ovl: decode lower file handles of unlinked but open files

Lookup overlay inode in cache by origin inode, so we can decode a file
handle of an open file even if the index has a whiteout index entry to
mark this overlay inode was unlinked.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index f475a10eec07978a61487bac1f65a3bca001ccd1..0bca38c792444b1238706ac48889be649b5a10dc 100644 (file)
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -443,14 +443,22 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
        struct ovl_path *stack = &origin;
        struct dentry *dentry = NULL;
        struct dentry *index = NULL;
+       struct inode *inode = NULL;
+       bool is_deleted = false;
        int err;
 
        /* First lookup indexed upper by fh */
        if (ofs->indexdir) {
                index = ovl_get_index_fh(ofs, fh);
                err = PTR_ERR(index);
-               if (IS_ERR(index))
-                       return ERR_PTR(err);
+               if (IS_ERR(index)) {
+                       if (err != -ESTALE)
+                               return ERR_PTR(err);
+
+                       /* Found a whiteout index - treat as deleted inode */
+                       is_deleted = true;
+                       index = NULL;
+               }
        }
 
        /* Then lookup origin by fh */
@@ -461,6 +469,16 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
                err = ovl_verify_origin(index, origin.dentry, false);
                if (err)
                        goto out_err;
+       } else if (is_deleted) {
+               /* Lookup deleted non-dir by origin inode */
+               if (!d_is_dir(origin.dentry))
+                       inode = ovl_lookup_inode(sb, origin.dentry);
+               err = -ESTALE;
+               if (!inode || atomic_read(&inode->i_count) == 1)
+                       goto out_err;
+
+               /* Deleted but still open? */
+               index = dget(ovl_i_dentry_upper(inode));
        }
 
        dentry = ovl_get_dentry(sb, NULL, &origin, index);
@@ -468,6 +486,7 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
 out:
        dput(origin.dentry);
        dput(index);
+       iput(inode);
        return dentry;
 
 out_err:

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index bfd7c766b5cd5a6c152fe6ff12725badacda6a18..56ba015b9f5e0d70cbbc600bba6186ba9e2b651f 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -645,6 +645,22 @@ 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 *inode, *key = d_inode(origin);
+
+       inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
+       if (!inode)
+               return NULL;
+
+       if (!ovl_verify_inode(inode, origin, NULL)) {
+               iput(inode);
+               return ERR_PTR(-ESTALE);
+       }
+
+       return inode;
+}
+
 struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
                            struct dentry *lowerdentry, struct dentry *index,
                            unsigned int numlower)

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 40ba11e412b16b9db78c0f76f12aa2c5ccd25142..a47f9142b6be00c38a102f8e765bc2f8eb6e5216 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -322,6 +322,7 @@ 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_get_inode(struct super_block *sb, struct dentry *upperdentry,
                            struct dentry *lowerdentry, struct dentry *index,
                            unsigned int numlower);