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Subject[PATCH 2/5] PM / Hibernate: snapshot cleanup
Date
From: Jiri Slaby <jirislaby@gmail.com>

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>
Cc: Nigel Cunningham <ncunningham@crca.org.au>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
---
kernel/power/power.h | 18 +-----
kernel/power/snapshot.c | 145 ++++++++++++++++++-----------------------------
kernel/power/swap.c | 8 +-
kernel/power/user.c | 37 ++++++++----
4 files changed, 88 insertions(+), 120 deletions(-)
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 46c5a26..b1e207d 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -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);

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index be861c2..25ce010 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();
}
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 66824d7..7f2a17e 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -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);
diff --git a/kernel/power/user.c b/kernel/power/user.c
index a8c9621..e819e17 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -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;
--
1.7.0.3



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