On 11/19/2009 01:36 AM, Tejun Heo wrote:
If ATA device failed FLUSH, it means that the device failed to write out some amount of data and the error needs to be reported to upper layers. As retries can't recover the lost data, FLUSH failures need to be reported immediately in general. However, if FLUSH fails due to transmission errors, the FLUSH needs to be retried; otherwise, filesystems may switch to RO mode and/or raid array may drop a drive for a random transmission glitch. This condition can be rather easily reproduced on certain ahci controllers which go through a PHY event after powersave mode switch + ext4 combination. Powersave mode switch is often closely followed by flush from the filesystem failing the FLUSH with ATA bus error which makes the filesystem code believe that data is lost and drop to RO mode. This was reported in the following bugzilla bug. http://bugzilla.kernel.org/show_bug.cgi?id=14543 This patch makes libata EH retry FLUSH if it wasn't failed by the device. Signed-off-by: Tejun Heo<tj@xxxxxxxxxx> Reported-by: Andrey Vihrov<andrey.vihrov@xxxxxxxxx> --- drivers/ata/libata-eh.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/libata.h | 2 - 2 files changed, 95 insertions(+), 1 deletion(-)
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