[PATCH 11/16] UML - Allow ubd devices to be shared in a cluster

From: Jeff Dike
Date: Fri Mar 24 2006 - 13:13:16 EST

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This adds a 'c' option to the ubd switch which turns off host file locking
so that the device can be shared, as with a cluster.
There's also some whitespace cleanup while I was in this file.

Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxx>

Index: linux-2.6.16/arch/um/drivers/ubd_kern.c
===================================================================
--- linux-2.6.16.orig/arch/um/drivers/ubd_kern.c 2006-03-23 17:15:05.000000000 -0500
+++ linux-2.6.16/arch/um/drivers/ubd_kern.c 2006-03-23 17:37:47.000000000 -0500
@@ -1,4 +1,4 @@
-/*
+/*
* Copyright (C) 2000 Jeff Dike (jdike@xxxxxxxxxx)
* Licensed under the GPL
*/
@@ -71,7 +71,7 @@ struct io_thread_req {
int error;
};

-extern int open_ubd_file(char *file, struct openflags *openflags,
+extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
char **backing_file_out, int *bitmap_offset_out,
unsigned long *bitmap_len_out, int *data_offset_out,
int *create_cow_out);
@@ -137,7 +137,7 @@ static int fake_major = MAJOR_NR;

static struct gendisk *ubd_gendisk[MAX_DEV];
static struct gendisk *fake_gendisk[MAX_DEV];
-
+
#ifdef CONFIG_BLK_DEV_UBD_SYNC
#define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
.cl = 1 })
@@ -168,6 +168,7 @@ struct ubd {
__u64 size;
struct openflags boot_openflags;
struct openflags openflags;
+ int shared;
int no_cow;
struct cow cow;
struct platform_device pdev;
@@ -189,6 +190,7 @@ struct ubd {
.boot_openflags = OPEN_FLAGS, \
.openflags = OPEN_FLAGS, \
.no_cow = 0, \
+ .shared = 0, \
.cow = DEFAULT_COW, \
}

@@ -305,7 +307,7 @@ static int ubd_setup_common(char *str, i
}
major = simple_strtoul(str, &end, 0);
if((*end != '\0') || (end == str)){
- printk(KERN_ERR
+ printk(KERN_ERR
"ubd_setup : didn't parse major number\n");
return(1);
}
@@ -316,7 +318,7 @@ static int ubd_setup_common(char *str, i
printk(KERN_ERR "Can't assign a fake major twice\n");
goto out1;
}
-
+
fake_major = major;

printk(KERN_INFO "Setting extra ubd major number to %d\n",
@@ -351,7 +353,7 @@ static int ubd_setup_common(char *str, i
if (index_out)
*index_out = n;

- for (i = 0; i < 4; i++) {
+ for (i = 0; i < sizeof("rscd="); i++) {
switch (*str) {
case 'r':
flags.w = 0;
@@ -362,11 +364,14 @@ static int ubd_setup_common(char *str, i
case 'd':
dev->no_cow = 1;
break;
+ case 'c':
+ dev->shared = 1;
+ break;
case '=':
str++;
goto break_loop;
default:
- printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r,s or d)\n");
+ printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r, s, c, or d)\n");
goto out;
}
str++;
@@ -515,7 +520,7 @@ static void ubd_handler(void)
spin_unlock(&ubd_io_lock);
return;
}
-
+
ubd_finish(rq, req.error);
reactivate_fd(thread_fd, UBD_IRQ);
do_ubd_request(ubd_queue);
@@ -532,7 +537,7 @@ static int io_pid = -1;

void kill_io_thread(void)
{
- if(io_pid != -1)
+ if(io_pid != -1)
os_kill_process(io_pid, 1);
}

@@ -567,14 +572,15 @@ static int ubd_open_dev(struct ubd *dev)
create_cow = 0;
create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
back_ptr = dev->no_cow ? NULL : &dev->cow.file;
- dev->fd = open_ubd_file(dev->file, &dev->openflags, back_ptr,
- &dev->cow.bitmap_offset, &dev->cow.bitmap_len,
- &dev->cow.data_offset, create_ptr);
+ dev->fd = open_ubd_file(dev->file, &dev->openflags, dev->shared,
+ back_ptr, &dev->cow.bitmap_offset,
+ &dev->cow.bitmap_len, &dev->cow.data_offset,
+ create_ptr);

if((dev->fd == -ENOENT) && create_cow){
- dev->fd = create_cow_file(dev->file, dev->cow.file,
+ dev->fd = create_cow_file(dev->file, dev->cow.file,
dev->openflags, 1 << 9, PAGE_SIZE,
- &dev->cow.bitmap_offset,
+ &dev->cow.bitmap_offset,
&dev->cow.bitmap_len,
&dev->cow.data_offset);
if(dev->fd >= 0){
@@ -598,16 +604,16 @@ static int ubd_open_dev(struct ubd *dev)
}
flush_tlb_kernel_vm();

- err = read_cow_bitmap(dev->fd, dev->cow.bitmap,
- dev->cow.bitmap_offset,
+ err = read_cow_bitmap(dev->fd, dev->cow.bitmap,
+ dev->cow.bitmap_offset,
dev->cow.bitmap_len);
if(err < 0)
goto error;

flags = dev->openflags;
flags.w = 0;
- err = open_ubd_file(dev->cow.file, &flags, NULL, NULL, NULL,
- NULL, NULL);
+ err = open_ubd_file(dev->cow.file, &flags, dev->shared, NULL,
+ NULL, NULL, NULL, NULL);
if(err < 0) goto error;
dev->cow.fd = err;
}
@@ -685,11 +691,11 @@ static int ubd_add(int n)
dev->size = ROUND_BLOCK(dev->size);

err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
- if(err)
+ if(err)
goto out_close;
-
+
if(fake_major != MAJOR_NR)
- ubd_new_disk(fake_major, dev->size, n,
+ ubd_new_disk(fake_major, dev->size, n,
&fake_gendisk[n]);

/* perhaps this should also be under the "if (fake_major)" above */
@@ -854,7 +860,7 @@ int ubd_init(void)
return -1;
}
platform_driver_register(&ubd_driver);
- for (i = 0; i < MAX_DEV; i++)
+ for (i = 0; i < MAX_DEV; i++)
ubd_add(i);
return 0;
}
@@ -872,16 +878,16 @@ int ubd_driver_init(void){
* enough. So use anyway the io thread. */
}
stack = alloc_stack(0, 0);
- io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
+ io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
&thread_fd);
if(io_pid < 0){
- printk(KERN_ERR
+ printk(KERN_ERR
"ubd : Failed to start I/O thread (errno = %d) - "
"falling back to synchronous I/O\n", -io_pid);
io_pid = -1;
return(0);
}
- err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
+ err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
SA_INTERRUPT, "ubd", ubd_dev);
if(err != 0)
printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
@@ -978,7 +984,7 @@ static void cowify_req(struct io_thread_
if(req->op == UBD_READ) {
for(i = 0; i < req->length >> 9; i++){
if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
- ubd_set_bit(i, (unsigned char *)
+ ubd_set_bit(i, (unsigned char *)
&req->sector_mask);
}
}
@@ -999,7 +1005,7 @@ static int prepare_request(struct reques

/* This should be impossible now */
if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
- printk("Write attempted on readonly ubd device %s\n",
+ printk("Write attempted on readonly ubd device %s\n",
disk->disk_name);
end_request(req, 0);
return(1);
@@ -1182,7 +1188,7 @@ int read_cow_bitmap(int fd, void *buf, i
return(0);
}

-int open_ubd_file(char *file, struct openflags *openflags,
+int open_ubd_file(char *file, struct openflags *openflags, int shared,
char **backing_file_out, int *bitmap_offset_out,
unsigned long *bitmap_len_out, int *data_offset_out,
int *create_cow_out)
@@ -1206,10 +1212,14 @@ int open_ubd_file(char *file, struct ope
return fd;
}

- err = os_lock_file(fd, openflags->w);
- if(err < 0){
- printk("Failed to lock '%s', err = %d\n", file, -err);
- goto out_close;
+ if(shared)
+ printk("Not locking \"%s\" on the host\n", file);
+ else {
+ err = os_lock_file(fd, openflags->w);
+ if(err < 0){
+ printk("Failed to lock '%s', err = %d\n", file, -err);
+ goto out_close;
+ }
}

/* Succesful return case! */
@@ -1260,7 +1270,7 @@ int create_cow_file(char *cow_file, char
int err, fd;

flags.c = 1;
- fd = open_ubd_file(cow_file, &flags, NULL, NULL, NULL, NULL, NULL);
+ fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
if(fd < 0){
err = fd;
printk("Open of COW file '%s' failed, errno = %d\n", cow_file,

-
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Next message: Jeff Dike: "[PATCH 9/16] UML - Move tty logging to os-Linux"
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