On Fri, Jun 14, 2024 at 02:23:45PM +0200, Niklas Cassel wrote:
From: Damien Le Moal dlemoal@kernel.org
The SCSI Removable Media Bit (RMB) should only be set for removable media, where the device stays and the media changes, e.g. CD-ROM or floppy.
The ATA removable media device bit is obsoleted since ATA-8 ACS (2006), but before that it was used to indicate that the device can have its media removed (while the device stays).
Commit 8a3e33cf92c7 ("ata: ahci: find eSATA ports and flag them as removable") introduced a change to set the RMB bit if the port has either the eSATA bit or the hot-plug capable bit set. The reasoning was that the author wanted his eSATA ports to get treated like a USB stick.
This is however wrong. See "20-082r23SPC-6: Removable Medium Bit Expectations" which has since been integrated to SPC, which states that:
""" Reports have been received that some USB Memory Stick device servers set the removable medium (RMB) bit to one. The rub comes when the medium is actually removed, because... The device server is removed concurrently with the medium removal. If there is no device server, then there is no device server that is waiting to have removable medium inserted.
Sufficient numbers of SCSI analysts see such a device:
- not as a device that supports removable medium;
but
- as a removable, hot pluggable device.
"""
The definition of the RMB bit in the SPC specification has since been clarified to match this.
Thus, a USB stick should not have the RMB bit set (and neither shall an eSATA nor a hot-plug capable port).
Commit dc8b4afc4a04 ("ata: ahci: don't mark HotPlugCapable Ports as external/removable") then changed so that the RMB bit is only set for the eSATA bit (and not for the hot-plug capable bit), because of a lot of bug reports of SATA devices were being automounted by udisks. However, treating eSATA and hot-plug capable ports differently is not correct.
From the AHCI 1.3.1 spec: Hot Plug Capable Port (HPCP): When set to '1', indicates that this port's signal and power connectors are externally accessible via a joint signal and power connector for blindmate device hot plug.
So a hot-plug capable port is an external port, just like commit 45b96d65ec68 ("ata: ahci: a hotplug capable port is an external port") claims.
In order to not violate the SPC specification, modify the SCSI INQUIRY data to only set the RMB bit if the ATA device can have its media removed.
This fixes a reported problem where GNOME/udisks was automounting devices connected to hot-plug capable ports.
Fixes: 45b96d65ec68 ("ata: ahci: a hotplug capable port is an external port") Cc: stable@vger.kernel.org Reviewed-by: Mario Limonciello mario.limonciello@amd.com Reviewed-by: Thomas Weißschuh linux@weissschuh.net Tested-by: Thomas Weißschuh linux@weissschuh.net Reported-by: Thomas Weißschuh linux@weissschuh.net Closes: https://lore.kernel.org/linux-ide/c0de8262-dc4b-4c22-9fac-33432e5bddd3@t-8ch... Signed-off-by: Damien Le Moal dlemoal@kernel.org [cassel: wrote commit message] Signed-off-by: Niklas Cassel cassel@kernel.org
Changes since v1: -Added Cc: stable. -Updated comment and commit message to correctly state that the ATA removable media device bit is obsoleted since ATA-8 ACS.
drivers/ata/libata-scsi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index cdf29b178ddc..bb4d30d377ae 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -1831,11 +1831,11 @@ static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf) 2 };
- /* set scsi removable (RMB) bit per ata bit, or if the
* AHCI port says it's external (Hotplug-capable, eSATA).
- /*
* Set the SCSI Removable Media Bit (RMB) if the ATA removable media* device bit (obsolete since ATA-8 ACS) is set.
- if (ata_id_removable(args->id) ||
(args->dev->link->ap->pflags & ATA_PFLAG_EXTERNAL))
- if (ata_id_removable(args->id)) hdr[1] |= (1 << 7);
if (args->dev->class == ATA_DEV_ZAC) { -- 2.45.2
Applied: https://git.kernel.org/pub/scm/linux/kernel/git/libata/linux.git/log/?h=for-...