diff mbox series

[v9,27/31] fanotify: Emit generic error info for error event

Message ID 20211025192746.66445-28-krisman@collabora.com (mailing list archive)
State New, archived
Headers show
Series file system-wide error monitoring | expand

Commit Message

Gabriel Krisman Bertazi Oct. 25, 2021, 7:27 p.m. UTC 
The error info is a record sent to users on FAN_FS_ERROR events
documenting the type of error.  It also carries an error count,
documenting how many errors were observed since the last reporting.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v6:
  - Rebase on top of pidfd patches
Changes since v5:
  - Move error code here
---
 fs/notify/fanotify/fanotify.c      |  1 +
 fs/notify/fanotify/fanotify.h      |  1 +
 fs/notify/fanotify/fanotify_user.c | 35 ++++++++++++++++++++++++++++++
 include/uapi/linux/fanotify.h      |  7 ++++++
 4 files changed, 44 insertions(+)

Comments

Jan Kara Oct. 26, 2021, 12:11 p.m. UTC | #1 
On Mon 25-10-21 16:27:42, Gabriel Krisman Bertazi wrote:
> The error info is a record sent to users on FAN_FS_ERROR events
> documenting the type of error.  It also carries an error count,
> documenting how many errors were observed since the last reporting.
> 
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

...

> @@ -530,6 +557,14 @@ static int copy_info_records_to_user(struct fanotify_event *event,
>  		total_bytes += ret;
>  	}
>  
> +	if (fanotify_is_error_event(event->mask)) {
> +		ret = copy_error_info_to_user(event, buf, count);
> +		if (ret < 0)
> +			return ret;
> +		buf += ret;
> +		count -= ret;
> +	}
> +
>  	return total_bytes;
>  }

This is currently harmless but we should add

total_bytes += ret;

here as well.

								Honza
diff mbox series

Patch

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 465f07e70e6d..af61425e6e3b 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -621,6 +621,7 @@  static struct fanotify_event *fanotify_alloc_error_event(
 		return NULL;
 
 	fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
+	fee->error = report->error;
 	fee->err_count = 1;
 	fee->fsid = *fsid;
 
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index edd7587adcc5..d25f500bf7e7 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -205,6 +205,7 @@  FANOTIFY_NE(struct fanotify_event *event)
 
 struct fanotify_error_event {
 	struct fanotify_event fae;
+	s32 error; /* Error reported by the Filesystem. */
 	u32 err_count; /* Suppressed errors count */
 
 	__kernel_fsid_t fsid; /* FSID this error refers to. */
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index ff4a7373f7a5..97ec5b005b50 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -115,6 +115,8 @@  struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
 	(sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
 #define FANOTIFY_PIDFD_INFO_HDR_LEN \
 	sizeof(struct fanotify_event_info_pidfd)
+#define FANOTIFY_ERROR_INFO_LEN \
+	(sizeof(struct fanotify_event_info_error))
 
 static int fanotify_fid_info_len(int fh_len, int name_len)
 {
@@ -139,6 +141,9 @@  static size_t fanotify_event_len(unsigned int info_mode,
 	if (!info_mode)
 		return event_len;
 
+	if (fanotify_is_error_event(event->mask))
+		event_len += FANOTIFY_ERROR_INFO_LEN;
+
 	info = fanotify_event_info(event);
 
 	if (fanotify_event_has_dir_fh(event)) {
@@ -324,6 +329,28 @@  static int process_access_response(struct fsnotify_group *group,
 	return -ENOENT;
 }
 
+static size_t copy_error_info_to_user(struct fanotify_event *event,
+				      char __user *buf, int count)
+{
+	struct fanotify_event_info_error info;
+	struct fanotify_error_event *fee = FANOTIFY_EE(event);
+
+	info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
+	info.hdr.pad = 0;
+	info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
+
+	if (WARN_ON(count < info.hdr.len))
+		return -EFAULT;
+
+	info.error = fee->error;
+	info.error_count = fee->err_count;
+
+	if (copy_to_user(buf, &info, sizeof(info)))
+		return -EFAULT;
+
+	return info.hdr.len;
+}
+
 static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
 				 int info_type, const char *name,
 				 size_t name_len,
@@ -530,6 +557,14 @@  static int copy_info_records_to_user(struct fanotify_event *event,
 		total_bytes += ret;
 	}
 
+	if (fanotify_is_error_event(event->mask)) {
+		ret = copy_error_info_to_user(event, buf, count);
+		if (ret < 0)
+			return ret;
+		buf += ret;
+		count -= ret;
+	}
+
 	return total_bytes;
 }
 
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 2990731ddc8b..bd1932c2074d 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -126,6 +126,7 @@  struct fanotify_event_metadata {
 #define FAN_EVENT_INFO_TYPE_DFID_NAME	2
 #define FAN_EVENT_INFO_TYPE_DFID	3
 #define FAN_EVENT_INFO_TYPE_PIDFD	4
+#define FAN_EVENT_INFO_TYPE_ERROR	5
 
 /* Variable length info record following event metadata */
 struct fanotify_event_info_header {
@@ -160,6 +161,12 @@  struct fanotify_event_info_pidfd {
 	__s32 pidfd;
 };
 
+struct fanotify_event_info_error {
+	struct fanotify_event_info_header hdr;
+	__s32 error;
+	__u32 error_count;
+};
+
 struct fanotify_response {
 	__s32 fd;
 	__u32 response;