From 50ef0322b4aecf8c5ea8031aa4f022619d255f10 Mon Sep 17 00:00:00 2001 From: Zhao Lei Date: Wed, 9 Sep 2015 21:32:21 +0800 Subject: 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 Signed-off-by: David Sterba --- btrfs-image.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'btrfs-image.c') 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; -- cgit v1.2.3