fsnotify: Retrieve super block from the data field

Some file system events (i.e. FS_ERROR) might not be associated with an
inode or directory.  For these, we can retrieve the super block from the
data field.  But, since the super_block is available in the data field
on every event type, simplify the code to always retrieve it from there,
through a new helper.

Link: https://lore.kernel.org/r/20211025192746.66445-11-krisman@collabora.com
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 963e6ce75b96113c5739a68698082b2aea7f3195..fde3a1115a170c905991b99b708befdade0220a3 100644 (file)
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -455,16 +455,16 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
  *             @file_name is relative to
  * @file_name: optional file name associated with event
  * @inode:     optional inode associated with event -
- *             either @dir or @inode must be non-NULL.
- *             if both are non-NULL event may be reported to both.
+ *             If @dir and @inode are both non-NULL, event may be
+ *             reported to both.
  * @cookie:    inotify rename cookie
  */
 int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
             const struct qstr *file_name, struct inode *inode, u32 cookie)
 {
        const struct path *path = fsnotify_data_path(data, data_type);
+       struct super_block *sb = fsnotify_data_sb(data, data_type);
        struct fsnotify_iter_info iter_info = {};
-       struct super_block *sb;
        struct mount *mnt = NULL;
        struct inode *parent = NULL;
        int ret = 0;
@@ -483,7 +483,6 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
                 */
                parent = dir;
        }
-       sb = inode->i_sb;
 
        /*
         * Optimization: srcu_read_lock() has a memory barrier which can

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index b323d0c4b9671f1dbafe9e4fb25730940740b41f..035438fe4a435e849b4cdfd000307af0b065971b 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -289,6 +289,21 @@ static inline const struct path *fsnotify_data_path(const void *data,
        }
 }
 
+static inline struct super_block *fsnotify_data_sb(const void *data,
+                                                  int data_type)
+{
+       switch (data_type) {
+       case FSNOTIFY_EVENT_INODE:
+               return ((struct inode *)data)->i_sb;
+       case FSNOTIFY_EVENT_DENTRY:
+               return ((struct dentry *)data)->d_sb;
+       case FSNOTIFY_EVENT_PATH:
+               return ((const struct path *)data)->dentry->d_sb;
+       default:
+               return NULL;
+       }
+}
+
 enum fsnotify_obj_type {
        FSNOTIFY_OBJ_TYPE_INODE,
        FSNOTIFY_OBJ_TYPE_PARENT,