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Subject[PATCH 13/28] ovl: Store lower data inode in ovl_inode
Date
From: Vivek Goyal <vgoyal@redhat.com>

Right now ovl_inode stores inode pointer for lower inode. This helps with
quickly getting lower inode given overlay inode (ovl_inode_lower()).

Now with metadata only copy-up, we can have metacopy inode in middle layer
as well and inode containing data can be different from ->lower. I need to
be able to open the real file in ovl_open_realfile() and for that I need to
quickly find the lower data inode.

Hence store lower data inode also in ovl_inode. Also provide an helper
ovl_inode_lowerdata() to access this field.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/overlayfs/inode.c | 2 +-
fs/overlayfs/namei.c | 2 ++
fs/overlayfs/overlayfs.h | 4 +++-
fs/overlayfs/ovl_entry.h | 5 ++++-
fs/overlayfs/super.c | 8 ++++++--
fs/overlayfs/util.c | 12 +++++++++++-
6 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 6a6693150c37..d4e643e9098b 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -864,7 +864,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
}
}
ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid);
- ovl_inode_init(inode, upperdentry, lowerdentry);
+ ovl_inode_init(inode, upperdentry, lowerdentry, oip->lowerdata);

if (upperdentry && ovl_is_impuredir(upperdentry))
ovl_set_flag(OVL_IMPURE, inode);
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index fcf0eb40d94b..b28b255ea8e2 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -1080,6 +1080,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
.index = index,
.numlower = ctr,
.redirect = upperredirect,
+ .lowerdata = (ctr > 1 && !d.is_dir) ?
+ stack[ctr - 1].dentry : NULL,
};

inode = ovl_get_inode(dentry->d_sb, &oip);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index ae06fd531b75..558a1b444286 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -227,6 +227,7 @@ 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);
struct inode *ovl_inode_lower(struct inode *inode);
+struct inode *ovl_inode_lowerdata(struct inode *inode);
struct inode *ovl_inode_real(struct inode *inode);
struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
@@ -246,7 +247,7 @@ bool ovl_redirect_dir(struct super_block *sb);
const char *ovl_dentry_get_redirect(struct dentry *dentry);
void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
- struct dentry *lowerdentry);
+ struct dentry *lowerdentry, struct dentry *lowerdata);
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
void ovl_dir_modified(struct dentry *dentry, bool impurity);
u64 ovl_dentry_version_get(struct dentry *dentry);
@@ -361,6 +362,7 @@ struct ovl_inode_params {
struct dentry *index;
unsigned int numlower;
char *redirect;
+ struct dentry *lowerdata;
};
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index da65118a0567..6d02ab1f8811 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -90,7 +90,10 @@ static inline struct ovl_entry *OVL_E(struct dentry *dentry)
}

struct ovl_inode {
- struct ovl_dir_cache *cache;
+ union {
+ struct ovl_dir_cache *cache; /* directory */
+ struct inode *lowerdata; /* regular file */
+ };
const char *redirect;
u64 version;
unsigned long flags;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index d96530717702..e0326a686f45 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -187,6 +187,7 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
oi->flags = 0;
oi->__upperdentry = NULL;
oi->lower = NULL;
+ oi->lowerdata = NULL;
mutex_init(&oi->lock);

return &oi->vfs_inode;
@@ -205,8 +206,11 @@ static void ovl_destroy_inode(struct inode *inode)

dput(oi->__upperdentry);
iput(oi->lower);
+ if (S_ISDIR(inode->i_mode))
+ ovl_dir_cache_free(inode);
+ else
+ iput(oi->lowerdata);
kfree(oi->redirect);
- ovl_dir_cache_free(inode);
mutex_destroy(&oi->lock);

call_rcu(&inode->i_rcu, ovl_i_callback);
@@ -1509,7 +1513,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
ovl_set_upperdata(d_inode(root_dentry));
ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
- ovl_dentry_lower(root_dentry));
+ ovl_dentry_lower(root_dentry), NULL);

sb->s_root = root_dentry;

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 4f9c2ecee74c..63311c536216 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -247,6 +247,14 @@ struct inode *ovl_inode_real(struct inode *inode)
return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
}

+/* Return inode which contains lower data. Do not return metacopy */
+struct inode *ovl_inode_lowerdata(struct inode *inode)
+{
+ if (WARN_ON(!S_ISREG(inode->i_mode)))
+ return NULL;
+
+ return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
+}

struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
{
@@ -381,7 +389,7 @@ void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
}

void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
- struct dentry *lowerdentry)
+ struct dentry *lowerdentry, struct dentry *lowerdata)
{
struct inode *realinode = d_inode(upperdentry ?: lowerdentry);

@@ -389,6 +397,8 @@ void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
OVL_I(inode)->__upperdentry = upperdentry;
if (lowerdentry)
OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
+ if (lowerdata)
+ OVL_I(inode)->lowerdata = igrab(d_inode(lowerdata));

ovl_copyattr(realinode, inode);
ovl_copyflags(realinode, inode);
--
2.14.3
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