debugfs: allow to store an additional opaque pointer at file creation

Set by debugfs_create_file_aux(name, mode, parent, data, aux, fops).
Plain debugfs_create_file() has it set to NULL.
Accessed by debugfs_get_aux(file).

Convenience macros for numeric opaque data - debugfs_create_file_aux_num
and debugfs_get_aux_num, resp.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20250112080705.141166-5-viro@zeniv.linux.org.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index ae014bd36a6ff641c2ae1005d6e8b7889ea7cace..e33cc77699cd56111ca19b9a91c1be92fb99affe 100644 (file)
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -47,6 +47,12 @@ const struct file_operations debugfs_noop_file_operations = {
 
 #define F_DENTRY(filp) ((filp)->f_path.dentry)
 
+const void *debugfs_get_aux(const struct file *file)
+{
+       return DEBUGFS_I(file_inode(file))->aux;
+}
+EXPORT_SYMBOL_GPL(debugfs_get_aux);
+
 const struct file_operations *debugfs_real_fops(const struct file *filp)
 {
        struct debugfs_fsdata *fsd = F_DENTRY(filp)->d_fsdata;

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index c4e8b7f758e0e29ace5653e2e2aba038b4f645fe..51d4c3e9d4220558d6f51f04a2734a7190dbf326 100644 (file)
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -424,6 +424,7 @@ static struct dentry *end_creating(struct dentry *dentry)
 
 static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
                                struct dentry *parent, void *data,
+                               const void *aux,
                                const struct file_operations *proxy_fops,
                                const void *real_fops)
 {
@@ -458,6 +459,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
                proxy_fops = &debugfs_noop_file_operations;
        inode->i_fop = proxy_fops;
        DEBUGFS_I(inode)->raw = real_fops;
+       DEBUGFS_I(inode)->aux = aux;
 
        d_instantiate(dentry, inode);
        fsnotify_create(d_inode(dentry->d_parent), dentry);
@@ -466,19 +468,21 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 
 struct dentry *debugfs_create_file_full(const char *name, umode_t mode,
                                        struct dentry *parent, void *data,
+                                       const void *aux,
                                        const struct file_operations *fops)
 {
-       return __debugfs_create_file(name, mode, parent, data,
+       return __debugfs_create_file(name, mode, parent, data, aux,
                                &debugfs_full_proxy_file_operations,
                                fops);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_file_full);
 
 struct dentry *debugfs_create_file_short(const char *name, umode_t mode,
-                                        struct dentry *parent, void *data,
-                                        const struct debugfs_short_fops *fops)
+                                       struct dentry *parent, void *data,
+                                       const void *aux,
+                                       const struct debugfs_short_fops *fops)
 {
-       return __debugfs_create_file(name, mode, parent, data,
+       return __debugfs_create_file(name, mode, parent, data, aux,
                                &debugfs_full_short_proxy_file_operations,
                                fops);
 }
@@ -516,7 +520,7 @@ struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
                                   const struct file_operations *fops)
 {
 
-       return __debugfs_create_file(name, mode, parent, data,
+       return __debugfs_create_file(name, mode, parent, data, NULL,
                                &debugfs_open_proxy_file_operations,
                                fops);
 }

diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h
index 8d2de647b42cb60119b3469cbcb02a69dccf2563..93483fe844257c4bcae05641d4eb6b6855a77217 100644 (file)
--- a/fs/debugfs/internal.h
+++ b/fs/debugfs/internal.h
@@ -19,6 +19,7 @@ struct debugfs_inode_info {
                const struct debugfs_short_fops *short_fops;
                debugfs_automount_t automount;
        };
+       const void *aux;
 };
 
 static inline struct debugfs_inode_info *DEBUGFS_I(struct inode *inode)

diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 59444b495d490e24a6de4324477f4701f4422fe0..7c97417d73b501e4af0b3fc7e6d95d678ad4af7d 100644 (file)
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -79,9 +79,11 @@ struct debugfs_short_fops {
 
 struct dentry *debugfs_create_file_full(const char *name, umode_t mode,
                                        struct dentry *parent, void *data,
+                                       const void *aux,
                                        const struct file_operations *fops);
 struct dentry *debugfs_create_file_short(const char *name, umode_t mode,
                                         struct dentry *parent, void *data,
+                                        const void *aux,
                                         const struct debugfs_short_fops *fops);
 
 /**
@@ -126,7 +128,15 @@ struct dentry *debugfs_create_file_short(const char *name, umode_t mode,
                 const struct debugfs_short_fops *: debugfs_create_file_short,  \
                 struct file_operations *: debugfs_create_file_full,            \
                 struct debugfs_short_fops *: debugfs_create_file_short)        \
-               (name, mode, parent, data, fops)
+               (name, mode, parent, data, NULL, fops)
+
+#define debugfs_create_file_aux(name, mode, parent, data, aux, fops)           \
+       _Generic(fops,                                                          \
+                const struct file_operations *: debugfs_create_file_full,      \
+                const struct debugfs_short_fops *: debugfs_create_file_short,  \
+                struct file_operations *: debugfs_create_file_full,            \
+                struct debugfs_short_fops *: debugfs_create_file_short)        \
+               (name, mode, parent, data, aux, fops)
 
 struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
                                   struct dentry *parent, void *data,
@@ -153,6 +163,7 @@ void debugfs_remove(struct dentry *dentry);
 void debugfs_lookup_and_remove(const char *name, struct dentry *parent);
 
 const struct file_operations *debugfs_real_fops(const struct file *filp);
+const void *debugfs_get_aux(const struct file *file);
 
 int debugfs_file_get(struct dentry *dentry);
 void debugfs_file_put(struct dentry *dentry);
@@ -259,6 +270,14 @@ static inline struct dentry *debugfs_lookup(const char *name,
        return ERR_PTR(-ENODEV);
 }
 
+static inline struct dentry *debugfs_create_file_aux(const char *name,
+                                       umode_t mode, struct dentry *parent,
+                                       void *data, void *aux,
+                                       const void *fops)
+{
+       return ERR_PTR(-ENODEV);
+}
+
 static inline struct dentry *debugfs_create_file(const char *name, umode_t mode,
                                        struct dentry *parent, void *data,
                                        const void *fops)
@@ -312,6 +331,7 @@ static inline void debugfs_lookup_and_remove(const char *name,
 { }
 
 const struct file_operations *debugfs_real_fops(const struct file *filp);
+void *debugfs_get_aux(const struct file *file);
 
 static inline int debugfs_file_get(struct dentry *dentry)
 {
@@ -452,6 +472,11 @@ static inline ssize_t debugfs_read_file_str(struct file *file,
 
 #endif
 
+#define debugfs_create_file_aux_num(name, mode, parent, data, n, fops) \
+       debugfs_create_file_aux(name, mode, parent, data, \
+                               (void *)(unsigned long)n, fops)
+#define debugfs_get_aux_num(f) (unsigned long)debugfs_get_aux(f)
+
 /**
  * debugfs_create_xul - create a debugfs file that is used to read and write an
  * unsigned long value, formatted in hexadecimal