For the case of all layers not on the same fs, return the copy up origin
inode st_dev/st_ino for non-dir from stat(2).
This guaranties constant and system-wide unique st_dev/st_ino for non-dir
across copy up. Like the same fs case, st_ino of non-dir is also
persistent. Unlike the same fs case, st_dev is not persistent.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/inode.c | 49 +++++++++++++++++++++++++++++--------------------
1 file changed, 29 insertions(+), 20 deletions(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 607a50c50042..d06de98808f6 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -74,6 +74,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
struct path realpath;
const struct cred *old_cred;
bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
+ bool samefs = ovl_same_sb(dentry->d_sb);
int err;
type = ovl_path_real(dentry, &realpath);
@@ -83,16 +84,13 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
goto out;
/*
- * 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.
- *
- * We also 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, if we
+ * know it. This guaranties constant st_dev/st_ino across copy up.
*
* If filesystem supports NFS export ops, this also guaranties
* persistent st_ino across mount cycle.
*/
- if (ovl_same_sb(dentry->d_sb)) {
+ if (!is_dir || samefs) {
if (OVL_TYPE_ORIGIN(type)) {
struct kstat lowerstat;
u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);
@@ -103,7 +101,6 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
if (err)
goto out;
- WARN_ON_ONCE(stat->dev != lowerstat.dev);
/*
* Lower hardlinks may be broken on copy up to different
* upper files, so we cannot use the lower origin st_ino
@@ -115,27 +112,39 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
if (is_dir || lowerstat.nlink == 1 ||
ovl_test_flag(OVL_INDEX, d_inode(dentry)))
stat->ino = lowerstat.ino;
+
+ if (samefs)
+ WARN_ON_ONCE(stat->dev != lowerstat.dev);
+ else
+ stat->dev = ovl_get_pseudo_dev(dentry);
}
- stat->dev = dentry->d_sb->s_dev;
- } else if (is_dir) {
+ 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 {
/*
- * 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.
- *
* 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 (!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);
}
/*
--
2.7.4
--
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