From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: [PATCH 3/9] ovl: Provide a mount option metacopy=on/off for metadata copyup Date: Tue, 10 Oct 2017 11:32:18 -0400 Message-ID: <1507649544-4539-4-git-send-email-vgoyal@redhat.com> References: <1507649544-4539-1-git-send-email-vgoyal@redhat.com> Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37724 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932243AbdJJPci (ORCPT ); Tue, 10 Oct 2017 11:32:38 -0400 In-Reply-To: <1507649544-4539-1-git-send-email-vgoyal@redhat.com> Sender: linux-unionfs-owner@vger.kernel.org List-Id: linux-unionfs@vger.kernel.org To: linux-unionfs@vger.kernel.org Cc: amir73il@gmail.com, miklos@szeredi.hu, vgoyal@redhat.com, ebiederm@xmission.com By default metadata only copy up is disabled. Provide a mount option so that users can choose one way or other. Also metadata copyup is conditional on index=on. If index=off and user specifies metacopy=on, it goes back to metacopy=off and a warning is printed. Also provide a kernel config and module option to enable/disable metacopy feature. Signed-off-by: Vivek Goyal --- fs/overlayfs/Kconfig | 9 +++++++++ fs/overlayfs/ovl_entry.h | 1 + fs/overlayfs/super.c | 32 ++++++++++++++++++++++++++++++++ 3 files changed, 42 insertions(+) diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index cbfc196e5dc5..94d4c61719c8 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -43,3 +43,12 @@ config OVERLAY_FS_INDEX outcomes. However, mounting the same overlay with an old kernel read-write and then mounting it again with a new kernel, will have unexpected results. + +config OVERLAY_FS_METACOPY + bool "Overlayfs: turn on metadata only copy up feature by default" + depends on OVERLAY_FS + depends on OVERLAY_FS_INDEX + help + If this config option is enabled then overlay filesystems will + copy up only metadata where appropriate and data copy up will + happen when a file is opended for WRITE operation. diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 25d9b5adcd42..6806f0b0fbc2 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -15,6 +15,7 @@ struct ovl_config { bool default_permissions; bool redirect_dir; bool index; + bool metacopy; }; /* private information held for overlayfs's superblock */ diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 092d150643c1..6f4c32e49298 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -39,6 +39,11 @@ module_param_named(index, ovl_index_def, bool, 0644); MODULE_PARM_DESC(ovl_index_def, "Default to on or off for the inodes index feature"); +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; @@ -303,6 +308,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) if (ufs->config.index != ovl_index_def) seq_printf(m, ",index=%s", ufs->config.index ? "on" : "off"); + if (ufs->config.metacopy != ovl_metacopy_def) + seq_printf(m, ",metacopy=%s", + ufs->config.metacopy ? "on" : "off"); return 0; } @@ -336,6 +344,8 @@ enum { OPT_REDIRECT_DIR_OFF, OPT_INDEX_ON, OPT_INDEX_OFF, + OPT_METACOPY_ON, + OPT_METACOPY_OFF, OPT_ERR, }; @@ -348,6 +358,8 @@ static const match_table_t ovl_tokens = { {OPT_REDIRECT_DIR_OFF, "redirect_dir=off"}, {OPT_INDEX_ON, "index=on"}, {OPT_INDEX_OFF, "index=off"}, + {OPT_METACOPY_ON, "metacopy=on"}, + {OPT_METACOPY_OFF, "metacopy=off"}, {OPT_ERR, NULL} }; @@ -428,6 +440,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->index = false; 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; @@ -847,6 +867,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ufs->config.redirect_dir = ovl_redirect_dir_def; ufs->config.index = ovl_index_def; + if (ovl_metacopy_def && !ovl_index_def) { + pr_warn("overlayfs: metadata copy up can not be enabled by default as index feature is not enabled by default.\n"); + ovl_metacopy_def = false; + } + ufs->config.metacopy = ovl_metacopy_def; + err = ovl_parse_opt((char *) data, &ufs->config); if (err) goto out_free_config; @@ -1091,6 +1117,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (!ufs->indexdir) ufs->config.index = false; + /* As of now metacopy=on is dependent on index=on */ + if (ufs->config.metacopy && !ufs->config.index) { + pr_warn("overlayfs: can not enable metadata only copyup with index=off. Falling back to metacopy=off\n"); + ufs->config.metacopy = false; + } + if (remote) sb->s_d_op = &ovl_reval_dentry_operations; else -- 2.13.5