Tejun Heo wrote:
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@xxxxxxxxx> Cc: Danny Kukawka <dkukawka@xxxxxxxxxx> Cc: Stefan Seyfried <seife@xxxxxxxxxx> --- * In ata_dev_configure(), use dev->n_sectors instead of reading it directly from id.
applied to #upstream -- I think this wants more testing than 2.6.19-rc5 will allow
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