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authorAmir Goldstein <amir73il@gmail.com>2018-01-17 14:40:27 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2018-01-24 11:26:05 +0100
commit061701540349c30d72e48a201449a840c77ad509 (patch)
tree46d3e9191ba287cd420af0a41bd5aba86bb50a89
parent4b91c30a5a19332e8dd10b601d05b72caf657730 (diff)
downloadlinux-061701540349c30d72e48a201449a840c77ad509.tar.bz2
ovl: lookup indexed ancestor of lower dir
ovl_lookup_real() in lower layer 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 called recursively with upper layer to walk back from indexed upper to the topmost connected/hashed upper parent (or up to root). ovl_lookup_real() in upper layer then walks forward to connect the topmost upper overlay dir dentry and ovl_lookup_real() in lower layer continues to walk forward to connect the decoded lower overlay dir dentry. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/overlayfs/export.c41
-rw-r--r--fs/overlayfs/namei.c20
-rw-r--r--fs/overlayfs/overlayfs.h2
3 files changed, 56 insertions, 7 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 092e6e8c9258..b65ea49de457 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -294,6 +294,10 @@ fail:
goto out;
}
+static struct dentry *ovl_lookup_real(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer);
+
/*
* Lookup an indexed or hashed overlay dentry by real inode.
*/
@@ -301,9 +305,16 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
struct dentry *real,
struct ovl_layer *layer)
{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
+ 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, !layer->idx);
if (IS_ERR(inode))
return ERR_CAST(inode);
@@ -312,7 +323,35 @@ 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 && layer->idx && ofs->indexdir && !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() in lower layer may call recursively once to
+ * ovl_lookup_real() in upper layer. 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, &upper_layer);
+ dput(upper);
+ }
+
if (!this)
return NULL;
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 6199bf7a77c7..c5449efd96d5 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -661,11 +661,9 @@ 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;
@@ -693,6 +691,16 @@ 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)) {
/*
@@ -706,7 +714,7 @@ 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);
@@ -943,7 +951,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (origin && ovl_indexdir(dentry->d_sb) &&
(!d.is_dir || ovl_index_all(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 bf17bf97c50f..0df25a9c94bd 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -274,6 +274,8 @@ 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);