ovl: factor out ovl_map_dev_ino() helper

A helper for ovl_getattr() to map the values of st_dev and st_ino
according to constant st_ino rules.

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 29069f29b3a6a9825d86d8ffa226f6cb8176b0cb..8a283ec21e34dca78026475f4e784d99f3ecacb1 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -16,13 +16,6 @@
 #include "overlayfs.h"
 
 
-static dev_t ovl_get_pseudo_dev(struct dentry *dentry)
-{
-       struct ovl_entry *oe = dentry->d_fsdata;
-
-       return oe->lowerstack[0].layer->pseudo_dev;
-}
-
 int ovl_setattr(struct dentry *dentry, struct iattr *attr)
 {
        int err;
@@ -66,6 +59,43 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
        return err;
 }
 
+static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
+                          struct ovl_layer *lower_layer)
+{
+       bool samefs = ovl_same_sb(dentry->d_sb);
+
+       if (samefs) {
+               /*
+                * When all layers are on the same fs, all real inode
+                * number are unique, so we use the overlay st_dev,
+                * which is friendly to du -x.
+                */
+               stat->dev = dentry->d_sb->s_dev;
+       } else if (S_ISDIR(dentry->d_inode->i_mode)) {
+               /*
+                * Always use the overlay st_dev for directories, so 'find
+                * -xdev' will scan the entire overlay mount and won't cross the
+                * overlay mount boundaries.
+                *
+                * If not all layers are on the same fs the pair {real st_ino;
+                * overlay st_dev} is not unique, so use the non persistent
+                * overlay st_ino for directories.
+                */
+               stat->dev = dentry->d_sb->s_dev;
+               stat->ino = dentry->d_inode->i_ino;
+       } else if (lower_layer) {
+               /*
+                * For non-samefs setup, if we cannot map all layers st_ino
+                * to a unified address space, we need to make sure that st_dev
+                * is unique per layer. Upper layer uses real st_dev and lower
+                * layers use the unique anonymous bdev.
+                */
+               stat->dev = lower_layer->pseudo_dev;
+       }
+
+       return 0;
+}
+
 int ovl_getattr(const struct path *path, struct kstat *stat,
                u32 request_mask, unsigned int flags)
 {
@@ -75,6 +105,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
        const struct cred *old_cred;
        bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
        bool samefs = ovl_same_sb(dentry->d_sb);
+       struct ovl_layer *lower_layer = NULL;
        int err;
 
        type = ovl_path_real(dentry, &realpath);
@@ -84,14 +115,16 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
                goto out;
 
        /*
-        * For non-dir or same fs, we use st_ino of the copy up origin, if we
-        * know it. This guaranties constant st_dev/st_ino across copy up.
+        * For non-dir or same fs, we use st_ino of the copy up origin.
+        * This guaranties constant st_dev/st_ino across copy up.
         *
-        * If filesystem supports NFS export ops, this also guaranties
+        * If lower filesystem supports NFS file handles, this also guaranties
         * persistent st_ino across mount cycle.
         */
        if (!is_dir || samefs) {
-               if (OVL_TYPE_ORIGIN(type)) {
+               if (!OVL_TYPE_UPPER(type)) {
+                       lower_layer = ovl_layer_lower(dentry);
+               } else if (OVL_TYPE_ORIGIN(type)) {
                        struct kstat lowerstat;
                        u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);
 
@@ -120,38 +153,15 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
                            (!ovl_verify_lower(dentry->d_sb) &&
                             (is_dir || lowerstat.nlink == 1))) {
                                stat->ino = lowerstat.ino;
-                               stat->dev = ovl_get_pseudo_dev(dentry);
+                               lower_layer = ovl_layer_lower(dentry);
                        }
                }
-               if (samefs) {
-                       /*
-                        * When all layers are on the same fs, all real inode
-                        * number are unique, so we use the overlay st_dev,
-                        * which is friendly to du -x.
-                        */
-                       stat->dev = dentry->d_sb->s_dev;
-               } else if (!OVL_TYPE_UPPER(type)) {
-                       /*
-                        * For non-samefs setup, to make sure that st_dev/st_ino
-                        * pair is unique across the system, we use a unique
-                        * anonymous st_dev for lower layer inode.
-                        */
-                       stat->dev = ovl_get_pseudo_dev(dentry);
-               }
-       } else {
-               /*
-                * Always use the overlay st_dev for directories, so 'find
-                * -xdev' will scan the entire overlay mount and won't cross the
-                * overlay mount boundaries.
-                *
-                * If not all layers are on the same fs the pair {real st_ino;
-                * overlay st_dev} is not unique, so use the non persistent
-                * overlay st_ino for directories.
-                */
-               stat->dev = dentry->d_sb->s_dev;
-               stat->ino = dentry->d_inode->i_ino;
        }
 
+       err = ovl_map_dev_ino(dentry, stat, lower_layer);
+       if (err)
+               goto out;
+
        /*
         * It's probably not worth it to count subdirs to get the
         * correct link count.  nlink=1 seems to pacify 'find' and

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index b51613b355c51cf5d86108a3cbbabfc0cc904956..09779f9111a84fd7932bcec7b5123f1cb4fd5f9f 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -215,6 +215,7 @@ void ovl_path_lower(struct dentry *dentry, struct path *path);
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
 struct dentry *ovl_dentry_upper(struct dentry *dentry);
 struct dentry *ovl_dentry_lower(struct dentry *dentry);
+struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
 struct dentry *ovl_dentry_real(struct dentry *dentry);
 struct dentry *ovl_i_dentry_upper(struct inode *inode);
 struct inode *ovl_inode_upper(struct inode *inode);

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 493f9b76fbf6460946e7671bd96e09f97dcc572c..5042293d2078902dbba3f96a55f6d73f126dba4e 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -172,6 +172,13 @@ struct dentry *ovl_dentry_lower(struct dentry *dentry)
        return oe->numlower ? oe->lowerstack[0].dentry : NULL;
 }
 
+struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
+{
+       struct ovl_entry *oe = dentry->d_fsdata;
+
+       return oe->numlower ? oe->lowerstack[0].layer : NULL;
+}
+
 struct dentry *ovl_dentry_real(struct dentry *dentry)
 {
        return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);