We set the BTRFS_BALANCE_RESUME flag in the btrfs_recover_balance()
only, which isn't called during the remount. So when resuming from
the paused balance we hit the bug:

 kernel: kernel BUG at fs/btrfs/volumes.c:3890!
 ::
 kernel:  balance_kthread+0x51/0x60 [btrfs]
 kernel:  kthread+0x111/0x130
 ::
 kernel: RIP: btrfs_balance+0x12e1/0x1570 [btrfs] RSP: ffffba7d0090bde8

Reproducer:
  On a mounted filesystem:

  btrfs balance start --full-balance /btrfs
  btrfs balance pause /btrfs
  mount -o remount,ro /dev/sdb /btrfs
  mount -o remount,rw /dev/sdb /btrfs

To fix this set the BTRFS_BALANCE_RESUME flag in
btrfs_resume_balance_async().

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The current calls are unclear in what way btrfs_dev_replace_lock takes
the locks, so drop the argument, split the helpers and use similar
naming as for read and write locks.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Using lockdep_assert_held is preferred, replace mutex_is_locked.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Any time the first block group of a new type is created, we add a new
kobject to sysfs to hold the attributes for that type.  Kobject-internal
allocations always use GFP_KERNEL, making them prone to fs-reclaim races.
While it appears as if this can occur any time a block group is created,
the only times the first block group of a new type can be created in
memory is at mount and when we create the first new block group during
raid conversion.

This patch adds a new list to track pending kobject additions and then
handles them after we do chunk relocation.  Between relocating the
target chunk (or forcing allocation of a new chunk in the case of data)
and removing the old chunk, we're in a safe place for fs-reclaim to
occur.  We're holding the volume mutex, which is already held across
page faults, and the delete_unused_bgs_mutex, which will only stall
the cleaner thread.
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Drop optimal argument from the function find_live_mirror() as we can
deduce it in the function itself. Also rename optimal to
preferred_mirror.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Obtain the stripes info from the map directly and so no need
to pass it as an argument.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When checking the minimal nr_devs, there is one dead and meaningless
condition:

if (ndevs < devs_increment * sub_stripes || ndevs < devs_min) {
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This condition is meaningless, @devs_increment has nothing to do with
@sub_stripes.

In fact, in btrfs_raid_array[], profile with sub_stripes larger than 1
(RAID10) already has the @devs_increment set to 2.
So no need to multiple it by @sub_stripes.

And above condition is also dead.
For RAID10, @devs_increment * @sub_stripes equals 4, which is also the
@devs_min of RAID10.
For other profiles, @sub_stripes is always 1, and since @ndevs is
rounded down to @devs_increment, the condition will always be true.

Remove the meaningless condition to make later reader wander less.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Some functions can filter metadata by the generation. Add a define that
will annotate such arguments.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This function btrfs_close_extra_devices() is about freeing
extra devids which once it may have belonged to this filesystem.
So rename it and add the comment. The _devid suffix is
appropriate as this function won't handle devices which are
outside of the filesytem being mounted.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

In the same function we just ran btrfs_alloc_device() which means the
btrfs_device::resized_list is sure to be empty and we are protected
with the btrfs_fs_info::volume_mutex.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Recently, the __init annotations have been added. There's unfortunatelly
only one case where we can add __exit, because most of the cleanup
helpers are also called from the __init phase.

As the __exit annotated functions get discarded completely for a
built-in code, we'd miss them from the init phase.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Function __get_raid_index() is used to convert block group flags into
raid index, which can be used to get various info directly from
btrfs_raid_array[].

Refactor this function a little:

1) Rename to btrfs_bg_flags_to_raid_index()
   Double underline prefix is normally for internal functions, while the
   function is used by both extent-tree and volumes.

   Although the name is a little longer, but it should explain its usage
   quite well.

2) Move it to volumes.h and make it static inline
   Just several if-else branches, really no need to define it as a normal
   function.

   This also makes later code re-use between kernel and btrfs-progs
   easier.

3) Remove function get_block_group_index()
   Really no need to do such a simple thing as an exported function.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Cleanup the following things:
1) open coded SZ_16M round up
2) use min() to replace open-coded size comparison
3) code style
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NGu Jinxiang <gujx@cn.fujitsu.com>
[ reformat comment ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Add opened device to the tail of dev_alloc_list instead of head, so that
it maintains the same order as dev_list.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

By maintaining the device list sorted lets us reproduce the problems
related to missing chunk in the degraded mode much more consistent. So
fix this by sorting the devices by devid within the kernel. So that we
know which device is assigned to the struct fs_info::latest_bdev when
all the devices are having and same SB generation.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
[ update changelog ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Enospc_debug makes extent allocator print more debug messages,
however for chunk allocation, there is no debug message for enospc_debug
at all.

This patch will add message for the following parts of chunk allocator:

1) No rw device at all
   Quite rare, but at least output one message for this case.

2) Not enough space for some device
   This debug message is quite handy for unbalanced disks with stripe
   based profiles (RAID0/10/5/6).

3) Not enough free devices
   This debug message should tell us if current chunk allocator is
   working correctly under minimal device requirements.

Although in most cases, we will hit other ENOSPC before we even hit a
chunk allocator ENOSPC, but such debug info won't help.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We already pass the btrfs_transaction which references fs_info so no
need to pass the later as an argument. Also use the opportunity to
shorten transaction->trans. No functional changes.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_init_dev_replace_tgtdev_for_resume() initializes replace
target device in a few simple steps, so do it at the parent function.
Moreover, there isn't any other caller so just open code it.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

In case of using DUP, we search for enough unallocated disk space on a
device to hold two stripes.

The devices_info[ndevs-1].max_avail that holds the amount of unallocated
space found is directly assigned to stripe_size, while it's actually
twice the stripe size.

Later on in the code, an unconditional division of stripe_size by
dev_stripes corrects the value, but in the meantime there's a check to
see if the stripe_size does not exceed max_chunk_size. Since during this
check stripe_size is twice the amount as intended, the check will reduce
the stripe_size to max_chunk_size if the actual correct to be used
stripe_size is more than half the amount of max_chunk_size.

The unconditional division later tries to correct stripe_size, but will
actually make sure we can't allocate more than half the max_chunk_size.

Fix this by moving the division by dev_stripes before the max chunk size
check, so it always contains the right value, instead of putting a duct
tape division in further on to get it fixed again.

Since in all other cases than DUP, dev_stripes is 1, this change only
affects DUP.

Other attempts in the past were made to fix this:
* 37db63a4 "Btrfs: fix max chunk size check in chunk allocator" tried
to fix the same problem, but still resulted in part of the code acting
on a wrongly doubled stripe_size value.
* 86db2578 "Btrfs: fix max chunk size on raid5/6" unintentionally
broke this fix again.

The real problem was already introduced with the rest of the code in
73c5de00.

The user visible result however will be that the max chunk size for DUP
will suddenly double, while it's actually acting according to the limits
in the code again like it was 5 years ago.
Reported-by: NNaohiro Aota <naohiro.aota@wdc.com>
Link: https://www.spinics.net/lists/linux-btrfs/msg69752.html
Fixes: 73c5de00 ("btrfs: quasi-round-robin for chunk allocation")
Fixes: 86db2578 ("Btrfs: fix max chunk size on raid5/6")
Signed-off-by: NHans van Kranenburg <hans.van.kranenburg@mendix.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ update comment ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Commit 4fde46f0 ("Btrfs: free the stale device") introduced
btrfs_free_stale_device which iterates the device lists for all
registered btrfs filesystems and deletes those devices which aren't
mounted. In a btrfs_devices structure has only 1 device attached to it
and it is unused then btrfs_free_stale_devices will proceed to also free
the btrfs_fs_devices struct itself. Currently this leads to a use after
free since list_for_each_entry will try to perform a check on the
already freed memory to see if it has to terminate the loop.

The fix is to use 'break' when we know we are freeing the current
fs_devs.

Fixes: 4fde46f0 ("Btrfs: free the stale device")
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

As struct btrfs_disk_super is being passed, so it can get devid
the same way its parent does.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Instead of pointer to btrfs_fs_devices as an arg in device_list_add()
better to get pointer to btrfs_device as return value, then we have
both, pointer to btrfs_device and btrfs_fs_devices. btrfs_device is
needed to handle reappearing missing device.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

There is no other parent for device_list_add() except for
btrfs_scan_one_device(), which would set btrfs_fs_devices::total_devices
if device_list_add is successful and this can be done with in
device_list_add() itself.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Commit 60999ca4 ("btrfs: make device scan less noisy")
adds return value 1 to device_list_add(), so that parent function can
call pr_info only when new device is added. Move the pr_info() part
into device_list_add() so that this function can be kept simple.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The btrfs_free_stale_devices() is updated to match for the given device
path and delete it. (It searches for only unmounted list of devices.)
Also drop the comment about different path being used for the same
device, since now we will have cli to clean any device that's not a
concern any more.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

No functional changes.
Rename btrfs_free_stale_devices() arg to skip_dev, so that it
reflects what that arg for.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This updates btrfs_free_stale_devices() helper function to delete all
unmouted devices, when arg is NULL.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Let the list iterator iterate further and find other stale
devices and delete it. This is in preparation to add support
for user land request-able stale devices cleanup. Also rename
btrfs_free_stale_device() to btrfs_free_stale_devices().
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

There is no need to check for btrfs_fs_devices::seeding when we
have checked for btrfs_fs_devices::opened, because we can't sprout
without its seed FS being opened.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The reada_lock in struct btrfs_device was only initialised, and not
actually used.  That's good because there's another lock also called
reada_lock in the btrfs_fs_info that was quite heavily used.  Remove
this one.
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We call btrfs_free_stale_device() only when we alloc a new struct
btrfs_device (ret=1), so move it closer to where we alloc the new
device. Also drop the comments.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We've avoided data losing raid profile when doing balance, but it
turns out that deleting a device could also result in the same
problem.

Say we have 3 disks, and they're created with '-d raid1' profile.

- We have chunk P (the only data chunk on the empty btrfs).

- Suppose that chunk P's two raid1 copies reside in disk A and disk B.

- Now, 'btrfs device remove disk B'
         btrfs_rm_device()
	   -> btrfs_shrink_device()
	      -> btrfs_relocate_chunk() #relocate any chunk on disk B
	      	 			 to other places.

- Chunk P will be removed and a new chunk will be created to hold
  those data, but as chunk P is the only one holding raid1 profile,
  after it goes away, the new chunk will be created as single profile
  which is our default profile.

This fixes the problem by creating an empty data chunk before
relocating the data chunk.

Metadata/System chunk are supposed to have non-zero bytes all the time
so their raid profile is preserved.
Reported-by: NJames Alandt <James.Alandt@wdc.com>
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Assign ret = -EINVAL where it is actually required.
Remove { } around single line if else code.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

There is a scenario that can end up with rebuild process failing to
return good content, i.e.
suppose that all disks can be read without problems and if the content
that was read out doesn't match its checksum, currently for raid6
btrfs at most retries twice,

- the 1st retry is to rebuild with all other stripes, it'll eventually
  be a raid5 xor rebuild,
- if the 1st fails, the 2nd retry will deliberately fail parity p so
  that it will do raid6 style rebuild,

however, the chances are that another non-parity stripe content also
has something corrupted, so that the above retries are not able to
return correct content, and users will think of this as data loss.
More seriouly, if the loss happens on some important internal btree
roots, it could refuse to mount.

This extends btrfs to do more retries and each retry fails only one
stripe.  Since raid6 can tolerate 2 disk failures, if there is one
more failure besides the failure on which we're recovering, this can
always work.

The worst case is to retry as many times as the number of raid6 disks,
but given the fact that such a scenario is really rare in practice,
it's still acceptable.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Update btrfs_check_rw_degradable() to check against the given device if
its lost.

We can use this function to know if the volume is going to be in
degraded mode OR failed state, when the given device fails.  Which is
needed when we are handling the device failed state.

A preparatory patch does not affect the flow as such.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
[ enhance comment ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This code was added in 492bb6de ("Btrfs: Hold a reference on bios
during submit_bio, add some extra bio checks"). However, holding a
reference on a bio is necessary only if it's going to be referenced
after the submit_bio returns and the bio is completed. In this
particular instance this is not the case so there is no need to hold
an extra reference since we directly return.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently device state is being managed by each individual int
variable such as struct btrfs_device::is_tgtdev_for_dev_replace.
Instead of that declare btrfs_device::dev_state
BTRFS_DEV_STATE_MISSING and use the bit operations.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
[ whitespace adjustments ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently device state is being managed by each individual int
variable such as struct btrfs_device::missing. Instead of that
declare btrfs_device::dev_state BTRFS_DEV_STATE_MISSING and use
the bit operations.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by : Nikolay Borisov <nborisov@suse.com>
[ whitespace adjustments ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>