[PATCH 5/8] vfs: Include origin of the SB error notification

Gabriel Krisman Bertazi
2020-12-08T00:32:35Z

When reporting a filesystem error, we really need to know where the
error came from, therefore, include "function:line" information in the
notification sent to userspace. There is no current users of notify_sb
in the kernel, so there are no callers to update.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
---
include/linux/fs.h | 11 +++++++++--
include/uapi/linux/watch_queue.h | 3 +++
2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index df588edc0a34..864d86fcc68c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3514,14 +3514,17 @@ static inline void notify_sb(struct super_block *s,
/**
* notify_sb_error: Post superblock error notification.
* @s: The superblock the notification is about.
+ * @function: function name reported as source of the warning.
+ * @line: source code line reported as source of the warning.
* @error: The error number to be recorded.
* @inode: The inode the error refers to (if available, 0 otherwise)
* @block: The block the error refers to (if available, 0 otherwise)
* @fmt: Formating string for extra information appended to the notification
* @args: arguments for extra information string appended to the notification
*/
-static inline int notify_sb_error(struct super_block *s, int error, u64 inode,
- u64 block, const char *fmt, va_list *args)
+static inline int notify_sb_error(struct super_block *s, const char *function, int line,
+ int error, u64 inode, u64 block,
+ const char *fmt, va_list *args)
{
#ifdef CONFIG_SB_NOTIFICATIONS
if (unlikely(s->s_watchers)) {
@@ -3534,8 +3537,12 @@ static inline int notify_sb_error(struct super_block *s, int error, u64 inode,
.error_cookie = 0,
.inode = inode,
.block = block,
+ .line = line,
};

+ memcpy(&n.function, function, SB_NOTIFICATION_FNAME_LEN);
+ n.function[SB_NOTIFICATION_FNAME_LEN-1] = '\0';
+
post_sb_notification(s, &n.s, fmt, args);
}
#endif
diff --git a/include/uapi/linux/watch_queue.h b/include/uapi/linux/watch_queue.h
index 937363d9f7b3..5fa5286c5cc7 100644
--- a/include/uapi/linux/watch_queue.h
+++ b/include/uapi/linux/watch_queue.h
@@ -114,6 +114,7 @@ enum superblock_notification_type {

#define NOTIFY_SUPERBLOCK_IS_NOW_RO WATCH_INFO_FLAG_0 /* Superblock changed to R/O */

+#define SB_NOTIFICATION_FNAME_LEN 30
/*
* Superblock notification record.
* - watch.type = WATCH_TYPE_MOUNT_NOTIFY
@@ -130,6 +131,8 @@ struct superblock_error_notification {
__u32 error_cookie;
__u64 inode;
__u64 block;
+ char function[SB_NOTIFICATION_FNAME_LEN];
+ __u16 line;
char desc[0];
};

--
2.29.2