[Libguestfs] [PATCH libnbd 1/3] copy: Allocate required size instead of maximum
If we cannot write zeroes efficiently, consider the command length when
allocating the buffer instead of allocating MAX_REQUEST_SIZE.
Signed-off-by: Nir Soffer <nsoffer(a)redhat.com>
---
copy/multi-thread-copying.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/copy/multi-thread-copying.c b/copy/multi-thread-copying.c
index f86621b..b1cc9a5 100644
--- a/copy/multi-thread-copying.c
+++ b/copy/multi-thread-copying.c
@@ -501,6 +501,7 @@ static void
fill_dst_range_with_zeroes (struct command *command)
{
char *data;
+ size_t data_size;
if (destination_is_zero)
goto free_and_return;
@@ -517,7 +518,8 @@ fill_dst_range_with_zeroes (struct command *command)
/* Fall back to loop writing zeroes. This is going to be slow
* anyway, so do it synchronously. XXX
*/
- data = calloc (1, MAX_REQUEST_SIZE);
+ data_size = MIN (MAX_REQUEST_SIZE, command->slice.len);
+ data = calloc (1, data_size);
if (!data) {
perror ("calloc");
exit (EXIT_FAILURE);
@@ -525,8 +527,8 @@ fill_dst_range_with_zeroes (struct command *command)
while (command->slice.len > 0) {
size_t len = command->slice.len;
- if (len > MAX_REQUEST_SIZE)
- len = MAX_REQUEST_SIZE;
+ if (len > data_size)
+ len = data_size;
dst->ops->synch_write (dst, data, len, command->offset);
command->slice.len -= len;
--
2.26.2