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author | Zhao Lei <zhaolei@cn.fujitsu.com> | 2015-09-09 21:32:21 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2015-09-11 17:00:10 +0200 |
commit | 50ef0322b4aecf8c5ea8031aa4f022619d255f10 (patch) | |
tree | dc0f23dff3e3929235d2a6a0c13192edc90509ff | |
parent | 73a894e51e5bcea9fddc4f3ded37d0ad81456e92 (diff) |
btrfs-progs: image: fix infinite looping with -t 0
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>
-rw-r--r-- | btrfs-image.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/btrfs-image.c b/btrfs-image.c index 630fdf8a..6eddbd5d 100644 --- a/btrfs-image.c +++ b/btrfs-image.c @@ -2690,7 +2690,7 @@ int main(int argc, char *argv[]) { char *source; char *target; - u64 num_threads = 1; + u64 num_threads = 0; u64 compress_level = 0; int create = 1; int old_restore = 0; @@ -2786,7 +2786,8 @@ int main(int argc, char *argv[]) } } - 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; |