mkfs with -t option on btrfs fails on wily

[Colin Ian King]

How to reproduce:

As root:

# dd if=/dev/zero of=test.img bs=1M count=1024
# mkfs -t btrfs -f test.img
mkfs: failed to execute mkfs.btrfs: No such file or directory

Does it exist?

# which mkfs.btrfs
/bin/mkfs.btrfs

Yes!

stracing mkfs shows why it fails:

# strace -f mkfs -t btrfs -f test.img
execve("/sbin/mkfs", ["mkfs", "-t", "btrfs", "-f", "test.img"], [/* 41 vars */]) = 0
brk(0) = 0xba3000
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8b0e914000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=155913, ...}) = 0
mmap(NULL, 155913, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f8b0e8ed000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\v\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1869392, ...}) = 0
mmap(NULL, 3972864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f8b0e329000
mprotect(0x7f8b0e4e9000, 2097152, PROT_NONE) = 0
mmap(0x7f8b0e6e9000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f8b0e6e9000
mmap(0x7f8b0e6ef000, 16128, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f8b0e6ef000
close(3) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8b0e8ec000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8b0e8eb000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8b0e8ea000
arch_prctl(ARCH_SET_FS, 0x7f8b0e8eb700) = 0
mprotect(0x7f8b0e6e9000, 16384, PROT_READ) = 0
mprotect(0x601000, 4096, PROT_READ) = 0
mprotect(0x7f8b0e916000, 4096, PROT_READ) = 0
munmap(0x7f8b0e8ed000, 155913) = 0
brk(0) = 0xba3000
brk(0xbc4000) = 0xbc4000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2919792, ...}) = 0
mmap(NULL, 2919792, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f8b0e060000
close(3) = 0
execve("/sbin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/sbin/fs.d/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/sbin/fs/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/home/king/android/android-ndk-r10e/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/home/king/bin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/home/king/coverity/cov-analysis-linux64-7.6.0/bin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/usr/local/sbin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/usr/local/bin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/usr/sbin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/usr/bin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/sbin/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)
execve("/bin\n/mkfs.btrfs", ["mkfs.btrfs", "-f", "test.img"], [/* 41 vars */]) = -1 ENOENT (No such file or directory)

What? the path is /bin\n/mkfs.btrfs? That is clearly why it is wrong. Hypothesis is that it is picking up the "\n" from the end of the $PATH env string. Add a dummy path at the end and it works!

PATH=$PATH:/bin/dummy
root@lenovo:~# mkfs -t btrfs -f test.img
btrfs-progs v4.0
See http://btrfs.wiki.kernel.org for more information.

Turning ON incompat feature 'extref': increased hardlink limit per file to 65536
Turning ON incompat feature 'skinny-metadata': reduced-size metadata extent refs
ERROR: device scan failed 'test.img' - Block device required
fs created label (null) on test.img
 nodesize 16384 leafsize 16384 sectorsize 4096 size 1.00GiB

Can this be fixed as it's screwing up a lot of regression tests we're doing with btrfs

[Steve Langasek (vorlon)]

this bug has been present upstream in util-linux for a decade, but has been exposed by btrfs-tools in wily moving mkfs.btrfs from /sbin to /bin.

[Launchpad Janitor (janitor)]

This bug was fixed in the package util-linux - 2.26.2-6ubuntu2

---------------
util-linux (2.26.2-6ubuntu2) wily; urgency=medium

  * debian/patches/no-newline-in-path.patch: mkfs: Don't append newline
    to $PATH variable. Closes LP: #1474473.

 -- Steve Langasek <email address hidden> Tue, 21 Jul 2015 15:07:53 -0700