On Wed, Nov 14, 2018 at 04:01:34PM +0200, Amir Goldstein wrote: > Theodore Ts'o reported a v4.19 regression with docker-dropbox: > https://marc.info/?l=linux-fsdevel&m=154070089431116&w=2 > > "I was rebuilding my dropbox Docker container, and it failed in 4.19 > with the following error: > ... > dpkg: error: error creating new backup file \ > '/var/lib/dpkg/status-old': Invalid cross-device link" > > The problem did not reproduce with metacopy feature disabled. > The error was caused by insufficient credentials to set > "trusted.overlay.redirect" xattr on link of a metacopy file. > Thanks Amir for fixiing this. This fix looks good to me. Acked-by: Vivek Goyal <vgoyal@xxxxxxxxxx> So this problem happened because looks like kernel enanbled metacopy by default (in Kconfig) and thence enabled redirect by default in Kconfig. I am wondering how does that impact docker build process. Because if redirect/metacopy is enabled, while during diff, docker falls back to using older naivediff interface as opposed to newer nativediff. I am not sure how slower naivediff is as compared to nativediff. I am raising this point here because I am curious. If somebody has that info, please share. Thanks Vivek > Reproducer: > > echo Y > /sys/module/overlay/parameters/redirect_dir > echo Y > /sys/module/overlay/parameters/metacopy > cd /tmp > mkdir l u w m > chmod 777 l u > touch l/foo > ln l/foo l/link > chmod 666 l/foo > mount -t overlay none -olowerdir=l,upperdir=u,workdir=w m > su fsgqa > ln m/foo m/bar > [ 21.455823] overlayfs: failed to set redirect (-1) > ln: failed to create hard link 'm/bar' => 'm/foo':\ > Invalid cross-device link > > Reported-by: Theodore Y. Ts'o <tytso@xxxxxxx> > Reported-by: Maciej Zięba <maciekz82@xxxxxxxxx> > Fixes: 4120fe64dce4 ("ovl: Set redirect on upper inode when it is linked") > Cc: <stable@xxxxxxxxxxxxxxx> # v4.19 > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> > --- > fs/overlayfs/dir.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c > index c6289147c787..82c129bfe58d 100644 > --- a/fs/overlayfs/dir.c > +++ b/fs/overlayfs/dir.c > @@ -651,6 +651,18 @@ static int ovl_symlink(struct inode *dir, struct dentry *dentry, > return ovl_create_object(dentry, S_IFLNK, 0, link); > } > > +static int ovl_set_link_redirect(struct dentry *dentry) > +{ > + const struct cred *old_cred; > + int err; > + > + old_cred = ovl_override_creds(dentry->d_sb); > + err = ovl_set_redirect(dentry, false); > + revert_creds(old_cred); > + > + return err; > +} > + > static int ovl_link(struct dentry *old, struct inode *newdir, > struct dentry *new) > { > @@ -670,7 +682,7 @@ static int ovl_link(struct dentry *old, struct inode *newdir, > goto out_drop_write; > > if (ovl_is_metacopy_dentry(old)) { > - err = ovl_set_redirect(old, false); > + err = ovl_set_link_redirect(old); > if (err) > goto out_drop_write; > } > -- > 2.17.1 >
