When upperdir has project quota and has different project id with workdir,
write may fail with error message "Invalid cross-device link" although mounted on r/w mode.
This patch checks project quota information of upperdir/workdir during ovl_fill_super(),
and if different mount on r/o mode. It doesn’t check detail inherit flag because
the implementations are different in specific filesystems.
Signed-off-by: Chengguang Xu <cgxu@xxxxxxxxxxxx>
Signed-off-by: Suyue <suyue@xxxxxxxxxxxxx>
---
fs/overlayfs/super.c | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index f5738e9..7b64d5c 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -276,10 +276,34 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
return err;
}
+static bool ovl_check_project_quota_ok(struct ovl_fs *ufs)
+{
+ struct super_block *sb;
+ kprojid_t upperdir_projid = KPROJIDT_INIT(-1);
+ kprojid_t workdir_projid = KPROJIDT_INIT(-1);
+
+ if (!ufs->upper_mnt || !ufs->workdir)
+ return true;
+
+ sb = ufs->upper_mnt->mnt_sb;
+ if (!(sb->s_quota_types & QTYPE_MASK_PRJ))
+ return true;
+
+ if (sb->dq_op && sb->dq_op->get_projid) {
+ sb->dq_op->get_projid(ufs->upper_mnt->mnt_root->d_inode, &upperdir_projid);
+ sb->dq_op->get_projid(ufs->workdir->d_inode, &workdir_projid);
+ if (projid_valid(upperdir_projid) && projid_valid(workdir_projid))
+ if (!projid_eq(upperdir_projid, workdir_projid))
+ return false;
+ }
+
+ return true;
+}
+
/* Will this overlay be forced to mount/remount ro? */
static bool ovl_force_readonly(struct ovl_fs *ufs)
{
- return (!ufs->upper_mnt || !ufs->workdir);
+ return (!ufs->upper_mnt || !ufs->workdir || !ovl_check_project_quota_ok(ufs));
}
/**
@@ -1060,6 +1084,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
else if (ufs->upper_mnt->mnt_sb != ufs->same_sb)
ufs->same_sb = NULL;
+ /* if upperdir and workdir have different project quota ids, we mark overlayfs r/o too */
+ if (!ovl_check_project_quota_ok(ufs)) {
+ pr_warn("overlayfs: mounting read-only because upperdir and workdir have different project quota ids.\n");
+ sb->s_flags |= MS_RDONLY;
+ }
+
if (!(ovl_force_readonly(ufs)) && ufs->config.index) {
/* Verify lower root is upper root origin */
err = ovl_verify_origin(upperpath.dentry, ufs->lower_mnt[0],
--
1.8.3.1
--
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