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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: Fabien Chouteau <fabien.chouteau@barco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Fabien Chouteau 2010-04-26 12:34:54 +02:00 committed by Greg Kroah-Hartman
parent f48cf80f93
commit 31436a1a64
1 changed files with 45 additions and 3 deletions
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48
drivers/usb/gadget/f_mass_storage.c
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@ -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;
}