On Mon 18-10-21 21:00:14, Gabriel Krisman Bertazi wrote: > Introduce an example of a FAN_FS_ERROR fanotify user to track filesystem > errors. > > Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx> > Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx> Looks good. Feel free to add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > Changes since v4: > - Protect file_handle defines with ifdef guards > > Changes since v1: > - minor fixes > --- > 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; > +} > -- > 2.33.0 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR