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From: fabien.chouteau on 26 Apr 2010 06:40
From: Fabien Chouteau <fabien.chouteau(a)barco.com>

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

Signed-off-by: Fabien Chouteau <fabien.chouteau(a)barco.com>
---
drivers/usb/gadget/f_mass_storage.c | 48 ++++++++++++++++++++++++++++++++--
1 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index f4911c0..c3e5dbb 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -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
@@ -1385,12 +1389,50 @@ 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;
}

--
1.7.0.5

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