ovl_lookup_real(is_upper=false) walks back lower parents to find the
topmost indexed parent. If an indexed ancestor is found before reaching
lower layer root, ovl_lookup_real(is_upper=true) is called recursively
to walk back from indexed upper to the topmost connected/hashed upper
parent (or up to root).
ovl_lookup_real(is_upper=true) then walks forward to connect the topmost
upper overlay dir dentry and ovl_lookup_real(is_upper=false) continues to
walk forward to connect the decoded lower overlay dir dentry.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/export.c | 39 ++++++++++++++++++++++++++++++++++++++-
fs/overlayfs/namei.c | 20 ++++++++++++++------
fs/overlayfs/overlayfs.h | 2 ++
3 files changed, 54 insertions(+), 7 deletions(-)
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 01c4e3f733c1..147d9061cc40 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -257,15 +257,24 @@ static struct dentry *ovl_lookup_real_one(struct dentry *parent,
return ERR_PTR(err);
}
+static struct dentry *ovl_lookup_real(struct super_block *sb,
+ struct dentry *real, bool is_upper);
+
/*
* Lookup an indexed or hashed overlay dentry by real inode.
*/
static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
struct dentry *real, bool is_upper)
{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct dentry *index = NULL;
struct dentry *this = NULL;
struct inode *inode;
+ /*
+ * Decoding upper dir from index is expensive, so first try to lookup
+ * overlay dentry in inode/dcache.
+ */
inode = ovl_lookup_inode(sb, real, is_upper);
if (IS_ERR(inode))
return ERR_CAST(inode);
@@ -274,7 +283,35 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
iput(inode);
}
- /* TODO: use index when looking up by origin inode */
+ /*
+ * For decoded lower dir file handle, lookup index by origin to check
+ * if lower dir was copied up and and/or removed.
+ */
+ if (!this && !is_upper && !WARN_ON(!d_is_dir(real))) {
+ index = ovl_lookup_index(ofs, NULL, real, false);
+ if (IS_ERR(index))
+ return index;
+ }
+
+ /* Get connected upper overlay dir from index */
+ if (index) {
+ struct dentry *upper = ovl_index_upper(ofs, index);
+
+ dput(index);
+ if (IS_ERR_OR_NULL(upper))
+ return upper;
+
+ /*
+ * ovl_lookup_real(is_upper=false) may call recursively once to
+ * ovl_lookup_real(is_upper=true). The first level call walks
+ * back lower parents to the topmost indexed parent. The second
+ * recursive call walks back from indexed upper to the topmost
+ * connected/hashed upper parent (or up to root).
+ */
+ this = ovl_lookup_real(sb, upper, true);
+ dput(upper);
+ }
+
if (!this)
return NULL;
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 13869108dc32..f728942a5a1f 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -665,11 +665,9 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
return ERR_PTR(err);
}
-static struct dentry *ovl_lookup_index(struct dentry *dentry,
- struct dentry *upper,
- struct dentry *origin)
+struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
+ struct dentry *origin, bool verify)
{
- struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct dentry *index;
struct inode *inode;
struct qstr name;
@@ -697,6 +695,16 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
inode = d_inode(index);
if (d_is_negative(index)) {
goto out_dput;
+ } else if (ovl_is_whiteout(index) && !verify) {
+ /*
+ * When index lookup is called with !verify for decoding an
+ * overlay file handle, a whiteout index implies that decode
+ * should treat file handle as stale and no need to print a
+ * warning about it.
+ */
+ dput(index);
+ index = ERR_PTR(-ESTALE);
+ goto out;
} else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
/*
@@ -710,7 +718,7 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
index, d_inode(index)->i_mode & S_IFMT,
d_inode(origin)->i_mode & S_IFMT);
goto fail;
- } else if (is_dir) {
+ } else if (is_dir && verify) {
if (!upper) {
pr_warn_ratelimited("overlayfs: suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
origin, index);
@@ -948,7 +956,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (origin && ovl_indexdir(dentry->d_sb) &&
(!d.is_dir || ovl_verify(dentry->d_sb))) {
- index = ovl_lookup_index(dentry, upperdentry, origin);
+ index = ovl_lookup_index(ofs, upperdentry, origin, true);
if (IS_ERR(index)) {
err = PTR_ERR(index);
index = NULL;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index d06299b27ec3..661f33bd9793 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -269,6 +269,8 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
int ovl_get_index_name(struct dentry *origin, struct qstr *name);
struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
+struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
+ struct dentry *origin, bool verify);
int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags);
--
2.7.4
