[PATCH] libata: use FLUSH_EXT only when driver is larger than LBA28 limit
Many drives support LBA48 even when its capacity is smaller than
1<<28, as LBA48 is required for many functionalities. FLUSH_EXT is
mandatory for drives w/ LBA48 support.
Interestingly, at least one of such drives (ST960812A) has problems
dealing with FLUSH_EXT. It eventually completes the command but takes
around 7 seconds to finish in many cases thus drastically slowing down
IO transactions. This seems to be a firmware bug which sneaked into
production probably because no other ATA driver including linux IDE
issues FLUSH_EXT to drives which report support for LBA48 & FLUSH_EXT
but is smaller than 1<<28 blocks.
This patch adds ATA_DFLAG_FLUSH_EXT which is set iff the drive
supports LBA48 & FLUSH_EXT and is larger than LBA28 limit. Both cache
flush paths are updated to issue FLUSH_EXT only when the flag is set.
Note that the changed behavior is more inline with the rest of libata.
libata prefers shorter commands whenever possible.
Signed-off-by: Tejun Heo <[email protected]>
Cc: Danny Kukawka <[email protected]>
Cc: Stefan Seyfried <[email protected]>
Signed-off-by: Jeff Garzik <[email protected]>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index f13dd07..7a55c2e4 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1027,8 +1027,7 @@
tf->flags |= ATA_TFLAG_DEVICE;
tf->protocol = ATA_PROT_NODATA;
- if ((qc->dev->flags & ATA_DFLAG_LBA48) &&
- (ata_id_has_flush_ext(qc->dev->id)))
+ if (qc->dev->flags & ATA_DFLAG_FLUSH_EXT)
tf->command = ATA_CMD_FLUSH_EXT;
else
tf->command = ATA_CMD_FLUSH;
