static void sdev_free(struct device *dev)
{
struct safe_device *sdev = dev_sdev(dev);
if (sdev->sb_n > 0) {
char *first_block = align_512(sdev->saved_blocks);
char *block = first_block +
((sdev->sb_n - 1) <<
dev_get_block_order(sdev->shadow_dev));
uint64_t *poffset = &sdev->sb_offsets[sdev->sb_n - 1];
int block_size = dev_get_block_size(sdev->shadow_dev);
/* Restore blocks in reverse order to cope with
* wraparound and chain drives.
*/
do {
int rc = sdev->shadow_dev->write_block(
sdev->shadow_dev, block, block_size, *poffset);
if (rc) {
/* Do not abort, try to recover all bocks. */
warn("Failed to recover block at offset 0x%"
PRIx64 " due to a write error",
*poffset);
}
block -= block_size;
poffset--;
} while (block >= first_block);
}
free(sdev->sb_bitmap);
free(sdev->sb_offsets);
free(sdev->saved_blocks);
free_device(sdev->shadow_dev);
}
/* Return true if @b1 and b2 are at most @tolerance_byte bytes different. */
static int similar_blk(struct device *dev, const char *b1, const char *b2,
int tolerance_byte)
{
const int block_size = dev_get_block_size(dev);
int i;
for (i = 0; i < block_size; i++) {
if (*b1 != *b2) {
tolerance_byte--;
if (tolerance_byte <= 0)
return false;
}
b1++;
b2++;
}
return true;
}
static int sdev_save_block(struct safe_device *sdev,
int length, uint64_t offset)
{
const int block_order = dev_get_block_order(sdev->shadow_dev);
lldiv_t idx = lldiv(offset >> block_order, SDEV_BITMAP_BITS_PER_WORD);
SDEV_BITMAP_WORD set_bit = (SDEV_BITMAP_WORD)1 << idx.rem;
char *block;
int rc;
/* The current implementation doesn't support variable lengths. */
assert(length == dev_get_block_size(sdev->shadow_dev));
/* Is this block already saved? */
if (!sdev->sb_bitmap) {
int i;
/* Running without bitmap. */
for (i = 0; i < sdev->sb_n; i++)
if (sdev->sb_offsets[i] == offset) {
/* The block at @offset is already saved. */
return 0;
}
} else if (sdev->sb_bitmap[idx.quot] & set_bit) {
/* The block at @offset is already saved. */
return 0;
}
/* The block at @offset hasn't been saved before. Save this block. */
assert(sdev->sb_n < sdev->sb_max);
block = (char *)align_512(sdev->saved_blocks) +
(sdev->sb_n << block_order);
rc = sdev->shadow_dev->read_block(sdev->shadow_dev, block,
length, offset);
if (rc)
return rc;
/* Bookkeeping. */
if (sdev->sb_bitmap)
sdev->sb_bitmap[idx.quot] |= set_bit;
sdev->sb_offsets[sdev->sb_n] = offset;
sdev->sb_n++;
return 0;
}
static inline int equal_blk(struct device *dev, const char *b1, const char *b2)
{
return !memcmp(b1, b2, dev_get_block_size(dev));
}