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/Documentation/ABI/testing/sysfs-devices-platform-_UDC_-gadget b/Documentation/ABI/testing/sysfs-devices-platform-_UDC_-gadget
index 34034027b13c603655d5df3d0bf18a7a08e70bb1..d548eaac230a43f51eb4b613b7db114f7ce70b19 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-platform-_UDC_-gadget
+++ b/Documentation/ABI/testing/sysfs-devices-platform-_UDC_-gadget
@@ -7,3 +7,15 @@ Description:
                0 -> resumed
 
                (_UDC_ is the name of the USB Device Controller driver)
+
+What:           /sys/devices/platform/_UDC_/gadget/gadget-lunX/nofua
+Date:           July 2010
+Contact:        Andy Shevchenko <andy.shevchenko@gmail.com>
+Description:
+               Show or set the reaction on the FUA (Force Unit Access) bit in
+               the SCSI WRITE(10,12) commands when a gadget in USB Mass
+               Storage mode.
+
+               Possible values are:
+                       1 -> ignore the FUA flag
+                       0 -> obey the FUA flag

diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index d57c09f764d6e948999af54af9b40116314f68ac..88e5ad2bc71064deac58c2ad7a52cd35aa303abb 100644 (file)
--- 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 @@ MODULE_LICENSE("Dual BSD/GPL");
 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_PARM_DESC(file, "names of backing files or devices");
 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 @@ static int do_write(struct fsg_dev *fsg)
                        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 @@ static int fsg_main_thread(void *fsg_)
 
 /* 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 @@ static int __ref fsg_bind(struct usb_gadget *gadget)
                }
        }
 
+       /* 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 @@ static int __ref fsg_bind(struct usb_gadget *gadget)
                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;
@@ -3400,6 +3415,8 @@ static int __ref fsg_bind(struct usb_gadget *gadget)
                }
                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);
@@ -3525,8 +3542,8 @@ static int __ref fsg_bind(struct usb_gadget *gadget)
                                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);

diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index 3bbddab72e571b35c51f194de9a37d639ced2e68..484acfb1a7c5a999e9b2ef5f48c4ab54d1c0a549 100644 (file)
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -284,6 +284,7 @@ struct fsg_lun {
        unsigned int    prevent_medium_removal:1;
        unsigned int    registered:1;
        unsigned int    info_valid:1;
+       unsigned int    nofua:1;
 
        u32             sense_data;
        u32             sense_data_info;
@@ -714,6 +715,14 @@ static ssize_t fsg_show_ro(struct device *dev, struct device_attribute *attr,
                                  : curlun->initially_ro);
 }
 
+static ssize_t fsg_show_nofua(struct device *dev, struct device_attribute *attr,
+                             char *buf)
+{
+       struct fsg_lun  *curlun = fsg_lun_from_dev(dev);
+
+       return sprintf(buf, "%u\n", curlun->nofua);
+}
+
 static ssize_t fsg_show_file(struct device *dev, struct device_attribute *attr,
                             char *buf)
 {
@@ -770,6 +779,25 @@ static ssize_t fsg_store_ro(struct device *dev, struct device_attribute *attr,
        return rc;
 }
 
+static ssize_t fsg_store_nofua(struct device *dev,
+                              struct device_attribute *attr,
+                              const char *buf, size_t count)
+{
+       struct fsg_lun  *curlun = fsg_lun_from_dev(dev);
+       unsigned long   nofua;
+
+       if (strict_strtoul(buf, 2, &nofua))
+               return -EINVAL;
+
+       /* Sync data when switching from async mode to sync */
+       if (!nofua && curlun->nofua)
+               fsg_lun_fsync_sub(curlun);
+
+       curlun->nofua = nofua;
+
+       return count;
+}
+
 static ssize_t fsg_store_file(struct device *dev, struct device_attribute *attr,
                              const char *buf, size_t count)
 {