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ovl: store lower path in ovl_inode

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Create some ovl_i_* helpers to get real path from ovl inode. Instead of
just stashing struct inode for the lower layer we stash struct path for
the lower layer. The helpers allow to retrieve a struct path for the
relevant upper or lower layer. This will be used when retrieving
information based on struct inode when copying up inode attributes from
upper or lower inodes to ovl inodes and when checking permissions in
ovl_permission() in following patches. This is needed to support
idmapped base layers with overlay.

Cc: <linux-unionfs@vger.kernel.org>
Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2022-04-04 12:51:53 +02:00 committed by Miklos Szeredi
parent ba9ea771ec
commit ffa5723c6d
5 changed files with 27 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/overlayfs/inode.c
View File

@ -779,13 +779,16 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
unsigned long ino, int fsid)
{
struct inode *realinode;
struct ovl_inode *oi = OVL_I(inode);
if (oip->upperdentry)
OVL_I(inode)->__upperdentry = oip->upperdentry;
if (oip->lowerpath && oip->lowerpath->dentry)
OVL_I(inode)->lower = igrab(d_inode(oip->lowerpath->dentry));
oi->__upperdentry = oip->upperdentry;
if (oip->lowerpath && oip->lowerpath->dentry) {
oi->lowerpath.dentry = dget(oip->lowerpath->dentry);
oi->lowerpath.layer = oip->lowerpath->layer;
}
if (oip->lowerdata)
OVL_I(inode)->lowerdata = igrab(d_inode(oip->lowerdata));
oi->lowerdata = igrab(d_inode(oip->lowerdata));
realinode = ovl_inode_real(inode);
ovl_copyattr(realinode, inode);

2
fs/overlayfs/overlayfs.h
View File

@ -374,11 +374,13 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry);
void ovl_path_upper(struct dentry *dentry, struct path *path);
void ovl_path_lower(struct dentry *dentry, struct path *path);
void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
void ovl_i_path_real(struct inode *inode, struct path *path);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
const struct ovl_layer *ovl_i_layer_lower(struct inode *inode);
const struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry);
struct dentry *ovl_i_dentry_upper(struct inode *inode);

2
fs/overlayfs/ovl_entry.h
View File

@ -134,7 +134,7 @@ struct ovl_inode {
unsigned long flags;
struct inode vfs_inode;
struct dentry *__upperdentry;
struct inode *lower;
struct ovl_path lowerpath;
/* synchronize copy up and more */
struct mutex lock;

5
fs/overlayfs/super.c
View File

@ -184,7 +184,8 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
oi->version = 0;
oi->flags = 0;
oi->__upperdentry = NULL;
oi->lower = NULL;
oi->lowerpath.dentry = NULL;
oi->lowerpath.layer = NULL;
oi->lowerdata = NULL;
mutex_init(&oi->lock);
@ -205,7 +206,7 @@ static void ovl_destroy_inode(struct inode *inode)
struct ovl_inode *oi = OVL_I(inode);
dput(oi->__upperdentry);
iput(oi->lower);
dput(oi->lowerpath.dentry);
if (S_ISDIR(inode->i_mode))
ovl_dir_cache_free(inode);
else

15
fs/overlayfs/util.c
View File

@ -250,6 +250,17 @@ struct dentry *ovl_i_dentry_upper(struct inode *inode)
return ovl_upperdentry_dereference(OVL_I(inode));
}
void ovl_i_path_real(struct inode *inode, struct path *path)
{
path->dentry = ovl_i_dentry_upper(inode);
if (!path->dentry) {
path->dentry = OVL_I(inode)->lowerpath.dentry;
path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
} else {
path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
}
}
struct inode *ovl_inode_upper(struct inode *inode)
{
struct dentry *upperdentry = ovl_i_dentry_upper(inode);
@ -259,7 +270,9 @@ struct inode *ovl_inode_upper(struct inode *inode)
struct inode *ovl_inode_lower(struct inode *inode)
{
return OVL_I(inode)->lower;
struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
return lowerdentry ? d_inode(lowerdentry) : NULL;
}
struct inode *ovl_inode_real(struct inode *inode)