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/*
* iobuf.c
*
* Keep track of the general-purpose IO-buffer structures used to track
* abstract kernel-space io buffers.
*
*/
#include <linux/iobuf.h>
#include <linux/malloc.h>
#include <linux/slab.h>
static kmem_cache_t *kiobuf_cachep;
/*
* The default IO completion routine for kiobufs: just wake up
* the kiobuf, nothing more.
*/
void simple_wakeup_kiobuf(struct kiobuf *kiobuf)
{
wake_up(&kiobuf->wait_queue);
}
void __init kiobuf_init(void)
{
kiobuf_cachep = kmem_cache_create("kiobuf",
sizeof(struct kiobuf),
0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if(!kiobuf_cachep)
panic("Cannot create kernel iobuf cache\n");
}
int alloc_kiovec(int nr, struct kiobuf **bufp)
{
int i;
struct kiobuf *iobuf;
for (i = 0; i < nr; i++) {
iobuf = kmem_cache_alloc(kiobuf_cachep, SLAB_KERNEL);
if (!iobuf) {
free_kiovec(i, bufp);
return -ENOMEM;
}
memset(iobuf, 0, sizeof(*iobuf));
init_waitqueue_head(&iobuf->wait_queue);
iobuf->end_io = simple_wakeup_kiobuf;
iobuf->array_len = KIO_STATIC_PAGES;
iobuf->pagelist = iobuf->page_array;
iobuf->maplist = iobuf->map_array;
*bufp++ = iobuf;
}
return 0;
}
void free_kiovec(int nr, struct kiobuf **bufp)
{
int i;
struct kiobuf *iobuf;
for (i = 0; i < nr; i++) {
iobuf = bufp[i];
if (iobuf->array_len > KIO_STATIC_PAGES) {
kfree (iobuf->pagelist);
kfree (iobuf->maplist);
}
kmem_cache_free(kiobuf_cachep, bufp[i]);
}
}
int expand_kiobuf(struct kiobuf *iobuf, int wanted)
{
unsigned long * pagelist;
struct page ** maplist;
if (iobuf->array_len >= wanted)
return 0;
pagelist = (unsigned long *)
kmalloc(wanted * sizeof(unsigned long), GFP_KERNEL);
if (!pagelist)
return -ENOMEM;
maplist = (struct page **)
kmalloc(wanted * sizeof(struct page **), GFP_KERNEL);
if (!maplist) {
kfree(pagelist);
return -ENOMEM;
}
/* Did it grow while we waited? */
if (iobuf->array_len >= wanted) {
kfree(pagelist);
kfree(maplist);
return 0;
}
memcpy (pagelist, iobuf->pagelist, wanted * sizeof(unsigned long));
memcpy (maplist, iobuf->maplist, wanted * sizeof(struct page **));
if (iobuf->array_len > KIO_STATIC_PAGES) {
kfree (iobuf->pagelist);
kfree (iobuf->maplist);
}
iobuf->pagelist = pagelist;
iobuf->maplist = maplist;
iobuf->array_len = wanted;
return 0;
}
void kiobuf_wait_for_io(struct kiobuf *kiobuf)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
add_wait_queue(&kiobuf->wait_queue, &wait);
repeat:
run_task_queue(&tq_disk);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (atomic_read(&kiobuf->io_count) != 0) {
schedule();
goto repeat;
}
tsk->state = TASK_RUNNING;
remove_wait_queue(&kiobuf->wait_queue, &wait);
}
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