On Thu, 8 Dec 2005, Fiala, Stefan wrote:
> The flag is set when the kernel/module is loaded.
No it isn't.
> For all but removeable the device must disappear/reappear
> Which fixes the flag.
No it doesn't. The flag does not get set if the media is not removable.
Here's the code from sd.c:sd_revalidate_disk():
if (sdkp->media_present) {
sd_read_capacity(sdkp, disk->disk_name, buffer);
if (sdp->removable)
sd_read_write_protect_flag(sdkp, disk->disk_name,
buffer);
sd_read_cache_type(sdkp, disk->disk_name, buffer);
}
That's the only place where sd_read_write_protect_flag gets called, so it
never is called if sdp->removable is clear.
> Leaving removeables, that on user interaction, can change.
> For instance:
> On an RW-optical [use sd], eject current cartridge, flip wrt-prot tab,
> Re-insert. Unless a user were accessing during this sequence
> [sounds painful] the state of the WP bit would silently change.
> Hence the revalidate on open if its removeable.
Alan Stern
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