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[PATCH] uml: Remove ubd-mmap support

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Finally rip out the ubd-mmap code, which turned out to be broken by design.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Dike 2005-05-20 13:59:11 -07:00 committed by Linus Torvalds
parent 9b67a3c4cd
commit 7b9014c1da
2 changed files with 3 additions and 322 deletions
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296
arch/um/drivers/ubd_kern.c
View file

@ -55,7 +55,7 @@
#include "mem_kern.h"
#include "cow.h"
enum ubd_req { UBD_READ, UBD_WRITE, UBD_MMAP };
enum ubd_req { UBD_READ, UBD_WRITE };
struct io_thread_req {
enum ubd_req op;
@ -68,8 +68,6 @@ struct io_thread_req {
unsigned long sector_mask;
unsigned long long cow_offset;
unsigned long bitmap_words[2];
int map_fd;
unsigned long long map_offset;
int error;
};
@ -122,10 +120,6 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
#define MAX_DEV (8)
/* Changed in early boot */
static int ubd_do_mmap = 0;
#define UBD_MMAP_BLOCK_SIZE PAGE_SIZE
static struct block_device_operations ubd_blops = {
.owner = THIS_MODULE,
.open = ubd_open,
@ -175,12 +169,6 @@ struct ubd {
int no_cow;
struct cow cow;
struct platform_device pdev;
int map_writes;
int map_reads;
int nomap_writes;
int nomap_reads;
int write_maps;
};
#define DEFAULT_COW { \
@ -200,11 +188,6 @@ struct ubd {
.openflags = OPEN_FLAGS, \
.no_cow = 0, \
.cow = DEFAULT_COW, \
.map_writes = 0, \
.map_reads = 0, \
.nomap_writes = 0, \
.nomap_reads = 0, \
.write_maps = 0, \
}
struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
@ -314,13 +297,6 @@ static int ubd_setup_common(char *str, int *index_out)
int major;
str++;
if(!strcmp(str, "mmap")){
CHOOSE_MODE(printk("mmap not supported by the ubd "
"driver in tt mode\n"),
ubd_do_mmap = 1);
return(0);
}
if(!strcmp(str, "sync")){
global_openflags = of_sync(global_openflags);
return(0);
@ -524,7 +500,7 @@ static void ubd_handler(void)
{
struct io_thread_req req;
struct request *rq = elv_next_request(ubd_queue);
int n, err;
int n;
do_ubd = NULL;
intr_count++;
@ -538,19 +514,6 @@ static void ubd_handler(void)
return;
}
if((req.op != UBD_MMAP) &&
((req.offset != ((__u64) (rq->sector)) << 9) ||
(req.length != (rq->current_nr_sectors) << 9)))
panic("I/O op mismatch");
if(req.map_fd != -1){
err = physmem_subst_mapping(req.buffer, req.map_fd,
req.map_offset, 1);
if(err)
printk("ubd_handler - physmem_subst_mapping failed, "
"err = %d\n", -err);
}
ubd_finish(rq, req.error);
reactivate_fd(thread_fd, UBD_IRQ);
do_ubd_request(ubd_queue);
@ -583,14 +546,10 @@ static int ubd_file_size(struct ubd *dev, __u64 *size_out)
static void ubd_close(struct ubd *dev)
{
if(ubd_do_mmap)
physmem_forget_descriptor(dev->fd);
os_close_file(dev->fd);
if(dev->cow.file == NULL)
return;
if(ubd_do_mmap)
physmem_forget_descriptor(dev->cow.fd);
os_close_file(dev->cow.fd);
vfree(dev->cow.bitmap);
dev->cow.bitmap = NULL;
@ -1010,94 +969,13 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
req->bitmap_words, bitmap_len);
}
static int mmap_fd(struct request *req, struct ubd *dev, __u64 offset)
{
__u64 sector;
unsigned char *bitmap;
int bit, i;
/* mmap must have been requested on the command line */
if(!ubd_do_mmap)
return(-1);
/* The buffer must be page aligned */
if(((unsigned long) req->buffer % UBD_MMAP_BLOCK_SIZE) != 0)
return(-1);
/* The request must be a page long */
if((req->current_nr_sectors << 9) != PAGE_SIZE)
return(-1);
if(dev->cow.file == NULL)
return(dev->fd);
sector = offset >> 9;
bitmap = (unsigned char *) dev->cow.bitmap;
bit = ubd_test_bit(sector, bitmap);
for(i = 1; i < req->current_nr_sectors; i++){
if(ubd_test_bit(sector + i, bitmap) != bit)
return(-1);
}
if(bit || (rq_data_dir(req) == WRITE))
offset += dev->cow.data_offset;
/* The data on disk must be page aligned */
if((offset % UBD_MMAP_BLOCK_SIZE) != 0)
return(-1);
return(bit ? dev->fd : dev->cow.fd);
}
static int prepare_mmap_request(struct ubd *dev, int fd, __u64 offset,
struct request *req,
struct io_thread_req *io_req)
{
int err;
if(rq_data_dir(req) == WRITE){
/* Writes are almost no-ops since the new data is already in the
* host page cache
*/
dev->map_writes++;
if(dev->cow.file != NULL)
cowify_bitmap(io_req->offset, io_req->length,
&io_req->sector_mask, &io_req->cow_offset,
dev->cow.bitmap, dev->cow.bitmap_offset,
io_req->bitmap_words,
dev->cow.bitmap_len);
}
else {
int w;
if((dev->cow.file != NULL) && (fd == dev->cow.fd))
w = 0;
else w = dev->openflags.w;
if((dev->cow.file != NULL) && (fd == dev->fd))
offset += dev->cow.data_offset;
err = physmem_subst_mapping(req->buffer, fd, offset, w);
if(err){
printk("physmem_subst_mapping failed, err = %d\n",
-err);
return(1);
}
dev->map_reads++;
}
io_req->op = UBD_MMAP;
io_req->buffer = req->buffer;
return(0);
}
/* Called with ubd_io_lock held */
static int prepare_request(struct request *req, struct io_thread_req *io_req)
{
struct gendisk *disk = req->rq_disk;
struct ubd *dev = disk->private_data;
__u64 offset;
int len, fd;
int len;
if(req->rq_status == RQ_INACTIVE) return(1);
@ -1114,34 +992,12 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
io_req->fds[1] = dev->fd;
io_req->map_fd = -1;
io_req->cow_offset = -1;
io_req->offset = offset;
io_req->length = len;
io_req->error = 0;
io_req->sector_mask = 0;
fd = mmap_fd(req, dev, io_req->offset);
if(fd > 0){
/* If mmapping is otherwise OK, but the first access to the
* page is a write, then it's not mapped in yet. So we have
* to write the data to disk first, then we can map the disk
* page in and continue normally from there.
*/
if((rq_data_dir(req) == WRITE) && !is_remapped(req->buffer)){
io_req->map_fd = dev->fd;
io_req->map_offset = io_req->offset +
dev->cow.data_offset;
dev->write_maps++;
}
else return(prepare_mmap_request(dev, fd, io_req->offset, req,
io_req));
}
if(rq_data_dir(req) == READ)
dev->nomap_reads++;
else dev->nomap_writes++;
io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
io_req->offsets[0] = 0;
io_req->offsets[1] = dev->cow.data_offset;
@ -1229,143 +1085,6 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
return(-EINVAL);
}
static int ubd_check_remapped(int fd, unsigned long address, int is_write,
__u64 offset)
{
__u64 bitmap_offset;
unsigned long new_bitmap[2];
int i, err, n;
/* If it's not a write access, we can't do anything about it */
if(!is_write)
return(0);
/* We have a write */
for(i = 0; i < sizeof(ubd_dev) / sizeof(ubd_dev[0]); i++){
struct ubd *dev = &ubd_dev[i];
if((dev->fd != fd) && (dev->cow.fd != fd))
continue;
/* It's a write to a ubd device */
/* This should be impossible now */
if(!dev->openflags.w){
/* It's a write access on a read-only device - probably
* shouldn't happen. If the kernel is trying to change
* something with no intention of writing it back out,
* then this message will clue us in that this needs
* fixing
*/
printk("Write access to mapped page from readonly ubd "
"device %d\n", i);
return(0);
}
/* It's a write to a writeable ubd device - it must be COWed
* because, otherwise, the page would have been mapped in
* writeable
*/
if(!dev->cow.file)
panic("Write fault on writeable non-COW ubd device %d",
i);
/* It should also be an access to the backing file since the
* COW pages should be mapped in read-write
*/
if(fd == dev->fd)
panic("Write fault on a backing page of ubd "
"device %d\n", i);
/* So, we do the write, copying the backing data to the COW
* file...
*/
err = os_seek_file(dev->fd, offset + dev->cow.data_offset);
if(err < 0)
panic("Couldn't seek to %lld in COW file of ubd "
"device %d, err = %d",
offset + dev->cow.data_offset, i, -err);
n = os_write_file(dev->fd, (void *) address, PAGE_SIZE);
if(n != PAGE_SIZE)
panic("Couldn't copy data to COW file of ubd "
"device %d, err = %d", i, -n);
/* ... updating the COW bitmap... */
cowify_bitmap(offset, PAGE_SIZE, NULL, &bitmap_offset,
dev->cow.bitmap, dev->cow.bitmap_offset,
new_bitmap, dev->cow.bitmap_len);
err = os_seek_file(dev->fd, bitmap_offset);
if(err < 0)
panic("Couldn't seek to %lld in COW file of ubd "
"device %d, err = %d", bitmap_offset, i, -err);
n = os_write_file(dev->fd, new_bitmap, sizeof(new_bitmap));
if(n != sizeof(new_bitmap))
panic("Couldn't update bitmap of ubd device %d, "
"err = %d", i, -n);
/* Maybe we can map the COW page in, and maybe we can't. If
* it is a pre-V3 COW file, we can't, since the alignment will
* be wrong. If it is a V3 or later COW file which has been
* moved to a system with a larger page size, then maybe we
* can't, depending on the exact location of the page.
*/
offset += dev->cow.data_offset;
/* Remove the remapping, putting the original anonymous page
* back. If the COW file can be mapped in, that is done.
* Otherwise, the COW page is read in.
*/
if(!physmem_remove_mapping((void *) address))
panic("Address 0x%lx not remapped by ubd device %d",
address, i);
if((offset % UBD_MMAP_BLOCK_SIZE) == 0)
physmem_subst_mapping((void *) address, dev->fd,
offset, 1);
else {
err = os_seek_file(dev->fd, offset);
if(err < 0)
panic("Couldn't seek to %lld in COW file of "
"ubd device %d, err = %d", offset, i,
-err);
n = os_read_file(dev->fd, (void *) address, PAGE_SIZE);
if(n != PAGE_SIZE)
panic("Failed to read page from offset %llx of "
"COW file of ubd device %d, err = %d",
offset, i, -n);
}
return(1);
}
/* It's not a write on a ubd device */
return(0);
}
static struct remapper ubd_remapper = {
.list = LIST_HEAD_INIT(ubd_remapper.list),
.proc = ubd_check_remapped,
};
static int ubd_remapper_setup(void)
{
if(ubd_do_mmap)
register_remapper(&ubd_remapper);
return(0);
}
__initcall(ubd_remapper_setup);
static int same_backing_files(char *from_cmdline, char *from_cow, char *cow)
{
struct uml_stat buf1, buf2;
@ -1568,15 +1287,6 @@ void do_io(struct io_thread_req *req)
int err;
__u64 off;
if(req->op == UBD_MMAP){
/* Touch the page to force the host to do any necessary IO to
* get it into memory
*/
n = *((volatile int *) req->buffer);
req->error = update_bitmap(req);
return;
}
nsectors = req->length / req->sectorsize;
start = 0;
do {

29
arch/um/kernel/trap_kern.c
View file

@ -107,33 +107,6 @@ int handle_page_fault(unsigned long address, unsigned long ip,
goto out;
}
LIST_HEAD(physmem_remappers);
void register_remapper(struct remapper *info)
{
list_add(&info->list, &physmem_remappers);
}
static int check_remapped_addr(unsigned long address, int is_write)
{
struct remapper *remapper;
struct list_head *ele;
__u64 offset;
int fd;
fd = phys_mapping(__pa(address), &offset);
if(fd == -1)
return(0);
list_for_each(ele, &physmem_remappers){
remapper = list_entry(ele, struct remapper, list);
if((*remapper->proc)(fd, address, is_write, offset))
return(1);
}
return(0);
}
/*
* We give a *copy* of the faultinfo in the regs to segv.
* This must be done, since nesting SEGVs could overwrite
@ -152,8 +125,6 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
flush_tlb_kernel_vm();
return(0);
}
else if(check_remapped_addr(address & PAGE_MASK, is_write))
return(0);
else if(current->mm == NULL)
panic("Segfault with no mm");
err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);