ovl: fix missing override creds in link of a metacopy upper
Amir Goldstein
maintainerPATCH 1/1 ovl: fix missing override creds in link of a metacopy upper
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.
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--- fs/overlayfs/dir.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
fs/overlayfs/dir.c +13 -1
@@ -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; }
Signature · 1 line
2.17.1
Quoted 9 lines · Amir Goldstein
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"
Quoted 4 lines
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.
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
Quoted 61 lines
Reproducer:
echo Y >
/sys/module/overlay/parameters/redirect_direcho Y >/sys/module/overlay/parameters/metacopycd /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 linkReported-by Theodore Y. Ts'o <[email protected]>Reported-by Maciej Zięba <[email protected]>Fixes 4120fe64dce4 ("ovl: Set redirect on upper inode when it is linked")Cc <[email protected]> # v4.19Signed-off-by Amir Goldstein <[email protected]>--- fs/overlayfs/dir.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)fs/overlayfs/dir.c +13
-1@@ -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; }Signature · 1 line
2.17.1
Miklos Szeredi
maintainerQuoted 15 lines · Vivek Goyal
Quoted 9 lines · Amir Goldstein
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"Quoted 4 lines
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.
Quoted 6 lines
Thanks Amir for fixiing this. This fix looks good to me.
Acked-by Vivek Goyal <[email protected]>So this problem happened because looks like kernel enanbled metacopy by default (in
Kconfig) and thence enabled redirect by default inKconfig.
OVERLAY_FS_METACOPY is off by default. So it seems people explicitly enable it, because it sounds useful :)
Thanks,
Miklos