usb: gadget: storage_common: pass filesem to fsg_store_cdrom

If cdrom flag is set ro flag is implied. Try setting the ro first, and
only if it succeeds set the cdrom flag.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/f_mass_storage.c

@@ -3281,7 +3281,12 @@ static ssize_t fsg_lun_opts_cdrom_show(struct fsg_lun_opts *opts, char *page)
 static ssize_t fsg_lun_opts_cdrom_store(struct fsg_lun_opts *opts,
 				       const char *page, size_t len)
 {
-	return fsg_store_cdrom(opts->lun, page, len);
+	struct fsg_opts *fsg_opts;
+
+	fsg_opts = to_fsg_opts(opts->group.cg_item.ci_parent);
+
+	return fsg_store_cdrom(opts->lun, &fsg_opts->common->filesem, page,
+			       len);
 }
 
 static struct fsg_lun_opts_attribute fsg_lun_opts_cdrom =

drivers/usb/gadget/storage_common.c

@@ -371,6 +371,23 @@ ssize_t fsg_show_removable(struct fsg_lun *curlun, char *buf)
 }
 EXPORT_SYMBOL(fsg_show_removable);
 
+/*
+ * The caller must hold fsg->filesem for reading when calling this function.
+ */
+static ssize_t _fsg_store_ro(struct fsg_lun *curlun, bool ro)
+{
+	if (fsg_lun_is_open(curlun)) {
+		LDBG(curlun, "read-only status change prevented\n");
+		return -EBUSY;
+	}
+
+	curlun->ro = ro;
+	curlun->initially_ro = ro;
+	LDBG(curlun, "read-only status set to %d\n", curlun->ro);
+
+	return 0;
+}
+
 ssize_t fsg_store_ro(struct fsg_lun *curlun, struct rw_semaphore *filesem,
 		     const char *buf, size_t count)
 {
@@ -386,16 +403,11 @@ ssize_t fsg_store_ro(struct fsg_lun *curlun, struct rw_semaphore *filesem,
 	 * backing file is closed.
 	 */
 	down_read(filesem);
-	if (fsg_lun_is_open(curlun)) {
-		LDBG(curlun, "read-only status change prevented\n");
-		rc = -EBUSY;
-	} else {
-		curlun->ro = ro;
-		curlun->initially_ro = ro;
-		LDBG(curlun, "read-only status set to %d\n", curlun->ro);
+	rc = _fsg_store_ro(curlun, ro);
+	if (!rc)
 		rc = count;
-	}
 	up_read(filesem);
+
 	return rc;
 }
 EXPORT_SYMBOL(fsg_store_ro);
@@ -450,7 +462,8 @@ ssize_t fsg_store_file(struct fsg_lun *curlun, struct rw_semaphore *filesem,
 }
 EXPORT_SYMBOL(fsg_store_file);
 
-ssize_t fsg_store_cdrom(struct fsg_lun *curlun, const char *buf, size_t count)
+ssize_t fsg_store_cdrom(struct fsg_lun *curlun, struct rw_semaphore *filesem,
+			const char *buf, size_t count)
 {
 	bool		cdrom;
 	int		ret;
@@ -459,9 +472,16 @@ ssize_t fsg_store_cdrom(struct fsg_lun *curlun, const char *buf, size_t count)
 	if (ret)
 		return ret;
 
-	curlun->cdrom = cdrom;
+	down_read(filesem);
+	ret = cdrom ? _fsg_store_ro(curlun, true) : 0;
 
-	return count;
+	if (!ret) {
+		curlun->cdrom = cdrom;
+		ret = count;
+	}
+	up_read(filesem);
+
+	return ret;
 }
 EXPORT_SYMBOL(fsg_store_cdrom);
 

drivers/usb/gadget/storage_common.h

@@ -221,7 +221,8 @@ ssize_t fsg_store_ro(struct fsg_lun *curlun, struct rw_semaphore *filesem,
 ssize_t fsg_store_nofua(struct fsg_lun *curlun, const char *buf, size_t count);
 ssize_t fsg_store_file(struct fsg_lun *curlun, struct rw_semaphore *filesem,
 		       const char *buf, size_t count);
-ssize_t fsg_store_cdrom(struct fsg_lun *curlun, const char *buf, size_t count);
+ssize_t fsg_store_cdrom(struct fsg_lun *curlun, struct rw_semaphore *filesem,
+			const char *buf, size_t count);
 ssize_t fsg_store_removable(struct fsg_lun *curlun, const char *buf,
 			    size_t count);