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#include <assert.h> /* for assert(3p) */
#include <errno.h> /* for errno */
#include <error.h> /* for error(3gnu) */
#include <fcntl.h> /* for open(2) */
#include <inttypes.h> /* for uint64_t, PRIu64 */
#include <linux/fs.h> /* for FIDEDUPRANGE and related */
#include <stdbool.h> /* for bool, true, false */
#include <stdlib.h> /* for exit(3p), EXIT_SUCCESS, EXIT_FAILURE, malloc(3p), calloc(3p), free(3p) */
#include <sys/ioctl.h> /* for ioctl(2) */
#include <unistd.h> /* for sysconf(3p), _SC_PAGESIZE */
#include "dedupe-range.h"
#define MIN(a, b) ((a) < (b) ? (a) : (b))
void dedupe_range(uint64_t src_length, struct filepos src, struct filepos *dsts) {
// Count how many destination ranges we have
size_t dst_count;
for (dst_count = 0; dsts[dst_count].filename; dst_count++);
// Figure the maximum number of destination ranges we can fit
// in 1 ioctl
const size_t max_dst_count = (sysconf(_SC_PAGESIZE) - sizeof(struct file_dedupe_range))
/ sizeof(struct file_dedupe_range_info);
assert(max_dst_count > 0);
// Open the source file
int src_fd = open(src.filename, src.flags);
if (src_fd < 0)
error(EXIT_FAILURE, errno, "open src: %s", src.filename);
// Open the destination files
struct file_dedupe_range_info *range_info =
calloc(dst_count, sizeof(struct file_dedupe_range_info));
if (!range_info)
error(EXIT_FAILURE, errno, "malloc");
for (size_t i = 0; i < dst_count; i++) {
int dst_fd = open(dsts[i].filename, dsts[i].flags);
if (dst_fd < 0)
error(EXIT_FAILURE, errno, "open dst[%zu]: %s", i, dsts[i].filename);
range_info[i].dest_fd = dst_fd;
range_info[i].dest_offset = dsts[i].offset;
}
// Do the work
struct file_dedupe_range *range = malloc(sysconf(_SC_PAGESIZE));
if (!range)
error(EXIT_FAILURE, errno, "malloc");
for (size_t files_deduped = 0; files_deduped < dst_count; ) {
// initialize the range structure
*range = (struct file_dedupe_range){0};
range->dest_count = MIN(dst_count - files_deduped, max_dst_count);
assert(range->dest_count > 0);
for (size_t i = 0;i < range->dest_count; i++)
range->info[i] = range_info[files_deduped+i];
// call FIDEDUPERANGE repeatedly to dedupe all of src_length
uint64_t bytes_todo = src_length;
uint64_t bytes_done = 0;
while (bytes_todo > 0) {
// allegedly, these need to be aligned to the
// fundamental block size (statfs->f_frsize,
// fall back to ->f_bsize)
range->src_offset = src.offset + bytes_done;
range->src_length = bytes_todo;
if (ioctl(src_fd, FIDEDUPERANGE, range) < 0)
error(EXIT_FAILURE, errno, "FIDEDUPERANGE");
// how much actually got done?
uint64_t bytes_deduped = range->info[0].bytes_deduped;
assert(bytes_deduped <= range->src_length);
bytes_done += bytes_deduped;
bytes_todo -= bytes_deduped;
// verify that dedupe for each dst went ok
bool erred = false;
for (size_t i = 0; i < range->dest_count; i ++) {
if (range->info[i].bytes_deduped != bytes_deduped) {
error(0, errno, "dedupe: %"PRIu64" != %"PRIu64": %s",
bytes_deduped,
range->info[i].bytes_deduped,
dsts[files_deduped+i].filename);
erred = true;
}
switch (range->info[i].status) {
case FILE_DEDUPE_RANGE_DIFFERS:
error(0, 0, "dedupe: range differs: %s", dsts[files_deduped+i].filename);
erred = true;
break;
case FILE_DEDUPE_RANGE_SAME:
range->info[i].dest_offset += range->info[i].bytes_deduped;
break;
default:
assert(range->info[i].status < 0);
error(0, -range->info[i].status, "dedupe: %s", dsts[files_deduped+i].filename);
erred = true;
break;
}
}
if (erred == true)
exit(EXIT_FAILURE);
}
files_deduped += range->dest_count;
}
free(range);
for (size_t i = 0; i < dst_count; i++)
close(range_info[i].dest_fd);
free(range_info);
close(src_fd);
}
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