Re: [PATCH v8 30/32] ext4: Send notifications on error

On Tue 19-10-21 17:44:26, Jan Kara wrote:

On Mon 18-10-21 21:00:13, Gabriel Krisman Bertazi wrote:

quoted

Send a FS_ERROR message via fsnotify to a userspace monitoring tool
whenever a ext4 error condition is triggered.  This follows the existing
error conditions in ext4, so it is hooked to the ext4_error* functions.

It also follows the current dmesg reporting in the format.  The
filesystem message is composed mostly by the string that would be
otherwise printed in dmesg.

A new ext4 specific record format is exposed in the uapi, such that a
monitoring tool knows what to expect when listening errors of an ext4
filesystem.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Gabriel Krisman Bertazi <redacted>

Looks good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Hum, I actually retract this because the code doesn't match what is written
in the documentation and I'm not 100% sure what is correct. In particular:

quoted

@@ -759,6 +760,8 @@ void __ext4_error(struct super_block *sb, const char *function,
 		       sb->s_id, function, line, current->comm, &vaf);
 		va_end(args);
 	}
+	fsnotify_sb_error(sb, NULL, error);
+

E.g. here you pass the 'error' to fsnotify. This will be just standard
'errno' number, not ext4 error code as described in the documentation. Also
note that frequently 'error' will be 0 which gets magically transformed to
EFSCORRUPTED in save_error_info() in the ext4 error handling below. So
there's clearly some more work to do...

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR