On Fri, May 21, 2021 at 5:42 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
> ---
> .../admin-guide/filesystem-monitoring.rst | 52 +++++++++++++++++++
> Documentation/admin-guide/index.rst | 1 +
> 2 files changed, 53 insertions(+)
> create mode 100644 Documentation/admin-guide/filesystem-monitoring.rst
>
> diff --git a/Documentation/admin-guide/filesystem-monitoring.rst b/Documentation/admin-guide/filesystem-monitoring.rst
> new file mode 100644
> index 000000000000..81e632f8e1de
> --- /dev/null
> +++ b/Documentation/admin-guide/filesystem-monitoring.rst
> @@ -0,0 +1,52 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +====================================
> +File system Monitoring with fanotify
> +====================================
> +
> +fanotify supports the FAN_ERROR mark for file system-wide error
> +reporting. It is meant to be used by file system health monitoring
> +daemons who listen on that interface and take actions (notify sysadmin,
> +start recovery) when a file system problem is detected by the kernel.
> +
> +By design, A FAN_ERROR notification exposes sufficient information for a
> +monitoring tool to know a problem in the file system has happened. It
> +doesn't necessarily provide a user space application with semantics to
> +verify an IO operation was successfully executed. That is outside of
> +scope of this feature. Instead, it is only meant as a framework for
> +early file system problem detection and reporting recovery tools.
> +
> +At the time of this writing, the only file system that emits this
> +FAN_ERROR notifications is ext4.
> +
> +A user space example code is provided at ``samples/fanotify/fs-monitor.c``.
> +
> +Usage
> +=====
> +
> +Notification structure
> +======================
> +
> +A FAN_ERROR Notification has the following format::
> +
> + [ Notification Metadata (Mandatory) ]
> + [ Generic Error Record (Mandatory) ]
> +
> +With the exception of the notification metadata and the generic
> +information, all information records are optional. Each record type is
> +identified by its unique ``struct fanotify_event_info_header.info_type``.
Out-dated. Unless you decide to add support for optional FID record.
> +
> +Generic error Location
'Location' seems irrelevant?
> +----------------------
> +
> +The Generic error record provides enough information for a file system
> +agnostic tool to learn about a problem in the file system, without
> +requiring any details about the problem.::
> +
> + struct fanotify_event_info_error {
> + struct fanotify_event_info_header hdr;
> + int error;
> + __kernel_fsid_t fsid;
> + unsigned long inode;
> + __u32 error_count;
> + };
Maybe add some text about the fact the inode info is optional,
purpose of error_count and the fact that the info is related to
the first observed error.
Thanks,
Amir.
