From: Gabriel Krisman Bertazi krisman@collabora.com
[ Upstream commit 5451093081db6ca1a708d149e11cfd219800bc4c ]
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: Amir Goldstein amir73il@gmail.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Gabriel Krisman Bertazi krisman@collabora.com Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Chuck Lever chuck.lever@oracle.com --- samples/Kconfig | 9 +++ samples/Makefile | 1 + samples/fanotify/Makefile | 5 ++ samples/fanotify/fs-monitor.c | 142 ++++++++++++++++++++++++++++++++++ 4 files changed, 157 insertions(+) create mode 100644 samples/fanotify/Makefile create mode 100644 samples/fanotify/fs-monitor.c
diff --git a/samples/Kconfig b/samples/Kconfig index b0503ef058d3..88353b8eac0b 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -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 diff --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..e20db1bdde3b --- /dev/null +++ b/samples/fanotify/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0-only +userprogs-always-y += fs-monitor + +userccflags += -I usr/include -Wall + diff --git a/samples/fanotify/fs-monitor.c b/samples/fanotify/fs-monitor.c new file mode 100644 index 000000000000..a0e44cd31e6f --- /dev/null +++ b/samples/fanotify/fs-monitor.c @@ -0,0 +1,142 @@ +// 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; +}