ovl: prepare to store lowerdata redirect for lazy lowerdata lookup

Prepare to allow ovl_lookup() to leave the last entry in a non-dir
lowerstack empty to signify lazy lowerdata lookup.

In this case, ovl_lookup() stores the redirect path from metacopy to
lowerdata in ovl_inode, which is going to be used later to perform the
lazy lowerdata lookup.

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

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 5239a5b..552059e 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -1005,6 +1005,7 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
        oi->__upperdentry = oip->upperdentry;
        oi->oe = oip->oe;
        oi->redirect = oip->redirect;
+       oi->lowerdata_redirect = oip->lowerdata_redirect;
 
        realinode = ovl_inode_real(inode);
        ovl_copyattr(inode);
@@ -1365,6 +1366,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
                        dput(upperdentry);
                        ovl_free_entry(oip->oe);
                        kfree(oip->redirect);
+                       kfree(oip->lowerdata_redirect);
                        goto out;
                }
 

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 517f31a..605108f 100644 (file)
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -1183,6 +1183,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
                        .redirect = upperredirect,
                };
 
+               /* Store lowerdata redirect for lazy lookup */
+               if (ctr > 1 && !d.is_dir && !stack[ctr - 1].dentry) {
+                       oip.lowerdata_redirect = d.redirect;
+                       d.redirect = NULL;
+               }
                inode = ovl_get_inode(dentry->d_sb, &oip);
                err = PTR_ERR(inode);
                if (IS_ERR(inode))

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 2ccd632..5cc03b8 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -405,6 +405,7 @@ struct inode *ovl_inode_lower(struct inode *inode);
 struct inode *ovl_inode_lowerdata(struct inode *inode);
 struct inode *ovl_inode_real(struct inode *inode);
 struct inode *ovl_inode_realdata(struct inode *inode);
+const char *ovl_lowerdata_redirect(struct inode *inode);
 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
@@ -656,6 +657,7 @@ struct ovl_inode_params {
        struct ovl_entry *oe;
        bool index;
        char *redirect;
+       char *lowerdata_redirect;
 };
 void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
                    unsigned long ino, int fsid);

diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 93ff299..513c2c4 100644 (file)
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -141,6 +141,7 @@ static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe)
        return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL;
 }
 
+/* May return NULL if lazy lookup of lowerdata is needed */
 static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe)
 {
        struct ovl_path *lowerdata = ovl_lowerdata(oe);
@@ -157,7 +158,7 @@ static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
 struct ovl_inode {
        union {
                struct ovl_dir_cache *cache;    /* directory */
-               /* place holder for non-dir */  /* regular file */
+               const char *lowerdata_redirect; /* regular file */
        };
        const char *redirect;
        u64 version;

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index be2bdf3..9de02ca 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -171,6 +171,7 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
        oi->version = 0;
        oi->flags = 0;
        oi->__upperdentry = NULL;
+       oi->lowerdata_redirect = NULL;
        oi->oe = NULL;
        mutex_init(&oi->lock);
 
@@ -194,6 +195,8 @@ static void ovl_destroy_inode(struct inode *inode)
        ovl_free_entry(oi->oe);
        if (S_ISDIR(inode->i_mode))
                ovl_dir_cache_free(inode);
+       else
+               kfree(oi->lowerdata_redirect);
 }
 
 static void ovl_free_fs(struct ovl_fs *ofs)

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index b6e66bf..72f565f 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -226,10 +226,11 @@ void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
 {
        struct ovl_entry *oe = OVL_E(dentry);
        struct ovl_path *lowerdata = ovl_lowerdata(oe);
+       struct dentry *lowerdata_dentry = ovl_lowerdata_dentry(oe);
 
-       if (ovl_numlower(oe)) {
+       if (lowerdata_dentry) {
                path->mnt = lowerdata->layer->mnt;
-               path->dentry = lowerdata->dentry;
+               path->dentry = lowerdata_dentry;
        } else {
                *path = (struct path) { };
        }
@@ -358,9 +359,15 @@ struct inode *ovl_inode_realdata(struct inode *inode)
        return ovl_inode_lowerdata(inode);
 }
 
+const char *ovl_lowerdata_redirect(struct inode *inode)
+{
+       return inode && S_ISREG(inode->i_mode) ?
+               OVL_I(inode)->lowerdata_redirect : NULL;
+}
+
 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
 {
-       return OVL_I(inode)->cache;
+       return inode && S_ISDIR(inode->i_mode) ? OVL_I(inode)->cache : NULL;
 }
 
 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)