Messages in this thread | | | Date | Wed, 14 Jul 2010 16:55:33 +0300 | From | Roger Quadros <> | Subject | Re: [PATCHv2] usb: gadget: storage: optional SCSI WRITE FUA bit |
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On 07/14/2010 04:44 PM, ext Andy Shevchenko wrote: > 2010/7/14 Michał Nazarewicz<m.nazarewicz@samsung.com>: >> On Wed, 14 Jul 2010 11:05:31 +0200, Andy Shevchenko >> <andy.shevchenko@gmail.com> wrote: >>> >>> MS Windows mounts removable storage in "Removal optimized mode" by >>> default. All the writes to the media are synchronous which is achieved >>> by setting FUA (Force Unit Access) bit in SCSI WRITE(10,12) commands. >>> This prevents I/O requests aggregation in block layer dramatically >>> decreasing performance. >> >>> diff --git a/drivers/usb/gadget/file_storage.c >>> b/drivers/usb/gadget/file_storage.c >>> index b49d86e..45f58d9 100644 >>> --- a/drivers/usb/gadget/file_storage.c >>> +++ b/drivers/usb/gadget/file_storage.c >>> @@ -93,6 +93,8 @@ >>> * removable Default false, boolean for removable media >>> * luns=N Default N = number of filenames, number of >>> * LUNs to support >>> + * fua=b[,b...] Default false, booleans for ignore FUA >>> flag >>> + * in SCSI WRITE(6,10,12) commands >> >> I wonder if it makes sense to make it per-LUN. I would imagine that it's >> great >> to ignore FUA if the device has its own power supply in which case after >> disconnect >> the data won't be lost. This is a per-device property not really per-LUN. >> As such >> I'd make this option global for the gadget. > Make sense only for removable media with one partition. > Otherwise. why we have sync option per partition f.e., not per device? > by partition do you mean medium? They are different terms. A storage medium may have 1 or more logical partitions. It is left upto the Host/user to decide how he wants to partition the medium.
file_storage driver does not deal with partitions. only mediums.
regards, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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