PM / Hibernate: Snapshot cleanup
Jiri Slaby [Sat, 1 May 2010 21:52:02 +0000 (23:52 +0200)]
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>

kernel/power/power.h
kernel/power/snapshot.c
kernel/power/swap.c
kernel/power/user.c

index 46c5a26..b1e207d 100644 (file)
@@ -97,24 +97,12 @@ extern int hibernate_preallocate_memory(void);
  */
 
 struct snapshot_handle {
-       loff_t          offset; /* number of the last byte ready for reading
-                                * or writing in the sequence
-                                */
        unsigned int    cur;    /* number of the block of PAGE_SIZE bytes the
                                 * next operation will refer to (ie. current)
                                 */
-       unsigned int    cur_offset;     /* offset with respect to the current
-                                        * block (for the next operation)
-                                        */
-       unsigned int    prev;   /* number of the block of PAGE_SIZE bytes that
-                                * was the current one previously
-                                */
        void            *buffer;        /* address of the block to read from
                                         * or write to
                                         */
-       unsigned int    buf_offset;     /* location to read from or write to,
-                                        * given as a displacement from 'buffer'
-                                        */
        int             sync_read;      /* Set to one to notify the caller of
                                         * snapshot_write_next() that it may
                                         * need to call wait_on_bio_chain()
@@ -125,12 +113,12 @@ struct snapshot_handle {
  * snapshot_read_next()/snapshot_write_next() is allowed to
  * read/write data after the function returns
  */
-#define data_of(handle)        ((handle).buffer + (handle).buf_offset)
+#define data_of(handle)        ((handle).buffer)
 
 extern unsigned int snapshot_additional_pages(struct zone *zone);
 extern unsigned long snapshot_get_image_size(void);
-extern int snapshot_read_next(struct snapshot_handle *handle, size_t count);
-extern int snapshot_write_next(struct snapshot_handle *handle, size_t count);
+extern int snapshot_read_next(struct snapshot_handle *handle);
+extern int snapshot_write_next(struct snapshot_handle *handle);
 extern void snapshot_write_finalize(struct snapshot_handle *handle);
 extern int snapshot_image_loaded(struct snapshot_handle *handle);
 
index be861c2..25ce010 100644 (file)
@@ -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();
        }
index 66824d7..7f2a17e 100644 (file)
@@ -431,7 +431,7 @@ static int save_image(struct swap_map_handle *handle,
        bio = NULL;
        do_gettimeofday(&start);
        while (1) {
-               ret = snapshot_read_next(snapshot, PAGE_SIZE);
+               ret = snapshot_read_next(snapshot);
                if (ret <= 0)
                        break;
                ret = swap_write_page(handle, data_of(*snapshot), &bio);
@@ -492,7 +492,7 @@ int swsusp_write(unsigned int flags)
                return error;
        }
        memset(&snapshot, 0, sizeof(struct snapshot_handle));
-       error = snapshot_read_next(&snapshot, PAGE_SIZE);
+       error = snapshot_read_next(&snapshot);
        if (error < PAGE_SIZE) {
                if (error >= 0)
                        error = -EFAULT;
@@ -615,7 +615,7 @@ static int load_image(struct swap_map_handle *handle,
        bio = NULL;
        do_gettimeofday(&start);
        for ( ; ; ) {
-               error = snapshot_write_next(snapshot, PAGE_SIZE);
+               error = snapshot_write_next(snapshot);
                if (error <= 0)
                        break;
                error = swap_read_page(handle, data_of(*snapshot), &bio);
@@ -660,7 +660,7 @@ int swsusp_read(unsigned int *flags_p)
        *flags_p = swsusp_header->flags;
 
        memset(&snapshot, 0, sizeof(struct snapshot_handle));
-       error = snapshot_write_next(&snapshot, PAGE_SIZE);
+       error = snapshot_write_next(&snapshot);
        if (error < PAGE_SIZE)
                return error < 0 ? error : -EFAULT;
        header = (struct swsusp_info *)data_of(snapshot);
index a8c9621..e819e17 100644 (file)
@@ -151,6 +151,7 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
 {
        struct snapshot_data *data;
        ssize_t res;
+       loff_t pg_offp = *offp & ~PAGE_MASK;
 
        mutex_lock(&pm_mutex);
 
@@ -159,14 +160,19 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
                res = -ENODATA;
                goto Unlock;
        }
-       res = snapshot_read_next(&data->handle, count);
-       if (res > 0) {
-               if (copy_to_user(buf, data_of(data->handle), res))
-                       res = -EFAULT;
-               else
-                       *offp = data->handle.offset;
+       if (!pg_offp) { /* on page boundary? */
+               res = snapshot_read_next(&data->handle);
+               if (res <= 0)
+                       goto Unlock;
+       } else {
+               res = PAGE_SIZE - pg_offp;
        }
 
+       res = simple_read_from_buffer(buf, count, &pg_offp,
+                       data_of(data->handle), res);
+       if (res > 0)
+               *offp += res;
+
  Unlock:
        mutex_unlock(&pm_mutex);
 
@@ -178,18 +184,25 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 {
        struct snapshot_data *data;
        ssize_t res;
+       loff_t pg_offp = *offp & ~PAGE_MASK;
 
        mutex_lock(&pm_mutex);
 
        data = filp->private_data;
-       res = snapshot_write_next(&data->handle, count);
-       if (res > 0) {
-               if (copy_from_user(data_of(data->handle), buf, res))
-                       res = -EFAULT;
-               else
-                       *offp = data->handle.offset;
+
+       if (!pg_offp) {
+               res = snapshot_write_next(&data->handle);
+               if (res <= 0)
+                       goto unlock;
+       } else {
+               res = PAGE_SIZE - pg_offp;
        }
 
+       res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
+                       buf, count);
+       if (res > 0)
+               *offp += res;
+unlock:
        mutex_unlock(&pm_mutex);
 
        return res;