Re: [PATCH] Documentation: Document the kernel flag bdev_allow_write_mounted

["Guilherme G. Piccoli" <gpiccoli@igalia.com>]

On 20/08/2024 13:23, Darrick J. Wong 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 to crash the kernel by breaking the
>> +			filesystem without its awareness, through direct block
>> +			device writes. Default is Y and can be changed through
>> +			the Kconfig option CONFIG_BLK_DEV_WRITE_MOUNTED.
> 
> Can we mention that this also solves the problem of naïve storage
> management tools (aka the ones that don't use O_EXCL) writing over a
> mounted filesystem and trashing it?
> 
> --D


Sure! At least from my side, fine with that.
How about the following string ?

+ 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 to crash the kernel by breaking the
+ filesystem without its awareness, through direct block
+ device writes. Also prevents issues from direct writes
+ of silly storage tooling (that doesn't use O_EXCL). The
+ default is Y and can be changed through the Kconfig
+ option CONFIG_BLK_DEV_WRITE_MOUNTED.


But feel free to improve / change it. I'll wait more feedback and
resubmit with a refined text.
Cheers,


Guilherme