---
Documentation/filesystems/locking.rst | 2 +-
Documentation/filesystems/vfs.rst | 16 ++++-----
fs/overlayfs/super.c | 52 ++++++++++++---------------
include/linux/dcache.h | 18 ++++++----
4 files changed, 41 insertions(+), 47 deletions(-)
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index d5bf4b6b7509..453039a2e49b 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -29,7 +29,7 @@ prototypes::
char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
struct vfsmount *(*d_automount)(struct path *path);
int (*d_manage)(const struct path *, bool);
- struct dentry *(*d_real)(struct dentry *, const struct inode *);
+ struct dentry *(*d_real)(struct dentry *, int type);
locking rules:
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index eebcc0f9e2bc..2a39e718fdf8 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -1264,7 +1264,7 @@ defined:
char *(*d_dname)(struct dentry *, char *, int);
struct vfsmount *(*d_automount)(struct path *);
int (*d_manage)(const struct path *, bool);
- struct dentry *(*d_real)(struct dentry *, const struct inode *);
+ struct dentry *(*d_real)(struct dentry *, int type);
};
``d_revalidate``
@@ -1419,16 +1419,14 @@ defined:
the dentry being transited from.
``d_real``
- overlay/union type filesystems implement this method to return
- one of the underlying dentries hidden by the overlay. It is
- used in two different modes:
+ overlay/union type filesystems implement this method to return one
+ of the underlying dentries of a regular file hidden by the overlay.
- Called from file_dentry() it returns the real dentry matching
- the inode argument. The real dentry may be from a lower layer
- already copied up, but still referenced from the file. This
- mode is selected with a non-NULL inode argument.
+ The 'type' argument takes the values D_REAL_DATA or D_REAL_METADATA
+ for returning the real underlying dentry that refers to the inode
+ hosting the file's data or metadata respectively.
- With NULL inode the topmost real underlying dentry is returned.
+ For non-regular files, the 'dentry' argument is returned.
Each dentry has a pointer to its parent dentry, as well as a hash list
of child dentries. Child dentries are basically like files in a
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 2eef6c70b2ae..938852a0a92b 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -28,41 +28,38 @@ MODULE_LICENSE("GPL");
struct ovl_dir_cache;
-static struct dentry *ovl_d_real(struct dentry *dentry,
- const struct inode *inode)
+static struct dentry *ovl_d_real(struct dentry *dentry, int type)
{
- struct dentry *real = NULL, *lower;
+ struct dentry *upper, *lower;
int err;
- /*
- * vfs is only expected to call d_real() with NULL from d_real_inode()
- * and with overlay inode from file_dentry() on an overlay file.
- *
- * TODO: remove @inode argument from d_real() API, remove code in this
- * function that deals with non-NULL @inode and remove d_real() call
- * from file_dentry().
- */
- if (inode && d_inode(dentry) == inode)
- return dentry;
- else if (inode)
+ switch (type) {
+ case D_REAL_DATA:
+ case D_REAL_METADATA:
+ break;
+ default:
goto bug;
+ }
if (!d_is_reg(dentry)) {
/* d_real_inode() is only relevant for regular files */
return dentry;
}
- real = ovl_dentry_upper(dentry);
- if (real && (inode == d_inode(real)))
- return real;
+ upper = ovl_dentry_upper(dentry);
+ if (upper && (type == D_REAL_METADATA ||
+ ovl_has_upperdata(d_inode(dentry))))
+ return upper;
- if (real && !inode && ovl_has_upperdata(d_inode(dentry)))
- return real;
+ if (type == D_REAL_METADATA) {
+ lower = ovl_dentry_lower(dentry);
+ goto real_lower;
+ }
/*
- * Best effort lazy lookup of lowerdata for !inode case to return
+ * Best effort lazy lookup of lowerdata for D_REAL_DATA case to return
* the real lowerdata dentry. The only current caller of d_real() with
- * NULL inode is d_real_inode() from trace_uprobe and this caller is
+ * D_REAL_DATA is d_real_inode() from trace_uprobe and this caller is
* likely going to be followed reading from the file, before placing
* uprobes on offset within the file, so lowerdata should be available
* when setting the uprobe.
@@ -73,18 +70,13 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
lower = ovl_dentry_lowerdata(dentry);
if (!lower)
goto bug;
- real = lower;
- /* Handle recursion */
- real = d_real(real, inode);
+real_lower:
+ /* Handle recursion into stacked lower fs */
+ return d_real(lower, type);
- if (!inode || inode == d_inode(real))
- return real;
bug:
- WARN(1, "%s(%pd4, %s:%lu): real dentry (%p/%lu) not found\n",
- __func__, dentry, inode ? inode->i_sb->s_id : "NULL",
- inode ? inode->i_ino : 0, real,
- real && d_inode(real) ? d_inode(real)->i_ino : 0);
+ WARN(1, "%s(%pd4, %d): real dentry not found\n", __func__, dentry, type);
return dentry;
}
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 1666c387861f..019ad02f2b7e 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -139,7 +139,7 @@ struct dentry_operations {
char *(*d_dname)(struct dentry *, char *, int);
struct vfsmount *(*d_automount)(struct path *);
int (*d_manage)(const struct path *, bool);
- struct dentry *(*d_real)(struct dentry *, const struct inode *);
+ struct dentry *(*d_real)(struct dentry *, int type);
} ____cacheline_aligned;
/*
@@ -543,27 +543,31 @@ static inline struct inode *d_backing_inode(const struct dentry *upper)
return inode;
}
+enum d_real_type {
+ D_REAL_DATA,
+ D_REAL_METADATA,
+};
+
/**
* d_real - Return the real dentry
* @dentry: the dentry to query
- * @inode: inode to select the dentry from multiple layers (can be NULL)
+ * @type: the type of real dentry (data or metadata)
*
* If dentry is on a union/overlay, then return the underlying, real dentry.
* Otherwise return the dentry itself.
*
* See also: Documentation/filesystems/vfs.rst
*/
-static inline struct dentry *d_real(struct dentry *dentry,
- const struct inode *inode)
+static inline struct dentry *d_real(struct dentry *dentry, int type)
{
if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
- return dentry->d_op->d_real(dentry, inode);
+ return dentry->d_op->d_real(dentry, type);
else
return dentry;
}
/**
- * d_real_inode - Return the real inode
+ * d_real_inode - Return the real inode hosting the data
* @dentry: The dentry to query
*
* If dentry is on a union/overlay, then return the underlying, real inode.
@@ -572,7 +576,7 @@ static inline struct dentry *d_real(struct dentry *dentry,
static inline struct inode *d_real_inode(const struct dentry *dentry)
{
/* This usage of d_real() results in const dentry */
- return d_backing_inode(d_real((struct dentry *) dentry, NULL));
+ return d_inode(d_real((struct dentry *) dentry, D_REAL_DATA));
}
struct name_snapshot {
