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authorChandan Rajendra <chandan@linux.vnet.ibm.com>2017-07-24 01:57:54 -0500
committerMiklos Szeredi <mszeredi@redhat.com>2017-11-09 10:23:27 +0100
commitba1e563cdc6b07f2d5d9eee854fb3cdf3596470f (patch)
tree6a68fdb6a0b6dfca8f1962ab327b85ea6cdbc14b /fs/overlayfs
parent2a9c6d066e98c1fe51a735b1439929f2f2afd891 (diff)
downloadlinux-ba1e563cdc6b07f2d5d9eee854fb3cdf3596470f.tar.bz2
ovl: return anonymous st_dev for lower inodes
For non-samefs setup, to make sure that st_dev/st_ino pair is unique across the system, we return a unique anonymous st_dev for stat(2) of lower layer inode. A following patch is going to fix constant st_dev/st_ino across copy up by returning origin st_dev/st_ino for copied up objects. If the st_dev/st_ino for copied up object would have been the same as that of the real underlying lower file, running diff on underlying lower file and overlay copied up file would result in diff reporting that the 2 files are equal when in fact, they may have different content. [amir: simplify ovl_get_pseudo_dev() split from allocate anonymous bdev patch] Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/inode.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 52aaa8530710..b599059d6f78 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -15,6 +15,14 @@
#include <linux/ratelimit.h>
#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;
@@ -121,6 +129,13 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
*/
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);
}
/*