely. > > > > Now with mount(8) and libmount supporting the new mount api I expect an > > increase in the number of bug reports and issues we're going to see with > > filesystems that don't yet support the new mount api. So it's time we > > rectify this. > > > > Signed-off-by: Christian Brauner <brauner@kernel.org> > > --- > > fs/overlayfs/super.c | 515 ++++++++++++++++++++++++++++----------------------- > > 1 file changed, 279 insertions(+), 236 deletions(-) > > > > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c > > index f97ad8b40dbb..ceaf05743f45 100644 > > --- a/fs/overlayfs/super.c > > +++ b/fs/overlayfs/super.c > > @@ -16,6 +16,8 @@ > > #include <linux/posix_acl_xattr.h> > > #include <linux/exportfs.h> > > #include <linux/file.h> > > +#include <linux/fs_context.h> > > +#include <linux/fs_parser.h> > > #include "overlayfs.h" > > > > MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); > > @@ -67,6 +69,59 @@ module_param_named(metacopy, ovl_metacopy_def, bool, 0644); > > MODULE_PARM_DESC(metacopy, > > "Default to on or off for the metadata only copy up feature"); > > > > +enum { > > + Opt_lowerdir, > > + Opt_upperdir, > > + Opt_workdir, > > + Opt_default_permissions, > > + Opt_redirect_dir, > > + Opt_index, > > + Opt_uuid, > > + Opt_nfs_export, > > + Opt_userxattr, > > + Opt_xino, > > + Opt_metacopy, > > + Opt_volatile, > > +}; > > + > > +static const struct constant_table ovl_parameter_bool[] = { > > + { "on", true }, > > + { "off", false }, > > + {} > > +}; > > + > > +static const struct constant_table ovl_parameter_xino[] = { > > + { "on", OVL_XINO_ON }, > > + { "off", OVL_XINO_OFF }, > > + { "auto", OVL_XINO_AUTO }, > > + {} > > +}; > > + > > +static const struct fs_parameter_spec ovl_parameter_spec[] = { > > + fsparam_string("lowerdir", Opt_lowerdir), > > + fsparam_string("upperdir", Opt_upperdir), > > + fsparam_string("workdir", Opt_workdir), > > + fsparam_flag("default_permissions", Opt_default_permissions), > > + fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_bool), > > + fsparam_enum("index", Opt_index, ovl_parameter_bool), > > + fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool), > > + fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool), > > + fsparam_flag("userxattr", Opt_userxattr), > > + fsparam_enum("xino", Opt_xino, ovl_parameter_xino), > > + fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool), > > + fsparam_flag("volatile", Opt_volatile), > > + {} > > +}; > > + > > +#define OVL_METACOPY_SET BIT(0) > > +#define OVL_REDIRECT_SET BIT(1) > > +#define OVL_NFS_EXPORT_SET BIT(2) > > +#define OVL_INDEX_SET BIT(3) > > + > > +struct ovl_fs_context { > > + u8 set; > > +}; > > + > > static void ovl_dentry_release(struct dentry *dentry) > > { > > struct ovl_entry *oe = dentry->d_fsdata; > > @@ -394,27 +449,6 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) > > return 0; > > } > > > > -static int ovl_remount(struct super_block *sb, int *flags, char *data) > > -{ > > - struct ovl_fs *ofs = sb->s_fs_info; > > - struct super_block *upper_sb; > > - int ret = 0; > > - > > - if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) > > - return -EROFS; > > - > > - if (*flags & SB_RDONLY && !sb_rdonly(sb)) { > > - upper_sb = ovl_upper_mnt(ofs)->mnt_sb; > > - if (ovl_should_sync(ofs)) { > > - down_read(&upper_sb->s_umount); > > - ret = sync_filesystem(upper_sb); > > - up_read(&upper_sb->s_umount); > > - } > > - } > > - > > - return ret; > > -} > > - > > static const struct super_operations ovl_super_operations = { > > .alloc_inode = ovl_alloc_inode, > > .free_inode = ovl_free_inode, > > @@ -424,76 +458,8 @@ static const struct super_operations ovl_super_operations = { > > .sync_fs = ovl_sync_fs, > > .statfs = ovl_statfs, > > .show_options = ovl_show_options, > > - .remount_fs = ovl_remount, > > -}; > > - > > -enum { > > - OPT_LOWERDIR, > > - OPT_UPPERDIR, > > - OPT_WORKDIR, > > - OPT_DEFAULT_PERMISSIONS, > > - OPT_REDIRECT_DIR, > > - OPT_INDEX_ON, > > - OPT_INDEX_OFF, > > - OPT_UUID_ON, > > - OPT_UUID_OFF, > > - OPT_NFS_EXPORT_ON, > > - OPT_USERXATTR, > > - OPT_NFS_EXPORT_OFF, > > - OPT_XINO_ON, > > - OPT_XINO_OFF, > > - OPT_XINO_AUTO, > > - OPT_METACOPY_ON, > > - OPT_METACOPY_OFF, > > - OPT_VOLATILE, > > - OPT_ERR, > > -}; > > - > > -static const match_table_t ovl_tokens = { > > - {OPT_LOWERDIR, "lowerdir=%s"}, > > - {OPT_UPPERDIR, "upperdir=%s"}, > > - {OPT_WORKDIR, "workdir=%s"}, > > - {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, > > - {OPT_REDIRECT_DIR, "redirect_dir=%s"}, > > - {OPT_INDEX_ON, "index=on"}, > > - {OPT_INDEX_OFF, "index=off"}, > > - {OPT_USERXATTR, "userxattr"}, > > - {OPT_UUID_ON, "uuid=on"}, > > - {OPT_UUID_OFF, "uuid=off"}, > > - {OPT_NFS_EXPORT_ON, "nfs_export=on"}, > > - {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, > > - {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_VOLATILE, "volatile"}, > > - {OPT_ERR, NULL} > > }; > > > > -static char *ovl_next_opt(char **s) > > -{ > > - char *sbegin = *s; > > - char *p; > > - > > - if (sbegin == NULL) > > - return NULL; > > - > > - for (p = sbegin; *p; p++) { > > - if (*p == '\\') { > > - p++; > > - if (!*p) > > - break; > > - } else if (*p == ',') { > > - *p = '\0'; > > - *s = p + 1; > > - return sbegin; > > - } > > - } > > - *s = NULL; > > - return sbegin; > > -} > > - > > static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) > > { > > if (strcmp(mode, "on") == 0) { > > @@ -517,123 +483,14 @@ static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) > > return 0; > > } > > > > -static int ovl_parse_opt(char *opt, struct ovl_config *config) > > +static int ovl_fs_params_verify(const struct ovl_fs_context *ctx, > > + struct ovl_config *config) > > { > > - char *p; > > int err; > > - bool metacopy_opt = false, redirect_opt = false; > > - bool nfs_export_opt = false, index_opt = false; > > - > > - config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); > > - if (!config->redirect_mode) > > - return -ENOMEM; > > - > > - while ((p = ovl_next_opt(&opt)) != NULL) { > > - int token; > > - substring_t args[MAX_OPT_ARGS]; > > - > > - if (!*p) > > - continue; > > - > > - token = match_token(p, ovl_tokens, args); > > - switch (token) { > > - case OPT_UPPERDIR: > > - kfree(config->upperdir); > > - config->upperdir = match_strdup(&args[0]); > > - if (!config->upperdir) > > - return -ENOMEM; > > - break; > > - > > - case OPT_LOWERDIR: > > - kfree(config->lowerdir); > > - config->lowerdir = match_strdup(&args[0]); > > - if (!config->lowerdir) > > - return -ENOMEM; > > - break; > > - > > - case OPT_WORKDIR: > > - kfree(config->workdir); > > - config->workdir = match_strdup(&args[0]); > > - if (!config->workdir) > > - return -ENOMEM; > > - break; > > - > > - case OPT_DEFAULT_PERMISSIONS: > > - config->default_permissions = true; > > - break; > > - > > - case OPT_REDIRECT_DIR: > > - kfree(config->redirect_mode); > > - config->redirect_mode = match_strdup(&args[0]); > > - if (!config->redirect_mode) > > - return -ENOMEM; > > - redirect_opt = true; > > - break; > > - > > - case OPT_INDEX_ON: > > - config->index = true; > > - index_opt = true; > > - break; > > - > > - case OPT_INDEX_OFF: > > - config->index = false; > > - index_opt = true; > > - break; > > - > > - case OPT_UUID_ON: > > - config->uuid = true; > > - break; > > - > > - case OPT_UUID_OFF: > > - config->uuid = false; > > - break; > > - > > - case OPT_NFS_EXPORT_ON: > > - config->nfs_export = true; > > - nfs_export_opt = true; > > - break; > > - > > - case OPT_NFS_EXPORT_OFF: > > - config->nfs_export = false; > > - nfs_export_opt = true; > > - break; > > - > > - case OPT_XINO_ON: > > - config->xino = OVL_XINO_ON; > > - break; > > - > > - case OPT_XINO_OFF: > > - config->xino = OVL_XINO_OFF; > > - break; > > - > > - case OPT_XINO_AUTO: > > - config->xino = OVL_XINO_AUTO; > > - break; > > - > > - case OPT_METACOPY_ON: > > - config->metacopy = true; > > - metacopy_opt = true; > > - break; > > - > > - case OPT_METACOPY_OFF: > > - config->metacopy = false; > > - metacopy_opt = true; > > - break; > > - > > - case OPT_VOLATILE: > > - config->ovl_volatile = true; > > - break; > > - > > - case OPT_USERXATTR: > > - config->userxattr = true; > > - break; > > - > > - default: > > - pr_err("unrecognized mount option \"%s\" or missing value\n", > > - p); > > - return -EINVAL; > > - } > > - } > > + bool metacopy_opt = ctx->set & OVL_METACOPY_SET, > > + redirect_opt = ctx->set & OVL_REDIRECT_SET; > > + bool nfs_export_opt = ctx->set & OVL_NFS_EXPORT_SET, > > + index_opt = ctx->set & OVL_INDEX_SET; > > Nit: please split lines here. > > > > > /* Workdir/index are useless in non-upper mount */ > > if (!config->upperdir) { > > @@ -1882,12 +1739,143 @@ static struct dentry *ovl_get_root(struct super_block *sb, > > return root; > > } > > > > -static int ovl_fill_super(struct super_block *sb, void *data, int silent) > > +static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) > > { > > - struct path upperpath = { }; > > + int err = 0; > > + struct fs_parse_result result; > > + struct ovl_fs *ofs = fc->s_fs_info; > > + struct ovl_config *config = &ofs->config; > > + struct ovl_fs_context *ctx = fc->fs_private; > > + struct path path; > > + char *dup; > > + int opt; > > + char *sval; > > + > > + /* > > + * On remount overlayfs has always ignored all mount options no > > + * matter if malformed or not so for backwards compatibility we > > + * do the same here. > > + */ > > + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) > > + return 0; > > + > > + opt = fs_parse(fc, ovl_parameter_spec, param, &result); > > + if (opt < 0) > > + return opt; > > + > > + switch (opt) { > > + case Opt_lowerdir: > > + dup = kstrdup(param->string, GFP_KERNEL); > > + if (!dup) { > > + path_put(&path); > > + err = -ENOMEM; > > + break; > > + } > > + > > + kfree(config->lowerdir); > > + config->lowerdir = dup; > > + break; > > + case Opt_upperdir: > > + dup = kstrdup(param->string, GFP_KERNEL); > > + if (!dup) { > > + path_put(&path); > > + err = -ENOMEM; > > + break; > > + } > > + > > + kfree(config->upperdir); > > + config->upperdir = dup; > > + break; > > + case Opt_workdir: > > + dup = kstrdup(param->string, GFP_KERNEL); > > + if (!dup) { > > + path_put(&path); > > + err = -ENOMEM; > > + break; > > + } > > + > > + kfree(config->workdir); > > + config->workdir = dup; > > + break; > > + case Opt_default_permissions: > > + config->default_permissions = true; > > + break; > > + case Opt_index: > > + config->index = result.uint_32; > > + ctx->set |= OVL_INDEX_SET; > > + break; > > + case Opt_uuid: > > + config->uuid = result.uint_32; > > + break; > > + case Opt_nfs_export: > > + config->nfs_export = result.uint_32; > > + ctx->set |= OVL_NFS_EXPORT_SET; > > + break; > > + case Opt_metacopy: > > + config->metacopy = result.uint_32; > > + ctx->set |= OVL_METACOPY_SET; > > + break; > > + case Opt_userxattr: > > + config->userxattr = true; > > + break; > > + case Opt_volatile: > > + config->ovl_volatile = true; > > + break; > > + case Opt_xino: > > + config->xino = result.uint_32; > > + break; > > + case Opt_redirect_dir: > > + if (result.uint_32 == true) > > + sval = kstrdup("on", GFP_KERNEL); > > + else > > + sval = kstrdup("off", GFP_KERNEL); > > + if (!sval) { > > + err = -ENOMEM; > > + break; > > + } > > + > > + kfree(config->redirect_mode); > > + config->redirect_mode = sval; > > + ctx->set |= OVL_REDIRECT_SET; > > + break; > > + default: > > + pr_err("unrecognized mount option \"%s\" or missing value\n", param->key); > > + return -EINVAL; > > + } > > + > > + return err; > > +} > > > For the end result, all these functions above should be in params.c > I don't mind if you move it with an extra patch at the beginning > Probably easier at the end. Just as long as you do not move > ovl_fs_params_verify() in the same patch that changes half of it. Ok.
On Fri, Jun 09, 2023 at 12:09:08PM -0400, Colin Walters wrote: > Cool work. It will be interesting to do some performance testing on what does it actually look like to create ~500 or whatever overlayfs layers now that we can. > > On Fri, Jun 9, 2023, at 11:41 AM, Christian Brauner wrote: > > > > +static int ovl_init_fs_context(struct fs_context *fc) > > +{ > > + struct ovl_fs_context *ctx = NULL; > > + struct ovl_fs *ofs = NULL; > > + > > + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); > > + if (!ctx) > > + goto out_err; > > It looks to me like in this case, ofs will be NULL, then: > > > +out_err: > > + ovl_fs_context_free(ctx); > > + ovl_free_fs(ofs); > > And then we'll jump here and `ovl_free_fs` is not NULL safe. > > I think the previous code was correct here as it just jumped directly to "out:". Good catch, thanks! > > > (I've always wondered why there's no usage of __attribute__((cleanup)) > in kernel code and in our userspace code doing that we have the free > functions be no-ops on NULL which systematically avoids these bugs, > but then again maybe the real fix is Rust ;) ) I have talked about this before and actually do have a PoC patch in my tree somewhere I never bothered to send it because it didn't feel like I had the time for the flamewar+bikeshed that would end up happening... Maybe I should just try.
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index f97ad8b40dbb..ceaf05743f45 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -16,6 +16,8 @@ #include <linux/posix_acl_xattr.h> #include <linux/exportfs.h> #include <linux/file.h> +#include <linux/fs_context.h> +#include <linux/fs_parser.h> #include "overlayfs.h" MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); @@ -67,6 +69,59 @@ module_param_named(metacopy, ovl_metacopy_def, bool, 0644); MODULE_PARM_DESC(metacopy, "Default to on or off for the metadata only copy up feature"); +enum { + Opt_lowerdir, + Opt_upperdir, + Opt_workdir, + Opt_default_permissions, + Opt_redirect_dir, + Opt_index, + Opt_uuid, + Opt_nfs_export, + Opt_userxattr, + Opt_xino, + Opt_metacopy, + Opt_volatile, +}; + +static const struct constant_table ovl_parameter_bool[] = { + { "on", true }, + { "off", false }, + {} +}; + +static const struct constant_table ovl_parameter_xino[] = { + { "on", OVL_XINO_ON }, + { "off", OVL_XINO_OFF }, + { "auto", OVL_XINO_AUTO }, + {} +}; + +static const struct fs_parameter_spec ovl_parameter_spec[] = { + fsparam_string("lowerdir", Opt_lowerdir), + fsparam_string("upperdir", Opt_upperdir), + fsparam_string("workdir", Opt_workdir), + fsparam_flag("default_permissions", Opt_default_permissions), + fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_bool), + fsparam_enum("index", Opt_index, ovl_parameter_bool), + fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool), + fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool), + fsparam_flag("userxattr", Opt_userxattr), + fsparam_enum("xino", Opt_xino, ovl_parameter_xino), + fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool), + fsparam_flag("volatile", Opt_volatile), + {} +}; + +#define OVL_METACOPY_SET BIT(0) +#define OVL_REDIRECT_SET BIT(1) +#define OVL_NFS_EXPORT_SET BIT(2) +#define OVL_INDEX_SET BIT(3) + +struct ovl_fs_context { + u8 set; +}; + static void ovl_dentry_release(struct dentry *dentry) { struct ovl_entry *oe = dentry->d_fsdata; @@ -394,27 +449,6 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) return 0; } -static int ovl_remount(struct super_block *sb, int *flags, char *data) -{ - struct ovl_fs *ofs = sb->s_fs_info; - struct super_block *upper_sb; - int ret = 0; - - if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) - return -EROFS; - - if (*flags & SB_RDONLY && !sb_rdonly(sb)) { - upper_sb = ovl_upper_mnt(ofs)->mnt_sb; - if (ovl_should_sync(ofs)) { - down_read(&upper_sb->s_umount); - ret = sync_filesystem(upper_sb); - up_read(&upper_sb->s_umount); - } - } - - return ret; -} - static const struct super_operations ovl_super_operations = { .alloc_inode = ovl_alloc_inode, .free_inode = ovl_free_inode, @@ -424,76 +458,8 @@ static const struct super_operations ovl_super_operations = { .sync_fs = ovl_sync_fs, .statfs = ovl_statfs, .show_options = ovl_show_options, - .remount_fs = ovl_remount, -}; - -enum { - OPT_LOWERDIR, - OPT_UPPERDIR, - OPT_WORKDIR, - OPT_DEFAULT_PERMISSIONS, - OPT_REDIRECT_DIR, - OPT_INDEX_ON, - OPT_INDEX_OFF, - OPT_UUID_ON, - OPT_UUID_OFF, - OPT_NFS_EXPORT_ON, - OPT_USERXATTR, - OPT_NFS_EXPORT_OFF, - OPT_XINO_ON, - OPT_XINO_OFF, - OPT_XINO_AUTO, - OPT_METACOPY_ON, - OPT_METACOPY_OFF, - OPT_VOLATILE, - OPT_ERR, -}; - -static const match_table_t ovl_tokens = { - {OPT_LOWERDIR, "lowerdir=%s"}, - {OPT_UPPERDIR, "upperdir=%s"}, - {OPT_WORKDIR, "workdir=%s"}, - {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, - {OPT_REDIRECT_DIR, "redirect_dir=%s"}, - {OPT_INDEX_ON, "index=on"}, - {OPT_INDEX_OFF, "index=off"}, - {OPT_USERXATTR, "userxattr"}, - {OPT_UUID_ON, "uuid=on"}, - {OPT_UUID_OFF, "uuid=off"}, - {OPT_NFS_EXPORT_ON, "nfs_export=on"}, - {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, - {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_VOLATILE, "volatile"}, - {OPT_ERR, NULL} }; -static char *ovl_next_opt(char **s) -{ - char *sbegin = *s; - char *p; - - if (sbegin == NULL) - return NULL; - - for (p = sbegin; *p; p++) { - if (*p == '\\') { - p++; - if (!*p) - break; - } else if (*p == ',') { - *p = '\0'; - *s = p + 1; - return sbegin; - } - } - *s = NULL; - return sbegin; -} - static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) { if (strcmp(mode, "on") == 0) { @@ -517,123 +483,14 @@ static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) return 0; } -static int ovl_parse_opt(char *opt, struct ovl_config *config) +static int ovl_fs_params_verify(const struct ovl_fs_context *ctx, + struct ovl_config *config) { - char *p; int err; - bool metacopy_opt = false, redirect_opt = false; - bool nfs_export_opt = false, index_opt = false; - - config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); - if (!config->redirect_mode) - return -ENOMEM; - - while ((p = ovl_next_opt(&opt)) != NULL) { - int token; - substring_t args[MAX_OPT_ARGS]; - - if (!*p) - continue; - - token = match_token(p, ovl_tokens, args); - switch (token) { - case OPT_UPPERDIR: - kfree(config->upperdir); - config->upperdir = match_strdup(&args[0]); - if (!config->upperdir) - return -ENOMEM; - break; - - case OPT_LOWERDIR: - kfree(config->lowerdir); - config->lowerdir = match_strdup(&args[0]); - if (!config->lowerdir) - return -ENOMEM; - break; - - case OPT_WORKDIR: - kfree(config->workdir); - config->workdir = match_strdup(&args[0]); - if (!config->workdir) - return -ENOMEM; - break; - - case OPT_DEFAULT_PERMISSIONS: - config->default_permissions = true; - break; - - case OPT_REDIRECT_DIR: - kfree(config->redirect_mode); - config->redirect_mode = match_strdup(&args[0]); - if (!config->redirect_mode) - return -ENOMEM; - redirect_opt = true; - break; - - case OPT_INDEX_ON: - config->index = true; - index_opt = true; - break; - - case OPT_INDEX_OFF: - config->index = false; - index_opt = true; - break; - - case OPT_UUID_ON: - config->uuid = true; - break; - - case OPT_UUID_OFF: - config->uuid = false; - break; - - case OPT_NFS_EXPORT_ON: - config->nfs_export = true; - nfs_export_opt = true; - break; - - case OPT_NFS_EXPORT_OFF: - config->nfs_export = false; - nfs_export_opt = true; - break; - - case OPT_XINO_ON: - config->xino = OVL_XINO_ON; - break; - - case OPT_XINO_OFF: - config->xino = OVL_XINO_OFF; - break; - - case OPT_XINO_AUTO: - config->xino = OVL_XINO_AUTO; - break; - - case OPT_METACOPY_ON: - config->metacopy = true; - metacopy_opt = true; - break; - - case OPT_METACOPY_OFF: - config->metacopy = false; - metacopy_opt = true; - break; - - case OPT_VOLATILE: - config->ovl_volatile = true; - break; - - case OPT_USERXATTR: - config->userxattr = true; - break; - - default: - pr_err("unrecognized mount option \"%s\" or missing value\n", - p); - return -EINVAL; - } - } + bool metacopy_opt = ctx->set & OVL_METACOPY_SET, + redirect_opt = ctx->set & OVL_REDIRECT_SET; + bool nfs_export_opt = ctx->set & OVL_NFS_EXPORT_SET, + index_opt = ctx->set & OVL_INDEX_SET; /* Workdir/index are useless in non-upper mount */ if (!config->upperdir) { @@ -1882,12 +1739,143 @@ static struct dentry *ovl_get_root(struct super_block *sb, return root; } -static int ovl_fill_super(struct super_block *sb, void *data, int silent) +static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) { - struct path upperpath = { }; + int err = 0; + struct fs_parse_result result; + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_config *config = &ofs->config; + struct ovl_fs_context *ctx = fc->fs_private; + struct path path; + char *dup; + int opt; + char *sval; + + /* + * On remount overlayfs has always ignored all mount options no + * matter if malformed or not so for backwards compatibility we + * do the same here. + */ + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) + return 0; + + opt = fs_parse(fc, ovl_parameter_spec, param, &result); + if (opt < 0) + return opt; + + switch (opt) { + case Opt_lowerdir: + dup = kstrdup(param->string, GFP_KERNEL); + if (!dup) { + path_put(&path); + err = -ENOMEM; + break; + } + + kfree(config->lowerdir); + config->lowerdir = dup; + break; + case Opt_upperdir: + dup = kstrdup(param->string, GFP_KERNEL); + if (!dup) { + path_put(&path); + err = -ENOMEM; + break; + } + + kfree(config->upperdir); + config->upperdir = dup; + break; + case Opt_workdir: + dup = kstrdup(param->string, GFP_KERNEL); + if (!dup) { + path_put(&path); + err = -ENOMEM; + break; + } + + kfree(config->workdir); + config->workdir = dup; + break; + case Opt_default_permissions: + config->default_permissions = true; + break; + case Opt_index: + config->index = result.uint_32; + ctx->set |= OVL_INDEX_SET; + break; + case Opt_uuid: + config->uuid = result.uint_32; + break; + case Opt_nfs_export: + config->nfs_export = result.uint_32; + ctx->set |= OVL_NFS_EXPORT_SET; + break; + case Opt_metacopy: + config->metacopy = result.uint_32; + ctx->set |= OVL_METACOPY_SET; + break; + case Opt_userxattr: + config->userxattr = true; + break; + case Opt_volatile: + config->ovl_volatile = true; + break; + case Opt_xino: + config->xino = result.uint_32; + break; + case Opt_redirect_dir: + if (result.uint_32 == true) + sval = kstrdup("on", GFP_KERNEL); + else + sval = kstrdup("off", GFP_KERNEL); + if (!sval) { + err = -ENOMEM; + break; + } + + kfree(config->redirect_mode); + config->redirect_mode = sval; + ctx->set |= OVL_REDIRECT_SET; + break; + default: + pr_err("unrecognized mount option \"%s\" or missing value\n", param->key); + return -EINVAL; + } + + return err; +} + + +static int ovl_reconfigure(struct fs_context *fc) +{ + struct super_block *sb = fc->root->d_sb; + struct ovl_fs *ofs = sb->s_fs_info; + struct super_block *upper_sb; + int ret = 0; + + if (!(fc->sb_flags & SB_RDONLY) && ovl_force_readonly(ofs)) + return -EROFS; + + if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb)) { + upper_sb = ovl_upper_mnt(ofs)->mnt_sb; + if (ovl_should_sync(ofs)) { + down_read(&upper_sb->s_umount); + ret = sync_filesystem(upper_sb); + up_read(&upper_sb->s_umount); + } + } + + return ret; +} + +static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) +{ + struct ovl_fs *ofs = sb->s_fs_info; + struct ovl_fs_context *ctx = fc->fs_private; + struct path upperpath = {}; struct dentry *root_dentry; struct ovl_entry *oe; - struct ovl_fs *ofs; struct ovl_layer *layers; struct cred *cred; char *splitlower = NULL; @@ -1895,36 +1883,24 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) int err; err = -EIO; - if (WARN_ON(sb->s_user_ns != current_user_ns())) - goto out; + if (WARN_ON(fc->user_ns != current_user_ns())) + goto out_err; + ofs->share_whiteout = true; sb->s_d_op = &ovl_dentry_operations; - err = -ENOMEM; - ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); - if (!ofs) - goto out; - err = -ENOMEM; ofs->creator_cred = cred = prepare_creds(); if (!cred) goto out_err; - /* Is there a reason anyone would want not to share whiteouts? */ - ofs->share_whiteout = true; - - ofs->config.index = ovl_index_def; - ofs->config.uuid = true; - 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); + err = ovl_fs_params_verify(ctx, &ofs->config); if (err) goto out_err; err = -EINVAL; if (!ofs->config.lowerdir) { - if (!silent) + if (fc->sb_flags & SB_SILENT) pr_err("missing 'lowerdir'\n"); goto out_err; } @@ -2070,25 +2046,92 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ovl_entry_stack_free(oe); kfree(oe); out_err: - kfree(splitlower); - path_put(&upperpath); - ovl_free_fs(ofs); -out: return err; } -static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, - const char *dev_name, void *raw_data) +static int ovl_get_tree(struct fs_context *fc) +{ + return get_tree_nodev(fc, ovl_fill_super); +} + +static inline void ovl_fs_context_free(struct ovl_fs_context *ctx) { - return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); + kfree(ctx); +} + +static void ovl_free(struct fs_context *fc) +{ + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_fs_context *ctx = fc->fs_private; + + /* + * ofs is stored in the fs_context when it is initialized. + * ofs is transferred to the superblock on a successful mount, + * but if an error occurs before the transfer we have to free + * it here. + */ + if (ofs) + ovl_free_fs(ofs); + + if (ctx) + ovl_fs_context_free(ctx); +} + +static const struct fs_context_operations ovl_context_ops = { + .parse_param = ovl_parse_param, + .get_tree = ovl_get_tree, + .reconfigure = ovl_reconfigure, + .free = ovl_free, +}; + +/* + * This is called during fsopen() and will record the user namespace of + * the caller in fc->user_ns since we've raised FS_USERNS_MOUNT. We'll + * need it when we actually create the superblock to verify that the + * process creating the superblock is in the same user namespace as + * process that called fsopen(). + */ +static int ovl_init_fs_context(struct fs_context *fc) +{ + struct ovl_fs_context *ctx = NULL; + struct ovl_fs *ofs = NULL; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); + if (!ctx) + goto out_err; + + ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); + if (!ofs) + goto out_err; + + ofs->config.redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); + if (!ofs->config.redirect_mode) + goto out_err; + + ofs->config.index = ovl_index_def; + ofs->config.uuid = true; + ofs->config.nfs_export = ovl_nfs_export_def; + ofs->config.xino = ovl_xino_def(); + ofs->config.metacopy = ovl_metacopy_def; + + fc->s_fs_info = ofs; + fc->fs_private = ctx; + fc->ops = &ovl_context_ops; + return 0; + +out_err: + ovl_fs_context_free(ctx); + ovl_free_fs(ofs); + return -ENOMEM; } static struct file_system_type ovl_fs_type = { - .owner = THIS_MODULE, - .name = "overlay", - .fs_flags = FS_USERNS_MOUNT, - .mount = ovl_mount, - .kill_sb = kill_anon_super, + .owner = THIS_MODULE, + .name = "overlay", + .init_fs_context = ovl_init_fs_context, + .parameters = ovl_parameter_spec, + .fs_flags = FS_USERNS_MOUNT, + .kill_sb = kill_anon_super, }; MODULE_ALIAS_FS("overlay");
We recently ported util-linux to the new mount api. Now the mount(8) tool will by default use the new mount api. While trying hard to fall back to the old mount api gracefully there are still cases where we run into issues that are difficult to handle nicely. Now with mount(8) and libmount supporting the new mount api I expect an increase in the number of bug reports and issues we're going to see with filesystems that don't yet support the new mount api. So it's time we rectify this. Signed-off-by: Christian Brauner <brauner@kernel.org> --- fs/overlayfs/super.c | 515 ++++++++++++++++++++++++++++----------------------- 1 file changed, 279 insertions(+), 236 deletions(-)