diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 361174810ce8bf9ddb08b6687bf2eee7f345d538..092e6e8c9258db968f404b13c49c02e539c8634d 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -294,6 +294,88 @@ static struct dentry *ovl_lookup_real_one(struct dentry *connected,
goto out;
}
+/*
+ * Lookup an indexed or hashed overlay dentry by real inode.
+ */
+static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer)
+{
+ struct dentry *this = NULL;
+ struct inode *inode;
+
+ inode = ovl_lookup_inode(sb, real, !layer->idx);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+ if (inode) {
+ this = d_find_any_alias(inode);
+ iput(inode);
+ }
+
+ /* TODO: use index when looking up by origin inode */
+ if (!this)
+ return NULL;
+
+ if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
+ dput(this);
+ this = ERR_PTR(-EIO);
+ }
+
+ return this;
+}
+
+/*
+ * Lookup an indexed or hashed overlay dentry, whose real dentry is an
+ * ancestor of @real.
+ */
+static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer)
+{
+ struct dentry *next, *parent = NULL;
+ struct dentry *ancestor = ERR_PTR(-EIO);
+
+ if (real == layer->mnt->mnt_root)
+ return dget(sb->s_root);
+
+ /* Find the topmost indexed or hashed ancestor */
+ next = dget(real);
+ for (;;) {
+ parent = dget_parent(next);
+
+ /*
+ * Lookup a matching overlay dentry in inode/dentry
+ * cache or in index by real inode.
+ */
+ ancestor = ovl_lookup_real_inode(sb, next, layer);
+ if (ancestor)
+ break;
+
+ if (parent == layer->mnt->mnt_root) {
+ ancestor = dget(sb->s_root);
+ break;
+ }
+
+ /*
+ * If @real has been moved out of the layer root directory,
+ * we will eventully hit the real fs root. This cannot happen
+ * by legit overlay rename, so we return error in that case.
+ */
+ if (parent == next) {
+ ancestor = ERR_PTR(-EXDEV);
+ break;
+ }
+
+ dput(next);
+ next = parent;
+ }
+
+ dput(parent);
+ dput(next);
+
+ return ancestor;
+}
+
/*
* Lookup a connected overlay dentry whose real dentry is @real.
* If @real is on upper layer, we lookup a child overlay dentry with the same
@@ -306,9 +388,10 @@ static struct dentry *ovl_lookup_real(struct super_block *sb,
struct dentry *connected;
int err = 0;
- /* TODO: use index when looking up by lower real dentry */
+ connected = ovl_lookup_real_ancestor(sb, real, layer);
+ if (IS_ERR(connected))
+ return connected;
- connected = dget(sb->s_root);
while (!err) {
struct dentry *next, *this;
struct dentry *parent = NULL;
@@ -365,11 +448,15 @@ static struct dentry *ovl_lookup_real(struct super_block *sb,
* overlay rename of child away from 'connected' parent.
* In this case, we need to restart the lookup from the
* top, because we cannot trust that 'real_connected' is
- * still an ancestor of 'real'.
+ * still an ancestor of 'real'. There is a good chance
+ * that the renamed overlay ancestor is now in cache, so
+ * ovl_lookup_real_ancestor() will find it and we can
+ * continue to connect exactly from where lookup failed.
*/
if (err == -ECHILD) {
- this = dget(sb->s_root);
- err = 0;
+ this = ovl_lookup_real_ancestor(sb, real,
+ layer);
+ err = IS_ERR(this) ? PTR_ERR(this) : 0;
}
if (!err) {
dput(connected);
@@ -494,7 +581,7 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
} else if (is_deleted) {
/* Lookup deleted non-dir by origin inode */
if (!d_is_dir(origin.dentry))
- inode = ovl_lookup_inode(sb, origin.dentry);
+ inode = ovl_lookup_inode(sb, origin.dentry, false);
err = -ESTALE;
if (!inode || atomic_read(&inode->i_count) == 1)
goto out_err;
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 416dc06835db4312f1d0263e648858a97ce2a130..fcd97b783fa1ffa82dc7ec2eb4b82f03a0be50ef 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -614,9 +614,15 @@ static int ovl_inode_set(struct inode *inode, void *data)
}
static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
- struct dentry *upperdentry)
+ struct dentry *upperdentry, bool strict)
{
- if (S_ISDIR(inode->i_mode)) {
+ /*
+ * For directories, @strict verify from lookup path performs consistency
+ * checks, so NULL lower/upper in dentry must match NULL lower/upper in
+ * inode. Non @strict verify from NFS handle decode path passes NULL for
+ * 'unknown' lower/upper.
+ */
+ if (S_ISDIR(inode->i_mode) && strict) {
/* Real lower dir moved to upper layer under us? */
if (!lowerdentry && ovl_inode_lower(inode))
return false;
@@ -645,15 +651,17 @@ static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
return true;
}
-struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *origin)
+struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
+ bool is_upper)
{
- struct inode *inode, *key = d_inode(origin);
+ struct inode *inode, *key = d_inode(real);
inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
if (!inode)
return NULL;
- if (!ovl_verify_inode(inode, origin, NULL)) {
+ if (!ovl_verify_inode(inode, is_upper ? NULL : real,
+ is_upper ? real : NULL, false)) {
iput(inode);
return ERR_PTR(-ESTALE);
}
@@ -704,7 +712,8 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
* Verify that the underlying files stored in the inode
* match those in the dentry.
*/
- if (!ovl_verify_inode(inode, lowerdentry, upperdentry)) {
+ if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
+ true)) {
iput(inode);
inode = ERR_PTR(-ESTALE);
goto out;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index a5d415aec1315a66356dc7df932fdc84ca0f0932..bf17bf97c50f35324cb2c7ab9aebe8942d3b3451 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -323,7 +323,8 @@ int ovl_update_time(struct inode *inode, struct timespec *ts, int flags);
bool ovl_is_private_xattr(const char *name);
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
-struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *origin);
+struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
+ bool is_upper);
struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
struct dentry *lowerdentry, struct dentry *index,
unsigned int numlower);