On Fri, Jul 22, 2016 at 01:55:56PM -0700, Vito Caputo wrote: > The patch eliminates the errors from tar in the test I've been using > to reproduce the user-reported issues. However, I'm doubtful of it > being a satisfactory general solution because the inode number of a > pre-existing directory which undergoes copy-up spuriously changes. > > There's probably a scenario where this still upsets tar when > extracting over an partial tree pre-existing in the lower layer, > adding names to existing directories, causing their inode numbers to > change. > > The relevant code where tar detects these shenanigans may be seen here: > http://git.savannah.gnu.org/cgit/tar.git/tree/src/extract.c#n867 > > Perhaps we can come up with a better, more general solution without > adding substantial complexity or overhead? Here's another try. It's simple enough, as to overhead, please let me know if you are comfortable with this. Thanks, Miklos --- From: Miklos Szeredi <mszeredi@xxxxxxxxxx> Subject: ovl: optionally copy up directory on getattr This is to make directory dev/ino stable. Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> --- fs/overlayfs/dir.c | 15 +++++++++++++-- fs/overlayfs/overlayfs.h | 6 ++++++ fs/overlayfs/super.c | 19 +++++++++++++++++++ 3 files changed, 38 insertions(+), 2 deletions(-) --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -139,6 +139,15 @@ static int ovl_dir_getattr(struct vfsmou enum ovl_path_type type; struct path realpath; const struct cred *old_cred; + bool devino_from_ovl = true; + + if (ovl_copy_up_type(dentry) == OVL_COPY_UP_ON_GETATTR) { + err = ovl_copy_up(dentry); + if (err) + return err; + + devino_from_ovl = false; + } type = ovl_path_real(dentry, &realpath); old_cred = ovl_override_creds(dentry->d_sb); @@ -147,8 +156,10 @@ static int ovl_dir_getattr(struct vfsmou if (err) return err; - stat->dev = dentry->d_sb->s_dev; - stat->ino = dentry->d_inode->i_ino; + if (devino_from_ovl) { + stat->dev = dentry->d_sb->s_dev; + stat->ino = dentry->d_inode->i_ino; + } /* * It's probably not worth it to count subdirs to get the --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -24,6 +24,11 @@ enum ovl_path_type { (OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type)) +enum ovl_copy_up_type { + OVL_COPY_UP_ON_MODIF, + OVL_COPY_UP_ON_GETATTR, +}; + #define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay" #define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX ".opaque" @@ -172,6 +177,7 @@ struct file *ovl_path_open(struct path * struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, struct kstat *stat, const char *link); +enum ovl_copy_up_type ovl_copy_up_type(struct dentry *dentry); /* readdir.c */ extern const struct file_operations ovl_dir_operations; --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -31,6 +31,7 @@ struct ovl_config { char *upperdir; char *workdir; bool default_permissions; + enum ovl_copy_up_type dir_copy_up_type; }; /* private information held for overlayfs's superblock */ @@ -203,6 +204,16 @@ struct dentry *ovl_workdir(struct dentry return ofs->workdir; } +enum ovl_copy_up_type ovl_copy_up_type(struct dentry *dentry) +{ + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; + + if (d_is_dir(dentry)) + return ofs->config.dir_copy_up_type; + + return OVL_COPY_UP_ON_MODIF; +} + bool ovl_dentry_is_opaque(struct dentry *dentry) { struct ovl_entry *oe = dentry->d_fsdata; @@ -681,6 +692,8 @@ static int ovl_show_options(struct seq_f } if (ufs->config.default_permissions) seq_puts(m, ",default_permissions"); + if (ufs->config.dir_copy_up_type == OVL_COPY_UP_ON_GETATTR) + seq_puts(m, ",dir_copy_up_on=getattr"); return 0; } @@ -707,6 +720,7 @@ enum { OPT_UPPERDIR, OPT_WORKDIR, OPT_DEFAULT_PERMISSIONS, + OPT_DIR_COPY_UP_ON_GETATTR, OPT_ERR, }; @@ -715,6 +729,7 @@ static const match_table_t ovl_tokens = {OPT_UPPERDIR, "upperdir=%s"}, {OPT_WORKDIR, "workdir=%s"}, {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, + {OPT_DIR_COPY_UP_ON_GETATTR, "dir_copy_up_on=getattr"}, {OPT_ERR, NULL} }; @@ -779,6 +794,10 @@ static int ovl_parse_opt(char *opt, stru config->default_permissions = true; break; + case OPT_DIR_COPY_UP_ON_GETATTR: + config->dir_copy_up_type = OVL_COPY_UP_ON_GETATTR; + break; + default: pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); return -EINVAL; -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
