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@xxxxxxxxx>
---
fs/overlayfs/inode.c | 83 +++++++++++++++++++++++++-----------------------
fs/overlayfs/overlayfs.h | 1 +
fs/overlayfs/util.c | 7 ++++
3 files changed, 52 insertions(+), 39 deletions(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 4689716f23d8..1ae53357b228 100644
--- 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 = ovl_layer_lower(dentry);
+ 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)
{
@@ -84,10 +114,10 @@ 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) {
@@ -123,38 +153,13 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
if (samefs)
WARN_ON_ONCE(stat->dev != lowerstat.dev);
- else
- stat->dev = ovl_get_pseudo_dev(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);
+ 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 225ff1171147..4432599ecbc6 100644
--- 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 493f9b76fbf6..5042293d2078 100644
--- 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);
--
2.7.4
--
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