Error compiling btrfs-tools from git (undefined reference to `pthread_create')

On Ubuntu 11.10 "Oneiric" with gcc 4.6.1, compiling the btrfs tools from git fails for me with the following error:

[lenz@metis btrfs-progs]% make
bash version.sh
gcc -lpthread -g -Werror -Os -o btrfs btrfs.o btrfs_cmds.o scrub.o \
ctree.o disk-io.o radix-tree.o extent-tree.o print-tree.o root-tree.o
dir-item.o file-item.o inode-item.o inode-map.o crc32c.o rbtree.o extent-cache.o extent_io.o volumes.o utils.o btrfs-list.o btrfslabel.o -luuid scrub.o: In function `scrub_start':
/space/tmp/btrfs-progs/scrub.c:1342: undefined reference to pthread_create' /space/tmp/btrfs-progs/scrub.c:1360: undefined reference to pthread_create' /space/tmp/btrfs-progs/scrub.c:1374: undefined reference to pthread_join' /space/tmp/btrfs-progs/scrub.c:1430: undefined reference to pthread_cancel' /space/tmp/btrfs-progs/scrub.c:1432: undefined reference to `pthread_join'
collect2: ld returned 1 exit status
make: *** [btrfs] Error 1

The following change fixed this for me, not sure if it's the appropriate approach:

index edee1a0..9e3a06f 100644
@@ -1,6 +1,6 @@
 CC = gcc
 AM_CFLAGS = -Wall -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2
-CFLAGS = -g -Werror -Os
+CFLAGS = -g -Werror -Os -pthread
 objects = ctree.o disk-io.o radix-tree.o extent-tree.o print-tree.o \
          root-tree.o dir-item.o file-item.o inode-item.o \
          inode-map.o crc32c.o rbtree.o extent-cache.o extent_io.o \

  Lenz Grimmer <[email protected]> - http://www.lenzg.net/

Which git repo?
git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git
builds on ubuntu just fine (just checked on a fresh checkout), and likewise the integration repo (but note that the integration repo's master branch is not useful to build; you need to check out one of the actual integration branches as described on the wiki).

Hi,

thank you for your reply.

That's likely the issue - the following commands reproduce the compile error for me:

git clone http://git.darksatanic.net/repo/btrfs-progs-unstable.git btrfs-progs cd btrfs-progs
make
[...]
gcc -lpthread -g -Werror -Os -o btrfs btrfs.o btrfs_cmds.o scrub.o \
ctree.o disk-io.o radix-tree.o extent-tree.o print-tree.o root-tree.o
dir-item.o file-item.o inode-item.o inode-map.o crc32c.o rbtree.o extent-cache.o extent_io.o volumes.o utils.o btrfs-list.o btrfslabel.o -luuid scrub.o: In function `scrub_start':
/space/tmp/btrfs-progs/scrub.c:1342: undefined reference to pthread_create' /space/tmp/btrfs-progs/scrub.c:1360: undefined reference to pthread_create' /space/tmp/btrfs-progs/scrub.c:1374: undefined reference to pthread_join' /space/tmp/btrfs-progs/scrub.c:1430: undefined reference to pthread_cancel' /space/tmp/btrfs-progs/scrub.c:1432: undefined reference to `pthread_join'
collect2: ld returned 1 exit status

However, using the integration-20120605 branch compiles fine. Thanks and sorry for the noise!

Bye,
LenZ

  Lenz Grimmer <[email protected]> - http://www.lenzg.net/