fsnotify: add empty fsnotify_{unlink,rmdir}() hooks [Linux 5.3]

This Linux kernel change "fsnotify: add empty fsnotify_{unlink,rmdir}() hooks" is included in the Linux 5.3 release. This change is authored by Amir Goldstein <amir73il [at] gmail.com> on Sun May 26 17:34:02 2019 +0300. The commit for this change in Linux stable tree is 116b973 (patch).

fsnotify: add empty fsnotify_{unlink,rmdir}() hooks

We would like to move fsnotify_nameremove() calls from d_delete()
into a higher layer where the hook makes more sense and so we can
consider every d_delete() call site individually.

Start by creating empty hook fsnotify_{unlink,rmdir}() and place
them in the proper VFS call sites.  After all d_delete() call sites
will be converted to use the new hook, the new hook will generate the
delete events and fsnotify_nameremove() hook will be removed.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

There are 28 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 fs/namei.c               |  2 ++
 include/linux/fsnotify.h | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index 20831c2..209c51a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3883,6 +3883,7 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
    dentry->d_inode->i_flags |= S_DEAD;
    dont_mount(dentry);
    detach_mounts(dentry);
+   fsnotify_rmdir(dir, dentry);

 out:
    inode_unlock(dentry->d_inode);
@@ -3999,6 +4000,7 @@ int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegate
            if (!error) {
                dont_mount(dentry);
                detach_mounts(dentry);
+               fsnotify_unlink(dir, dentry);
            }
        }
    }
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 94972e8..7f23edd 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -189,6 +189,19 @@ static inline void fsnotify_link(struct inode *dir, struct inode *inode, struct
 }

 /*
+ * fsnotify_unlink - 'name' was unlinked
+ *
+ * Caller must make sure that dentry->d_name is stable.
+ */
+static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
+{
+   /* Expected to be called before d_delete() */
+   WARN_ON_ONCE(d_is_negative(dentry));
+
+   /* TODO: call fsnotify_dirent() */
+}
+
+/*
  * fsnotify_mkdir - directory 'name' was created
  */
 static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
@@ -199,6 +212,19 @@ static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
 }

 /*
+ * fsnotify_rmdir - directory 'name' was removed
+ *
+ * Caller must make sure that dentry->d_name is stable.
+ */
+static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
+{
+   /* Expected to be called before d_delete() */
+   WARN_ON_ONCE(d_is_negative(dentry));
+
+   /* TODO: call fsnotify_dirent() */
+}
+
+/*
  * fsnotify_access - file was read
  */
 static inline void fsnotify_access(struct file *file)

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