From: Tom Yan <tom.ty89@xxxxxxxxx> Currently block layer limit max_hw_sectors is set to ATA_MAX_SECTORS_LBA48 (65535), for devices with LBA48 support. However, block layer limit max_sectors (which is the effective one; also adjustable, upper-bounded by max_hw_sectors) is set to BLK_DEF_MAX_SECTORS (currently 2560) by the scsi disk driver, since libata's SATL does not report an Optimal Transfer Length. This does not make much sense, especially when the current BLK_DEF_MAX_SECTORS appears to be unsafe for some ATA devices (see ATA_HORKAGE_MAX_SEC_1024). Truth is, the current value appears to be arbitrary anyway. See commit d2be537c3ba3 ("block: bump BLK_DEF_MAX_SECTORS to 2560"). Therefore, avoid setting dev->max_sectors when it is strictly necessary. Leave it as 0 otherwise, so that both block layer limits will remain as SCSI_DEFAULT_MAX_SECTORS (currently 1024). diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 0749f71..07259d8 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -2610,10 +2610,8 @@ int ata_dev_configure(struct ata_device *dev) dma_dir_string); } - /* determine max_sectors */ - dev->max_sectors = ATA_MAX_SECTORS; - if (dev->flags & ATA_DFLAG_LBA48) - dev->max_sectors = ATA_MAX_SECTORS_LBA48; + if (!(dev->flags & ATA_DFLAG_LBA48)) + dev->max_sectors = ATA_MAX_SECTORS; /* Limit PATA drive on SATA cable bridge transfers to udma5, 200 sectors */ -- 2.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html