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Date: Fri, 24 Apr 2015 09:17:26 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Ming Lin <mlin@...nel.org>
Cc: linux-kernel@...r.kernel.org,
Christoph Hellwig <hch@...radead.org>,
Kent Overstreet <kent.overstreet@...il.com>,
Jens Axboe <axboe@...nel.dk>,
Dongsu Park <dongsu.park@...fitbricks.com>,
linux-pm@...r.kernel.org, pavel@....cz, rjw@...k.pl
Subject: Re: [PATCH v3 4/4] PM: submit bio in a sane way in cases without
bio_chain
On Thu, Apr 23, 2015 at 04:04:35PM -0700, Ming Lin wrote:
> From: Kent Overstreet <kent.overstreet@...il.com>
>
> Make bio submission in kernel/power/block_io.c to properly submit
> bios also when bio_chain is not available. In that case, it's not
> necessary to handle refcount with bio_get(), but it's saner to simply
> call a predefined helper submit_bio_wait(). So call bio_get() only
> when bio_chain is given.
The patch looks correct, buth that whole code is a f****ing mess.
For one it really shouldn't mess with pages states nor abuse
end_swap_bio_read.
Something like the untested patch below should do it, but it really
needs some solid testing from people that know how to even exercise
it.
---
>From af56dde07c34b203f5c40c8864bfd55697b0aad0 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@....de>
Date: Fri, 24 Apr 2015 11:26:00 +0200
Subject: suspend: sane block I/O handling
stop abusing struct page functionality and the swap end_io handler, and
instead add a modified version of the blk-lib.c bio_batch helpers.
Also move the block I/O code into swap.c as they are directly tied into
each other.
Signed-off-by: Christoph Hellwig <hch@....de>
---
include/linux/swap.h | 1 -
kernel/power/Makefile | 3 +-
kernel/power/block_io.c | 103 -------------------------------
kernel/power/power.h | 9 ---
kernel/power/swap.c | 159 ++++++++++++++++++++++++++++++++++++------------
mm/page_io.c | 2 +-
6 files changed, 122 insertions(+), 155 deletions(-)
delete mode 100644 kernel/power/block_io.c
diff --git a/include/linux/swap.h b/include/linux/swap.h
index cee108c..3887472 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -377,7 +377,6 @@ extern void end_swap_bio_write(struct bio *bio, int err);
extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
void (*end_write_func)(struct bio *, int));
extern int swap_set_page_dirty(struct page *page);
-extern void end_swap_bio_read(struct bio *bio, int err);
int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
unsigned long nr_pages, sector_t start_block);
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 29472bf..cb880a1 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -7,8 +7,7 @@ obj-$(CONFIG_VT_CONSOLE_SLEEP) += console.o
obj-$(CONFIG_FREEZER) += process.o
obj-$(CONFIG_SUSPEND) += suspend.o
obj-$(CONFIG_PM_TEST_SUSPEND) += suspend_test.o
-obj-$(CONFIG_HIBERNATION) += hibernate.o snapshot.o swap.o user.o \
- block_io.o
+obj-$(CONFIG_HIBERNATION) += hibernate.o snapshot.o swap.o user.o
obj-$(CONFIG_PM_AUTOSLEEP) += autosleep.o
obj-$(CONFIG_PM_WAKELOCKS) += wakelock.o
diff --git a/kernel/power/block_io.c b/kernel/power/block_io.c
deleted file mode 100644
index 9a58bc2..0000000
--- a/kernel/power/block_io.c
+++ /dev/null
@@ -1,103 +0,0 @@
-/*
- * This file provides functions for block I/O operations on swap/file.
- *
- * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@....cz>
- * Copyright (C) 2006 Rafael J. Wysocki <rjw@...k.pl>
- *
- * This file is released under the GPLv2.
- */
-
-#include <linux/bio.h>
-#include <linux/kernel.h>
-#include <linux/pagemap.h>
-#include <linux/swap.h>
-
-#include "power.h"
-
-/**
- * submit - submit BIO request.
- * @rw: READ or WRITE.
- * @off physical offset of page.
- * @page: page we're reading or writing.
- * @bio_chain: list of pending biod (for async reading)
- *
- * Straight from the textbook - allocate and initialize the bio.
- * If we're reading, make sure the page is marked as dirty.
- * Then submit it and, if @bio_chain == NULL, wait.
- */
-static int submit(int rw, struct block_device *bdev, sector_t sector,
- struct page *page, struct bio **bio_chain)
-{
- const int bio_rw = rw | REQ_SYNC;
- struct bio *bio;
-
- bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
- bio->bi_iter.bi_sector = sector;
- bio->bi_bdev = bdev;
- bio->bi_end_io = end_swap_bio_read;
-
- if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
- printk(KERN_ERR "PM: Adding page to bio failed at %llu\n",
- (unsigned long long)sector);
- bio_put(bio);
- return -EFAULT;
- }
-
- lock_page(page);
- bio_get(bio);
-
- if (bio_chain == NULL) {
- submit_bio(bio_rw, bio);
- wait_on_page_locked(page);
- if (rw == READ)
- bio_set_pages_dirty(bio);
- bio_put(bio);
- } else {
- if (rw == READ)
- get_page(page); /* These pages are freed later */
- bio->bi_private = *bio_chain;
- *bio_chain = bio;
- submit_bio(bio_rw, bio);
- }
- return 0;
-}
-
-int hib_bio_read_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
-{
- return submit(READ, hib_resume_bdev, page_off * (PAGE_SIZE >> 9),
- virt_to_page(addr), bio_chain);
-}
-
-int hib_bio_write_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
-{
- return submit(WRITE, hib_resume_bdev, page_off * (PAGE_SIZE >> 9),
- virt_to_page(addr), bio_chain);
-}
-
-int hib_wait_on_bio_chain(struct bio **bio_chain)
-{
- struct bio *bio;
- struct bio *next_bio;
- int ret = 0;
-
- if (bio_chain == NULL)
- return 0;
-
- bio = *bio_chain;
- if (bio == NULL)
- return 0;
- while (bio) {
- struct page *page;
-
- next_bio = bio->bi_private;
- page = bio->bi_io_vec[0].bv_page;
- wait_on_page_locked(page);
- if (!PageUptodate(page) || PageError(page))
- ret = -EIO;
- put_page(page);
- bio_put(bio);
- bio = next_bio;
- }
- *bio_chain = NULL;
- return ret;
-}
diff --git a/kernel/power/power.h b/kernel/power/power.h
index ce9b832..caadb56 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -163,15 +163,6 @@ extern void swsusp_close(fmode_t);
extern int swsusp_unmark(void);
#endif
-/* kernel/power/block_io.c */
-extern struct block_device *hib_resume_bdev;
-
-extern int hib_bio_read_page(pgoff_t page_off, void *addr,
- struct bio **bio_chain);
-extern int hib_bio_write_page(pgoff_t page_off, void *addr,
- struct bio **bio_chain);
-extern int hib_wait_on_bio_chain(struct bio **bio_chain);
-
struct timeval;
/* kernel/power/swsusp.c */
extern void swsusp_show_speed(ktime_t, ktime_t, unsigned int, char *);
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 570aff8..8a0b64d 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -212,7 +212,84 @@ int swsusp_swap_in_use(void)
*/
static unsigned short root_swap = 0xffff;
-struct block_device *hib_resume_bdev;
+static struct block_device *hib_resume_bdev;
+
+struct hib_bio_batch {
+ atomic_t count;
+ wait_queue_head_t wait;
+ int error;
+};
+
+static void hib_init_batch(struct hib_bio_batch *hb)
+{
+ atomic_set(&hb->count, 0);
+ init_waitqueue_head(&hb->wait);
+ hb->error = 0;
+}
+
+static void hib_end_io(struct bio *bio, int error)
+{
+ struct hib_bio_batch *hb = bio->bi_private;
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct page *page = bio->bi_io_vec[0].bv_page;
+
+ if (!uptodate || error) {
+ printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
+ imajor(bio->bi_bdev->bd_inode),
+ iminor(bio->bi_bdev->bd_inode),
+ (unsigned long long)bio->bi_iter.bi_sector);
+
+ if (!error)
+ error = -EIO;
+ }
+
+ if (bio_data_dir(bio) == WRITE)
+ put_page(page);
+
+ if (error && !hb->error)
+ hb->error = error;
+ if (atomic_dec_and_test(&hb->count))
+ wake_up(&hb->wait);
+
+ bio_put(bio);
+}
+
+static int hib_submit_io(int rw, pgoff_t page_off, void *addr,
+ struct hib_bio_batch *hb)
+{
+ struct page *page = virt_to_page(addr);
+ struct bio *bio;
+ int error = 0;
+
+ bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
+ bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9);
+ bio->bi_bdev = hib_resume_bdev;
+
+ if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
+ printk(KERN_ERR "PM: Adding page to bio failed at %llu\n",
+ (unsigned long long)bio->bi_iter.bi_sector);
+ bio_put(bio);
+ return -EFAULT;
+ }
+
+ if (hb) {
+ bio->bi_end_io = hib_end_io;
+ bio->bi_private = hb;
+ atomic_inc(&hb->count);
+ submit_bio(rw, bio);
+ } else {
+ error = submit_bio_wait(rw, bio);
+ bio_put(bio);
+ }
+
+ return error;
+}
+
+static int hib_wait_io(struct hib_bio_batch *hb)
+{
+ wait_event(hb->wait, atomic_read(&hb->count) == 0);
+ return hb->error;
+}
/*
* Saving part
@@ -222,7 +299,7 @@ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
{
int error;
- hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
+ hib_submit_io(READ_SYNC, swsusp_resume_block, swsusp_header, NULL);
if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
!memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
@@ -231,7 +308,7 @@ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
swsusp_header->flags = flags;
if (flags & SF_CRC32_MODE)
swsusp_header->crc32 = handle->crc32;
- error = hib_bio_write_page(swsusp_resume_block,
+ error = hib_submit_io(WRITE_SYNC, swsusp_resume_block,
swsusp_header, NULL);
} else {
printk(KERN_ERR "PM: Swap header not found!\n");
@@ -271,10 +348,10 @@ static int swsusp_swap_check(void)
* write_page - Write one page to given swap location.
* @buf: Address we're writing.
* @offset: Offset of the swap page we're writing to.
- * @bio_chain: Link the next write BIO here
+ * @hb: bio completion batch
*/
-static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
+static int write_page(void *buf, sector_t offset, struct hib_bio_batch *hb)
{
void *src;
int ret;
@@ -282,13 +359,13 @@ static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
if (!offset)
return -ENOSPC;
- if (bio_chain) {
+ if (hb) {
src = (void *)__get_free_page(__GFP_WAIT | __GFP_NOWARN |
__GFP_NORETRY);
if (src) {
copy_page(src, buf);
} else {
- ret = hib_wait_on_bio_chain(bio_chain); /* Free pages */
+ ret = hib_wait_io(hb); /* Free pages */
if (ret)
return ret;
src = (void *)__get_free_page(__GFP_WAIT |
@@ -298,14 +375,14 @@ static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
copy_page(src, buf);
} else {
WARN_ON_ONCE(1);
- bio_chain = NULL; /* Go synchronous */
+ hb = NULL; /* Go synchronous */
src = buf;
}
}
} else {
src = buf;
}
- return hib_bio_write_page(offset, src, bio_chain);
+ return hib_submit_io(WRITE_SYNC, offset, src, hb);
}
static void release_swap_writer(struct swap_map_handle *handle)
@@ -348,7 +425,7 @@ err_close:
}
static int swap_write_page(struct swap_map_handle *handle, void *buf,
- struct bio **bio_chain)
+ struct hib_bio_batch *hb)
{
int error = 0;
sector_t offset;
@@ -356,7 +433,7 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
if (!handle->cur)
return -EINVAL;
offset = alloc_swapdev_block(root_swap);
- error = write_page(buf, offset, bio_chain);
+ error = write_page(buf, offset, hb);
if (error)
return error;
handle->cur->entries[handle->k++] = offset;
@@ -365,15 +442,15 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
if (!offset)
return -ENOSPC;
handle->cur->next_swap = offset;
- error = write_page(handle->cur, handle->cur_swap, bio_chain);
+ error = write_page(handle->cur, handle->cur_swap, hb);
if (error)
goto out;
clear_page(handle->cur);
handle->cur_swap = offset;
handle->k = 0;
- if (bio_chain && low_free_pages() <= handle->reqd_free_pages) {
- error = hib_wait_on_bio_chain(bio_chain);
+ if (hb && low_free_pages() <= handle->reqd_free_pages) {
+ error = hib_wait_io(hb);
if (error)
goto out;
/*
@@ -445,23 +522,24 @@ static int save_image(struct swap_map_handle *handle,
int ret;
int nr_pages;
int err2;
- struct bio *bio;
+ struct hib_bio_batch hb;
ktime_t start;
ktime_t stop;
+ hib_init_batch(&hb);
+
printk(KERN_INFO "PM: Saving image data pages (%u pages)...\n",
nr_to_write);
m = nr_to_write / 10;
if (!m)
m = 1;
nr_pages = 0;
- bio = NULL;
start = ktime_get();
while (1) {
ret = snapshot_read_next(snapshot);
if (ret <= 0)
break;
- ret = swap_write_page(handle, data_of(*snapshot), &bio);
+ ret = swap_write_page(handle, data_of(*snapshot), &hb);
if (ret)
break;
if (!(nr_pages % m))
@@ -469,7 +547,7 @@ static int save_image(struct swap_map_handle *handle,
nr_pages / m * 10);
nr_pages++;
}
- err2 = hib_wait_on_bio_chain(&bio);
+ err2 = hib_wait_io(&hb);
stop = ktime_get();
if (!ret)
ret = err2;
@@ -580,7 +658,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
int ret = 0;
int nr_pages;
int err2;
- struct bio *bio;
+ struct hib_bio_batch hb;
ktime_t start;
ktime_t stop;
size_t off;
@@ -589,6 +667,8 @@ static int save_image_lzo(struct swap_map_handle *handle,
struct cmp_data *data = NULL;
struct crc_data *crc = NULL;
+ hib_init_batch(&hb);
+
/*
* We'll limit the number of threads for compression to limit memory
* footprint.
@@ -674,7 +754,6 @@ static int save_image_lzo(struct swap_map_handle *handle,
if (!m)
m = 1;
nr_pages = 0;
- bio = NULL;
start = ktime_get();
for (;;) {
for (thr = 0; thr < nr_threads; thr++) {
@@ -748,7 +827,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
off += PAGE_SIZE) {
memcpy(page, data[thr].cmp + off, PAGE_SIZE);
- ret = swap_write_page(handle, page, &bio);
+ ret = swap_write_page(handle, page, &hb);
if (ret)
goto out_finish;
}
@@ -759,7 +838,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
}
out_finish:
- err2 = hib_wait_on_bio_chain(&bio);
+ err2 = hib_wait_io(&hb);
stop = ktime_get();
if (!ret)
ret = err2;
@@ -906,7 +985,7 @@ static int get_swap_reader(struct swap_map_handle *handle,
return -ENOMEM;
}
- error = hib_bio_read_page(offset, tmp->map, NULL);
+ error = hib_submit_io(READ_SYNC, offset, tmp->map, NULL);
if (error) {
release_swap_reader(handle);
return error;
@@ -919,7 +998,7 @@ static int get_swap_reader(struct swap_map_handle *handle,
}
static int swap_read_page(struct swap_map_handle *handle, void *buf,
- struct bio **bio_chain)
+ struct hib_bio_batch *hb)
{
sector_t offset;
int error;
@@ -930,7 +1009,7 @@ static int swap_read_page(struct swap_map_handle *handle, void *buf,
offset = handle->cur->entries[handle->k];
if (!offset)
return -EFAULT;
- error = hib_bio_read_page(offset, buf, bio_chain);
+ error = hib_submit_io(READ_SYNC, offset, buf, hb);
if (error)
return error;
if (++handle->k >= MAP_PAGE_ENTRIES) {
@@ -968,27 +1047,28 @@ static int load_image(struct swap_map_handle *handle,
int ret = 0;
ktime_t start;
ktime_t stop;
- struct bio *bio;
+ struct hib_bio_batch hb;
int err2;
unsigned nr_pages;
+ hib_init_batch(&hb);
+
printk(KERN_INFO "PM: Loading image data pages (%u pages)...\n",
nr_to_read);
m = nr_to_read / 10;
if (!m)
m = 1;
nr_pages = 0;
- bio = NULL;
start = ktime_get();
for ( ; ; ) {
ret = snapshot_write_next(snapshot);
if (ret <= 0)
break;
- ret = swap_read_page(handle, data_of(*snapshot), &bio);
+ ret = swap_read_page(handle, data_of(*snapshot), &hb);
if (ret)
break;
if (snapshot->sync_read)
- ret = hib_wait_on_bio_chain(&bio);
+ ret = hib_wait_io(&hb);
if (ret)
break;
if (!(nr_pages % m))
@@ -996,7 +1076,7 @@ static int load_image(struct swap_map_handle *handle,
nr_pages / m * 10);
nr_pages++;
}
- err2 = hib_wait_on_bio_chain(&bio);
+ err2 = hib_wait_io(&hb);
stop = ktime_get();
if (!ret)
ret = err2;
@@ -1067,7 +1147,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
unsigned int m;
int ret = 0;
int eof = 0;
- struct bio *bio;
+ struct hib_bio_batch hb;
ktime_t start;
ktime_t stop;
unsigned nr_pages;
@@ -1080,6 +1160,8 @@ static int load_image_lzo(struct swap_map_handle *handle,
struct dec_data *data = NULL;
struct crc_data *crc = NULL;
+ hib_init_batch(&hb);
+
/*
* We'll limit the number of threads for decompression to limit memory
* footprint.
@@ -1190,7 +1272,6 @@ static int load_image_lzo(struct swap_map_handle *handle,
if (!m)
m = 1;
nr_pages = 0;
- bio = NULL;
start = ktime_get();
ret = snapshot_write_next(snapshot);
@@ -1199,7 +1280,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
for(;;) {
for (i = 0; !eof && i < want; i++) {
- ret = swap_read_page(handle, page[ring], &bio);
+ ret = swap_read_page(handle, page[ring], &hb);
if (ret) {
/*
* On real read error, finish. On end of data,
@@ -1226,7 +1307,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
if (!asked)
break;
- ret = hib_wait_on_bio_chain(&bio);
+ ret = hib_wait_io(&hb);
if (ret)
goto out_finish;
have += asked;
@@ -1281,7 +1362,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
* Wait for more data while we are decompressing.
*/
if (have < LZO_CMP_PAGES && asked) {
- ret = hib_wait_on_bio_chain(&bio);
+ ret = hib_wait_io(&hb);
if (ret)
goto out_finish;
have += asked;
@@ -1430,7 +1511,7 @@ int swsusp_check(void)
if (!IS_ERR(hib_resume_bdev)) {
set_blocksize(hib_resume_bdev, PAGE_SIZE);
clear_page(swsusp_header);
- error = hib_bio_read_page(swsusp_resume_block,
+ error = hib_submit_io(READ_SYNC, swsusp_resume_block,
swsusp_header, NULL);
if (error)
goto put;
@@ -1438,7 +1519,7 @@ int swsusp_check(void)
if (!memcmp(HIBERNATE_SIG, swsusp_header->sig, 10)) {
memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
/* Reset swap signature now */
- error = hib_bio_write_page(swsusp_resume_block,
+ error = hib_submit_io(WRITE_SYNC, swsusp_resume_block,
swsusp_header, NULL);
} else {
error = -EINVAL;
@@ -1482,10 +1563,10 @@ int swsusp_unmark(void)
{
int error;
- hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
+ hib_submit_io(READ_SYNC, swsusp_resume_block, swsusp_header, NULL);
if (!memcmp(HIBERNATE_SIG,swsusp_header->sig, 10)) {
memcpy(swsusp_header->sig,swsusp_header->orig_sig, 10);
- error = hib_bio_write_page(swsusp_resume_block,
+ error = hib_submit_io(WRITE_SYNC, swsusp_resume_block,
swsusp_header, NULL);
} else {
printk(KERN_ERR "PM: Cannot find swsusp signature!\n");
diff --git a/mm/page_io.c b/mm/page_io.c
index 6424869..520baa4 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -69,7 +69,7 @@ void end_swap_bio_write(struct bio *bio, int err)
bio_put(bio);
}
-void end_swap_bio_read(struct bio *bio, int err)
+static void end_swap_bio_read(struct bio *bio, int err)
{
const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
struct page *page = bio->bi_io_vec[0].bv_page;
--
1.9.1
--
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