On 8/23/24 7:26 AM, Guilherme G. Piccoli wrote:

+	bdev_allow_write_mounted=
+			Format: <bool>
+			Control the ability of directly writing to mounted block
+			devices' page cache, i.e., allow / disallow writes that
+			bypasses the FS. This was implemented as a means to
+			prevent fuzzers from crashing the kernel by overwriting
+			the metadata underneath a mounted FS without its awareness.
+			This also prevents destructive formatting of mounted
+			filesystems by naive storage tooling that don't use
+			O_EXCL. Default is Y and can be changed through the
+			Kconfig option CONFIG_BLK_DEV_WRITE_MOUNTED.
+

Does this flag also affect direct I/O? If so, does this mean that the
reference to the page cache should be left out?

Thanks,

Bart.