PM / Hibernate: Snapshot cleanup

Remove support of reads with offset. This means snapshot_read/write_next
now does not accept count parameter. It allows to clean up the functions
and snapshot handle which no longer needs to care about offsets.

/dev/snapshot handler is converted to simple_{read_from,write_to}_buffer
which take care of offsets.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 56 insertions, 89 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index be861c26dda7..25ce010e9f8b 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1604,14 +1604,9 @@ pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
  *      snapshot_handle structure.  The structure gets updated and a pointer
  *      to it should be passed to this function every next time.
  *
- *      The @count parameter should contain the number of bytes the caller
- *      wants to read from the snapshot.  It must not be zero.
- *
  *      On success the function returns a positive number.  Then, the caller
  *      is allowed to read up to the returned number of bytes from the memory
- *      location computed by the data_of() macro.  The number returned
- *      may be smaller than @count, but this only happens if the read would
- *      cross a page boundary otherwise.
+ *      location computed by the data_of() macro.
  *
  *      The function returns 0 to indicate the end of data stream condition,
  *      and a negative number is returned on error.  In such cases the
@@ -1619,7 +1614,7 @@ pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
  *      any more.
  */
 
-int snapshot_read_next(struct snapshot_handle *handle, size_t count)
+int snapshot_read_next(struct snapshot_handle *handle)
 {
         if (handle->cur > nr_meta_pages + nr_copy_pages)
                 return 0;
@@ -1630,7 +1625,7 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count)
                 if (!buffer)
                         return -ENOMEM;
         }
-        if (!handle->offset) {
+        if (!handle->cur) {
                 int error;
 
                 error = init_header((struct swsusp_info *)buffer);
@@ -1639,42 +1634,30 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count)
                 handle->buffer = buffer;
                 memory_bm_position_reset(&orig_bm);
                 memory_bm_position_reset(&copy_bm);
-        }
-        if (handle->prev < handle->cur) {
-                if (handle->cur <= nr_meta_pages) {
-                        memset(buffer, 0, PAGE_SIZE);
-                        pack_pfns(buffer, &orig_bm);
-                } else {
-                        struct page *page;
+        } else if (handle->cur <= nr_meta_pages) {
+                memset(buffer, 0, PAGE_SIZE);
+                pack_pfns(buffer, &orig_bm);
+        } else {
+                struct page *page;
 
-                        page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
-                        if (PageHighMem(page)) {
-                                /* Highmem pages are copied to the buffer,
-                                 * because we can't return with a kmapped
-                                 * highmem page (we may not be called again).
-                                 */
-                                void *kaddr;
+                page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
+                if (PageHighMem(page)) {
+                        /* Highmem pages are copied to the buffer,
+                         * because we can't return with a kmapped
+                         * highmem page (we may not be called again).
+                         */
+                        void *kaddr;
 
-                                kaddr = kmap_atomic(page, KM_USER0);
-                                memcpy(buffer, kaddr, PAGE_SIZE);
-                                kunmap_atomic(kaddr, KM_USER0);
-                                handle->buffer = buffer;
-                        } else {
-                                handle->buffer = page_address(page);
-                        }
+                        kaddr = kmap_atomic(page, KM_USER0);
+                        memcpy(buffer, kaddr, PAGE_SIZE);
+                        kunmap_atomic(kaddr, KM_USER0);
+                        handle->buffer = buffer;
+                } else {
+                        handle->buffer = page_address(page);
                 }
-                handle->prev = handle->cur;
-        }
-        handle->buf_offset = handle->cur_offset;
-        if (handle->cur_offset + count >= PAGE_SIZE) {
-                count = PAGE_SIZE - handle->cur_offset;
-                handle->cur_offset = 0;
-                handle->cur++;
-        } else {
-                handle->cur_offset += count;
         }
-        handle->offset += count;
-        return count;
+        handle->cur++;
+        return PAGE_SIZE;
 }
 
 /**
@@ -2133,14 +2116,9 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
  *      snapshot_handle structure.  The structure gets updated and a pointer
  *      to it should be passed to this function every next time.
  *
- *      The @count parameter should contain the number of bytes the caller
- *      wants to write to the image.  It must not be zero.
- *
  *      On success the function returns a positive number.  Then, the caller
  *      is allowed to write up to the returned number of bytes to the memory
- *      location computed by the data_of() macro.  The number returned
- *      may be smaller than @count, but this only happens if the write would
- *      cross a page boundary otherwise.
+ *      location computed by the data_of() macro.
  *
  *      The function returns 0 to indicate the "end of file" condition,
  *      and a negative number is returned on error.  In such cases the
@@ -2148,16 +2126,18 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
  *      any more.
  */
 
-int snapshot_write_next(struct snapshot_handle *handle, size_t count)
+int snapshot_write_next(struct snapshot_handle *handle)
 {
         static struct chain_allocator ca;
         int error = 0;
 
         /* Check if we have already loaded the entire image */
-        if (handle->prev && handle->cur > nr_meta_pages + nr_copy_pages)
+        if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages)
                 return 0;
 
-        if (handle->offset == 0) {
+        handle->sync_read = 1;
+
+        if (!handle->cur) {
                 if (!buffer)
                         /* This makes the buffer be freed by swsusp_free() */
                         buffer = get_image_page(GFP_ATOMIC, PG_ANY);
@@ -2166,56 +2146,43 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count)
                         return -ENOMEM;
 
                 handle->buffer = buffer;
-        }
-        handle->sync_read = 1;
-        if (handle->prev < handle->cur) {
-                if (handle->prev == 0) {
-                        error = load_header(buffer);
-                        if (error)
-                                return error;
+        } else if (handle->cur == 1) {
+                error = load_header(buffer);
+                if (error)
+                        return error;
 
-                        error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
-                        if (error)
-                                return error;
+                error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
+                if (error)
+                        return error;
+
+        } else if (handle->cur <= nr_meta_pages + 1) {
+                error = unpack_orig_pfns(buffer, &copy_bm);
+                if (error)
+                        return error;
 
-                } else if (handle->prev <= nr_meta_pages) {
-                        error = unpack_orig_pfns(buffer, &copy_bm);
+                if (handle->cur == nr_meta_pages + 1) {
+                        error = prepare_image(&orig_bm, &copy_bm);
                         if (error)
                                 return error;
 
-                        if (handle->prev == nr_meta_pages) {
-                                error = prepare_image(&orig_bm, &copy_bm);
-                                if (error)
-                                        return error;
-
-                                chain_init(&ca, GFP_ATOMIC, PG_SAFE);
-                                memory_bm_position_reset(&orig_bm);
-                                restore_pblist = NULL;
-                                handle->buffer = get_buffer(&orig_bm, &ca);
-                                handle->sync_read = 0;
-                                if (IS_ERR(handle->buffer))
-                                        return PTR_ERR(handle->buffer);
-                        }
-                } else {
-                        copy_last_highmem_page();
+                        chain_init(&ca, GFP_ATOMIC, PG_SAFE);
+                        memory_bm_position_reset(&orig_bm);
+                        restore_pblist = NULL;
                         handle->buffer = get_buffer(&orig_bm, &ca);
+                        handle->sync_read = 0;
                         if (IS_ERR(handle->buffer))
                                 return PTR_ERR(handle->buffer);
-                        if (handle->buffer != buffer)
-                                handle->sync_read = 0;
                 }
-                handle->prev = handle->cur;
-        }
-        handle->buf_offset = handle->cur_offset;
-        if (handle->cur_offset + count >= PAGE_SIZE) {
-                count = PAGE_SIZE - handle->cur_offset;
-                handle->cur_offset = 0;
-                handle->cur++;
         } else {
-                handle->cur_offset += count;
+                copy_last_highmem_page();
+                handle->buffer = get_buffer(&orig_bm, &ca);
+                if (IS_ERR(handle->buffer))
+                        return PTR_ERR(handle->buffer);
+                if (handle->buffer != buffer)
+                        handle->sync_read = 0;
         }
-        handle->offset += count;
-        return count;
+        handle->cur++;
+        return PAGE_SIZE;
 }
 
 /**
@@ -2230,7 +2197,7 @@ void snapshot_write_finalize(struct snapshot_handle *handle)
 {
         copy_last_highmem_page();
         /* Free only if we have loaded the image entirely */
-        if (handle->prev && handle->cur > nr_meta_pages + nr_copy_pages) {
+        if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages) {
                 memory_bm_free(&orig_bm, PG_UNSAFE_CLEAR);
                 free_highmem_data();
         }