diff options
| -rw-r--r-- | Documentation/filesystems/overlayfs.rst | 5 | ||||
| -rw-r--r-- | fs/overlayfs/copy_up.c | 3 | ||||
| -rw-r--r-- | fs/overlayfs/namei.c | 4 | ||||
| -rw-r--r-- | fs/overlayfs/ovl_entry.h | 1 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 20 |
5 files changed, 31 insertions, 2 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst index 580ab9a0fe31..a3e588dc8437 100644 --- a/Documentation/filesystems/overlayfs.rst +++ b/Documentation/filesystems/overlayfs.rst @@ -563,6 +563,11 @@ This verification may cause significant overhead in some cases. Note: the mount options index=off,nfs_export=on are conflicting for a read-write mount and will result in an error. +Note: the mount option uuid=off can be used to replace UUID of the underlying +filesystem in file handles with null, and effectively disable UUID checks. This +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. Volatile mount -------------- diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 3380039036d6..0b7e7a90a435 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -320,7 +320,8 @@ 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; - fh->fb.uuid = *uuid; + if (ofs->config.uuid) + fh->fb.uuid = *uuid; return fh; diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index f058bf8e8b87..f731eb4d35f9 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -159,8 +159,10 @@ struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh, /* * Make sure that the stored uuid matches the uuid of the lower * layer where file handle will be decoded. + * In case of uuid=off option just make sure that stored uuid is null. */ - if (!uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid)) + if (ofs->config.uuid ? !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/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 1b5a2094df8e..b7a73ea147b8 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -14,6 +14,7 @@ struct ovl_config { bool redirect_follow; const char *redirect_mode; bool index; + bool uuid; bool nfs_export; int xino; bool metacopy; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 290983bcfbb3..4717244e7d7a 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -356,6 +356,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); 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.nfs_export != ovl_nfs_export_def) seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? "on" : "off"); @@ -410,6 +412,8 @@ enum { OPT_REDIRECT_DIR, OPT_INDEX_ON, OPT_INDEX_OFF, + OPT_UUID_ON, + OPT_UUID_OFF, OPT_NFS_EXPORT_ON, OPT_NFS_EXPORT_OFF, OPT_XINO_ON, @@ -429,6 +433,8 @@ static const match_table_t ovl_tokens = { {OPT_REDIRECT_DIR, "redirect_dir=%s"}, {OPT_INDEX_ON, "index=on"}, {OPT_INDEX_OFF, "index=off"}, + {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"}, @@ -549,6 +555,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) 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; @@ -1877,6 +1891,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 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; @@ -1956,6 +1971,11 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 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_force_readonly(ofs) && ofs->config.index) { err = ovl_get_indexdir(sb, ofs, oe, &upperpath); if (err) |