[PATCH v3 06/14] fsnotify: pass dentry instead of inode for events possible on child

[Amir Goldstein <amir73il@gmail.com>]

Most events that can be reported to watching parent pass
FSNOTIFY_EVENT_PATH as event data, except for FS_ARRTIB and FS_MODIFY
as a result of truncate.

Define a new data type to pass for event - FSNOTIFY_EVENT_DENTRY
and use it to pass the dentry instead of it's ->d_inode for those events.

Soon, we are going to use the dentry data type to report events
with name info in fanotify backend.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 include/linux/fsnotify.h         |  4 ++--
 include/linux/fsnotify_backend.h | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 860018f3e545..d286663fcef2 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -49,8 +49,8 @@ static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_ISDIR;
 
-	fsnotify_parent(dentry, mask, inode, FSNOTIFY_EVENT_INODE);
-	fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+	fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
+	fsnotify(inode, mask, dentry, FSNOTIFY_EVENT_DENTRY, NULL, 0);
 }
 
 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 337c87cf34d6..ab0913619403 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -217,6 +217,7 @@ enum fsnotify_data_type {
 	FSNOTIFY_EVENT_NONE,
 	FSNOTIFY_EVENT_PATH,
 	FSNOTIFY_EVENT_INODE,
+	FSNOTIFY_EVENT_DENTRY,
 };
 
 static inline const struct inode *fsnotify_data_inode(const void *data,
@@ -225,6 +226,8 @@ static inline const struct inode *fsnotify_data_inode(const void *data,
 	switch (data_type) {
 	case FSNOTIFY_EVENT_INODE:
 		return data;
+	case FSNOTIFY_EVENT_DENTRY:
+		return d_inode(data);
 	case FSNOTIFY_EVENT_PATH:
 		return d_inode(((const struct path *)data)->dentry);
 	default:
@@ -232,6 +235,20 @@ static inline const struct inode *fsnotify_data_inode(const void *data,
 	}
 }
 
+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)
 {
-- 
2.17.1