From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amir Goldstein Subject: [PATCH v3 2/5] ovl: relax same fs constrain for constant st_ino Date: Thu, 1 Jun 2017 12:02:56 +0300 Message-ID: <1496307779-2766-3-git-send-email-amir73il@gmail.com> References: <1496307779-2766-1-git-send-email-amir73il@gmail.com> Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:36400 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751093AbdFAJCv (ORCPT ); Thu, 1 Jun 2017 05:02:51 -0400 Received: by mail-wm0-f68.google.com with SMTP id k15so9568837wmh.3 for ; Thu, 01 Jun 2017 02:02:51 -0700 (PDT) In-Reply-To: <1496307779-2766-1-git-send-email-amir73il@gmail.com> Sender: linux-unionfs-owner@vger.kernel.org List-Id: linux-unionfs@vger.kernel.org To: Miklos Szeredi Cc: Chandan Rajendra , linux-unionfs@vger.kernel.org For the case of all layers not on the same fs, use the copy up origin st_ino/st_dev for non-dir, if we know it. This guarantied constant and persistent st_ino/st_dev for non-dir, but not system-wide uniqueness, like in the same fs case. Signed-off-by: Amir Goldstein --- fs/overlayfs/inode.c | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index d613e2c41242..5f285c179bbd 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -65,6 +65,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat, struct path realpath; const struct cred *old_cred; bool is_dir = S_ISDIR(dentry->d_inode->i_mode); + bool samefs = ovl_same_sb(dentry->d_sb); int err; type = ovl_path_real(dentry, &realpath); @@ -74,16 +75,16 @@ int ovl_getattr(const struct path *path, struct kstat *stat, goto out; /* - * When all layers are on the same fs, all real inode number are - * unique, so we use the overlay st_dev, which is friendly to du -x. - * - * We also use st_ino of the copy up origin, if we know it. - * This guaranties constant st_dev/st_ino across copy up. + * For non-dir or same fs, we use st_ino of the copy up origin, if we + * know it. This guaranties constant st_dev/st_ino across copy up. * * If filesystem supports NFS export ops, this also guaranties * persistent st_ino across mount cycle. + * + * When all layers are on the same fs, all real inode number are + * unique, so we use the overlay st_dev, which is friendly to du -x. */ - if (ovl_same_sb(dentry->d_sb)) { + if (!is_dir || samefs) { if (OVL_TYPE_ORIGIN(type)) { struct kstat lowerstat; u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0); @@ -94,7 +95,6 @@ int ovl_getattr(const struct path *path, struct kstat *stat, if (err) goto out; - WARN_ON_ONCE(stat->dev != lowerstat.dev); /* * Lower hardlinks are broken on copy up to different * upper files, so we cannot use the lower origin st_ino @@ -102,17 +102,23 @@ int ovl_getattr(const struct path *path, struct kstat *stat, */ if (is_dir || lowerstat.nlink == 1) stat->ino = lowerstat.ino; + + if (samefs) + WARN_ON_ONCE(stat->dev != lowerstat.dev); + else + stat->dev = lowerstat.dev; } - stat->dev = dentry->d_sb->s_dev; - } else if (is_dir) { + if (samefs) + stat->dev = dentry->d_sb->s_dev; + } else { /* - * If not all layers are on the same fs the pair {real st_ino; - * overlay st_dev} is not unique, so use the non persistent - * overlay st_ino. - * * Always use the overlay st_dev for directories, so 'find * -xdev' will scan the entire overlay mount and won't cross the * overlay mount boundaries. + * + * If not all layers are on the same fs the pair {real st_ino; + * overlay st_dev} is not unique, so use the non persistent + * overlay st_ino for directories. */ stat->dev = dentry->d_sb->s_dev; stat->ino = dentry->d_inode->i_ino; -- 2.7.4