USB: gadget: storage: optional SCSI WRITE FUA bit
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.
This patch brings an option to accept or ignore mentioned bit
a) via specifying module parameter "nofua", or
b) through sysfs entry
/sys/devices/platform/_UDC_/gadget/gadget-lunX/nofua
(_UDC_ is the name of the USB Device Controller driver)
Patch is based on the work that was done by Denis Karpov for Maemo 5
platform.
Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Denis Karpov <ext-denis.2.karpov@nokia.com>
Cc: Adrian Hunter <adrian.hunter@nokia.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index d57c09f..88e5ad2 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
+ * nofua=b[,b...] Default false, booleans for ignore FUA flag
+ * in SCSI WRITE(10,12) commands
* stall Default determined according to the type of
* USB device controller (usually true),
* boolean to permit the driver to halt
@@ -112,12 +114,12 @@
* PAGE_CACHE_SIZE)
*
* If CONFIG_USB_FILE_STORAGE_TEST is not set, only the "file", "ro",
- * "removable", "luns", "stall", and "cdrom" options are available; default
- * values are used for everything else.
+ * "removable", "luns", "nofua", "stall", and "cdrom" options are available;
+ * default values are used for everything else.
*
* The pathnames of the backing files and the ro settings are available in
- * the attribute files "file" and "ro" in the lun<n> subdirectory of the
- * gadget's sysfs directory. If the "removable" option is set, writing to
+ * the attribute files "file", "nofua", and "ro" in the lun<n> subdirectory of
+ * the gadget's sysfs directory. If the "removable" option is set, writing to
* these files will simulate ejecting/loading the medium (writing an empty
* line means eject) and adjusting a write-enable tab. Changes to the ro
* setting are not allowed when the medium is loaded or if CD-ROM emulation
@@ -304,8 +306,10 @@
static struct {
char *file[FSG_MAX_LUNS];
int ro[FSG_MAX_LUNS];
+ int nofua[FSG_MAX_LUNS];
unsigned int num_filenames;
unsigned int num_ros;
+ unsigned int num_nofuas;
unsigned int nluns;
int removable;
@@ -345,6 +349,10 @@
module_param_array_named(ro, mod_data.ro, bool, &mod_data.num_ros, S_IRUGO);
MODULE_PARM_DESC(ro, "true to force read-only");
+module_param_array_named(nofua, mod_data.nofua, bool, &mod_data.num_nofuas,
+ S_IRUGO);
+MODULE_PARM_DESC(nofua, "true to ignore SCSI WRITE(10,12) FUA bit");
+
module_param_named(luns, mod_data.nluns, uint, S_IRUGO);
MODULE_PARM_DESC(luns, "number of LUNs");
@@ -1279,7 +1287,8 @@
curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
return -EINVAL;
}
- if (fsg->cmnd[1] & 0x08) { // FUA
+ /* FUA */
+ if (!curlun->nofua && (fsg->cmnd[1] & 0x08)) {
spin_lock(&curlun->filp->f_lock);
curlun->filp->f_flags |= O_DSYNC;
spin_unlock(&curlun->filp->f_lock);
@@ -3133,6 +3142,7 @@
/* The write permissions and store_xxx pointers are set in fsg_bind() */
static DEVICE_ATTR(ro, 0444, fsg_show_ro, NULL);
+static DEVICE_ATTR(nofua, 0644, fsg_show_nofua, NULL);
static DEVICE_ATTR(file, 0444, fsg_show_file, NULL);
@@ -3362,6 +3372,10 @@
}
}
+ /* Only for removable media? */
+ dev_attr_nofua.attr.mode = 0644;
+ dev_attr_nofua.store = fsg_store_nofua;
+
/* Find out how many LUNs there should be */
i = mod_data.nluns;
if (i == 0)
@@ -3387,6 +3401,7 @@
curlun->ro = mod_data.cdrom || mod_data.ro[i];
curlun->initially_ro = curlun->ro;
curlun->removable = mod_data.removable;
+ curlun->nofua = mod_data.nofua[i];
curlun->dev.release = lun_release;
curlun->dev.parent = &gadget->dev;
curlun->dev.driver = &fsg_driver.driver;
@@ -3401,6 +3416,8 @@
if ((rc = device_create_file(&curlun->dev,
&dev_attr_ro)) != 0 ||
(rc = device_create_file(&curlun->dev,
+ &dev_attr_nofua)) != 0 ||
+ (rc = device_create_file(&curlun->dev,
&dev_attr_file)) != 0) {
device_unregister(&curlun->dev);
goto out;
@@ -3525,8 +3542,8 @@
if (IS_ERR(p))
p = NULL;
}
- LINFO(curlun, "ro=%d, file: %s\n",
- curlun->ro, (p ? p : "(error)"));
+ LINFO(curlun, "ro=%d, nofua=%d, file: %s\n",
+ curlun->ro, curlun->nofua, (p ? p : "(error)"));
}
}
kfree(pathbuf);