Re: [PATCH 10/11] samples: Add fs error monitoring example
From: Amir Goldstein <amir73il@gmail.com>
Date: 2021-05-21 09:48:53
Also in:
linux-fsdevel
On Fri, May 21, 2021 at 5:42 AM Gabriel Krisman Bertazi [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Introduce an example of a FAN_ERROR fanotify user to track filesystem errors. Signed-off-by: Gabriel Krisman Bertazi <redacted> --- samples/Kconfig | 8 +++ samples/Makefile | 1 + samples/fanotify/Makefile | 3 ++ samples/fanotify/fs-monitor.c | 91 +++++++++++++++++++++++++++++++++++ 4 files changed, 103 insertions(+) create mode 100644 samples/fanotify/Makefile create mode 100644 samples/fanotify/fs-monitor.cdiff --git a/samples/Kconfig b/samples/Kconfig index b5a1a7aa7e23..e421556ec3e5 100644 --- a/samples/Kconfig +++ b/samples/Kconfig@@ -120,6 +120,14 @@ 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_ERROR + fanotify mechanism to monitor filesystem errors. + Documentation/admin-guide/filesystem-monitoring.rst + config SAMPLE_HIDRAW bool "hidraw sample" depends on CC_CAN_LINK && HEADERS_INSTALLdiff --git a/samples/Makefile b/samples/Makefile index 087e0988ccc5..931a81847c48 100644 --- a/samples/Makefile +++ b/samples/Makefile@@ -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/diff --git a/samples/fanotify/Makefile b/samples/fanotify/Makefile new file mode 100644 index 000000000000..b3d5cc826e6f --- /dev/null +++ b/samples/fanotify/Makefile@@ -0,0 +1,3 @@ +userprogs-always-y += fs-monitor + +userccflags += -I usr/includediff --git a/samples/fanotify/fs-monitor.c b/samples/fanotify/fs-monitor.c new file mode 100644 index 000000000000..49d3e2a872e4 --- /dev/null +++ b/samples/fanotify/fs-monitor.c@@ -0,0 +1,91 @@ +// 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/stat.h> +#include <sys/types.h> + +#ifndef FAN_ERROR +#define FAN_ERROR 0x00008000 +#define FAN_EVENT_INFO_TYPE_ERROR 5 + +struct fanotify_event_info_error { + struct fanotify_event_info_header hdr; + int error; + __kernel_fsid_t fsid; + unsigned long inode; + __u32 error_count; +}; +#endif + +static void handle_notifications(char *buffer, int len) +{ + struct fanotify_event_metadata *metadata; + struct fanotify_event_info_error *error; + + for (metadata = (struct fanotify_event_metadata *) buffer; + FAN_EVENT_OK(metadata, len); metadata = FAN_EVENT_NEXT(metadata, len)) { + if (!(metadata->mask == FAN_ERROR)) {
Nit: != FAN_ERROR
+ printf("unexpected FAN MARK: %llx\n", metadata->mask);
+ continue;
+ } else if (metadata->fd != FAN_NOFD) {
+ printf("Unexpected fd (!= FAN_NOFD)\n");
+ continue;
+ }
+
+ printf("FAN_ERROR found len=%d\n", metadata->event_len);
+
+ error = (struct fanotify_event_info_error *) (metadata+1);
+ if (error->hdr.info_type == FAN_EVENT_INFO_TYPE_ERROR) {You meant != FAN_EVENT_INFO_TYPE_ERROR ?
+ printf("unknown record: %d\n", error->hdr.info_type);
+ continue;
+ }
+
+ printf(" Generic Error Record: len=%d\n", error->hdr.len);
+ printf(" fsid: %llx\n", error->fsid);
+ printf(" error: %d\n", error->error);
+ printf(" inode: %lu\n", error->inode);
+ printf(" error_count: %d\n", error->error_count);
+ }
+}
+
+int main(int argc, char **argv)
+{
+ int fd;
+ char buffer[BUFSIZ];BUFSIZ not defined?
+
+ if (argc < 2) {
+ printf("Missing path argument\n");
+ return 1;
+ }
+
+ fd = fanotify_init(FAN_CLASS_NOTIF, O_RDONLY);
+ if (fd < 0)
+ errx(1, "fanotify_init");
+
+ if (fanotify_mark(fd, FAN_MARK_ADD|FAN_MARK_FILESYSTEM,
+ FAN_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;
+}
--
2.31.0