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ovl: check on mount time if upper fs supports setting xattr

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xattr are needed by overlayfs for setting opaque dir, redirect dir
and copy up origin.

Check at mount time by trying to set the overlay.opaque xattr on the
workdir and if that fails issue a warning message.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-05-17 00:12:40 +03:00 committed by Miklos Szeredi
parent 8137ae26d2
commit 82b749b2c6
4 changed files with 38 additions and 0 deletions
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3
fs/overlayfs/overlayfs.h
View file

@ -279,3 +279,6 @@ int ovl_copy_up(struct dentry *dentry);
int ovl_copy_up_flags(struct dentry *dentry, int flags);
int ovl_copy_xattr(struct dentry *old, struct dentry *new);
int ovl_set_attr(struct dentry *upper, struct kstat *stat);
int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
const char *name, const void *value, size_t size,
int xerr);

1
fs/overlayfs/ovl_entry.h
View file

@ -28,6 +28,7 @@ struct ovl_fs {
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
bool tmpfile;
bool noxattr;
wait_queue_head_t copyup_wq;
/* sb common to all layers */
struct super_block *same_sb;

13
fs/overlayfs/super.c
View file

@ -891,6 +891,19 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
dput(temp);
else
pr_warn("overlayfs: upper fs does not support tmpfile.\n");
/*
* Check if upper/work fs supports trusted.overlay.*
* xattr
*/
err = ovl_do_setxattr(ufs->workdir, OVL_XATTR_OPAQUE,
"0", 1, 0);
if (err) {
ufs->noxattr = true;
pr_warn("overlayfs: upper fs does not support xattr.\n");
} else {
vfs_removexattr(ufs->workdir, OVL_XATTR_OPAQUE);
}
}
}

21
fs/overlayfs/util.c
View file

@ -303,3 +303,24 @@ void ovl_copy_up_end(struct dentry *dentry)
wake_up_locked(&ofs->copyup_wq);
spin_unlock(&ofs->copyup_wq.lock);
}
int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
const char *name, const void *value, size_t size,
int xerr)
{
int err;
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
if (ofs->noxattr)
return xerr;
err = ovl_do_setxattr(upperdentry, name, value, size, 0);
if (err == -EOPNOTSUPP) {
pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
ofs->noxattr = true;
return xerr;
}
return err;
}