static int rw_swap_page_base(int rw, swp_entry_t entry, struct page *page)
{
unsigned long offset;
int zones[PAGE_SIZE/512];
int zones_used;
kdev_t dev = 0;
int block_size;
struct inode *swapf = 0;
if (rw == READ) {
ClearPageUptodate(page);
kstat.pswpin++;
} else
kstat.pswpout++;
get_swaphandle_info(entry, &offset, &dev, &swapf);
if (dev) {
zones[0] = offset;
zones_used = 1;
block_size = PAGE_SIZE;
} else if (swapf) {
int i, j;
unsigned int block = offset
<< (PAGE_SHIFT - swapf->i_sb->s_blocksize_bits);
block_size = swapf->i_sb->s_blocksize;
for (i=0, j=0; j< PAGE_SIZE ; i++, j += block_size)
if (!(zones[i] = bmap(swapf,block++))) {
printk("rw_swap_page: bad swap file\n");
return 0;
}
zones_used = i;
dev = swapf->i_dev;
} else {
return 0;
}
/* block_size == PAGE_SIZE/zones_used */
brw_page(rw, page, dev, zones, block_size);
/* Note! For consistency we do all of the logic,
* decrementing the page count, and unlocking the page in the
* swap lock map - in the IO completion handler.
*/
return 1;
}
/*
* Swap partitions are now read via brw_page. ll_rw_page is an
* asynchronous function now --- we must call wait_on_page afterwards
* if synchronous IO is required.
*/
void ll_rw_page(int rw, kdev_t dev, unsigned long page, char * buffer)
{
int block = page;
switch (rw) {
case READ:
break;
case WRITE:
if (is_read_only(dev)) {
printk("Can't page to read-only device %s\n",
kdevname(dev));
return;
}
break;
default:
panic("ll_rw_page: bad block dev cmd, must be R/W");
}
if (set_bit(PG_locked, &mem_map[MAP_NR(buffer)].flags))
panic ("ll_rw_page: page already locked");
brw_page(rw, (unsigned long) buffer, dev, &block, PAGE_SIZE, 0);
}
static void rw_swap_page_base(int rw, unsigned long entry, struct page *page, int wait)
{
unsigned long type, offset;
struct swap_info_struct * p;
int zones[PAGE_SIZE/512];
int zones_used;
kdev_t dev = 0;
int block_size;
#ifdef DEBUG_SWAP
printk ("DebugVM: %s_swap_page entry %08lx, page %p (count %d), %s\n",
(rw == READ) ? "read" : "write",
entry, (char *) page_address(page), atomic_read(&page->count),
wait ? "wait" : "nowait");
#endif
type = SWP_TYPE(entry);
if (type >= nr_swapfiles) {
printk("Internal error: bad swap-device\n");
return;
}
/* Don't allow too many pending pages in flight.. */
if (atomic_read(&nr_async_pages) > pager_daemon.swap_cluster)
wait = 1;
p = &swap_info[type];
offset = SWP_OFFSET(entry);
if (offset >= p->max) {
printk("rw_swap_page: weirdness\n");
return;
}
if (p->swap_map && !p->swap_map[offset]) {
printk(KERN_ERR "rw_swap_page: "
"Trying to %s unallocated swap (%08lx)\n",
(rw == READ) ? "read" : "write", entry);
return;
}
if (!(p->flags & SWP_USED)) {
printk(KERN_ERR "rw_swap_page: "
"Trying to swap to unused swap-device\n");
return;
}
if (!PageLocked(page)) {
printk(KERN_ERR "VM: swap page is unlocked\n");
return;
}
if (PageSwapCache(page)) {
/* Make sure we are the only process doing I/O with this swap page. */
if (test_and_set_bit(offset, p->swap_lockmap))
{
struct wait_queue __wait;
__wait.task = current;
add_wait_queue(&lock_queue, &__wait);
for (;;) {
current->state = TASK_UNINTERRUPTIBLE;
mb();
if (!test_and_set_bit(offset, p->swap_lockmap))
break;
run_task_queue(&tq_disk);
schedule();
}
current->state = TASK_RUNNING;
remove_wait_queue(&lock_queue, &__wait);
}
/*
* Make sure that we have a swap cache association for this
* page. We need this to find which swap page to unlock once
* the swap IO has completed to the physical page. If the page
* is not already in the cache, just overload the offset entry
* as if it were: we are not allowed to manipulate the inode
* hashing for locked pages.
*/
if (page->offset != entry) {
printk ("swap entry mismatch");
return;
}
}
if (rw == READ) {
clear_bit(PG_uptodate, &page->flags);
kstat.pswpin++;
} else
kstat.pswpout++;
atomic_inc(&page->count);
if (p->swap_device) {
zones[0] = offset;
zones_used = 1;
dev = p->swap_device;
block_size = PAGE_SIZE;
} else if (p->swap_file) {
struct inode *swapf = p->swap_file->d_inode;
int i;
if (swapf->i_op->bmap == NULL
&& swapf->i_op->smap != NULL){
/*
With MS-DOS, we use msdos_smap which returns
a sector number (not a cluster or block number).
It is a patch to enable the UMSDOS project.
Other people are working on better solution.
It sounds like ll_rw_swap_file defined
its operation size (sector size) based on
PAGE_SIZE and the number of blocks to read.
So using bmap or smap should work even if
smap will require more blocks.
*/
int j;
unsigned int block = offset << 3;
for (i=0, j=0; j< PAGE_SIZE ; i++, j += 512){
if (!(zones[i] = swapf->i_op->smap(swapf,block++))) {
printk("rw_swap_page: bad swap file\n");
return;
}
}
block_size = 512;
}else{
int j;
unsigned int block = offset
<< (PAGE_SHIFT - swapf->i_sb->s_blocksize_bits);
block_size = swapf->i_sb->s_blocksize;
for (i=0, j=0; j< PAGE_SIZE ; i++, j += block_size)
if (!(zones[i] = bmap(swapf,block++))) {
printk("rw_swap_page: bad swap file\n");
return;
}
zones_used = i;
dev = swapf->i_dev;
}
} else {
printk(KERN_ERR "rw_swap_page: no swap file or device\n");
/* Do some cleaning up so if this ever happens we can hopefully
* trigger controlled shutdown.
*/
if (PageSwapCache(page)) {
if (!test_and_clear_bit(offset,p->swap_lockmap))
printk("swap_after_unlock_page: lock already cleared\n");
wake_up(&lock_queue);
}
atomic_dec(&page->count);
return;
}
if (!wait) {
set_bit(PG_decr_after, &page->flags);
atomic_inc(&nr_async_pages);
}
if (PageSwapCache(page)) {
/* only lock/unlock swap cache pages! */
set_bit(PG_swap_unlock_after, &page->flags);
}
set_bit(PG_free_after, &page->flags);
/* block_size == PAGE_SIZE/zones_used */
brw_page(rw, page, dev, zones, block_size, 0);
/* Note! For consistency we do all of the logic,
* decrementing the page count, and unlocking the page in the
* swap lock map - in the IO completion handler.
*/
if (!wait)
return;
wait_on_page(page);
/* This shouldn't happen, but check to be sure. */
if (atomic_read(&page->count) == 0)
printk(KERN_ERR "rw_swap_page: page unused while waiting!\n");
#ifdef DEBUG_SWAP
printk ("DebugVM: %s_swap_page finished on page %p (count %d)\n",
(rw == READ) ? "read" : "write",
(char *) page_adddress(page),
atomic_read(&page->count));
#endif
}
