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Groups > linux.kernel > #1333865
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 3.10 11/64] Revert "dm mpath: fix stalls when handling invalid ioctls" |
| Date | 2016-02-15 00:50 +0100 |
| Message-ID | <r2eAr-1fL-47@gated-at.bofh.it> (permalink) |
| References | <r2dO1-Ir-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
commit 47796938c46b943d157ac8a6f9ed4e3b98b83cf4 upstream.
This reverts commit a1989b330093578ea5470bea0a00f940c444c466.
That commit introduced a regression at least for the case of the SG_IO ioctl()
running without CAP_SYS_RAWIO capability (e.g., unprivileged users) when there
are no active paths: the ioctl() fails with the ENOTTY errno immediately rather
than blocking due to queue_if_no_path until a path becomes active, for example.
That case happens to be exercised by QEMU KVM guests with 'scsi-block' devices
(qemu "-device scsi-block" [1], libvirt "<disk type='block' device='lun'>" [2])
from multipath devices; which leads to SCSI/filesystem errors in such a guest.
More general scenarios can hit that regression too. The following demonstration
employs a SG_IO ioctl() with a standard SCSI INQUIRY command for this objective
(some output & user changes omitted for brevity and comments added for clarity).
Reverting that commit restores normal operation (queueing) in failing scenarios;
tested on linux-next (next-20151022).
1) Test-case is based on sg_simple0 [3] (just SG_IO; remove SG_GET_VERSION_NUM)
$ cat sg_simple0.c
... see [3] ...
$ sed '/SG_GET_VERSION_NUM/,/}/d' sg_simple0.c > sgio_inquiry.c
$ gcc sgio_inquiry.c -o sgio_inquiry
2) The ioctl() works fine with active paths present.
# multipath -l 85ag56
85ag56 (...) dm-19 IBM ,2145
size=60G features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=0 status=active
| |- 8:0:11:0 sdz 65:144 active undef running
| `- 9:0:9:0 sdbf 67:144 active undef running
`-+- policy='service-time 0' prio=0 status=enabled
|- 8:0:12:0 sdae 65:224 active undef running
`- 9:0:12:0 sdbo 68:32 active undef running
$ ./sgio_inquiry /dev/mapper/85ag56
Some of the INQUIRY command's response:
IBM 2145 0000
INQUIRY duration=0 millisecs, resid=0
3) The ioctl() fails with ENOTTY errno with _no_ active paths present,
for unprivileged users (rather than blocking due to queue_if_no_path).
# for path in $(multipath -l 85ag56 | grep -o 'sd[a-z]\+'); \
do multipathd -k"fail path $path"; done
# multipath -l 85ag56
85ag56 (...) dm-19 IBM ,2145
size=60G features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=0 status=enabled
| |- 8:0:11:0 sdz 65:144 failed undef running
| `- 9:0:9:0 sdbf 67:144 failed undef running
`-+- policy='service-time 0' prio=0 status=enabled
|- 8:0:12:0 sdae 65:224 failed undef running
`- 9:0:12:0 sdbo 68:32 failed undef running
$ ./sgio_inquiry /dev/mapper/85ag56
sg_simple0: Inquiry SG_IO ioctl error: Inappropriate ioctl for device
4) dmesg shows that scsi_verify_blk_ioctl() failed for SG_IO (0x2285);
it returns -ENOIOCTLCMD, later replaced with -ENOTTY in vfs_ioctl().
$ dmesg
<...>
[] device-mapper: multipath: Failing path 65:144.
[] device-mapper: multipath: Failing path 67:144.
[] device-mapper: multipath: Failing path 65:224.
[] device-mapper: multipath: Failing path 68:32.
[] sgio_inquiry: sending ioctl 2285 to a partition!
5) The ioctl() only works if the SYS_CAP_RAWIO capability is present
(then queueing happens -- in this example, queue_if_no_path is set);
this is due to a conditional check in scsi_verify_blk_ioctl().
# capsh --drop=cap_sys_rawio -- -c './sgio_inquiry /dev/mapper/85ag56'
sg_simple0: Inquiry SG_IO ioctl error: Inappropriate ioctl for device
# ./sgio_inquiry /dev/mapper/85ag56 &
[1] 72830
# cat /proc/72830/stack
[<c00000171c0df700>] 0xc00000171c0df700
[<c000000000015934>] __switch_to+0x204/0x350
[<c000000000152d4c>] msleep+0x5c/0x80
[<c00000000077dfb0>] dm_blk_ioctl+0x70/0x170
[<c000000000487c40>] blkdev_ioctl+0x2b0/0x9b0
[<c0000000003128e4>] block_ioctl+0x64/0xd0
[<c0000000002dd3b0>] do_vfs_ioctl+0x490/0x780
[<c0000000002dd774>] SyS_ioctl+0xd4/0xf0
[<c000000000009358>] system_call+0x38/0xd0
6) This is the function call chain exercised in this analysis:
SYSCALL_DEFINE3(ioctl, <...>) @ fs/ioctl.c
-> do_vfs_ioctl()
-> vfs_ioctl()
...
error = filp->f_op->unlocked_ioctl(filp, cmd, arg);
...
-> dm_blk_ioctl() @ drivers/md/dm.c
-> multipath_ioctl() @ drivers/md/dm-mpath.c
...
(bdev = NULL, due to no active paths)
...
if (!bdev || <...>) {
int err = scsi_verify_blk_ioctl(NULL, cmd);
if (err)
r = err;
}
...
-> scsi_verify_blk_ioctl() @ block/scsi_ioctl.c
...
if (bd && bd == bd->bd_contains) // not taken (bd = NULL)
return 0;
...
if (capable(CAP_SYS_RAWIO)) // not taken (unprivileged user)
return 0;
...
printk_ratelimited(KERN_WARNING
"%s: sending ioctl %x to a partition!\n" <...>);
return -ENOIOCTLCMD;
<-
...
return r ? : <...>
<-
...
if (error == -ENOIOCTLCMD)
error = -ENOTTY;
out:
return error;
...
Links:
[1] http://git.qemu.org/?p=qemu.git;a=commit;h=336a6915bc7089fb20fea4ba99972ad9a97c5f52
[2] https://libvirt.org/formatdomain.html#elementsDisks (see 'disk' -> 'device')
[3] http://tldp.org/HOWTO/SCSI-Generic-HOWTO/pexample.html (Revision 1.2, 2002-05-03)
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-mpath.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1608,11 +1608,8 @@ static int multipath_ioctl(struct dm_tar
/*
* Only pass ioctls through if the device sizes match exactly.
*/
- if (!bdev || ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT) {
- int err = scsi_verify_blk_ioctl(NULL, cmd);
- if (err)
- r = err;
- }
+ if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
+ r = scsi_verify_blk_ioctl(NULL, cmd);
if (r == -ENOTCONN && !fatal_signal_pending(current))
queue_work(kmultipathd, &m->process_queued_ios);
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[PATCH 3.10 00/64] 3.10.97-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 03/64] crypto: algif_hash - Only export and import on sockets with data Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 31/64] ALSA: rawmidi: Remove kernel WARNING for NULL user-space buffer check Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 55/64] crypto: af_alg - Disallow bind/setkey/... after accept(2) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 25/64] fix sysvfs symlinks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 01/64] recordmcount: Fix endianness handling bug for nop_mcount Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 37/64] ALSA: seq: Fix lockdep warnings due to double mutex locks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 60/64] crypto: algif_hash - wait for crypto_ahash_init() to complete Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 59/64] ahci: Intel DNV device IDs SATA Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 07/64] kernel/signal.c: unexport sigsuspend() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 24/64] [media] media: vb2 dma-contig: Fully cache synchronise buffers in prepare and finish Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 39/64] ALSA: timer: Fix leftover link at closing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 28/64] ALSA: compress: Disable GET_CODEC_CAPS ioctl for some architectures Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 23/64] [media] v4l2-compat-ioctl32: fix alignment for ARM64 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 05/64] HID: usbhid: fix recursive deadlock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 57/64] AHCI: Fix softreset failed issue of Port Multiplier Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 04/64] dm btree: fix leak of bufio-backed block in btree_split_sibling error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:40 +0100
[PATCH 3.10 16/64] vTPM: fix memory allocation flag for rtce buffer at kernel boot Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 14/64] wlcore/wl12xx: spi: fix oops on firmware load Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 15/64] wlcore/wl12xx: spi: fix NULL pointer dereference (Oops) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 22/64] parisc: Fix __ARCH_SI_PREAMBLE_SIZE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 19/64] [PATCH] fix calculation of meta_bg descriptor backups Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 18/64] jbd2: Fix unreclaimed pages after truncate in data=journal mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 17/64] mtd: mtdpart: fix add_mtd_partitions error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 12/64] spi: atmel: Fix DMA-setup for transfers with more than 8 bits per word Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 21/64] parisc: Fix syscall restarts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 11/64] Revert "dm mpath: fix stalls when handling invalid ioctls" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 13/64] spi: fix parent-device reference leak Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
[PATCH 3.10 02/64] xhci: fix placement of call to usb_disabled() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 00:50 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Guenter Roeck <linux@roeck-us.net> - 2016-02-15 06:30 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-15 19:20 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Guenter Roeck <linux@roeck-us.net> - 2016-02-15 16:50 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-02-15 18:20 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-02-17 21:40 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Willy Tarreau <w@1wt.eu> - 2016-02-18 00:30 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-02-18 00:40 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-02-18 04:30 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-19 23:30 +0100
Re: [PATCH 3.10 00/64] 3.10.97-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-02-17 21:40 +0100
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