[RFC][PATCH 2/2] ovl: cram opaque boolean into type flags

Amir Goldstein
2017-03-21T16:16:47Z

Like the other type flags, 'opaque' is a state discovered in lookup,
set on certain ops (e.g.: create, rename) and never cleared.

We would like to add more state info to ovl_entry soon (for const ino)
and this state info would be added as type flags. It makes little sense
to have the 'opaque' state occupy a boolean, so drop the boolean member
of ovl_entry and use a type bit to represent opaqueness.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/overlayfs/namei.c | 9 +++++----
fs/overlayfs/overlayfs.h | 2 ++
fs/overlayfs/ovl_entry.h | 1 -
fs/overlayfs/util.c | 5 +++--
4 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index c230ee1..ac6dc9c 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -356,7 +356,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
struct dentry *upperdir, *upperdentry = NULL;
unsigned int ctr = 0;
struct inode *inode = NULL;
- bool upperopaque = false;
+ enum ovl_path_type type = 0;
char *upperredirect = NULL;
struct dentry *this;
unsigned int i;
@@ -404,7 +404,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
poe = dentry->d_sb->s_root->d_fsdata;
d.by_name = false;
}
- upperopaque = d.opaque;
+ if (d.opaque)
+ type |= __OVL_PATH_OPAQUE;
}

if (!d.stop && poe->numlower) {
@@ -474,7 +475,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
}

revert_creds(old_cred);
- oe->opaque = upperopaque;
+ oe->type = type;
oe->redirect = upperredirect;
oe->__upperdentry = upperdentry;
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
@@ -515,7 +516,7 @@ bool ovl_lower_positive(struct dentry *dentry)
* whiteout.
*/
if (!dentry->d_inode)
- return oe->opaque;
+ return OVL_TYPE_OPAQUE(oe->type);

/* Negative upper -> positive lower */
if (!oe->__upperdentry)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index d37ec4c..bb8861c 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -12,10 +12,12 @@
enum ovl_path_type {
__OVL_PATH_UPPER = (1 << 0),
__OVL_PATH_MERGE = (1 << 1),
+ __OVL_PATH_OPAQUE = (1 << 2),
};

#define OVL_TYPE_UPPER(type) ((type) & __OVL_PATH_UPPER)
#define OVL_TYPE_MERGE(type) ((type) & __OVL_PATH_MERGE)
+#define OVL_TYPE_OPAQUE(type) ((type) & __OVL_PATH_OPAQUE)

#define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
#define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index b07c29f..985e706 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -43,7 +43,6 @@ struct ovl_entry {
struct {
u64 version;
const char *redirect;
- bool opaque;
bool copying;
};
struct rcu_head rcu;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index f9693a8..95cbc3d 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -167,7 +167,8 @@ void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
bool ovl_dentry_is_opaque(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
- return oe->opaque;
+
+ return OVL_TYPE_OPAQUE(oe->type);
}

bool ovl_dentry_is_whiteout(struct dentry *dentry)
@@ -179,7 +180,7 @@ void ovl_dentry_set_opaque(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;

- oe->opaque = true;
+ oe->type |= __OVL_PATH_OPAQUE;
}

bool ovl_redirect_dir(struct super_block *sb)
--
2.7.4