[PATCH] libata: use FLUSH_EXT only when driver is larger than LBA28 limit (6fc49adb) · Commits · 戴 / test

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 <htejun@gmail.com> Cc: Danny Kukawka <dkukawka@novell.com> Cc: Stefan Seyfried <seife@novell.com> Signed-off-by:

Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-core.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -1457,6 +1457,10 @@ int ata_dev_configure(struct ata_device *dev)
		if (ata_id_has_lba48(id)) {
		dev->flags \|= ATA_DFLAG_LBA48;
		lba_desc = "LBA48";

		if (dev->n_sectors >= (1UL << 28) &&
		ata_id_has_flush_ext(id))
		dev->flags \|= ATA_DFLAG_FLUSH_EXT;
		}

		/* config NCQ */
		@@ -5128,7 +5132,7 @@ int ata_flush_cache(struct ata_device *dev)
		if (!ata_try_flush_cache(dev))
		return 0;

		if (ata_id_has_flush_ext(dev->id))
		if (dev->flags & ATA_DFLAG_FLUSH_EXT)
		cmd = ATA_CMD_FLUSH_EXT;
		else
		cmd = ATA_CMD_FLUSH;

drivers/ata/libata-scsi.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1027,8 +1027,7 @@ static unsigned int ata_scsi_flush_xlat(struct ata_queued_cmd qc, const u8 scs
		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;

include/linux/libata.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -140,6 +140,7 @@ enum {
		ATA_DFLAG_LBA48 = (1 << 1), /* device supports LBA48 */
		ATA_DFLAG_CDB_INTR = (1 << 2), /* device asserts INTRQ when ready for CDB */
		ATA_DFLAG_NCQ = (1 << 3), /* device supports NCQ */
		ATA_DFLAG_FLUSH_EXT = (1 << 4), /* do FLUSH_EXT instead of FLUSH */
		ATA_DFLAG_CFG_MASK = (1 << 8) - 1,

		ATA_DFLAG_PIO = (1 << 8), /* device limited to PIO mode */

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