[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 <htejun@gmail.com> Cc: Danny Kukawka <dkukawka@novell.com> Cc: Stefan Seyfried <seife@novell.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
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@ -1457,6 +1457,10 @@ int ata_dev_configure(struct ata_device *dev)
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if (ata_id_has_lba48(id)) {
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dev->flags |= ATA_DFLAG_LBA48;
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lba_desc = "LBA48";
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if (dev->n_sectors >= (1UL << 28) &&
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ata_id_has_flush_ext(id))
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dev->flags |= ATA_DFLAG_FLUSH_EXT;
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}
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/* config NCQ */
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@ -5128,7 +5132,7 @@ int ata_flush_cache(struct ata_device *dev)
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if (!ata_try_flush_cache(dev))
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return 0;
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if (ata_id_has_flush_ext(dev->id))
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if (dev->flags & ATA_DFLAG_FLUSH_EXT)
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cmd = ATA_CMD_FLUSH_EXT;
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else
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cmd = ATA_CMD_FLUSH;
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