[bug] <subvol> doesn't belong to btrfs mount point

[bug] <subvol> doesn't belong to btrfs mount point

[Chris Murphy]

Summary: When a btrfs subvolume is mounted with -o subvol, and a nested ro subvol/snapshot is created, btrfs send returns with an error. If the top level (id 5) is mounted instead, the send command succeeds.

3.17.0-0.rc4.git0.1.fc22.i686
Btrfs v3.16

This may also be happening on x86_64, and this bug suggests the problem is commit de22c28ef31d9721606ba05965a093a8044be0de

https://bugzilla.kernel.org/show_bug.cgi?id=83741



[root@lati ~]# strace btrfs send /root/rpms.ro | btrfs receive /mnt/
execve("/usr/sbin/btrfs", ["btrfs", "send", "/root/rpms.ro"], [/* 26 vars */]) = 0
brk(0)                                  = 0x866a000
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7767000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=84972, ...}) = 0
mmap2(NULL, 84972, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7752000
close(3)                                = 0
open("/lib/libuuid.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320\17\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=19100, ...}) = 0
mmap2(NULL, 20692, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb774c000
mmap2(0xb7750000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0xb7750000
close(3)                                = 0
open("/lib/libblkid.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320P\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=271276, ...}) = 0
mmap2(NULL, 271832, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7709000
mmap2(0xb7748000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3e000) = 0xb7748000
mmap2(0xb774b000, 1496, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb774b000
close(3)                                = 0
open("/lib/libm.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0pF\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=357384, ...}) = 0
mmap2(NULL, 311456, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76bc000
mmap2(0xb7707000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x4b000) = 0xb7707000
close(3)                                = 0
open("/lib/libz.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\30\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=93444, ...}) = 0
mmap2(NULL, 94464, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76a4000
mmap2(0xb76ba000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15000) = 0xb76ba000
close(3)                                = 0
open("/lib/liblzo2.so.2", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@ \0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=145984, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76a3000
mmap2(NULL, 147584, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb767e000
mmap2(0xb76a1000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0xb76a1000
close(3)                                = 0
open("/lib/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320O\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=142932, ...}) = 0
mmap2(NULL, 115404, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7661000
mprotect(0xb7679000, 4096, PROT_NONE)   = 0
mmap2(0xb767a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x18000) = 0xb767a000
mmap2(0xb767c000, 4812, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb767c000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\0\200\1\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=2166836, ...}) = 0
mmap2(NULL, 1933020, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7489000
mmap2(0xb765a000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1d0000) = 0xb765a000
mmap2(0xb765f000, 7900, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb765f000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7488000
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7487000
set_thread_area({entry_number:-1, base_addr:0xb7487800, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0 (entry_number:6)
mprotect(0xb765a000, 12288, PROT_READ)  = 0
mprotect(0xb767a000, 4096, PROT_READ)   = 0
mprotect(0xb76a1000, 4096, PROT_READ)   = 0
mprotect(0xb76ba000, 4096, PROT_READ)   = 0
mprotect(0xb7707000, 4096, PROT_READ)   = 0
mprotect(0xb7750000, 4096, PROT_READ)   = 0
mprotect(0xb7748000, 8192, PROT_READ)   = 0
mprotect(0x80c8000, 8192, PROT_READ)    = 0
mprotect(0xb7790000, 4096, PROT_READ)   = 0
munmap(0xb7752000, 84972)               = 0
set_tid_address(0xb7487868)             = 3024
set_robust_list(0xb7487870, 12)         = 0
rt_sigaction(SIGRTMIN, {0xb7665a50, [], SA_SIGINFO}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0xb7665ad0, [], SA_RESTART|SA_SIGINFO}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
uname({sys="Linux", node="lati.localdomain", ...}) = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, 0xbfdfdef8) = -1 ENOTTY (Inappropriate ioctl for device)
brk(0)                                  = 0x866a000
brk(0x868c000)                          = 0x868c000
brk(0)                                  = 0x868c000
lstat64("/root", {st_mode=S_IFDIR|0550, st_size=172, ...}) = 0
lstat64("/root/rpms.ro", {st_mode=S_IFDIR|0755, st_size=24834, ...}) = 0
open("/root/rpms.ro", O_RDONLY|O_LARGEFILE|O_NOATIME) = 3
close(3)                                = 0
open("/proc/self/mounts", O_RDONLY|O_CLOEXEC) = 3
futex(0xb765f114, FUTEX_WAKE_PRIVATE, 2147483647) = 0
fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7766000
read(3, "rootfs / rootfs rw,seclabel 0 0\n"..., 1024) = 1024
read(3, "memory 0 0\ncgroup /sys/fs/cgroup"..., 1024) = 1024
read(3, "s /run/user/42 tmpfs rw,seclabel"..., 1024) = 405
read(3, "", 1024)                       = 0
close(3)                                = 0
munmap(0xb7766000, 4096)                = 0
write(2, "ERROR: /root/rpms.ro doesn't bel"..., 57ERROR: /root/rpms.ro doesn't belong to btrfs mount point
) = 57
close(0)                                = 0
exit_group(1)                           = ?
+++ exited with 1 +++


Chris Murphy

Re: [bug] <subvol> doesn't belong to btrfs mount point

[Chris Murphy]

On Sep 12, 2014, at 5:39 PM, Chris Murphy <lists@colorremedies.com> wrote:

> Summary: When a btrfs subvolume is mounted with -o subvol, and a nested ro subvol/snapshot is created, btrfs send returns with an error. If the top level (id 5) is mounted instead, the send command succeeds.

I'm not able to reproduce this, so at the moment I'm going to say it's user error until I can.


Chris Murphy

Re: [bug] <subvol> doesn't belong to btrfs mount point

[Qu Wenruo]

I am very sorry that my commit caused the problem.

In fact some users have already find the problem and I sent the fix some 
time ago.

The patch is https://patchwork.kernel.org/patch/4842201/

Hopes this helps.

Thanks,
Qu
-------- Original Message --------
Subject: Re: [bug] <subvol> doesn't belong to btrfs mount point
From: Chris Murphy <lists@colorremedies.com>
To: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Date: 2014年09月16日 10:08
> On Sep 12, 2014, at 5:39 PM, Chris Murphy <lists@colorremedies.com> wrote:
>
>> Summary: When a btrfs subvolume is mounted with -o subvol, and a nested ro subvol/snapshot is created, btrfs send returns with an error. If the top level (id 5) is mounted instead, the send command succeeds.
> I'm not able to reproduce this, so at the moment I'm going to say it's user error until I can.
>
>
> Chris Murphy--
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html