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* [PATCH 0/4] btrfs: fix issues due to alien device
@ 2019-10-04  7:49 Anand Jain
  2019-10-04  7:50 ` [PATCH 1/4] btrfs: drop useless goto in open_fs_devices Anand Jain
                   ` (4 more replies)
  0 siblings, 5 replies; 15+ messages in thread
From: Anand Jain @ 2019-10-04  7:49 UTC (permalink / raw)
  To: linux-btrfs

Alien device is a device in fs_devices list having a different fsid than
the expected fsid. This patch set fixes issues found due to the same.

Patch1: is a cleanup patch, not related.
Patch2: fixes the missing device not missing in the userland, by
        hardening the function btrfs_open_one_device().
Patch3: fixes failing to mount a degraded RAID1 (but it can apply
        to RAID5/6/10 as well), by hardening the function
	btrfs_free_extra_devids().
Patch4: eliminates the source of the alien device in the fs_devices.

Anand Jain (4):
  btrfs: drop useless goto in open_fs_devices
  btrfs: delete identified alien device in open_fs_devices
  btrfs: include non-missing as a qualifier for the latest_bdev
  btrfs: free alien device due to device add

 fs/btrfs/volumes.c | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH 1/4] btrfs: drop useless goto in open_fs_devices
  2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
@ 2019-10-04  7:50 ` Anand Jain
  2019-10-04  8:12   ` Nikolay Borisov
  2019-10-04  7:50 ` [PATCH 2/4] btrfs: delete identified alien device " Anand Jain
                   ` (3 subsequent siblings)
  4 siblings, 1 reply; 15+ messages in thread
From: Anand Jain @ 2019-10-04  7:50 UTC (permalink / raw)
  To: linux-btrfs

There is no need of goto out in open_fs_devices() as there is nothing
special done at %out:. So refactor it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e176346afed1..06ec3577c6b4 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1330,7 +1330,6 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 {
 	struct btrfs_device *device;
 	struct btrfs_device *latest_dev = NULL;
-	int ret = 0;
 
 	flags |= FMODE_EXCL;
 
@@ -1343,15 +1342,14 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 		    device->generation > latest_dev->generation)
 			latest_dev = device;
 	}
-	if (fs_devices->open_devices == 0) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (fs_devices->open_devices == 0)
+		return -EINVAL;
+
 	fs_devices->opened = 1;
 	fs_devices->latest_bdev = latest_dev->bdev;
 	fs_devices->total_rw_bytes = 0;
-out:
-	return ret;
+
+	return 0;
 }
 
 static int devid_cmp(void *priv, struct list_head *a, struct list_head *b)
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH 2/4] btrfs: delete identified alien device in open_fs_devices
  2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
  2019-10-04  7:50 ` [PATCH 1/4] btrfs: drop useless goto in open_fs_devices Anand Jain
@ 2019-10-04  7:50 ` " Anand Jain
  2019-10-04  8:18   ` Nikolay Borisov
  2019-10-04  7:50 ` [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev Anand Jain
                   ` (2 subsequent siblings)
  4 siblings, 1 reply; 15+ messages in thread
From: Anand Jain @ 2019-10-04  7:50 UTC (permalink / raw)
  To: linux-btrfs

In open_fs_devices() we identify alien device but we don't reset its
the device::name. So progs device list does not show the device missing
as shown in the script below.

mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
mkfs.btrfs -fq -draid1 -mraid1 /dev/sdc /dev/sdb
sleep 3 # avoid racing with udev's useless scans if needed
btrfs dev add -f /dev/sdb /btrfs
mount -o degraded /dev/sdc /btrfs1

No missing device:
btrfs fi show -m /btrfs1
Label: none  uuid: 3eb7cd50-4594-458f-9d68-c243cc49954d
	Total devices 2 FS bytes used 128.00KiB
	devid    1 size 12.00GiB used 1.26GiB path /dev/sdc
	devid    2 size 12.00GiB used 1.26GiB path /dev/sdb

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
PS: Fundamentally its wrong approach that btrfs-progs deduces the device
missing state in the userland instead of obtaining it from the kernel.
I objected on the patch, but still those patches got merged, this bug is
one of its side effects. Ironically I wrote patches to read device_state
from the kernel using ioctl, procfs and sysfs but didn't get the due
attention till a merger.

 fs/btrfs/volumes.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 06ec3577c6b4..05ade8c7342b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -803,10 +803,10 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
 	disk_super = (struct btrfs_super_block *)bh->b_data;
 	devid = btrfs_stack_device_id(&disk_super->dev_item);
 	if (devid != device->devid)
-		goto error_brelse;
+		goto free_alien;
 
 	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE))
-		goto error_brelse;
+		goto free_alien;
 
 	device->generation = btrfs_super_generation(disk_super);
 
@@ -845,6 +845,11 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
 
 	return 0;
 
+free_alien:
+	fs_devices->num_devices--;
+	list_del(&device->dev_list);
+	btrfs_free_device(device);
+
 error_brelse:
 	brelse(bh);
 	blkdev_put(bdev, flags);
@@ -1329,11 +1334,13 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 				fmode_t flags, void *holder)
 {
 	struct btrfs_device *device;
+	struct btrfs_device *tmp_device;
 	struct btrfs_device *latest_dev = NULL;
 
 	flags |= FMODE_EXCL;
 
-	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+	list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
+				 dev_list) {
 		/* Just open everything we can; ignore failures here */
 		if (btrfs_open_one_device(fs_devices, device, flags, holder))
 			continue;
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev
  2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
  2019-10-04  7:50 ` [PATCH 1/4] btrfs: drop useless goto in open_fs_devices Anand Jain
  2019-10-04  7:50 ` [PATCH 2/4] btrfs: delete identified alien device " Anand Jain
@ 2019-10-04  7:50 ` Anand Jain
  2019-10-04  8:11   ` Nikolay Borisov
  2019-10-04  7:50 ` [PATCH 4/4] btrfs: free alien device due to device add Anand Jain
  2019-10-04  8:19 ` [PATCH 0/4] btrfs: fix issues due to alien device Nikolay Borisov
  4 siblings, 1 reply; 15+ messages in thread
From: Anand Jain @ 2019-10-04  7:50 UTC (permalink / raw)
  To: linux-btrfs

btrfs_free_extra_devids() reorgs fs_devices::latest_bdev
to point to the bdev with greatest device::generation number.
For a typical-missing device the generation number is zero so
fs_devices::latest_bdev will never point to it.

But if the missing device is due to alienating [1], then
device::generation is not-zero and if it is >= to rest of
device::generation in the list, then fs_devices::latest_bdev
ends up pointing to the missing device and reports the error
like this [2]

[1]
mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
sleep 3 # avoid racing with udev's useless scans if needed
btrfs dev add -f /dev/sdb /btrfs

mount -o degraded /dev/sdc /btrfs1

[2]
mount: wrong fs type, bad option, bad superblock on /dev/sdc,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.

kernel: BTRFS warning (device sdc): devid 1 uuid 072a0192-675b-4d5a-8640-a5cf2b2c704d is missing
kernel: BTRFS error (device sdc): failed to read devices
kernel: BTRFS error (device sdc): open_ctree failed

Fix the root of the issue, by checking if the the device is not
missing before it can be a contender for the fs_devices::latest_bdev
title.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 05ade8c7342b..6c42048ec099 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1186,6 +1186,8 @@ void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step)
 							&device->dev_state)) {
 			if (!test_bit(BTRFS_DEV_STATE_REPLACE_TGT,
 			     &device->dev_state) &&
+			    !test_bit(BTRFS_DEV_STATE_MISSING,
+			     &device->dev_state) &&
 			     (!latest_dev ||
 			      device->generation > latest_dev->generation)) {
 				latest_dev = device;
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH 4/4] btrfs: free alien device due to device add
  2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
                   ` (2 preceding siblings ...)
  2019-10-04  7:50 ` [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev Anand Jain
@ 2019-10-04  7:50 ` Anand Jain
  2019-10-04  8:19 ` [PATCH 0/4] btrfs: fix issues due to alien device Nikolay Borisov
  4 siblings, 0 replies; 15+ messages in thread
From: Anand Jain @ 2019-10-04  7:50 UTC (permalink / raw)
  To: linux-btrfs

When the old device has new fsid through btrfs device add -f <dev> our
fs_devices list has an alien device in one of the fs_devices.

By having an alien device in fs_devices, we have two issues so far

1. missing device is not shows as missing in the userland

Which is due to cracks in the function btrfs_open_one_device() and
hardened by patch
 btrfs: delete identified alien device in open_fs_devices

2. mount of a degraded fs_devices fails

Which is due to cracks in the function btrfs_free_extra_devids() and
hardened by patch
 btrfs: include non-missing as a qualifier for the latest_bdev

Now the reason for both of this issue is that there is an alien (does not
contain the intended fsid) device in the fs_devices.

We know a device can be scanned/added through
btrfs-control::BTRFS_IOC_SCAN_DEV|BTRFS_IOC_DEVICES_READY
or by
ioctl::BTRFS_IOC_ADD_DEV

And device coming through btrfs-control is checked against the all other
devices in btrfs kernel but not coming through BTRFS_IOC_ADD_DEV.

This patch checks if the device add is alienating any other scanned
device and deletes it.

In fact, this patch fixes both the issues 1 and 2 (above) by eliminating
the source of the issue, but still they have their own patch as well
because its the right way to harden the functions and fill the cracks.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6c42048ec099..f8b21e82df2a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2736,6 +2736,19 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 
 	/* Update ctime/mtime for libblkid */
 	update_dev_time(device_path);
+
+	/*
+	 * Now that we have written a new sb into this device, check all other
+	 * fs_devices list if it alienates any scanned device.
+	 */
+	mutex_lock(&uuid_mutex);
+	/*
+	 * Ignore the return as we are successfull in the core task - to added
+	 * the device
+	 */
+	btrfs_free_stale_devices(device_path, NULL);
+	mutex_unlock(&uuid_mutex);
+
 	return ret;
 
 error_sysfs:
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev
  2019-10-04  7:50 ` [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev Anand Jain
@ 2019-10-04  8:11   ` Nikolay Borisov
  2019-10-04  9:08     ` [Not TLS] " Graham Cobb
  0 siblings, 1 reply; 15+ messages in thread
From: Nikolay Borisov @ 2019-10-04  8:11 UTC (permalink / raw)
  To: Anand Jain, linux-btrfs



On 4.10.19 г. 10:50 ч., Anand Jain wrote:
> btrfs_free_extra_devids() reorgs fs_devices::latest_bdev
> to point to the bdev with greatest device::generation number.
> For a typical-missing device the generation number is zero so
> fs_devices::latest_bdev will never point to it.
> 
> But if the missing device is due to alienating [1], then
> device::generation is not-zero and if it is >= to rest of
> device::generation in the list, then fs_devices::latest_bdev
> ends up pointing to the missing device and reports the error
> like this [2]
> 
> [1]
> mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
> mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
> sleep 3 # avoid racing with udev's useless scans if needed
> btrfs dev add -f /dev/sdb /btrfs

Hm, here I think the correct way is to refuse adding /dev/sdb to an
existing fs if it's detected to be part of a different one. I.e it
should require wipefs to be done.

> 
> mount -o degraded /dev/sdc /btrfs1
> 
> [2]
> mount: wrong fs type, bad option, bad superblock on /dev/sdc,
>        missing codepage or helper program, or other error
> 
>        In some cases useful info is found in syslog - try
>        dmesg | tail or so.
> 
> kernel: BTRFS warning (device sdc): devid 1 uuid 072a0192-675b-4d5a-8640-a5cf2b2c704d is missing
> kernel: BTRFS error (device sdc): failed to read devices
> kernel: BTRFS error (device sdc): open_ctree failed
> 
> Fix the root of the issue, by checking if the the device is not
> missing before it can be a contender for the fs_devices::latest_bdev
> title.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/volumes.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 05ade8c7342b..6c42048ec099 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1186,6 +1186,8 @@ void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step)
>  							&device->dev_state)) {
>  			if (!test_bit(BTRFS_DEV_STATE_REPLACE_TGT,
>  			     &device->dev_state) &&
> +			    !test_bit(BTRFS_DEV_STATE_MISSING,
> +			     &device->dev_state) &&
>  			     (!latest_dev ||
>  			      device->generation > latest_dev->generation)) {
>  				latest_dev = device;
> 

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 1/4] btrfs: drop useless goto in open_fs_devices
  2019-10-04  7:50 ` [PATCH 1/4] btrfs: drop useless goto in open_fs_devices Anand Jain
@ 2019-10-04  8:12   ` Nikolay Borisov
  0 siblings, 0 replies; 15+ messages in thread
From: Nikolay Borisov @ 2019-10-04  8:12 UTC (permalink / raw)
  To: Anand Jain, linux-btrfs



On 4.10.19 г. 10:50 ч., Anand Jain wrote:
> There is no need of goto out in open_fs_devices() as there is nothing
> special done at %out:. So refactor it.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  fs/btrfs/volumes.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index e176346afed1..06ec3577c6b4 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1330,7 +1330,6 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
>  {
>  	struct btrfs_device *device;
>  	struct btrfs_device *latest_dev = NULL;
> -	int ret = 0;
>  
>  	flags |= FMODE_EXCL;
>  
> @@ -1343,15 +1342,14 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
>  		    device->generation > latest_dev->generation)
>  			latest_dev = device;
>  	}
> -	if (fs_devices->open_devices == 0) {
> -		ret = -EINVAL;
> -		goto out;
> -	}
> +	if (fs_devices->open_devices == 0)
> +		return -EINVAL;
> +
>  	fs_devices->opened = 1;
>  	fs_devices->latest_bdev = latest_dev->bdev;
>  	fs_devices->total_rw_bytes = 0;
> -out:
> -	return ret;
> +
> +	return 0;
>  }
>  
>  static int devid_cmp(void *priv, struct list_head *a, struct list_head *b)
> 

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 2/4] btrfs: delete identified alien device in open_fs_devices
  2019-10-04  7:50 ` [PATCH 2/4] btrfs: delete identified alien device " Anand Jain
@ 2019-10-04  8:18   ` Nikolay Borisov
  2019-10-06  2:47     ` [PATCH v2 " Anand Jain
  2019-10-06  2:51     ` [PATCH " Anand Jain
  0 siblings, 2 replies; 15+ messages in thread
From: Nikolay Borisov @ 2019-10-04  8:18 UTC (permalink / raw)
  To: Anand Jain, linux-btrfs



On 4.10.19 г. 10:50 ч., Anand Jain wrote:
> In open_fs_devices() we identify alien device but we don't reset its
> the device::name. So progs device list does not show the device missing
> as shown in the script below.
> 
> mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
> mkfs.btrfs -fq -draid1 -mraid1 /dev/sdc /dev/sdb
> sleep 3 # avoid racing with udev's useless scans if needed
> btrfs dev add -f /dev/sdb /btrfs
> mount -o degraded /dev/sdc /btrfs1
> 
> No missing device:
> btrfs fi show -m /btrfs1
> Label: none  uuid: 3eb7cd50-4594-458f-9d68-c243cc49954d
> 	Total devices 2 FS bytes used 128.00KiB
> 	devid    1 size 12.00GiB used 1.26GiB path /dev/sdc
> 	devid    2 size 12.00GiB used 1.26GiB path /dev/sdb
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
> PS: Fundamentally its wrong approach that btrfs-progs deduces the device
> missing state in the userland instead of obtaining it from the kernel.
> I objected on the patch, but still those patches got merged, this bug is
> one of its side effects. Ironically I wrote patches to read device_state
> from the kernel using ioctl, procfs and sysfs but didn't get the due
> attention till a merger.
> 
>  fs/btrfs/volumes.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 06ec3577c6b4..05ade8c7342b 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -803,10 +803,10 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
>  	disk_super = (struct btrfs_super_block *)bh->b_data;
>  	devid = btrfs_stack_device_id(&disk_super->dev_item);
>  	if (devid != device->devid)
> -		goto error_brelse;
> +		goto free_alien;
>  
>  	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE))
> -		goto error_brelse;
> +		goto free_alien;
>  

Imo a better approach is to return a particular error code and do the
deletion in open_fs_devices. Otherwise it's not apparent why you use
list_for_each_entry_safe in one function to delete something in a
different one (whose name by the way doesn't suggest a deletion is going
on). Looking at the error I think enodev/enxio is appropriate.

>  	device->generation = btrfs_super_generation(disk_super);
>  
> @@ -845,6 +845,11 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
>  
>  	return 0;
>  
> +free_alien:
> +	fs_devices->num_devices--;
> +	list_del(&device->dev_list);
> +	btrfs_free_device(device);
> +
>  error_brelse:
>  	brelse(bh);
>  	blkdev_put(bdev, flags);
> @@ -1329,11 +1334,13 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
>  				fmode_t flags, void *holder)
>  {
>  	struct btrfs_device *device;
> +	struct btrfs_device *tmp_device;
>  	struct btrfs_device *latest_dev = NULL;
>  
>  	flags |= FMODE_EXCL;
>  
> -	list_for_each_entry(device, &fs_devices->devices, dev_list) {
> +	list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
> +				 dev_list) {
>  		/* Just open everything we can; ignore failures here */
>  		if (btrfs_open_one_device(fs_devices, device, flags, holder))
>  			continue;
> 

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 0/4] btrfs: fix issues due to alien device
  2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
                   ` (3 preceding siblings ...)
  2019-10-04  7:50 ` [PATCH 4/4] btrfs: free alien device due to device add Anand Jain
@ 2019-10-04  8:19 ` Nikolay Borisov
  2019-10-07  9:42   ` Anand Jain
  4 siblings, 1 reply; 15+ messages in thread
From: Nikolay Borisov @ 2019-10-04  8:19 UTC (permalink / raw)
  To: Anand Jain, linux-btrfs



On 4.10.19 г. 10:49 ч., Anand Jain wrote:
> Alien device is a device in fs_devices list having a different fsid than
> the expected fsid. This patch set fixes issues found due to the same.

Are you going to submit an fstests patch for this bug ?

> 
> Patch1: is a cleanup patch, not related.
> Patch2: fixes the missing device not missing in the userland, by
>         hardening the function btrfs_open_one_device().
> Patch3: fixes failing to mount a degraded RAID1 (but it can apply
>         to RAID5/6/10 as well), by hardening the function
> 	btrfs_free_extra_devids().
> Patch4: eliminates the source of the alien device in the fs_devices.
> 
> Anand Jain (4):
>   btrfs: drop useless goto in open_fs_devices
>   btrfs: delete identified alien device in open_fs_devices
>   btrfs: include non-missing as a qualifier for the latest_bdev
>   btrfs: free alien device due to device add
> 
>  fs/btrfs/volumes.c | 40 ++++++++++++++++++++++++++++++----------
>  1 file changed, 30 insertions(+), 10 deletions(-)
> 

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [Not TLS] Re: [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev
  2019-10-04  8:11   ` Nikolay Borisov
@ 2019-10-04  9:08     ` " Graham Cobb
  2019-10-04  9:20       ` Nikolay Borisov
  0 siblings, 1 reply; 15+ messages in thread
From: Graham Cobb @ 2019-10-04  9:08 UTC (permalink / raw)
  To: Nikolay Borisov, Anand Jain, linux-btrfs

On 04/10/2019 09:11, Nikolay Borisov wrote:
> 
> 
> On 4.10.19 г. 10:50 ч., Anand Jain wrote:
>> btrfs_free_extra_devids() reorgs fs_devices::latest_bdev
>> to point to the bdev with greatest device::generation number.
>> For a typical-missing device the generation number is zero so
>> fs_devices::latest_bdev will never point to it.
>>
>> But if the missing device is due to alienating [1], then
>> device::generation is not-zero and if it is >= to rest of
>> device::generation in the list, then fs_devices::latest_bdev
>> ends up pointing to the missing device and reports the error
>> like this [2]
>>
>> [1]
>> mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
>> mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
>> sleep 3 # avoid racing with udev's useless scans if needed
>> btrfs dev add -f /dev/sdb /btrfs
> 
> Hm, here I think the correct way is to refuse adding /dev/sdb to an
> existing fs if it's detected to be part of a different one. I.e it
> should require wipefs to be done.

I disagree. -f means "force overwrite of existing filesystem on the
given disk(s)". It shouldn't be any different whether the existing fs is
btrfs or something else.

Graham

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [Not TLS] Re: [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev
  2019-10-04  9:08     ` [Not TLS] " Graham Cobb
@ 2019-10-04  9:20       ` Nikolay Borisov
  0 siblings, 0 replies; 15+ messages in thread
From: Nikolay Borisov @ 2019-10-04  9:20 UTC (permalink / raw)
  To: Graham Cobb, Anand Jain, linux-btrfs



On 4.10.19 г. 12:08 ч., Graham Cobb wrote:
> On 04/10/2019 09:11, Nikolay Borisov wrote:
>>
>>
>> On 4.10.19 г. 10:50 ч., Anand Jain wrote:
>>> btrfs_free_extra_devids() reorgs fs_devices::latest_bdev
>>> to point to the bdev with greatest device::generation number.
>>> For a typical-missing device the generation number is zero so
>>> fs_devices::latest_bdev will never point to it.
>>>
>>> But if the missing device is due to alienating [1], then
>>> device::generation is not-zero and if it is >= to rest of
>>> device::generation in the list, then fs_devices::latest_bdev
>>> ends up pointing to the missing device and reports the error
>>> like this [2]
>>>
>>> [1]
>>> mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
>>> mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
>>> sleep 3 # avoid racing with udev's useless scans if needed
>>> btrfs dev add -f /dev/sdb /btrfs
>>
>> Hm, here I think the correct way is to refuse adding /dev/sdb to an
>> existing fs if it's detected to be part of a different one. I.e it
>> should require wipefs to be done.
> 
> I disagree. -f means "force overwrite of existing filesystem on the
> given disk(s)". It shouldn't be any different whether the existing fs is
> btrfs or something else.

You are right, looking at btrfs device add implementation though it
seems that wipefs is being done on the device to be added:

cmd_device_add
 btrfs_prepare_device
  btrfs_wipe_existing_sb

So if the device to be added is formatted and then it goes through
btrfs_init_new_device which commits the transaction which in turns
rewrites the sb then why is the error happening in the first place?


> 
> Graham
> 

^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH v2 2/4] btrfs: delete identified alien device in open_fs_devices
  2019-10-04  8:18   ` Nikolay Borisov
@ 2019-10-06  2:47     ` " Anand Jain
  2019-10-06 11:44       ` Nikolay Borisov
  2019-10-06  2:51     ` [PATCH " Anand Jain
  1 sibling, 1 reply; 15+ messages in thread
From: Anand Jain @ 2019-10-06  2:47 UTC (permalink / raw)
  To: linux-btrfs; +Cc: nborisov

In open_fs_devices() we identify alien device but we don't reset its
the device::name. So progs device list does not show the device missing
as shown in the script below.

mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
mkfs.btrfs -fq -draid1 -mraid1 /dev/sdc /dev/sdb
sleep 3 # avoid racing with udev's useless scans if needed
btrfs dev add -f /dev/sdb /btrfs
mount -o degraded /dev/sdc /btrfs1

No missing device:
btrfs fi show -m /btrfs1
Label: none  uuid: 3eb7cd50-4594-458f-9d68-c243cc49954d
	Total devices 2 FS bytes used 128.00KiB
	devid    1 size 12.00GiB used 1.26GiB path /dev/sdc
	devid    2 size 12.00GiB used 1.26GiB path /dev/sdb

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v2: Move free alien part to its parent function btrfs_open_one_device.
    Thanks Nikolay.

PS: Fundamentally its wrong approach that btrfs-progs deduces the device
missing state in the userland instead of obtaining it from the kernel.
I objected on the patch, but still those patches got merged, this bug is
one of its side effects. Ironically I wrote patches to read device_state
from the kernel using ioctl, procfs and sysfs but didn't get the due
attention till a merger.

 fs/btrfs/volumes.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c223a8147bfd..21aaf64c59b2 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -591,13 +591,18 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
 	if (ret)
 		return ret;
 
+	ret = -EINVAL;
 	disk_super = (struct btrfs_super_block *)bh->b_data;
 	devid = btrfs_stack_device_id(&disk_super->dev_item);
-	if (devid != device->devid)
+	if (devid != device->devid) {
+		ret = -EUCLEAN;
 		goto error_brelse;
+	}
 
-	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE))
+	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE)) {
+		ret = -EUCLEAN;
 		goto error_brelse;
+	}
 
 	device->generation = btrfs_super_generation(disk_super);
 
@@ -640,7 +645,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
 	brelse(bh);
 	blkdev_put(bdev, flags);
 
-	return -EINVAL;
+	return ret;
 }
 
 /*
@@ -1121,19 +1126,28 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 				fmode_t flags, void *holder)
 {
+	int ret;
 	struct btrfs_device *device;
+	struct btrfs_device *tmp_device;
 	struct btrfs_device *latest_dev = NULL;
 
 	flags |= FMODE_EXCL;
 
-	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+	list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
+				 dev_list) {
 		/* Just open everything we can; ignore failures here */
-		if (btrfs_open_one_device(fs_devices, device, flags, holder))
-			continue;
-
-		if (!latest_dev ||
-		    device->generation > latest_dev->generation)
+		ret = btrfs_open_one_device(fs_devices, device, flags, holder);
+		if (ret == 0 && (!latest_dev ||
+		    device->generation > latest_dev->generation)) {
 			latest_dev = device;
+			continue;
+		}
+		if (ret == -EUCLEAN) {
+			/* An alien device. Clean it up */
+			fs_devices->num_devices--;
+			list_del(&device->dev_list);
+			btrfs_free_device(device);
+		}
 	}
 	if (fs_devices->open_devices == 0)
 		return -EINVAL;
-- 
2.23.0


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 2/4] btrfs: delete identified alien device in open_fs_devices
  2019-10-04  8:18   ` Nikolay Borisov
  2019-10-06  2:47     ` [PATCH v2 " Anand Jain
@ 2019-10-06  2:51     ` " Anand Jain
  1 sibling, 0 replies; 15+ messages in thread
From: Anand Jain @ 2019-10-06  2:51 UTC (permalink / raw)
  To: Nikolay Borisov; +Cc: linux-btrfs



>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index 06ec3577c6b4..05ade8c7342b 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -803,10 +803,10 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
>>   	disk_super = (struct btrfs_super_block *)bh->b_data;
>>   	devid = btrfs_stack_device_id(&disk_super->dev_item);
>>   	if (devid != device->devid)
>> -		goto error_brelse;
>> +		goto free_alien;
>>   
>>   	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE))
>> -		goto error_brelse;
>> +		goto free_alien;
>>   
> 
> Imo a better approach is to return a particular error code and do the
> deletion in open_fs_devices. Otherwise it's not apparent why you use
> list_for_each_entry_safe in one function to delete something in a
> different one (whose name by the way doesn't suggest a deletion is going
> on). Looking at the error I think enodev/enxio is appropriate.

  Agreed. And used -EUCLEAN I think that's most appropriate.
  Thanks, Anand

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH v2 2/4] btrfs: delete identified alien device in open_fs_devices
  2019-10-06  2:47     ` [PATCH v2 " Anand Jain
@ 2019-10-06 11:44       ` Nikolay Borisov
  0 siblings, 0 replies; 15+ messages in thread
From: Nikolay Borisov @ 2019-10-06 11:44 UTC (permalink / raw)
  To: Anand Jain, linux-btrfs



On 6.10.19 г. 5:47 ч., Anand Jain wrote:
> In open_fs_devices() we identify alien device but we don't reset its
> the device::name. So progs device list does not show the device missing
> as shown in the script below.
> 
> mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
> mkfs.btrfs -fq -draid1 -mraid1 /dev/sdc /dev/sdb
> sleep 3 # avoid racing with udev's useless scans if needed
> btrfs dev add -f /dev/sdb /btrfs
> mount -o degraded /dev/sdc /btrfs1
> 
> No missing device:
> btrfs fi show -m /btrfs1
> Label: none  uuid: 3eb7cd50-4594-458f-9d68-c243cc49954d
> 	Total devices 2 FS bytes used 128.00KiB
> 	devid    1 size 12.00GiB used 1.26GiB path /dev/sdc
> 	devid    2 size 12.00GiB used 1.26GiB path /dev/sdb
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
> v2: Move free alien part to its parent function btrfs_open_one_device.
>     Thanks Nikolay.
> 
> PS: Fundamentally its wrong approach that btrfs-progs deduces the device
> missing state in the userland instead of obtaining it from the kernel.
> I objected on the patch, but still those patches got merged, this bug is
> one of its side effects. Ironically I wrote patches to read device_state
> from the kernel using ioctl, procfs and sysfs but didn't get the due
> attention till a merger.
> 
>  fs/btrfs/volumes.c | 32 +++++++++++++++++++++++---------
>  1 file changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index c223a8147bfd..21aaf64c59b2 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -591,13 +591,18 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
>  	if (ret)
>  		return ret;
>  
> +	ret = -EINVAL;
>  	disk_super = (struct btrfs_super_block *)bh->b_data;
>  	devid = btrfs_stack_device_id(&disk_super->dev_item);
> -	if (devid != device->devid)
> +	if (devid != device->devid) {
> +		ret = -EUCLEAN;
>  		goto error_brelse;
> +	}
>  
> -	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE))
> +	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE)) {
> +		ret = -EUCLEAN;
>  		goto error_brelse;
> +	}
>  
>  	device->generation = btrfs_super_generation(disk_super);
>  
> @@ -640,7 +645,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
>  	brelse(bh);
>  	blkdev_put(bdev, flags);
>  
> -	return -EINVAL;
> +	return ret;
>  }
>  
>  /*
> @@ -1121,19 +1126,28 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
>  static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
>  				fmode_t flags, void *holder)
>  {
> +	int ret;
>  	struct btrfs_device *device;
> +	struct btrfs_device *tmp_device;
>  	struct btrfs_device *latest_dev = NULL;
>  
>  	flags |= FMODE_EXCL;
>  
> -	list_for_each_entry(device, &fs_devices->devices, dev_list) {
> +	list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
> +				 dev_list) {
>  		/* Just open everything we can; ignore failures here */
> -		if (btrfs_open_one_device(fs_devices, device, flags, holder))
> -			continue;
> -
> -		if (!latest_dev ||
> -		    device->generation > latest_dev->generation)
> +		ret = btrfs_open_one_device(fs_devices, device, flags, holder);
> +		if (ret == 0 && (!latest_dev ||
> +		    device->generation > latest_dev->generation)) {
>  			latest_dev = device;
> +			continue;
> +		}

nit: Had you used if () {} else if {}  you could have done away with the
continue.

> +		if (ret == -EUCLEAN) {
> +			/* An alien device. Clean it up */
> +			fs_devices->num_devices--;
> +			list_del(&device->dev_list);
> +			btrfs_free_device(device);
> +		}
>  	}
>  	if (fs_devices->open_devices == 0)
>  		return -EINVAL;
> 

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 0/4] btrfs: fix issues due to alien device
  2019-10-04  8:19 ` [PATCH 0/4] btrfs: fix issues due to alien device Nikolay Borisov
@ 2019-10-07  9:42   ` Anand Jain
  0 siblings, 0 replies; 15+ messages in thread
From: Anand Jain @ 2019-10-07  9:42 UTC (permalink / raw)
  To: Nikolay Borisov, linux-btrfs

On 4/10/19 4:19 PM, Nikolay Borisov wrote:
> 
> 
> On 4.10.19 г. 10:49 ч., Anand Jain wrote:
>> Alien device is a device in fs_devices list having a different fsid than
>> the expected fsid. This patch set fixes issues found due to the same.
> 
> Are you going to submit an fstests patch for this bug ?

  Yes. Done.


^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, back to index

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-04  7:49 [PATCH 0/4] btrfs: fix issues due to alien device Anand Jain
2019-10-04  7:50 ` [PATCH 1/4] btrfs: drop useless goto in open_fs_devices Anand Jain
2019-10-04  8:12   ` Nikolay Borisov
2019-10-04  7:50 ` [PATCH 2/4] btrfs: delete identified alien device " Anand Jain
2019-10-04  8:18   ` Nikolay Borisov
2019-10-06  2:47     ` [PATCH v2 " Anand Jain
2019-10-06 11:44       ` Nikolay Borisov
2019-10-06  2:51     ` [PATCH " Anand Jain
2019-10-04  7:50 ` [PATCH 3/4] btrfs: include non-missing as a qualifier for the latest_bdev Anand Jain
2019-10-04  8:11   ` Nikolay Borisov
2019-10-04  9:08     ` [Not TLS] " Graham Cobb
2019-10-04  9:20       ` Nikolay Borisov
2019-10-04  7:50 ` [PATCH 4/4] btrfs: free alien device due to device add Anand Jain
2019-10-04  8:19 ` [PATCH 0/4] btrfs: fix issues due to alien device Nikolay Borisov
2019-10-07  9:42   ` Anand Jain

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