Bug:
# btrfs-image -t0 -c9 /dev/sda6 /tmp/btrfs_image.img
(hang)
# btrfs-image -r -t0 /tmp/btrfs_image.img /dev/sda6
(hang)
Reason:
The program need to create at least 1 thread for
compression/decompression. If the user specifies -t0, it overwrites the
default value of 1, then the program really creates 0 thread, and
ends up looping
Fix:
We can add a check, to make the program not to allow -t0 argument,
but there is another problem:
For example, on a node with 4 cpus:
btrfs-image -c9 -t1: 4 threads (1 means use NR_CPUS)
-c9 -t2: 2 threads
-c9 -t3: 3 threads
...
(-t1 has more threads than -t2 and -t3)
So we change to use value of 0 as "use NR_CPUS threads", then:
btrfs-image [no -t arg]: use NR_CPUS threads
-t0: use NR_CPUS threads
-t val: use val threads.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
{
char *source;
char *target;
- u64 num_threads = 1;
+ u64 num_threads = 0;
u64 compress_level = 0;
int create = 1;
int old_restore = 0;
}
}
- if (num_threads == 1 && compress_level > 0) {
+ if ((compress_level > 0 || create == 0) &&
+ num_threads == 0) {
num_threads = sysconf(_SC_NPROCESSORS_ONLN);
if (num_threads <= 0)
num_threads = 1;