Commit 54510930 authored by Gabriel Krisman Bertazi's avatar Gabriel Krisman Bertazi Committed by Jan Kara
Browse files

samples: Add fs error monitoring example 

Introduce an example of a FAN_FS_ERROR fanotify user to track filesystem
errors.

Link: https://lore.kernel.org/r/20211025192746.66445-31-krisman@collabora.com


Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 9a089b21

samples/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -120,6 +120,15 @@ config SAMPLE_CONNECTOR 
	  with it.

	  See also Documentation/driver-api/connector.rst



config SAMPLE_FANOTIFY_ERROR

	bool "Build fanotify error monitoring sample"

	depends on FANOTIFY

	help

	  When enabled, this builds an example code that uses the

	  FAN_FS_ERROR fanotify mechanism to monitor filesystem

	  errors.

	  See also Documentation/admin-guide/filesystem-monitoring.rst.



config SAMPLE_HIDRAW

	bool "hidraw sample"

	depends on CC_CAN_LINK && HEADERS_INSTALL

samples/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ subdir-$(CONFIG_SAMPLE_AUXDISPLAY) += auxdisplay 
subdir-$(CONFIG_SAMPLE_ANDROID_BINDERFS) += binderfs

obj-$(CONFIG_SAMPLE_CONFIGFS)		+= configfs/

obj-$(CONFIG_SAMPLE_CONNECTOR)		+= connector/

obj-$(CONFIG_SAMPLE_FANOTIFY_ERROR)	+= fanotify/

subdir-$(CONFIG_SAMPLE_HIDRAW)		+= hidraw

obj-$(CONFIG_SAMPLE_HW_BREAKPOINT)	+= hw_breakpoint/

obj-$(CONFIG_SAMPLE_KDB)		+= kdb/

samples/fanotify/Makefile

0 → 100644
+5 −0
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# SPDX-License-Identifier: GPL-2.0-only

userprogs-always-y += fs-monitor



userccflags += -I usr/include -Wall

samples/fanotify/fs-monitor.c

0 → 100644
+142 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright 2021, Collabora Ltd.

 */



#define _GNU_SOURCE

#include <errno.h>

#include <err.h>

#include <stdlib.h>

#include <stdio.h>

#include <fcntl.h>

#include <sys/fanotify.h>

#include <sys/types.h>

#include <unistd.h>

#include <sys/types.h>



#ifndef FAN_FS_ERROR

#define FAN_FS_ERROR		0x00008000

#define FAN_EVENT_INFO_TYPE_ERROR	5



struct fanotify_event_info_error {

	struct fanotify_event_info_header hdr;

	__s32 error;

	__u32 error_count;

};

#endif



#ifndef FILEID_INO32_GEN

#define FILEID_INO32_GEN	1

#endif



#ifndef FILEID_INVALID

#define	FILEID_INVALID		0xff

#endif



static void print_fh(struct file_handle *fh)

{

	int i;

	uint32_t *h = (uint32_t *) fh->f_handle;



	printf("\tfh: ");

	for (i = 0; i < fh->handle_bytes; i++)

		printf("%hhx", fh->f_handle[i]);

	printf("\n");



	printf("\tdecoded fh: ");

	if (fh->handle_type == FILEID_INO32_GEN)

		printf("inode=%u gen=%u\n", h[0], h[1]);

	else if (fh->handle_type == FILEID_INVALID && !fh->handle_bytes)

		printf("Type %d (Superblock error)\n", fh->handle_type);

	else

		printf("Type %d (Unknown)\n", fh->handle_type);



}



static void handle_notifications(char *buffer, int len)

{

	struct fanotify_event_metadata *event =

		(struct fanotify_event_metadata *) buffer;

	struct fanotify_event_info_header *info;

	struct fanotify_event_info_error *err;

	struct fanotify_event_info_fid *fid;

	int off;



	for (; FAN_EVENT_OK(event, len); event = FAN_EVENT_NEXT(event, len)) {



		if (event->mask != FAN_FS_ERROR) {

			printf("unexpected FAN MARK: %llx\n", event->mask);

			goto next_event;

		}



		if (event->fd != FAN_NOFD) {

			printf("Unexpected fd (!= FAN_NOFD)\n");

			goto next_event;

		}



		printf("FAN_FS_ERROR (len=%d)\n", event->event_len);



		for (off = sizeof(*event) ; off < event->event_len;

		     off += info->len) {

			info = (struct fanotify_event_info_header *)

				((char *) event + off);



			switch (info->info_type) {

			case FAN_EVENT_INFO_TYPE_ERROR:

				err = (struct fanotify_event_info_error *) info;



				printf("\tGeneric Error Record: len=%d\n",

				       err->hdr.len);

				printf("\terror: %d\n", err->error);

				printf("\terror_count: %d\n", err->error_count);

				break;



			case FAN_EVENT_INFO_TYPE_FID:

				fid = (struct fanotify_event_info_fid *) info;



				printf("\tfsid: %x%x\n",

				       fid->fsid.val[0], fid->fsid.val[1]);

				print_fh((struct file_handle *) &fid->handle);

				break;



			default:

				printf("\tUnknown info type=%d len=%d:\n",

				       info->info_type, info->len);

			}

		}

next_event:

		printf("---\n\n");

	}

}



int main(int argc, char **argv)

{

	int fd;



	char buffer[BUFSIZ];



	if (argc < 2) {

		printf("Missing path argument\n");

		return 1;

	}



	fd = fanotify_init(FAN_CLASS_NOTIF|FAN_REPORT_FID, O_RDONLY);

	if (fd < 0)

		errx(1, "fanotify_init");



	if (fanotify_mark(fd, FAN_MARK_ADD|FAN_MARK_FILESYSTEM,

			  FAN_FS_ERROR, AT_FDCWD, argv[1])) {

		errx(1, "fanotify_mark");

	}



	while (1) {

		int n = read(fd, buffer, BUFSIZ);



		if (n < 0)

			errx(1, "read");



		handle_notifications(buffer, n);

	}



	return 0;

}