On 10/27/22 09:50, Damien Le Moal wrote:
If a user issues a write command with the FUA bit set for a device with
NCQ support disabled (that is, the device queue depth was set to 1), the
LBA 48 command WRITE DMA FUA EXT must be used. However,
ata_build_rw_tf() ignores this and first test if LBA 28 can be used.
That is, for small FUA writes at low LBAs, ata_rwcmd_protocol() will
cause the write to fail.
Fix this by preventing the use of LBA 28 for any FUA write request.
While at it, also early test if the request is a FUA read and fail these
requests for the NCQ-disabled case instead of relying on
ata_rwcmd_protocol() returning an error.
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
---
drivers/ata/libata-core.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 81b20ffb1554..fea06f41f371 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -725,9 +725,21 @@ int ata_build_rw_tf(struct ata_queued_cmd *qc, u64 block, u32 n_block,
class == IOPRIO_CLASS_RT)
tf->hob_nsect |= ATA_PRIO_HIGH << ATA_SHIFT_PRIO;
} else if (dev->flags & ATA_DFLAG_LBA) {
+ bool lba28_ok;
+
+ if (tf->flags & ATA_TFLAG_FUA) {
+ /* FUA reads are not defined */
+ if (!(tf->flags & ATA_TFLAG_WRITE))
+ return -EINVAL;
+ /* We need LBA48 / WRITE DMA FUA EXT for FUA writes */
+ lba28_ok = false;
+ } else {
+ lba28_ok = lba_28_ok(block, n_block);
+ }
+
tf->flags |= ATA_TFLAG_LBA;
- if (lba_28_ok(block, n_block)) {
+ if (lba28_ok) {
/* use LBA28 */
tf->device |= (block >> 24) & 0xf;
} else if (lba_48_ok(block, n_block)) {
I am still skeptical about this change.
Having checked the code I don't think that we ever issue a
REQ_READ|REQ_FUA; but at the same time there doesn't seem to be a strict
rule. I wonder if we shouldn't move that check into the block layer, and
error out any attempts to issue such?
Otherwise we would error out an otherwise fine I/O (which we _could_
have handled via PREFLUSH etc semantics), which I don't think is a good
idea.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman
