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``.
+
+Generic error Location
+----------------------
+
+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;
+ };
diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
index dc00afcabb95..1bedab498104 100644
--- a/Documentation/admin-guide/index.rst
+++ b/Documentation/admin-guide/index.rst
@@ -82,6 +82,7 @@ configure specific aspects of kernel behavior to your liking.
edid
efi-stub
ext4
+ filesystem-monitoring
nfs/index
gpio/index
highuid
--
2.31.0
