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dm-crypt: sort writes 

Write requests are sorted in a red-black tree structure and are submitted
in the sorted order.

In theory the sorting should be performed by the underlying disk scheduler,
however, in practice the disk scheduler accepts and sorts only 128 requests.
In order to sort more requests, we need to implement our own sorting.

CRs-fixed: 670391
Change-Id: Iffd9345fa1253f5cf2a556893ed36e08f1ac51aa
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Patch-mainline: dm-devel @ 04/05/14, 14:09
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
This commit is contained in:
Mikulas Patocka 2014-05-29 15:08:22 -07:00 committed by Joonwoo Park
parent 980c01db22
commit 364a180149
1 changed files with 35 additions and 15 deletions
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50
drivers/md/dm-crypt.c
View File

@ -21,6 +21,7 @@
#include <linux/backing-dev.h>
#include <linux/atomic.h>
#include <linux/scatterlist.h>
#include <linux/rbtree.h>
#include <asm/page.h>
#include <asm/unaligned.h>
#include <crypto/hash.h>
@ -61,7 +62,7 @@ struct dm_crypt_io {
int error;
sector_t sector;
struct list_head list;
struct rb_node rb_node;
} CRYPTO_MINALIGN_ATTR;
struct dm_crypt_request {
@ -127,7 +128,7 @@ struct crypt_config {
struct task_struct *write_thread;
wait_queue_head_t write_thread_wait;
struct list_head write_thread_list;
struct rb_root write_tree;
char *cipher;
char *cipher_string;
@ -1013,7 +1014,7 @@ static int dmcrypt_write(void *data)
{
struct crypt_config *cc = data;
while (1) {
struct list_head local_list;
struct rb_root write_tree;
struct blk_plug plug;
DECLARE_WAITQUEUE(wait, current);
@ -1021,7 +1022,7 @@ static int dmcrypt_write(void *data)
spin_lock_irq(&cc->write_thread_wait.lock);
continue_locked:
if (!list_empty(&cc->write_thread_list))
if (!RB_EMPTY_ROOT(&cc->write_tree))
goto pop_from_list;
__set_current_state(TASK_INTERRUPTIBLE);
@ -1043,20 +1044,23 @@ continue_locked:
goto continue_locked;
pop_from_list:
local_list = cc->write_thread_list;
local_list.next->prev = &local_list;
local_list.prev->next = &local_list;
INIT_LIST_HEAD(&cc->write_thread_list);
write_tree = cc->write_tree;
cc->write_tree = RB_ROOT;
spin_unlock_irq(&cc->write_thread_wait.lock);
BUG_ON(rb_parent(write_tree.rb_node));
/*
* Note: we cannot walk the tree here with rb_next because
* the structures may be freed when kcryptd_io_write is called.
*/
blk_start_plug(&plug);
do {
struct dm_crypt_io *io = container_of(local_list.next,
struct dm_crypt_io, list);
list_del(&io->list);
struct dm_crypt_io *io = rb_entry(rb_first(&write_tree),
struct dm_crypt_io, rb_node);
rb_erase(&io->rb_node, &write_tree);
kcryptd_io_write(io);
} while (!list_empty(&local_list));
} while (!RB_EMPTY_ROOT(&write_tree));
blk_finish_plug(&plug);
}
return 0;
@ -1067,6 +1071,8 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io)
struct bio *clone = io->ctx.bio_out;
struct crypt_config *cc = io->cc;
unsigned long flags;
sector_t sector;
struct rb_node **p, *parent;
if (unlikely(io->error < 0)) {
crypt_free_buffer_pages(cc, clone);
@ -1081,7 +1087,21 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io)
clone->bi_sector = cc->start + io->sector;
spin_lock_irqsave(&cc->write_thread_wait.lock, flags);
list_add_tail(&io->list, &cc->write_thread_list);
p = &cc->write_tree.rb_node;
parent = NULL;
sector = io->sector;
while (*p) {
parent = *p;
#define io_node rb_entry(parent, struct dm_crypt_io, rb_node)
if (sector < io_node->sector)
p = &io_node->rb_node.rb_left;
else
p = &io_node->rb_node.rb_right;
#undef io_node
}
rb_link_node(&io->rb_node, parent, p);
rb_insert_color(&io->rb_node, &cc->write_tree);
wake_up_locked(&cc->write_thread_wait);
spin_unlock_irqrestore(&cc->write_thread_wait.lock, flags);
}
@ -1635,7 +1655,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
init_waitqueue_head(&cc->write_thread_wait);
INIT_LIST_HEAD(&cc->write_thread_list);
cc->write_tree = RB_ROOT;
cc->write_thread = kthread_create(dmcrypt_write, cc, "dmcrypt_write");
if (IS_ERR(cc->write_thread)) {