The generic block device lookup or cleanup does not need the uuid mutex,
that's only for the device_list_add.
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>

The fs_info is always available from the context so we don't need to
store it in the structure.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This function is used in only one place and devid argument is always
passed 0. So just remove it, similarly to how it was removed in the
userspace code.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

In btrfs_shrink_device, before btrfs_search_slot, path->reada is set to
READA_FORWARD. But I think READA_BACK is correct.

Since:

 1. key.offset is set to (u64)-1
 2. after btrfs_search_slot, btrfs_previous_item is called

So, for readahead previous items, READA_BACK is the correct one.
Signed-off-by: NGu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Add a new member struct btrfs_raid_attr::mindev_error so that
btrfs_raid_array can maintain the error code to return if the minimum
number of devices condition is not met while trying to delete a device
in the given raid. And so we can drop btrfs_raid_mindev_error.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Add a new member struct btrfs_raid_attr::bg_flag so that
btrfs_raid_array can maintain the bit map flag of the raid type, and
so we can drop btrfs_raid_group.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Add a new member struct btrfs_raid_attr::raid_name so that
btrfs_raid_array can maintain the name of the raid type, and so we can
drop btrfs_raid_type_names.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The helper is quite simple and I'd like to see the locking in the
caller.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

While the spinlock does not cause problems, using the mutex is more
correct and consistent with others. The global status of balance is eg.
checked from btrfs_pause_balance or btrfs_cancel_balance with mutex.

Resuming balance happens during mount or ro->rw remount. In the former
case, no other user of the balance_ctl exists, in the latter, balance
cannot run until the ro/rw transition is finished.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The parameter controls locking of the stats part but we can lock it
unconditionally, as this only happens once when balance starts. This is
not performance critical.

Add the prefix for an exported function.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Balance cannot be started on a read-only filesystem and will have to
finish/exit before eg. going to read-only via remount.

In case the filesystem is forcibly set to read-only after an error,
balance will finish anyway and if the cancel call is too fast it will
just wait for that to happen.

The last case is when the balance is paused after mount but it's
read-only and cancelling would want to delete the item. The test is
moved after the check if balance is running at all, as it looks more
logical to report "no balance running" instead of "read-only
filesystem".
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently fs_info::balance_running is 0 or 1 and does not use the
semantics of atomics. The pause and cancel check for 0, that can happen
only after __btrfs_balance exits for whatever reason.

Parallel calls to balance ioctl may enter btrfs_ioctl_balance multiple
times but will block on the balance_mutex that protects the
fs_info::flags bit.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Mutual exclusion of device add/rm and balance was done by the volume
mutex up to version 3.7. The commit 5ac00add ("Btrfs: disallow
mutually exclusive admin operations from user mode") added a bit that
essentially tracked the same information.

The status bit has an advantage over a mutex that it can be set without
restrictions of function context, so it started to be used in the
mount-time resuming of balance or device replace.

But we don't really need to track the same information in two ways.

1) After the previous cleanups, the main ioctl handlers for
   add/del/resize copy the EXCL_OP bit next to the volume mutex, here
   it's clearly safe.

2) Resuming balance during mount or after rw remount will set only the
   EXCL_OP bit and the volume_mutex is held in the kernel thread that
   calls btrfs_balance.

3) Resuming device replace during mount or after rw remount is done
   after balance and is excluded by the EXCL_OP bit. It does not take
   the volume_mutex at all and completely relies on the EXCL_OP bit.

4) The resuming of balance and dev-replace cannot hapen at the same time
   as the ioctls cannot be started in parallel. Nevertheless, a crafted
   image could trigger that and a warning is printed.

5) Balance is normally excluded by EXCL_OP and also uses own mutex to
   protect against concurrent access to its status data. There's some
   trickery to maintain the right lock nesting in case we need to
   reexamine the status in btrfs_ioctl_balance. The volume_mutex is
   removed and the unlock/lock sequence is left in place as we might
   expect other waiters to proceed.

6) Similar to 5, the unlock/lock sequence is kept in
   btrfs_cancel_balance to allow waiters to continue.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The volume mutex does not protect against anything in this case, the
comment about scrub is right but not related to locking and looks
confusing. The comment in btrfs_find_device_missing_or_by_path is wrong
and confusing too.

The device_list_mutex is not held here to protect device lookup, but in
this case device replace cannot run in parallel with device removal (due
to exclusive op protection), so we don't need further locking here.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The function __cancel_balance name is confusing with the cancel
operation of balance and it really resets the state of balance back to
zero. The unset_balance_control helper is called only from one place and
simple enough to be inlined.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Replace a WARN_ON with a proper check and message in case something goes
really wrong and resumed balance cannot set up its exclusive status.
The check is a user friendly assertion, I don't expect to ever happen
under normal circumstances.

Also document that the paused balance starts here and owns the exclusive
op status.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Make the clearning visible in the callers so we can pair it with the
test_and_set part.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Move locking and unlocking next to the BTRFS_FS_EXCL_OP bit manipulation
so it's obvious that the two happen at the same time.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The function logically belongs there and there's only a single caller,
no need to export it. No code changes.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The function will be used outside of volumes.c, the allocation
btrfs_alloc_device is also exported.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This is a preparatory cleanup that will make clear that the only
successful way out of btrfs_init_dev_replace_tgtdev will also set the
device_out to a valid pointer. With this guarantee, the callers can be
simplified.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This function uses fs_info::fs_devices number of time, however we
declare and use it only at the end, instead do it in the beginning of
the function and use it.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

find_device() declares struct list_head *head pointer and used only once,
instead just use it directly.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

__btrfs_open_devices() is un-exported drop __ prefix and rename it to
open_fs_devices().
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

__btrfs_close_devices() is un-exported, drop the __ prefix and rename it
to close_fs_devices().
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

__btrfs_open_devices() declares struct list_head *head, however head is
used only once, instead use btrfs_fs_devices::devices directly.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_fs_devices::list is the list of BTRFS fsid in the kernel, a generic
name 'list' makes it's search very difficult, rename it to fs_list.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Adds comments about BTRFS_FS_EXCL_OP to existing comments
about the device locks.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ minor updates ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

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>