[PATCH v3 14/18] tftp: implement 'windowsize' (RFC 7440) support
Enrico Scholz
enrico.scholz at sigma-chemnitz.de
Mon Aug 15 01:42:18 PDT 2022
Results (with the reorder patch; numbers in bytes/s) on an iMX8MP are:
| windowsize | VPN | 1 Gb/s | 100 Mb/s |
|------------|-----------|------------|------------|
| 128 | 3.869.284 | 98.643.085 | 11.434.852 |
| 64 | 3.863.581 | 98.550.375 | 11.434.852 |
| 48 | 3.431.580 | 94.211.680 | 11.275.010 |
| 32 | 2.835.129 | 85.250.081 | 10.985.605 |
| 24 | 2.344.858 | 77.787.537 | 10.765.667 |
| 16 | 1.734.186 | 67.519.381 | 10.210.087 |
| 12 | 1.403.340 | 61.972.576 | 9.915.612 |
| 8 | 1.002.462 | 50.852.376 | 9.016.130 |
| 6 | 775.573 | 42.781.558 | 8.422.297 |
| 4 | 547.845 | 32.066.544 | 6.835.567 |
| 3 | 412.987 | 26.526.081 | 6.322.435 |
| 2 | 280.987 | 19.120.641 | 5.494.241 |
| 1 | 141.699 | 10.431.516 | 2.967.224 |
(VPN = OpenVPN on ADSL 50 Mb/s).
The window size can be configured at runtime.
This commit increases barebox size by
| add/remove: 1/0 grow/shrink: 4/1 up/down: 144/-16 (128)
| Function old new delta
| tftp_send 316 364 +48
| tftp_init 16 60 +44
| tftp_handler 824 868 +44
| tftp_do_open 532 536 +4
| g_tftp_window_size - 4 +4
| tftp_poll 180 164 -16
| Total: Before=626311, After=626439, chg +0.02%
Setting FS_TFTP_MAX_WINDOW_SIZE to zero reduces it to
| add/remove: 1/0 grow/shrink: 3/2 up/down: 92/-52 (40)
| Function old new delta
| tftp_init 16 60 +44
| tftp_handler 824 864 +40
| tftp_do_open 532 536 +4
| g_tftp_window_size - 4 +4
| tftp_poll 180 164 -16
| tftp_send 316 280 -36
| Total: Before=626311, After=626351, chg +0.01%
Signed-off-by: Enrico Scholz <enrico.scholz at sigma-chemnitz.de>
---
fs/Kconfig | 14 ++++++++++++++
fs/tftp.c | 54 +++++++++++++++++++++++++++++++++++++++++-------------
2 files changed, 55 insertions(+), 13 deletions(-)
diff --git a/fs/Kconfig b/fs/Kconfig
index aeba00073eed..0c4934285942 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -43,6 +43,20 @@ config FS_TFTP
prompt "tftp support"
depends on NET
+config FS_TFTP_MAX_WINDOW_SIZE
+ int
+ prompt "maximum tftp window size (RFC 7440)"
+ depends on FS_TFTP
+ default 128
+ range 1 128
+ help
+ The maximum allowed tftp "windowsize" (RFC 7440). Higher
+ value increase speed of the tftp download with the cost of
+ memory (1432 bytes per slot).
+
+ Requires tftp "windowsize" (RFC 7440) support on server side
+ to have an effect.
+
config FS_OMAP4_USBBOOT
bool
prompt "Filesystem over usb boot"
diff --git a/fs/tftp.c b/fs/tftp.c
index 5c3e56a6cb22..4c3980404dc1 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -26,9 +26,11 @@
#include <libgen.h>
#include <fcntl.h>
#include <getopt.h>
+#include <globalvar.h>
#include <init.h>
#include <linux/stat.h>
#include <linux/err.h>
+#include <linux/kernel.h>
#include <kfifo.h>
#include <parseopt.h>
#include <linux/sizes.h>
@@ -69,14 +71,18 @@
#define TFTP_BLOCK_SIZE 512 /* default TFTP block size */
#define TFTP_MTU_SIZE 1432 /* MTU based block size */
+#define TFTP_MAX_WINDOW_SIZE CONFIG_FS_TFTP_MAX_WINDOW_SIZE
#define TFTP_ERR_RESEND 1
+static int g_tftp_window_size = DIV_ROUND_UP(TFTP_MAX_WINDOW_SIZE, 2);
+
struct file_priv {
struct net_connection *tftp_con;
int push;
uint16_t block;
uint16_t last_block;
+ uint16_t ack_block;
int state;
int err;
char *filename;
@@ -86,7 +92,7 @@ struct file_priv {
struct kfifo *fifo;
void *buf;
int blocksize;
- int block_requested;
+ unsigned int windowsize;
bool is_getattr;
};
@@ -118,6 +124,7 @@ static int tftp_send(struct file_priv *priv)
int len = 0;
uint16_t *s;
unsigned char *pkt = net_udp_get_payload(priv->tftp_con);
+ unsigned int window_size;
int ret;
pr_vdebug("%s: state %s\n", __func__, tftp_states[priv->state]);
@@ -125,6 +132,15 @@ static int tftp_send(struct file_priv *priv)
switch (priv->state) {
case STATE_RRQ:
case STATE_WRQ:
+ if (priv->push || priv->is_getattr)
+ /* atm, windowsize is supported only for RRQ and there
+ is no need to request a full window when we are
+ just looking up file attributes */
+ window_size = 1;
+ else
+ window_size = min_t(unsigned int, g_tftp_window_size,
+ TFTP_MAX_WINDOW_SIZE);
+
xp = pkt;
s = (uint16_t *)pkt;
if (priv->state == STATE_RRQ)
@@ -152,18 +168,24 @@ static int tftp_send(struct file_priv *priv)
operations, */
priv->is_getattr ? TFTP_BLOCK_SIZE : TFTP_MTU_SIZE);
pkt++;
+
+ if (window_size > 1)
+ pkt += sprintf((unsigned char *)pkt,
+ "windowsize%c%u%c",
+ '\0', window_size,
+ '\0');
+
len = pkt - xp;
break;
case STATE_RDATA:
- if (priv->block == priv->block_requested)
- return 0;
case STATE_OACK:
xp = pkt;
s = (uint16_t *)pkt;
*s++ = htons(TFTP_ACK);
- *s++ = htons(priv->block);
- priv->block_requested = priv->block;
+ *s++ = htons(priv->last_block);
+ priv->ack_block = priv->last_block;
+ priv->ack_block += priv->windowsize;
pkt = (unsigned char *)s;
len = pkt - xp;
break;
@@ -206,7 +228,6 @@ static int tftp_poll(struct file_priv *priv)
if (is_timeout(priv->resend_timeout, TFTP_RESEND_TIMEOUT)) {
printf("T ");
priv->resend_timeout = get_time_ns();
- priv->block_requested = -1;
return TFTP_ERR_RESEND;
}
@@ -243,11 +264,15 @@ static int tftp_parse_oack(struct file_priv *priv, unsigned char *pkt, int len)
priv->filesize = simple_strtoull(val, NULL, 10);
if (!strcmp(opt, "blksize"))
priv->blocksize = simple_strtoul(val, NULL, 10);
+ if (!strcmp(opt, "windowsize"))
+ priv->windowsize = simple_strtoul(val, NULL, 10);
pr_debug("OACK opt: %s val: %s\n", opt, val);
s = val + strlen(val) + 1;
}
- if (priv->blocksize > TFTP_MTU_SIZE) {
+ if (priv->blocksize > TFTP_MTU_SIZE ||
+ priv->windowsize > TFTP_MAX_WINDOW_SIZE ||
+ priv->windowsize == 0) {
pr_warn("tftp: invalid oack response\n");
return -EINVAL;
}
@@ -362,8 +387,7 @@ static void tftp_recv(struct file_priv *priv,
}
}
- if (priv->block == priv->last_block)
- /* Same block again; ignore it. */
+ if (priv->block != (uint16_t)(priv->last_block + 1))
break;
tftp_timer_reset(priv);
@@ -402,7 +426,9 @@ static void tftp_handler(void *ctx, char *packet, unsigned len)
static int tftp_start_transfer(struct file_priv *priv)
{
- priv->fifo = kfifo_alloc(priv->blocksize);
+ /* multiplication is safe; both operands where checked in tftp_parse_oack()
+ and are small integers */
+ priv->fifo = kfifo_alloc(priv->blocksize * priv->windowsize);
if (!priv->fifo)
return -ENOMEM;
@@ -422,7 +448,7 @@ static int tftp_start_transfer(struct file_priv *priv)
} else {
/* send ACK */
priv->state = STATE_OACK;
- priv->block = 0;
+ priv->last_block = 0;
tftp_send(priv);
}
@@ -458,7 +484,7 @@ static struct file_priv *tftp_do_open(struct device_d *dev,
priv->err = -EINVAL;
priv->filename = dpath(dentry, fsdev->vfsmount.mnt_root);
priv->blocksize = TFTP_BLOCK_SIZE;
- priv->block_requested = -1;
+ priv->windowsize = 1;
priv->is_getattr = is_getattr;
parseopt_hu(fsdev->options, "port", &port);
@@ -617,7 +643,7 @@ static int tftp_read(struct device_d *dev, FILE *f, void *buf, size_t insize)
if (priv->state == STATE_DONE)
return outsize;
- if (kfifo_len(priv->fifo) == 0)
+ if (priv->last_block == priv->ack_block)
tftp_send(priv);
ret = tftp_poll(priv);
@@ -809,6 +835,8 @@ static struct fs_driver_d tftp_driver = {
static int tftp_init(void)
{
+ globalvar_add_simple_int("tftp.windowsize", &g_tftp_window_size, "%u");
+
return register_fs_driver(&tftp_driver);
}
coredevice_initcall(tftp_init);
--
2.37.1
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