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Commit 31436a1a authored by Fabien Chouteau's avatar Fabien Chouteau Committed by Greg Kroah-Hartman
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USB: Mass storage gadget: Handle eject request 



This patch adds handling of the "Start/Stop Unit" SCSI request
to simulate media ejection.

Signed-off-by: default avatarFabien Chouteau <fabien.chouteau@barco.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent f48cf80f

drivers/usb/gadget/f_mass_storage.c

+45 −3
Original line number Diff line number Diff line
@@ -163,6 +163,10 @@ 
 * ro setting are not allowed when the medium is loaded or if CD-ROM

 * emulation is being used.

 *

 * When a LUN receive an "eject" SCSI request (Start/Stop Unit),

 * if the LUN is removable, the backing file is released to simulate

 * ejection.

 *

 *

 * This function is heavily based on "File-backed Storage Gadget" by

 * Alan Stern which in turn is heavily based on "Gadget Zero" by David
@@ -1384,12 +1388,50 @@ static int do_mode_sense(struct fsg_common *common, struct fsg_buffhd *bh) 


static int do_start_stop(struct fsg_common *common)

{

	if (!common->curlun) {

	struct fsg_lun	*curlun = common->curlun;

	int		loej, start;



	if (!curlun) {

		return -EINVAL;

	} else if (!common->curlun->removable) {

		common->curlun->sense_data = SS_INVALID_COMMAND;

	} else if (!curlun->removable) {

		curlun->sense_data = SS_INVALID_COMMAND;

		return -EINVAL;

	}



	loej = common->cmnd[4] & 0x02;

	start = common->cmnd[4] & 0x01;



	/* eject code from file_storage.c:do_start_stop() */



	if ((common->cmnd[1] & ~0x01) != 0 ||	  /* Mask away Immed */

		(common->cmnd[4] & ~0x03) != 0) { /* Mask LoEj, Start */

		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;

		return -EINVAL;

	}



	if (!start) {

		/* Are we allowed to unload the media? */

		if (curlun->prevent_medium_removal) {

			LDBG(curlun, "unload attempt prevented\n");

			curlun->sense_data = SS_MEDIUM_REMOVAL_PREVENTED;

			return -EINVAL;

		}

		if (loej) {	/* Simulate an unload/eject */

			up_read(&common->filesem);

			down_write(&common->filesem);

			fsg_lun_close(curlun);

			up_write(&common->filesem);

			down_read(&common->filesem);

		}

	} else {



		/* Our emulation doesn't support mounting; the medium is

		 * available for use as soon as it is loaded. */

		if (!fsg_lun_is_open(curlun)) {

			curlun->sense_data = SS_MEDIUM_NOT_PRESENT;

			return -EINVAL;

		}

	}

	return 0;

}