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Date: Wed, 16 May 2012 08:54:49 +0000
From: Pantelis Antoniou <panto@...oniou-consulting.com>
To: Russ.Dill@...com, linux-kernel@...r.kernel.org
Cc: Pantelis Antoniou <panto@...oniou-consulting.com>
Subject: [PATCH] [g_mass_storage] Fix unmount problem with OS-X
OS-X uses a sequence on unmounting that makes us close the backing
file. Apparently there's no way to open it again, which makes it
impossible to remount without rmmod'ing g_mass_storage.
Fix this by adding a media_ejected flag to each lun, and keeping
track of it properly.
Any other method (i.e. preventing unmount, and not keeping track
of the eject status) failed due to OS-X sending start stop commands
after the unmount and checking again.
---
drivers/usb/gadget/f_mass_storage.c | 21 ++++++++++++++-------
drivers/usb/gadget/storage_common.c | 11 +++++++++++
2 files changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index cb8c162..b865d20 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -1445,6 +1445,9 @@ static int do_start_stop(struct fsg_common *common)
curlun->sense_data = SS_MEDIUM_NOT_PRESENT;
return -EINVAL;
}
+
+ /* if the host is trying again, the media are mounted */
+ fsg_lun_set_ejected(curlun, 0);
return 0;
}
@@ -1468,11 +1471,15 @@ static int do_start_stop(struct fsg_common *common)
return 0;
}
- up_read(&common->filesem);
- down_write(&common->filesem);
- fsg_lun_close(curlun);
- up_write(&common->filesem);
- down_read(&common->filesem);
+ /*
+ * Do not close the LUNs, just made them invisible.
+ * When the next exception comes we make them visible
+ * again. This fixes the bug where MacOSX unmounts
+ * and then it's impossible to mount again, since
+ * fsg_lun_open is never called again.
+ */
+
+ fsg_lun_set_ejected(curlun, 1);
return common->ops && common->ops->post_eject
? min(0, common->ops->post_eject(common, curlun,
@@ -1531,7 +1538,6 @@ static int do_mode_select(struct fsg_common *common, struct fsg_buffhd *bh)
return -EINVAL;
}
-
/*-------------------------------------------------------------------------*/
static int halt_bulk_in_endpoint(struct fsg_dev *fsg)
@@ -1917,7 +1923,7 @@ static int check_command(struct fsg_common *common, int cmnd_size,
/* If the medium isn't mounted and the command needs to access
* it, return an error. */
- if (curlun && !fsg_lun_is_open(curlun) && needs_medium) {
+ if (curlun && !fsg_lun_is_open_and_mounted(curlun) && needs_medium) {
curlun->sense_data = SS_MEDIUM_NOT_PRESENT;
return -EINVAL;
}
@@ -2533,6 +2539,7 @@ static void handle_exception(struct fsg_common *common)
curlun->unit_attention_data = SS_NO_SENSE;
curlun->sense_data_info = 0;
curlun->info_valid = 0;
+ curlun->media_ejected = 0;
}
common->state = FSG_STATE_IDLE;
}
diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index 8081ca3..723c6aa 100644
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -199,6 +199,7 @@ struct fsg_lun {
unsigned int registered:1;
unsigned int info_valid:1;
unsigned int nofua:1;
+ unsigned int media_ejected:1;
u32 sense_data;
u32 sense_data_info;
@@ -211,6 +212,16 @@ struct fsg_lun {
#define fsg_lun_is_open(curlun) ((curlun)->filp != NULL)
+#define fsg_lun_is_ejected(curlun) ((curlun)->media_ejected)
+
+#define fsg_lun_set_ejected(curlun, v) ((curlun)->media_ejected = !!(v))
+
+#define fsg_lun_is_open_and_mounted(curlun) \
+ ({ \
+ const struct fsg_lun *_curlun = (curlun); \
+ fsg_lun_is_open(_curlun) && !fsg_lun_is_ejected(_curlun); \
+ })
+
static struct fsg_lun *fsg_lun_from_dev(struct device *dev)
{
return container_of(dev, struct fsg_lun, dev);
--
1.7.1
--
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