On Fri, Aug 13, 2021 at 12:41 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> Plumb the pieces to add a FID report to error records. Since all error
> event memory must be pre-allocated, we estimate a file handle size and
> if it is insuficient, we report an invalid FID and increase the
> prediction for the next error slot allocation.
>
> For errors that don't expose a file handle report it with an invalid
> FID.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
>
> ---
> Changes since v5:
> - Use preallocated MAX_HANDLE_SZ FH buffer
> - Report superblock errors with a zerolength INVALID FID (jan, amir)
> ---
> fs/notify/fanotify/fanotify.c | 15 +++++++++++++++
> fs/notify/fanotify/fanotify.h | 11 +++++++++++
> fs/notify/fanotify/fanotify_user.c | 7 +++++++
> 3 files changed, 33 insertions(+)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 0c7667d3f5d1..f5c16ac37835 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -734,6 +734,8 @@ static int fanotify_handle_error_event(struct fsnotify_iter_info *iter_info,
> struct fanotify_sb_mark *sb_mark =
> FANOTIFY_SB_MARK(fsnotify_iter_sb_mark(iter_info));
> struct fanotify_error_event *fee = sb_mark->fee_slot;
> + struct inode *inode = report->inode;
> + int fh_len;
>
> spin_lock(&group->notification_lock);
> if (fee->err_count++) {
> @@ -743,6 +745,19 @@ static int fanotify_handle_error_event(struct fsnotify_iter_info *iter_info,
> spin_unlock(&group->notification_lock);
>
> fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
> + fee->fsid = fee->sb_mark->fsn_mark.connector->fsid;
> +
> + fh_len = fanotify_encode_fh_len(inode);
> + if (WARN_ON(fh_len > MAX_HANDLE_SZ)) {
> + /*
> + * Fallback to reporting the error against the super
> + * block. It should never happen.
> + */
> + inode = NULL;
> + fh_len = fanotify_encode_fh_len(NULL);
> + }
> +
> + fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0);
>
> if (fsnotify_insert_event(group, &fee->fae.fse,
> NULL, fanotify_insert_error_event)) {
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index eeb4a85af74e..158cf0c4b0bd 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -223,6 +223,13 @@ struct fanotify_error_event {
> u32 err_count; /* Suppressed errors count */
>
> struct fanotify_sb_mark *sb_mark; /* Back reference to the mark. */
> +
> + __kernel_fsid_t fsid; /* FSID this error refers to. */
> +
> + /* object_fh must be followed by the inline handle buffer. */
> + struct fanotify_fh object_fh;
> + /* Reserve space in object_fh.buf[] - access with fanotify_fh_buf() */
> + unsigned char _inline_fh_buf[MAX_HANDLE_SZ];
> };
>
> static inline struct fanotify_error_event *
> @@ -237,6 +244,8 @@ static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
> return &FANOTIFY_FE(event)->fsid;
> else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
> return &FANOTIFY_NE(event)->fsid;
> + else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
> + return &FANOTIFY_EE(event)->fsid;
> else
> return NULL;
> }
> @@ -248,6 +257,8 @@ static inline struct fanotify_fh *fanotify_event_object_fh(
> return &FANOTIFY_FE(event)->object_fh;
> else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
> return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
> + else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
> + return &FANOTIFY_EE(event)->object_fh;
> else
> return NULL;
> }
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 3fff0c994dc8..1ab8f9d8b3ac 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -177,6 +177,13 @@ static struct fanotify_event *fanotify_dup_error_to_stack(
> error_on_stack->err_count = fee->err_count;
> error_on_stack->sb_mark = fee->sb_mark;
>
> + error_on_stack->fsid = fee->fsid;
> +
> + memcpy(&error_on_stack->object_fh, &fee->object_fh,
> + sizeof(fee->object_fh));
> + memcpy(error_on_stack->object_fh.buf, fee->object_fh.buf,
> + fee->object_fh.len);
> +
I would go with:
size_t len = offsetof(struct fanotify_error_event, _inline_fh_buf)
+ fee->object_fh.len);
memcpy(error_on_stack, fee, len);
But maybe it's just me, so I don't insist.
Thanks,
Amir.
