fsnotify: pass dentry instead of inode data

Define a new data type to pass for event - FSNOTIFY_EVENT_DENTRY.
Use it to pass the dentry instead of it's ->d_inode where available.

This is needed in preparation to the refactor to retrieve the super
block from the data field.  In some cases (i.e. mkdir in kernfs), the
data inode comes from a negative dentry, such that no super block
information would be available. By receiving the dentry itself, instead
of the inode, fsnotify can derive the super block even on these cases.

Link: https://lore.kernel.org/r/20211025192746.66445-3-krisman@collabora.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
[Expand explanation in commit message]
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index d1144d7c353637c826fdcd34ed65a8a8532a56e2..df0fa4687a186a30b9d59b8a797b5bf6af4552c5 100644 (file)
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -39,8 +39,7 @@ static inline int fsnotify_name(__u32 mask, const void *data, int data_type,
 static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
                                   __u32 mask)
 {
-       fsnotify_name(mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
-                     dir, &dentry->d_name, 0);
+       fsnotify_name(mask, dentry, FSNOTIFY_EVENT_DENTRY, dir, &dentry->d_name, 0);
 }
 
 static inline void fsnotify_inode(struct inode *inode, __u32 mask)
@@ -87,7 +86,7 @@ notify_child:
  */
 static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
 {
-       fsnotify_parent(dentry, mask, d_inode(dentry), FSNOTIFY_EVENT_INODE);
+       fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
 }
 
 static inline int fsnotify_file(struct file *file, __u32 mask)

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 1ce66748a2d299dbfac1b3438ed7f1ac48f48527..a2db821e8a8f232a2824f2f732ee032621433a1b 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -248,6 +248,7 @@ enum fsnotify_data_type {
        FSNOTIFY_EVENT_NONE,
        FSNOTIFY_EVENT_PATH,
        FSNOTIFY_EVENT_INODE,
+       FSNOTIFY_EVENT_DENTRY,
 };
 
 static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
@@ -255,6 +256,8 @@ static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
        switch (data_type) {
        case FSNOTIFY_EVENT_INODE:
                return (struct inode *)data;
+       case FSNOTIFY_EVENT_DENTRY:
+               return d_inode(data);
        case FSNOTIFY_EVENT_PATH:
                return d_inode(((const struct path *)data)->dentry);
        default:
@@ -262,6 +265,19 @@ static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
        }
 }
 
+static inline struct dentry *fsnotify_data_dentry(const void *data, int data_type)
+{
+       switch (data_type) {
+       case FSNOTIFY_EVENT_DENTRY:
+               /* Non const is needed for dget() */
+               return (struct dentry *)data;
+       case FSNOTIFY_EVENT_PATH:
+               return ((const struct path *)data)->dentry;
+       default:
+               return NULL;
+       }
+}
+
 static inline const struct path *fsnotify_data_path(const void *data,
                                                    int data_type)
 {