fsnotify: clarify contract for create event hooks

Clarify argument names and contract for fsnotify_create() and
fsnotify_mkdir() to reflect the anomaly of kernfs, which leaves dentries
negavite after mkdir/create.

Remove the WARN_ON(!inode) in audit code that were added by the Fixes
commit under the wrong assumption that dentries cannot be negative after
mkdir/create.

Fixes: aa93bdc5500c ("fsnotify: use helpers to access data by data_type")
Link: https://lore.kernel.org/linux-fsdevel/87mtp5yz0q.fsf@collabora.com/
Link: https://lore.kernel.org/r/20211025192746.66445-4-krisman@collabora.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reported-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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 df0fa4687a186a30b9d59b8a797b5bf6af4552c5..1e5f7435a4b5720a6d55d926c0a37db3121d2cb0 100644 (file)
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -192,16 +192,22 @@ static inline void fsnotify_inoderemove(struct inode *inode)
 
 /*
  * fsnotify_create - 'name' was linked in
+ *
+ * Caller must make sure that dentry->d_name is stable.
+ * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
+ * ->d_inode later
  */
-static inline void fsnotify_create(struct inode *inode, struct dentry *dentry)
+static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
 {
-       audit_inode_child(inode, dentry, AUDIT_TYPE_CHILD_CREATE);
+       audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
 
-       fsnotify_dirent(inode, dentry, FS_CREATE);
+       fsnotify_dirent(dir, dentry, FS_CREATE);
 }
 
 /*
  * fsnotify_link - new hardlink in 'inode' directory
+ *
+ * Caller must make sure that new_dentry->d_name is stable.
  * Note: We have to pass also the linked inode ptr as some filesystems leave
  *   new_dentry->d_inode NULL and instantiate inode pointer later
  */
@@ -230,12 +236,16 @@ static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
 
 /*
  * fsnotify_mkdir - directory 'name' was created
+ *
+ * Caller must make sure that dentry->d_name is stable.
+ * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
+ * ->d_inode later
  */
-static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
+static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
 {
-       audit_inode_child(inode, dentry, AUDIT_TYPE_CHILD_CREATE);
+       audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
 
-       fsnotify_dirent(inode, dentry, FS_CREATE | FS_ISDIR);
+       fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);
 }
 
 /*

diff --git a/kernel/audit_fsnotify.c b/kernel/audit_fsnotify.c
index 60739d5e3373f8da84e9732b93822a5b8007f8de..02348b48447cf72b906bf0195c6c42afb91da6f2 100644 (file)
--- a/kernel/audit_fsnotify.c
+++ b/kernel/audit_fsnotify.c
@@ -160,8 +160,7 @@ static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
 
        audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
 
-       if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group) ||
-           WARN_ON_ONCE(!inode))
+       if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group))
                return 0;
 
        if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {

diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 2acf7ca4915421f71199554b4d638a8b4c714de8..223eed7b39cd7945fd5b2f676890f15de67da91c 100644 (file)
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -472,8 +472,7 @@ static int audit_watch_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
 
        parent = container_of(inode_mark, struct audit_parent, mark);
 
-       if (WARN_ON_ONCE(inode_mark->group != audit_watch_group) ||
-           WARN_ON_ONCE(!inode))
+       if (WARN_ON_ONCE(inode_mark->group != audit_watch_group))
                return 0;
 
        if (mask & (FS_CREATE|FS_MOVED_TO) && inode)