From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
vfs_mkdir() may succeed and leave the dentry passed to it unhashed and
negative. ovl_create_real() is the last caller breaking when that
happens.
Pass newdentry to ovl_create_real() by ref, so in the case above, if
lookup finds a good dentry, newdentry will be replaced by the positive
hashed one.
[amir: split re-factoring to prep patch and pass dentry by ref]
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/dir.c | 24 +++++++++++++++++++++---
fs/overlayfs/overlayfs.h | 2 +-
fs/overlayfs/super.c | 2 +-
3 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index eb3fed19b1af..aeb40dcd9dd4 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -114,9 +114,10 @@ int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
goto out;
}
-int ovl_create_real(struct inode *dir, struct dentry *newdentry,
+int ovl_create_real(struct inode *dir, struct dentry **pnewdentry,
struct cattr *attr, struct dentry *hardlink, bool debug)
{
+ struct dentry *newdentry = *pnewdentry;
int err;
if (newdentry->d_inode)
@@ -140,6 +141,23 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
case S_IFSOCK:
err = ovl_do_mknod(dir, newdentry,
attr->mode, attr->rdev, debug);
+ /*
+ * vfs_mkdir() may succeed and leave the dentry passed
+ * to it unhashed and negative. If that happens, try to
+ * lookup a new hashed and positive dentry.
+ */
+ if (!err && unlikely(d_unhashed(newdentry))) {
+ struct dentry *d;
+
+ d = lookup_one_len(newdentry->d_name.name,
+ newdentry->d_parent,
+ newdentry->d_name.len);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+
+ dput(newdentry);
+ *pnewdentry = newdentry = d;
+ }
break;
case S_IFLNK:
@@ -171,7 +189,7 @@ struct dentry *ovl_create_temp(struct dentry *workdir, struct cattr *attr,
if (IS_ERR(temp))
return temp;
- err = ovl_create_real(wdir, temp, attr, hardlink, true);
+ err = ovl_create_real(wdir, &temp, attr, hardlink, true);
if (err) {
dput(temp);
return ERR_PTR(err);
@@ -256,7 +274,7 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
err = PTR_ERR(newdentry);
if (IS_ERR(newdentry))
goto out_unlock;
- err = ovl_create_real(udir, newdentry, attr, hardlink, false);
+ err = ovl_create_real(udir, &newdentry, attr, hardlink, false);
if (err)
goto out_dput;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index fc0b3e876636..2fb738d3ff6a 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -378,7 +378,7 @@ struct cattr {
umode_t mode;
const char *link;
};
-int ovl_create_real(struct inode *dir, struct dentry *newdentry,
+int ovl_create_real(struct inode *dir, struct dentry **pnewdentry,
struct cattr *attr,
struct dentry *hardlink, bool debug);
struct dentry *ovl_create_temp(struct dentry *workdir, struct cattr *attr,
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 492d534058ae..d83c0543c03c 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -603,7 +603,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
goto retry;
}
- err = ovl_create_real(dir, work,
+ err = ovl_create_real(dir, &work,
&(struct cattr){.mode = S_IFDIR | 0},
NULL, true);
if (err)
--
2.7.4
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