From: Mike Lockwood <lockwood@android.com>
Date: Fri, 12 Mar 2010 16:01:05 +0000 (-0500)
Subject: USB: gadget: f_mass_storage: Flush writes after every 4 MB.
X-Git-Tag: firefly_0821_release~7613^2~815
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f6205641334bf29e59de6cbe62de618d7ee339e6;p=firefly-linux-kernel-4.4.55.git
USB: gadget: f_mass_storage: Flush writes after every 4 MB.
This avoids excessive caching at the block level layer when copying large
files to the storage device.
Signed-off-by: Mike Lockwood <lockwood@android.com>
---
diff --git a/drivers/usb/gadget/f_mass_storage_tmp.c b/drivers/usb/gadget/f_mass_storage_tmp.c
index 065448a8dd79..2312db113aa5 100644
--- a/drivers/usb/gadget/f_mass_storage_tmp.c
+++ b/drivers/usb/gadget/f_mass_storage_tmp.c
@@ -79,6 +79,9 @@
#define BULK_BUFFER_SIZE 4096
+/* flush after every 4 meg of writes to avoid excessive block level caching */
+#define MAX_UNFLUSHED_BYTES (4 * 1024 * 1024)
+
/*-------------------------------------------------------------------------*/
#define DRIVER_NAME "usb_mass_storage"
@@ -226,6 +229,7 @@ struct lun {
struct file *filp;
loff_t file_length;
loff_t num_sectors;
+ unsigned int unflushed_bytes;
unsigned int ro : 1;
unsigned int prevent_medium_removal : 1;
@@ -392,7 +396,7 @@ static struct fsg_dev *the_fsg;
static void close_backing_file(struct fsg_dev *fsg, struct lun *curlun);
static void close_all_backing_files(struct fsg_dev *fsg);
-
+static int fsync_sub(struct lun *curlun);
/*-------------------------------------------------------------------------*/
@@ -1039,6 +1043,13 @@ static int do_write(struct fsg_dev *fsg)
amount_left_to_write -= nwritten;
fsg->residue -= nwritten;
+#ifdef MAX_UNFLUSHED_BYTES
+ curlun->unflushed_bytes += nwritten;
+ if (curlun->unflushed_bytes >= MAX_UNFLUSHED_BYTES) {
+ fsync_sub(curlun);
+ curlun->unflushed_bytes = 0;
+ }
+#endif
/* If an error occurred, report it and its position */
if (nwritten < amount) {
curlun->sense_data = SS_WRITE_ERROR;
@@ -2515,6 +2526,7 @@ static int open_backing_file(struct fsg_dev *fsg, struct lun *curlun,
curlun->ro = ro;
curlun->filp = filp;
curlun->file_length = size;
+ curlun->unflushed_bytes = 0;
curlun->num_sectors = num_sectors;
LDBG(curlun, "open backing file: %s size: %lld num_sectors: %lld\n",
filename, size, num_sectors);