Block devices can be protected by the ro attribute and this is sometimes done by default for some devices. For example, https://www.kernel.org/doc/Documentation/mmc/mmc-dev-parts.txt in such case the devices can only be written when it's "unlocked" through the force_ro "knob". However, I noticed that when I run `blkdiscard [- s]` on such devices, the protection will simply be ignored. Like I can't write anything to it with `dd` or so, but `blkdiscard` will wipe them straight away. Although according to the code in kernel, the BLKDISCARD and BLKSECDISCARD ioctls seems to do a write mode check when they are called, it does not prevent `blkdiscard` from wiping emmc boot partitions, which are "ro" by default, somehow. Experiencing this with vanilla Linux 4.2.5. -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
