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 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/kernel/power/swap.c
  *
  * This file provides functions for reading the suspend image from
  * and writing it to a swap partition.
  *
  * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  * Copyright (C) 2010-2012 Bojan Smojver <bojan@rexursive.com>
  */
 
 #define pr_fmt(fmt) "PM: " fmt
 
 #include <linux/module.h>
 #include <linux/file.h>
 #include <linux/delay.h>
 #include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
 #include <linux/pm.h>
 #include <linux/slab.h>
 #include <linux/lzo.h>
 #include <linux/vmalloc.h>
 #include <linux/cpumask.h>
 #include <linux/atomic.h>
 #include <linux/kthread.h>
 #include <linux/crc32.h>
 #include <linux/ktime.h>
 
 #include "power.h"
 
 #define HIBERNATE_SIG   "S1SUSPEND"
 
 u32 swsusp_hardware_signature;
 
 /*
  * When reading an {un,}compressed image, we may restore pages in place,
  * in which case some architectures need these pages cleaning before they
  * can be executed. We don't know which pages these may be, so clean the lot.
  */
 static bool clean_pages_on_read;
 static bool clean_pages_on_decompress;
 
 /*
  *  The swap map is a data structure used for keeping track of each page
  *  written to a swap partition.  It consists of many swap_map_page
  *  structures that contain each an array of MAP_PAGE_ENTRIES swap entries.
  *  These structures are stored on the swap and linked together with the
  *  help of the .next_swap member.
  *
  *  The swap map is created during suspend.  The swap map pages are
  *  allocated and populated one at a time, so we only need one memory
  *  page to set up the entire structure.
  *
  *  During resume we pick up all swap_map_page structures into a list.
  */
 
 #define MAP_PAGE_ENTRIES    (PAGE_SIZE / sizeof(sector_t) - 1)
 
 /*
  * Number of free pages that are not high.
  */
 static inline unsigned long low_free_pages(void)
 {
     return nr_free_pages() - nr_free_highpages();
 }
 
 /*
  * Number of pages required to be kept free while writing the image. Always
  * half of all available low pages before the writing starts.
  */
 static inline unsigned long reqd_free_pages(void)
 {
     return low_free_pages() / 2;
 }
 
 struct swap_map_page {
     sector_t entries[MAP_PAGE_ENTRIES];
     sector_t next_swap;
 };
 
 struct swap_map_page_list {
     struct swap_map_page *map;
     struct swap_map_page_list *next;
 };
 
 /*
  *  The swap_map_handle structure is used for handling swap in
  *  a file-alike way
  */
 
 struct swap_map_handle {
     struct swap_map_page *cur;
     struct swap_map_page_list *maps;
     sector_t cur_swap;
     sector_t first_sector;
     unsigned int k;
     unsigned long reqd_free_pages;
     u32 crc32;
 };
 
 struct swsusp_header {
     char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -
                   sizeof(u32) - sizeof(u32)];
     u32 hw_sig;
     u32 crc32;
     sector_t image;
     unsigned int flags; /* Flags to pass to the "boot" kernel */
     char    orig_sig[10];
     char    sig[10];
 } __packed;
 
 static struct swsusp_header *swsusp_header;
 
 /*
  *  The following functions are used for tracing the allocated
  *  swap pages, so that they can be freed in case of an error.
  */
 
 struct swsusp_extent {
     struct rb_node node;
     unsigned long start;
     unsigned long end;
 };
 
 static struct rb_root swsusp_extents = RB_ROOT;
 
 static int swsusp_extents_insert(unsigned long swap_offset)
 {
     struct rb_node **new = &(swsusp_extents.rb_node);
     struct rb_node *parent = NULL;
     struct swsusp_extent *ext;
 
     /* Figure out where to put the new node */
     while (*new) {
         ext = rb_entry(*new, struct swsusp_extent, node);
         parent = *new;
         if (swap_offset < ext->start) {
             /* Try to merge */
             if (swap_offset == ext->start - 1) {
                 ext->start--;
                 return 0;
             }
             new = &((*new)->rb_left);
         } else if (swap_offset > ext->end) {
             /* Try to merge */
             if (swap_offset == ext->end + 1) {
                 ext->end++;
                 return 0;
             }
             new = &((*new)->rb_right);
         } else {
             /* It already is in the tree */
             return -EINVAL;
         }
     }
     /* Add the new node and rebalance the tree. */
     ext = kzalloc(sizeof(struct swsusp_extent), GFP_KERNEL);
     if (!ext)
         return -ENOMEM;
 
     ext->start = swap_offset;
     ext->end = swap_offset;
     rb_link_node(&ext->node, parent, new);
     rb_insert_color(&ext->node, &swsusp_extents);
     return 0;
 }
 
 /*
  *  alloc_swapdev_block - allocate a swap page and register that it has
  *  been allocated, so that it can be freed in case of an error.
  */
 
 sector_t alloc_swapdev_block(int swap)
 {
     unsigned long offset;
 
     offset = swp_offset(get_swap_page_of_type(swap));
     if (offset) {
         if (swsusp_extents_insert(offset))
             swap_free(swp_entry(swap, offset));
         else
             return swapdev_block(swap, offset);
     }
     return 0;
 }
 
 /*
  *  free_all_swap_pages - free swap pages allocated for saving image data.
  *  It also frees the extents used to register which swap entries had been
  *  allocated.
  */
 
 void free_all_swap_pages(int swap)
 {
     struct rb_node *node;
 
     while ((node = swsusp_extents.rb_node)) {
         struct swsusp_extent *ext;
         unsigned long offset;
 
         ext = rb_entry(node, struct swsusp_extent, node);
         rb_erase(node, &swsusp_extents);
         for (offset = ext->start; offset <= ext->end; offset++)
             swap_free(swp_entry(swap, offset));
 
         kfree(ext);
     }
 }
 
 int swsusp_swap_in_use(void)
 {
     return (swsusp_extents.rb_node != NULL);
 }
 
 /*
  * General things
  */
 
 static unsigned short root_swap = 0xffff;
 static struct block_device *hib_resume_bdev;
 
 struct hib_bio_batch {
     atomic_t        count;
     wait_queue_head_t   wait;
     blk_status_t        error;
     struct blk_plug     plug;
 };
 
 static void hib_init_batch(struct hib_bio_batch *hb)
 {
     atomic_set(&hb->count, 0);
     init_waitqueue_head(&hb->wait);
     hb->error = BLK_STS_OK;
     blk_start_plug(&hb->plug);
 }
 
 static void hib_finish_batch(struct hib_bio_batch *hb)
 {
     blk_finish_plug(&hb->plug);
 }
 
 static void hib_end_io(struct bio *bio)
 {
     struct hib_bio_batch *hb = bio->bi_private;
     struct page *page = bio_first_page_all(bio);
 
     if (bio->bi_status) {
         pr_alert("Read-error on swap-device (%u:%u:%Lu)\n",
              MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
              (unsigned long long)bio->bi_iter.bi_sector);
     }
 
     if (bio_data_dir(bio) == WRITE)
         put_page(page);
     else if (clean_pages_on_read)
         flush_icache_range((unsigned long)page_address(page),
                    (unsigned long)page_address(page) + PAGE_SIZE);
 
     if (bio->bi_status && !hb->error)
         hb->error = bio->bi_status;
     if (atomic_dec_and_test(&hb->count))
         wake_up(&hb->wait);
 
     bio_put(bio);
 }
 
 static int hib_submit_io(blk_opf_t opf, 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(hib_resume_bdev, 1, opf, GFP_NOIO | __GFP_HIGH);
     bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9);
 
     if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
         pr_err("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(bio);
     } else {
         error = submit_bio_wait(bio);
         bio_put(bio);
     }
 
     return error;
 }
 
 static int hib_wait_io(struct hib_bio_batch *hb)
 {
     /*
      * We are relying on the behavior of blk_plug that a thread with
      * a plug will flush the plug list before sleeping.
      */
     wait_event(hb->wait, atomic_read(&hb->count) == 0);
     return blk_status_to_errno(hb->error);
 }
 
 /*
  * Saving part
  */
 static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
 {
     int error;
 
     hib_submit_io(REQ_OP_READ, 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);
         memcpy(swsusp_header->sig, HIBERNATE_SIG, 10);
         swsusp_header->image = handle->first_sector;
         if (swsusp_hardware_signature) {
             swsusp_header->hw_sig = swsusp_hardware_signature;
             flags |= SF_HW_SIG;
         }
         swsusp_header->flags = flags;
         if (flags & SF_CRC32_MODE)
             swsusp_header->crc32 = handle->crc32;
         error = hib_submit_io(REQ_OP_WRITE | REQ_SYNC,
                       swsusp_resume_block, swsusp_header, NULL);
     } else {
         pr_err("Swap header not found!\n");
         error = -ENODEV;
     }
     return error;
 }
 
 /**
  *  swsusp_swap_check - check if the resume device is a swap device
  *  and get its index (if so)
  *
  *  This is called before saving image
  */
 static int swsusp_swap_check(void)
 {
     int res;
 
     if (swsusp_resume_device)
         res = swap_type_of(swsusp_resume_device, swsusp_resume_block);
     else
         res = find_first_swap(&swsusp_resume_device);
     if (res < 0)
         return res;
     root_swap = res;
 
     hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device, FMODE_WRITE,
             NULL);
     if (IS_ERR(hib_resume_bdev))
         return PTR_ERR(hib_resume_bdev);
 
     res = set_blocksize(hib_resume_bdev, PAGE_SIZE);
     if (res < 0)
         blkdev_put(hib_resume_bdev, FMODE_WRITE);
 
     return res;
 }
 
 /**
  *  write_page - Write one page to given swap location.
  *  @buf:       Address we're writing.
  *  @offset:    Offset of the swap page we're writing to.
  *  @hb:        bio completion batch
  */
 
 static int write_page(void *buf, sector_t offset, struct hib_bio_batch *hb)
 {
     void *src;
     int ret;
 
     if (!offset)
         return -ENOSPC;
 
     if (hb) {
         src = (void *)__get_free_page(GFP_NOIO | __GFP_NOWARN |
                                       __GFP_NORETRY);
         if (src) {
             copy_page(src, buf);
         } else {
             ret = hib_wait_io(hb); /* Free pages */
             if (ret)
                 return ret;
             src = (void *)__get_free_page(GFP_NOIO |
                                           __GFP_NOWARN |
                                           __GFP_NORETRY);
             if (src) {
                 copy_page(src, buf);
             } else {
                 WARN_ON_ONCE(1);
                 hb = NULL;  /* Go synchronous */
                 src = buf;
             }
         }
     } else {
         src = buf;
     }
     return hib_submit_io(REQ_OP_WRITE | REQ_SYNC, offset, src, hb);
 }
 
 static void release_swap_writer(struct swap_map_handle *handle)
 {
     if (handle->cur)
         free_page((unsigned long)handle->cur);
     handle->cur = NULL;
 }
 
 static int get_swap_writer(struct swap_map_handle *handle)
 {
     int ret;
 
     ret = swsusp_swap_check();
     if (ret) {
         if (ret != -ENOSPC)
             pr_err("Cannot find swap device, try swapon -a\n");
         return ret;
     }
     handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
     if (!handle->cur) {
         ret = -ENOMEM;
         goto err_close;
     }
     handle->cur_swap = alloc_swapdev_block(root_swap);
     if (!handle->cur_swap) {
         ret = -ENOSPC;
         goto err_rel;
     }
     handle->k = 0;
     handle->reqd_free_pages = reqd_free_pages();
     handle->first_sector = handle->cur_swap;
     return 0;
 err_rel:
     release_swap_writer(handle);
 err_close:
     swsusp_close(FMODE_WRITE);
     return ret;
 }
 
 static int swap_write_page(struct swap_map_handle *handle, void *buf,
         struct hib_bio_batch *hb)
 {
     int error = 0;
     sector_t offset;
 
     if (!handle->cur)
         return -EINVAL;
     offset = alloc_swapdev_block(root_swap);
     error = write_page(buf, offset, hb);
     if (error)
         return error;
     handle->cur->entries[handle->k++] = offset;
     if (handle->k >= MAP_PAGE_ENTRIES) {
         offset = alloc_swapdev_block(root_swap);
         if (!offset)
             return -ENOSPC;
         handle->cur->next_swap = offset;
         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 (hb && low_free_pages() <= handle->reqd_free_pages) {
             error = hib_wait_io(hb);
             if (error)
                 goto out;
             /*
              * Recalculate the number of required free pages, to
              * make sure we never take more than half.
              */
             handle->reqd_free_pages = reqd_free_pages();
         }
     }
  out:
     return error;
 }
 
 static int flush_swap_writer(struct swap_map_handle *handle)
 {
     if (handle->cur && handle->cur_swap)
         return write_page(handle->cur, handle->cur_swap, NULL);
     else
         return -EINVAL;
 }
 
 static int swap_writer_finish(struct swap_map_handle *handle,
         unsigned int flags, int error)
 {
     if (!error) {
         pr_info("S");
         error = mark_swapfiles(handle, flags);
         pr_cont("|\n");
         flush_swap_writer(handle);
     }
 
     if (error)
         free_all_swap_pages(root_swap);
     release_swap_writer(handle);
     swsusp_close(FMODE_WRITE);
 
     return error;
 }
 
 /* We need to remember how much compressed data we need to read. */
 #define LZO_HEADER  sizeof(size_t)
 
 /* Number of pages/bytes we'll compress at one time. */
 #define LZO_UNC_PAGES   32
 #define LZO_UNC_SIZE    (LZO_UNC_PAGES * PAGE_SIZE)
 
 /* Number of pages/bytes we need for compressed data (worst case). */
 #define LZO_CMP_PAGES   DIV_ROUND_UP(lzo1x_worst_compress(LZO_UNC_SIZE) + \
                          LZO_HEADER, PAGE_SIZE)
 #define LZO_CMP_SIZE    (LZO_CMP_PAGES * PAGE_SIZE)
 
 /* Maximum number of threads for compression/decompression. */
 #define LZO_THREADS 3
 
 /* Minimum/maximum number of pages for read buffering. */
 #define LZO_MIN_RD_PAGES    1024
 #define LZO_MAX_RD_PAGES    8192
 
 
 /**
  *  save_image - save the suspend image data
  */
 
 static int save_image(struct swap_map_handle *handle,
                       struct snapshot_handle *snapshot,
                       unsigned int nr_to_write)
 {
     unsigned int m;
     int ret;
     int nr_pages;
     int err2;
     struct hib_bio_batch hb;
     ktime_t start;
     ktime_t stop;
 
     hib_init_batch(&hb);
 
     pr_info("Saving image data pages (%u pages)...\n",
         nr_to_write);
     m = nr_to_write / 10;
     if (!m)
         m = 1;
     nr_pages = 0;
     start = ktime_get();
     while (1) {
         ret = snapshot_read_next(snapshot);
         if (ret <= 0)
             break;
         ret = swap_write_page(handle, data_of(*snapshot), &hb);
         if (ret)
             break;
         if (!(nr_pages % m))
             pr_info("Image saving progress: %3d%%\n",
                 nr_pages / m * 10);
         nr_pages++;
     }
     err2 = hib_wait_io(&hb);
     hib_finish_batch(&hb);
     stop = ktime_get();
     if (!ret)
         ret = err2;
     if (!ret)
         pr_info("Image saving done\n");
     swsusp_show_speed(start, stop, nr_to_write, "Wrote");
     return ret;
 }
 
 /**
  * Structure used for CRC32.
  */
 struct crc_data {
     struct task_struct *thr;                  /* thread */
     atomic_t ready;                           /* ready to start flag */
     atomic_t stop;                            /* ready to stop flag */
     unsigned run_threads;                     /* nr current threads */
     wait_queue_head_t go;                     /* start crc update */
     wait_queue_head_t done;                   /* crc update done */
     u32 *crc32;                               /* points to handle's crc32 */
     size_t *unc_len[LZO_THREADS];             /* uncompressed lengths */
     unsigned char *unc[LZO_THREADS];          /* uncompressed data */
 };
 
 /**
  * CRC32 update function that runs in its own thread.
  */
 static int crc32_threadfn(void *data)
 {
     struct crc_data *d = data;
     unsigned i;
 
     while (1) {
         wait_event(d->go, atomic_read(&d->ready) ||
                           kthread_should_stop());
         if (kthread_should_stop()) {
             d->thr = NULL;
             atomic_set(&d->stop, 1);
             wake_up(&d->done);
             break;
         }
         atomic_set(&d->ready, 0);
 
         for (i = 0; i < d->run_threads; i++)
             *d->crc32 = crc32_le(*d->crc32,
                                  d->unc[i], *d->unc_len[i]);
         atomic_set(&d->stop, 1);
         wake_up(&d->done);
     }
     return 0;
 }
 /**
  * Structure used for LZO data compression.
  */
 struct cmp_data {
     struct task_struct *thr;                  /* thread */
     atomic_t ready;                           /* ready to start flag */
     atomic_t stop;                            /* ready to stop flag */
     int ret;                                  /* return code */
     wait_queue_head_t go;                     /* start compression */
     wait_queue_head_t done;                   /* compression done */
     size_t unc_len;                           /* uncompressed length */
     size_t cmp_len;                           /* compressed length */
     unsigned char unc[LZO_UNC_SIZE];          /* uncompressed buffer */
     unsigned char cmp[LZO_CMP_SIZE];          /* compressed buffer */
     unsigned char wrk[LZO1X_1_MEM_COMPRESS];  /* compression workspace */
 };
 
 /**
  * Compression function that runs in its own thread.
  */
 static int lzo_compress_threadfn(void *data)
 {
     struct cmp_data *d = data;
 
     while (1) {
         wait_event(d->go, atomic_read(&d->ready) ||
                           kthread_should_stop());
         if (kthread_should_stop()) {
             d->thr = NULL;
             d->ret = -1;
             atomic_set(&d->stop, 1);
             wake_up(&d->done);
             break;
         }
         atomic_set(&d->ready, 0);
 
         d->ret = lzo1x_1_compress(d->unc, d->unc_len,
                                   d->cmp + LZO_HEADER, &d->cmp_len,
                                   d->wrk);
         atomic_set(&d->stop, 1);
         wake_up(&d->done);
     }
     return 0;
 }
 
 /**
  * save_image_lzo - Save the suspend image data compressed with LZO.
  * @handle: Swap map handle to use for saving the image.
  * @snapshot: Image to read data from.
  * @nr_to_write: Number of pages to save.
  */
 static int save_image_lzo(struct swap_map_handle *handle,
                           struct snapshot_handle *snapshot,
                           unsigned int nr_to_write)
 {
     unsigned int m;
     int ret = 0;
     int nr_pages;
     int err2;
     struct hib_bio_batch hb;
     ktime_t start;
     ktime_t stop;
     size_t off;
     unsigned thr, run_threads, nr_threads;
     unsigned char *page = NULL;
     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.
      */
     nr_threads = num_online_cpus() - 1;
     nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);
 
     page = (void *)__get_free_page(GFP_NOIO | __GFP_HIGH);
     if (!page) {
         pr_err("Failed to allocate LZO page\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     data = vzalloc(array_size(nr_threads, sizeof(*data)));
     if (!data) {
         pr_err("Failed to allocate LZO data\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     crc = kzalloc(sizeof(*crc), GFP_KERNEL);
     if (!crc) {
         pr_err("Failed to allocate crc\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     /*
      * Start the compression threads.
      */
     for (thr = 0; thr < nr_threads; thr++) {
         init_waitqueue_head(&data[thr].go);
         init_waitqueue_head(&data[thr].done);
 
         data[thr].thr = kthread_run(lzo_compress_threadfn,
                                     &data[thr],
                                     "image_compress/%u", thr);
         if (IS_ERR(data[thr].thr)) {
             data[thr].thr = NULL;
             pr_err("Cannot start compression threads\n");
             ret = -ENOMEM;
             goto out_clean;
         }
     }
 
     /*
      * Start the CRC32 thread.
      */
     init_waitqueue_head(&crc->go);
     init_waitqueue_head(&crc->done);
 
     handle->crc32 = 0;
     crc->crc32 = &handle->crc32;
     for (thr = 0; thr < nr_threads; thr++) {
         crc->unc[thr] = data[thr].unc;
         crc->unc_len[thr] = &data[thr].unc_len;
     }
 
     crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
     if (IS_ERR(crc->thr)) {
         crc->thr = NULL;
         pr_err("Cannot start CRC32 thread\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     /*
      * Adjust the number of required free pages after all allocations have
      * been done. We don't want to run out of pages when writing.
      */
     handle->reqd_free_pages = reqd_free_pages();
 
     pr_info("Using %u thread(s) for compression\n", nr_threads);
     pr_info("Compressing and saving image data (%u pages)...\n",
         nr_to_write);
     m = nr_to_write / 10;
     if (!m)
         m = 1;
     nr_pages = 0;
     start = ktime_get();
     for (;;) {
         for (thr = 0; thr < nr_threads; thr++) {
             for (off = 0; off < LZO_UNC_SIZE; off += PAGE_SIZE) {
                 ret = snapshot_read_next(snapshot);
                 if (ret < 0)
                     goto out_finish;
 
                 if (!ret)
                     break;
 
                 memcpy(data[thr].unc + off,
                        data_of(*snapshot), PAGE_SIZE);
 
                 if (!(nr_pages % m))
                     pr_info("Image saving progress: %3d%%\n",
                         nr_pages / m * 10);
                 nr_pages++;
             }
             if (!off)
                 break;
 
             data[thr].unc_len = off;
 
             atomic_set(&data[thr].ready, 1);
             wake_up(&data[thr].go);
         }
 
         if (!thr)
             break;
 
         crc->run_threads = thr;
         atomic_set(&crc->ready, 1);
         wake_up(&crc->go);
 
         for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
             wait_event(data[thr].done,
                        atomic_read(&data[thr].stop));
             atomic_set(&data[thr].stop, 0);
 
             ret = data[thr].ret;
 
             if (ret < 0) {
                 pr_err("LZO compression failed\n");
                 goto out_finish;
             }
 
             if (unlikely(!data[thr].cmp_len ||
                          data[thr].cmp_len >
                          lzo1x_worst_compress(data[thr].unc_len))) {
                 pr_err("Invalid LZO compressed length\n");
                 ret = -1;
                 goto out_finish;
             }
 
             *(size_t *)data[thr].cmp = data[thr].cmp_len;
 
             /*
              * Given we are writing one page at a time to disk, we
              * copy that much from the buffer, although the last
              * bit will likely be smaller than full page. This is
              * OK - we saved the length of the compressed data, so
              * any garbage at the end will be discarded when we
              * read it.
              */
             for (off = 0;
                  off < LZO_HEADER + data[thr].cmp_len;
                  off += PAGE_SIZE) {
                 memcpy(page, data[thr].cmp + off, PAGE_SIZE);
 
                 ret = swap_write_page(handle, page, &hb);
                 if (ret)
                     goto out_finish;
             }
         }
 
         wait_event(crc->done, atomic_read(&crc->stop));
         atomic_set(&crc->stop, 0);
     }
 
 out_finish:
     err2 = hib_wait_io(&hb);
     stop = ktime_get();
     if (!ret)
         ret = err2;
     if (!ret)
         pr_info("Image saving done\n");
     swsusp_show_speed(start, stop, nr_to_write, "Wrote");
 out_clean:
     hib_finish_batch(&hb);
     if (crc) {
         if (crc->thr)
             kthread_stop(crc->thr);
         kfree(crc);
     }
     if (data) {
         for (thr = 0; thr < nr_threads; thr++)
             if (data[thr].thr)
                 kthread_stop(data[thr].thr);
         vfree(data);
     }
     if (page) free_page((unsigned long)page);
 
     return ret;
 }
 
 /**
  *  enough_swap - Make sure we have enough swap to save the image.
  *
  *  Returns TRUE or FALSE after checking the total amount of swap
  *  space available from the resume partition.
  */
 
 static int enough_swap(unsigned int nr_pages)
 {
     unsigned int free_swap = count_swap_pages(root_swap, 1);
     unsigned int required;
 
     pr_debug("Free swap pages: %u\n", free_swap);
 
     required = PAGES_FOR_IO + nr_pages;
     return free_swap > required;
 }
 
 /**
  *  swsusp_write - Write entire image and metadata.
  *  @flags: flags to pass to the "boot" kernel in the image header
  *
  *  It is important _NOT_ to umount filesystems at this point. We want
  *  them synced (in case something goes wrong) but we DO not want to mark
  *  filesystem clean: it is not. (And it does not matter, if we resume
  *  correctly, we'll mark system clean, anyway.)
  */
 
 int swsusp_write(unsigned int flags)
 {
     struct swap_map_handle handle;
     struct snapshot_handle snapshot;
     struct swsusp_info *header;
     unsigned long pages;
     int error;
 
     pages = snapshot_get_image_size();
     error = get_swap_writer(&handle);
     if (error) {
         pr_err("Cannot get swap writer\n");
         return error;
     }
     if (flags & SF_NOCOMPRESS_MODE) {
         if (!enough_swap(pages)) {
             pr_err("Not enough free swap\n");
             error = -ENOSPC;
             goto out_finish;
         }
     }
     memset(&snapshot, 0, sizeof(struct snapshot_handle));
     error = snapshot_read_next(&snapshot);
     if (error < (int)PAGE_SIZE) {
         if (error >= 0)
             error = -EFAULT;
 
         goto out_finish;
     }
     header = (struct swsusp_info *)data_of(snapshot);
     error = swap_write_page(&handle, header, NULL);
     if (!error) {
         error = (flags & SF_NOCOMPRESS_MODE) ?
             save_image(&handle, &snapshot, pages - 1) :
             save_image_lzo(&handle, &snapshot, pages - 1);
     }
 out_finish:
     error = swap_writer_finish(&handle, flags, error);
     return error;
 }
 
 /**
  *  The following functions allow us to read data using a swap map
  *  in a file-alike way
  */
 
 static void release_swap_reader(struct swap_map_handle *handle)
 {
     struct swap_map_page_list *tmp;
 
     while (handle->maps) {
         if (handle->maps->map)
             free_page((unsigned long)handle->maps->map);
         tmp = handle->maps;
         handle->maps = handle->maps->next;
         kfree(tmp);
     }
     handle->cur = NULL;
 }
 
 static int get_swap_reader(struct swap_map_handle *handle,
         unsigned int *flags_p)
 {
     int error;
     struct swap_map_page_list *tmp, *last;
     sector_t offset;
 
     *flags_p = swsusp_header->flags;
 
     if (!swsusp_header->image) /* how can this happen? */
         return -EINVAL;
 
     handle->cur = NULL;
     last = handle->maps = NULL;
     offset = swsusp_header->image;
     while (offset) {
         tmp = kzalloc(sizeof(*handle->maps), GFP_KERNEL);
         if (!tmp) {
             release_swap_reader(handle);
             return -ENOMEM;
         }
         if (!handle->maps)
             handle->maps = tmp;
         if (last)
             last->next = tmp;
         last = tmp;
 
         tmp->map = (struct swap_map_page *)
                __get_free_page(GFP_NOIO | __GFP_HIGH);
         if (!tmp->map) {
             release_swap_reader(handle);
             return -ENOMEM;
         }
 
         error = hib_submit_io(REQ_OP_READ, offset, tmp->map, NULL);
         if (error) {
             release_swap_reader(handle);
             return error;
         }
         offset = tmp->map->next_swap;
     }
     handle->k = 0;
     handle->cur = handle->maps->map;
     return 0;
 }
 
 static int swap_read_page(struct swap_map_handle *handle, void *buf,
         struct hib_bio_batch *hb)
 {
     sector_t offset;
     int error;
     struct swap_map_page_list *tmp;
 
     if (!handle->cur)
         return -EINVAL;
     offset = handle->cur->entries[handle->k];
     if (!offset)
         return -EFAULT;
     error = hib_submit_io(REQ_OP_READ, offset, buf, hb);
     if (error)
         return error;
     if (++handle->k >= MAP_PAGE_ENTRIES) {
         handle->k = 0;
         free_page((unsigned long)handle->maps->map);
         tmp = handle->maps;
         handle->maps = handle->maps->next;
         kfree(tmp);
         if (!handle->maps)
             release_swap_reader(handle);
         else
             handle->cur = handle->maps->map;
     }
     return error;
 }
 
 static int swap_reader_finish(struct swap_map_handle *handle)
 {
     release_swap_reader(handle);
 
     return 0;
 }
 
 /**
  *  load_image - load the image using the swap map handle
  *  @handle and the snapshot handle @snapshot
  *  (assume there are @nr_pages pages to load)
  */
 
 static int load_image(struct swap_map_handle *handle,
                       struct snapshot_handle *snapshot,
                       unsigned int nr_to_read)
 {
     unsigned int m;
     int ret = 0;
     ktime_t start;
     ktime_t stop;
     struct hib_bio_batch hb;
     int err2;
     unsigned nr_pages;
 
     hib_init_batch(&hb);
 
     clean_pages_on_read = true;
     pr_info("Loading image data pages (%u pages)...\n", nr_to_read);
     m = nr_to_read / 10;
     if (!m)
         m = 1;
     nr_pages = 0;
     start = ktime_get();
     for ( ; ; ) {
         ret = snapshot_write_next(snapshot);
         if (ret <= 0)
             break;
         ret = swap_read_page(handle, data_of(*snapshot), &hb);
         if (ret)
             break;
         if (snapshot->sync_read)
             ret = hib_wait_io(&hb);
         if (ret)
             break;
         if (!(nr_pages % m))
             pr_info("Image loading progress: %3d%%\n",
                 nr_pages / m * 10);
         nr_pages++;
     }
     err2 = hib_wait_io(&hb);
     hib_finish_batch(&hb);
     stop = ktime_get();
     if (!ret)
         ret = err2;
     if (!ret) {
         pr_info("Image loading done\n");
         snapshot_write_finalize(snapshot);
         if (!snapshot_image_loaded(snapshot))
             ret = -ENODATA;
     }
     swsusp_show_speed(start, stop, nr_to_read, "Read");
     return ret;
 }
 
 /**
  * Structure used for LZO data decompression.
  */
 struct dec_data {
     struct task_struct *thr;                  /* thread */
     atomic_t ready;                           /* ready to start flag */
     atomic_t stop;                            /* ready to stop flag */
     int ret;                                  /* return code */
     wait_queue_head_t go;                     /* start decompression */
     wait_queue_head_t done;                   /* decompression done */
     size_t unc_len;                           /* uncompressed length */
     size_t cmp_len;                           /* compressed length */
     unsigned char unc[LZO_UNC_SIZE];          /* uncompressed buffer */
     unsigned char cmp[LZO_CMP_SIZE];          /* compressed buffer */
 };
 
 /**
  * Decompression function that runs in its own thread.
  */
 static int lzo_decompress_threadfn(void *data)
 {
     struct dec_data *d = data;
 
     while (1) {
         wait_event(d->go, atomic_read(&d->ready) ||
                           kthread_should_stop());
         if (kthread_should_stop()) {
             d->thr = NULL;
             d->ret = -1;
             atomic_set(&d->stop, 1);
             wake_up(&d->done);
             break;
         }
         atomic_set(&d->ready, 0);
 
         d->unc_len = LZO_UNC_SIZE;
         d->ret = lzo1x_decompress_safe(d->cmp + LZO_HEADER, d->cmp_len,
                                        d->unc, &d->unc_len);
         if (clean_pages_on_decompress)
             flush_icache_range((unsigned long)d->unc,
                        (unsigned long)d->unc + d->unc_len);
 
         atomic_set(&d->stop, 1);
         wake_up(&d->done);
     }
     return 0;
 }
 
 /**
  * load_image_lzo - Load compressed image data and decompress them with LZO.
  * @handle: Swap map handle to use for loading data.
  * @snapshot: Image to copy uncompressed data into.
  * @nr_to_read: Number of pages to load.
  */
 static int load_image_lzo(struct swap_map_handle *handle,
                           struct snapshot_handle *snapshot,
                           unsigned int nr_to_read)
 {
     unsigned int m;
     int ret = 0;
     int eof = 0;
     struct hib_bio_batch hb;
     ktime_t start;
     ktime_t stop;
     unsigned nr_pages;
     size_t off;
     unsigned i, thr, run_threads, nr_threads;
     unsigned ring = 0, pg = 0, ring_size = 0,
              have = 0, want, need, asked = 0;
     unsigned long read_pages = 0;
     unsigned char **page = NULL;
     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.
      */
     nr_threads = num_online_cpus() - 1;
     nr_threads = clamp_val(nr_threads, 1, LZO_THREADS);
 
     page = vmalloc(array_size(LZO_MAX_RD_PAGES, sizeof(*page)));
     if (!page) {
         pr_err("Failed to allocate LZO page\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     data = vzalloc(array_size(nr_threads, sizeof(*data)));
     if (!data) {
         pr_err("Failed to allocate LZO data\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     crc = kzalloc(sizeof(*crc), GFP_KERNEL);
     if (!crc) {
         pr_err("Failed to allocate crc\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     clean_pages_on_decompress = true;
 
     /*
      * Start the decompression threads.
      */
     for (thr = 0; thr < nr_threads; thr++) {
         init_waitqueue_head(&data[thr].go);
         init_waitqueue_head(&data[thr].done);
 
         data[thr].thr = kthread_run(lzo_decompress_threadfn,
                                     &data[thr],
                                     "image_decompress/%u", thr);
         if (IS_ERR(data[thr].thr)) {
             data[thr].thr = NULL;
             pr_err("Cannot start decompression threads\n");
             ret = -ENOMEM;
             goto out_clean;
         }
     }
 
     /*
      * Start the CRC32 thread.
      */
     init_waitqueue_head(&crc->go);
     init_waitqueue_head(&crc->done);
 
     handle->crc32 = 0;
     crc->crc32 = &handle->crc32;
     for (thr = 0; thr < nr_threads; thr++) {
         crc->unc[thr] = data[thr].unc;
         crc->unc_len[thr] = &data[thr].unc_len;
     }
 
     crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
     if (IS_ERR(crc->thr)) {
         crc->thr = NULL;
         pr_err("Cannot start CRC32 thread\n");
         ret = -ENOMEM;
         goto out_clean;
     }
 
     /*
      * Set the number of pages for read buffering.
      * This is complete guesswork, because we'll only know the real
      * picture once prepare_image() is called, which is much later on
      * during the image load phase. We'll assume the worst case and
      * say that none of the image pages are from high memory.
      */
     if (low_free_pages() > snapshot_get_image_size())
         read_pages = (low_free_pages() - snapshot_get_image_size()) / 2;
     read_pages = clamp_val(read_pages, LZO_MIN_RD_PAGES, LZO_MAX_RD_PAGES);
 
     for (i = 0; i < read_pages; i++) {
         page[i] = (void *)__get_free_page(i < LZO_CMP_PAGES ?
                           GFP_NOIO | __GFP_HIGH :
                           GFP_NOIO | __GFP_NOWARN |
                           __GFP_NORETRY);
 
         if (!page[i]) {
             if (i < LZO_CMP_PAGES) {
                 ring_size = i;
                 pr_err("Failed to allocate LZO pages\n");
                 ret = -ENOMEM;
                 goto out_clean;
             } else {
                 break;
             }
         }
     }
     want = ring_size = i;
 
     pr_info("Using %u thread(s) for decompression\n", nr_threads);
     pr_info("Loading and decompressing image data (%u pages)...\n",
         nr_to_read);
     m = nr_to_read / 10;
     if (!m)
         m = 1;
     nr_pages = 0;
     start = ktime_get();
 
     ret = snapshot_write_next(snapshot);
     if (ret <= 0)
         goto out_finish;
 
     for(;;) {
         for (i = 0; !eof && i < want; i++) {
             ret = swap_read_page(handle, page[ring], &hb);
             if (ret) {
                 /*
                  * On real read error, finish. On end of data,
                  * set EOF flag and just exit the read loop.
                  */
                 if (handle->cur &&
                     handle->cur->entries[handle->k]) {
                     goto out_finish;
                 } else {
                     eof = 1;
                     break;
                 }
             }
             if (++ring >= ring_size)
                 ring = 0;
         }
         asked += i;
         want -= i;
 
         /*
          * We are out of data, wait for some more.
          */
         if (!have) {
             if (!asked)
                 break;
 
             ret = hib_wait_io(&hb);
             if (ret)
                 goto out_finish;
             have += asked;
             asked = 0;
             if (eof)
                 eof = 2;
         }
 
         if (crc->run_threads) {
             wait_event(crc->done, atomic_read(&crc->stop));
             atomic_set(&crc->stop, 0);
             crc->run_threads = 0;
         }
 
         for (thr = 0; have && thr < nr_threads; thr++) {
             data[thr].cmp_len = *(size_t *)page[pg];
             if (unlikely(!data[thr].cmp_len ||
                          data[thr].cmp_len >
                          lzo1x_worst_compress(LZO_UNC_SIZE))) {
                 pr_err("Invalid LZO compressed length\n");
                 ret = -1;
                 goto out_finish;
             }
 
             need = DIV_ROUND_UP(data[thr].cmp_len + LZO_HEADER,
                                 PAGE_SIZE);
             if (need > have) {
                 if (eof > 1) {
                     ret = -1;
                     goto out_finish;
                 }
                 break;
             }
 
             for (off = 0;
                  off < LZO_HEADER + data[thr].cmp_len;
                  off += PAGE_SIZE) {
                 memcpy(data[thr].cmp + off,
                        page[pg], PAGE_SIZE);
                 have--;
                 want++;
                 if (++pg >= ring_size)
                     pg = 0;
             }
 
             atomic_set(&data[thr].ready, 1);
             wake_up(&data[thr].go);
         }
 
         /*
          * Wait for more data while we are decompressing.
          */
         if (have < LZO_CMP_PAGES && asked) {
             ret = hib_wait_io(&hb);
             if (ret)
                 goto out_finish;
             have += asked;
             asked = 0;
             if (eof)
                 eof = 2;
         }
 
         for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
             wait_event(data[thr].done,
                        atomic_read(&data[thr].stop));
             atomic_set(&data[thr].stop, 0);
 
             ret = data[thr].ret;
 
             if (ret < 0) {
                 pr_err("LZO decompression failed\n");
                 goto out_finish;
             }
 
             if (unlikely(!data[thr].unc_len ||
                          data[thr].unc_len > LZO_UNC_SIZE ||
                          data[thr].unc_len & (PAGE_SIZE - 1))) {
                 pr_err("Invalid LZO uncompressed length\n");
                 ret = -1;
                 goto out_finish;
             }
 
             for (off = 0;
                  off < data[thr].unc_len; off += PAGE_SIZE) {
                 memcpy(data_of(*snapshot),
                        data[thr].unc + off, PAGE_SIZE);
 
                 if (!(nr_pages % m))
                     pr_info("Image loading progress: %3d%%\n",
                         nr_pages / m * 10);
                 nr_pages++;
 
                 ret = snapshot_write_next(snapshot);
                 if (ret <= 0) {
                     crc->run_threads = thr + 1;
                     atomic_set(&crc->ready, 1);
                     wake_up(&crc->go);
                     goto out_finish;
                 }
             }
         }
 
         crc->run_threads = thr;
         atomic_set(&crc->ready, 1);
         wake_up(&crc->go);
     }
 
 out_finish:
     if (crc->run_threads) {
         wait_event(crc->done, atomic_read(&crc->stop));
         atomic_set(&crc->stop, 0);
     }
     stop = ktime_get();
     if (!ret) {
         pr_info("Image loading done\n");
         snapshot_write_finalize(snapshot);
         if (!snapshot_image_loaded(snapshot))
             ret = -ENODATA;
         if (!ret) {
             if (swsusp_header->flags & SF_CRC32_MODE) {
                 if(handle->crc32 != swsusp_header->crc32) {
                     pr_err("Invalid image CRC32!\n");
                     ret = -ENODATA;
                 }
             }
         }
     }
     swsusp_show_speed(start, stop, nr_to_read, "Read");
 out_clean:
     hib_finish_batch(&hb);
     for (i = 0; i < ring_size; i++)
         free_page((unsigned long)page[i]);
     if (crc) {
         if (crc->thr)
             kthread_stop(crc->thr);
         kfree(crc);
     }
     if (data) {
         for (thr = 0; thr < nr_threads; thr++)
             if (data[thr].thr)
                 kthread_stop(data[thr].thr);
         vfree(data);
     }
     vfree(page);
 
     return ret;
 }
 
 /**
  *  swsusp_read - read the hibernation image.
  *  @flags_p: flags passed by the "frozen" kernel in the image header should
  *        be written into this memory location
  */
 
 int swsusp_read(unsigned int *flags_p)
 {
     int error;
     struct swap_map_handle handle;
     struct snapshot_handle snapshot;
     struct swsusp_info *header;
 
     memset(&snapshot, 0, sizeof(struct snapshot_handle));
     error = snapshot_write_next(&snapshot);
     if (error < (int)PAGE_SIZE)
         return error < 0 ? error : -EFAULT;
     header = (struct swsusp_info *)data_of(snapshot);
     error = get_swap_reader(&handle, flags_p);
     if (error)
         goto end;
     if (!error)
         error = swap_read_page(&handle, header, NULL);
     if (!error) {
         error = (*flags_p & SF_NOCOMPRESS_MODE) ?
             load_image(&handle, &snapshot, header->pages - 1) :
             load_image_lzo(&handle, &snapshot, header->pages - 1);
     }
     swap_reader_finish(&handle);
 end:
     if (!error)
         pr_debug("Image successfully loaded\n");
     else
         pr_debug("Error %d resuming\n", error);
     return error;
 }
 
 /**
  *      swsusp_check - Check for swsusp signature in the resume device
  */
 
 int swsusp_check(void)
 {
     int error;
     void *holder;
 
     hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device,
                         FMODE_READ | FMODE_EXCL, &holder);
     if (!IS_ERR(hib_resume_bdev)) {
         set_blocksize(hib_resume_bdev, PAGE_SIZE);
         clear_page(swsusp_header);
         error = hib_submit_io(REQ_OP_READ, swsusp_resume_block,
                     swsusp_header, NULL);
         if (error)
             goto put;
 
         if (!memcmp(HIBERNATE_SIG, swsusp_header->sig, 10)) {
             memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
             /* Reset swap signature now */
             error = hib_submit_io(REQ_OP_WRITE | REQ_SYNC,
                         swsusp_resume_block,
                         swsusp_header, NULL);
         } else {
             error = -EINVAL;
         }
         if (!error && swsusp_header->flags & SF_HW_SIG &&
             swsusp_header->hw_sig != swsusp_hardware_signature) {
             pr_info("Suspend image hardware signature mismatch (%08x now %08x); aborting resume.\n",
                 swsusp_header->hw_sig, swsusp_hardware_signature);
             error = -EINVAL;
         }
 
 put:
         if (error)
             blkdev_put(hib_resume_bdev, FMODE_READ | FMODE_EXCL);
         else
             pr_debug("Image signature found, resuming\n");
     } else {
         error = PTR_ERR(hib_resume_bdev);
     }
 
     if (error)
         pr_debug("Image not found (code %d)\n", error);
 
     return error;
 }
 
 /**
  *  swsusp_close - close swap device.
  */
 
 void swsusp_close(fmode_t mode)
 {
     if (IS_ERR(hib_resume_bdev)) {
         pr_debug("Image device not initialised\n");
         return;
     }
 
     blkdev_put(hib_resume_bdev, mode);
 }
 
 /**
  *      swsusp_unmark - Unmark swsusp signature in the resume device
  */
 
 #ifdef CONFIG_SUSPEND
 int swsusp_unmark(void)
 {
     int error;
 
     hib_submit_io(REQ_OP_READ, 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_submit_io(REQ_OP_WRITE | REQ_SYNC,
                     swsusp_resume_block,
                     swsusp_header, NULL);
     } else {
         pr_err("Cannot find swsusp signature!\n");
         error = -ENODEV;
     }
 
     /*
      * We just returned from suspend, we don't need the image any more.
      */
     free_all_swap_pages(root_swap);
 
     return error;
 }
 #endif
 
 static int __init swsusp_header_init(void)
 {
     swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
     if (!swsusp_header)
         panic("Could not allocate memory for swsusp_header\n");
     return 0;
 }
 
 core_initcall(swsusp_header_init);

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