Merge tag 'ovl-fixes-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "Fix some bugs and documentation"

* tag 'ovl-fixes-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  docs: filesystems: overlayfs: Fix restview warnings
  docs: filesystems: overlayfs: Rename overlayfs.txt to .rst
  ovl: relax WARN_ON() on rename to self
  ovl: fix corner case of non-unique st_dev;st_ino
  ovl: don't use a temp buf for encoding real fh
  ovl: make sure that real fid is 32bit aligned in memory
  ovl: fix lookup failure on multi lower squashfs

1 files changed, 28 insertions, 6 deletions

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 6934bcf030f0..f283b1d69a9e 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -71,20 +71,36 @@ enum ovl_entry_flag {
 #error Endianness not defined
 #endif
 
-/* The type returned by overlay exportfs ops when encoding an ovl_fh handle */
-#define OVL_FILEID	0xfb
+/* The type used to be returned by overlay exportfs for misaligned fid */
+#define OVL_FILEID_V0	0xfb
+/* The type returned by overlay exportfs for 32bit aligned fid */
+#define OVL_FILEID_V1	0xf8
 
-/* On-disk and in-memeory format for redirect by file handle */
-struct ovl_fh {
+/* On-disk format for "origin" file handle */
+struct ovl_fb {
 	u8 version;	/* 0 */
 	u8 magic;	/* 0xfb */
 	u8 len;		/* size of this header + size of fid */
 	u8 flags;	/* OVL_FH_FLAG_* */
 	u8 type;	/* fid_type of fid */
 	uuid_t uuid;	/* uuid of filesystem */
-	u8 fid[0];	/* file identifier */
+	u32 fid[0];	/* file identifier should be 32bit aligned in-memory */
 } __packed;
 
+/* In-memory and on-wire format for overlay file handle */
+struct ovl_fh {
+	u8 padding[3];	/* make sure fb.fid is 32bit aligned */
+	union {
+		struct ovl_fb fb;
+		u8 buf[0];
+	};
+} __packed;
+
+#define OVL_FH_WIRE_OFFSET	offsetof(struct ovl_fh, fb)
+#define OVL_FH_LEN(fh)		(OVL_FH_WIRE_OFFSET + (fh)->fb.len)
+#define OVL_FH_FID_OFFSET	(OVL_FH_WIRE_OFFSET + \
+				 offsetof(struct ovl_fb, fid))
+
 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
 {
 	int err = vfs_rmdir(dir, dentry);
@@ -302,7 +318,13 @@ static inline void ovl_inode_unlock(struct inode *inode)
 
 
 /* namei.c */
-int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
+int ovl_check_fb_len(struct ovl_fb *fb, int fb_len);
+
+static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
+{
+	return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET);
+}
+
 struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
 				  bool connected);
 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,