Ext4, the mount option sync?

Question

Ext4, the mount option sync?

A couple of times ran across the statement

Some Linux filesystems don't support-o sync and -o dirsync (the ext2, ext3, fat and vfat filesystems do support synchronous updates (a la BSD) when mounted with the sync option).

source
well, or in Russian:

Note:
It should be remembered that not every file system supports all the parameters.
For example, the sync option today the only supported file systems are ext2, ext3, fat, vfat and ufs.

source
From this we can conclude that Ext4 has ceased to maintain sync. However, if we assume that these fragments were written before the advent of Ext4, then it will be not so. Something I can't find confirmation or the other hypothesis. Experiments with mounting the Ext4 partition with the command mount-o sync doesn't generate errors, the output from the mount then shows the line which takes into account the sync option, it looks like if it works for Ext4. Unfortunately, the real way to check - whether the drive is in synchronous mode is not found.

loren.Rutherfo asked June 8th 19 at 17:12

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1 answer

Domingo.Keeling11 answered on · Accepted Answer · 2019-06-08T17:14:40.427Z

man mount tried to read? In fact this should have started.

FILESYSTEM-INDEPENDENT MOUNT OPTIONS
 Some of these options are only useful when they appear in the /etc/fstab file.

 Some of these options could be enabled or disabled by default in the system kernel. To check the current setting
 see the options in /proc/mounts. Note that filesystems also have per-filesystem specific default mount options (see
 for example tune2fs -l output for extN filesystems).

 The following options apply to any filesystem that is being mounted (but not every filesystem actually honors them –
 e.g., the sync option today has an effect only for ext2, ext3, fat, vfat and ufs):

A direct answer to the question.