Wire up the FAN_FS_ERROR event in the fanotify_mark syscall, allowing
user space to request the monitoring of FAN_FS_ERROR events.

These events are limited to filesystem marks, so check it is the
case in the syscall handler.

Signed-off-by: Gabriel Krisman Bertazi <redacted>
---
 fs/notify/fanotify/fanotify.c      | 2 +-
 fs/notify/fanotify/fanotify_user.c | 5 +++++
 include/linux/fanotify.h           | 6 +++++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 47e28f418711..d449a23d603f 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c

@@ -827,7 +827,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
        BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
        BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);

-       BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
+       BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);

        mask = fanotify_group_event_mask(group, iter_info, mask, data,
                                         data_type, dir);

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 8f7c2f4ce674..5edfd7e3f356 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c

@@ -1585,6 +1585,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
                fsid = &__fsid;
        }

+       if (mask & FAN_FS_ERROR && mark_type != FAN_MARK_FILESYSTEM) {
+               ret = -EINVAL;
+               goto path_put_and_out;
+       }
+