Commit Graph

884 Commits

Author SHA1 Message Date
Nikolay Borisov
4f5ad7bd63 btrfs: Remove fs_info from btrfs_destroy_dev_replace_tgtdev
This function is always passed a well-formed tgtdevice so the fs_info
can be referenced from there.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:57 +02:00
Nikolay Borisov
d6507cf1e2 btrfs: Remove fs_info from btrfs_assign_next_active_device
It can be referenced from the passed 'device' argument which is always
a well-formed device.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:57 +02:00
Nikolay Borisov
5495f195fc btrfs: remove fs_info argument from update_dev_stat_item
It can be referenced from the passed transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:57 +02:00
Nikolay Borisov
68a9db5f23 btrfs: Remove fs_info from btrfs_rm_dev_replace_remove_srcdev
It can be referenced from the passed srcdev argument.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:57 +02:00
Nikolay Borisov
8e87e85627 btrfs: Remove fs_info argument from btrfs_add_dev_item
It can be referenced form the passed transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:56 +02:00
Gu Jinxiang
315409b009 btrfs: validate type when reading a chunk
Reported in https://bugzilla.kernel.org/show_bug.cgi?id=199839, with an
image that has an invalid chunk type but does not return an error.

Add chunk type check in btrfs_check_chunk_valid, to detect the wrong
type combinations.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199839
Reported-by: Xu Wen <wen.xu@gatech.edu>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:55 +02:00
David Sterba
46df06b85e btrfs: refactor block group replication factor calculation to a helper
There are many places that open code the duplicity factor of the block
group profiles, create a common helper. This can be easily extended for
more copies.

Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:53 +02:00
Anand Jain
321a4bf72b btrfs: use the assigned fs_devices instead of the dereference
We have assigned the %fs_info->fs_devices in %fs_devices as its not
modified just use it for the mutex_lock().

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:53 +02:00
Gu Jinxiang
36350e95a2 btrfs: return device pointer from btrfs_scan_one_device
Return device pointer (with the IS_ERR semantics) from
btrfs_scan_one_device so we don't have to return in through pointer.

And since btrfs_fs_devices can be obtained from btrfs_device, return that.

Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ fixed conflics after recent changes to btrfs_scan_one_device ]
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:48 +02:00
David Sterba
f5194e34ca btrfs: lift uuid_mutex to callers of btrfs_open_devices
Prepartory work to fix race between mount and device scan.

The callers will have to manage the critical section, eg. mount wants to
scan and then call btrfs_open_devices without the ioctl scan walking in
and modifying the fs devices in the meantime.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:47 +02:00
David Sterba
899f9307c3 btrfs: lift uuid_mutex to callers of btrfs_scan_one_device
Prepartory work to fix race between mount and device scan.

The callers will have to manage the critical section, eg. mount wants to
scan and then call btrfs_open_devices without the ioctl scan walking in
and modifying the fs devices in the meantime.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:47 +02:00
Anand Jain
7bcb8164ad btrfs: use device_list_mutex when removing stale devices
btrfs_free_stale_devices() finds a stale (not opened) device matching
path in the fs_uuid list. We are already under uuid_mutex so when we
check for each fs_devices, hold the device_list_mutex too.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:47 +02:00
Anand Jain
fa6d2ae540 btrfs: rename local devices for fs_devices in btrfs_free_stale_devices(
Over the years we named %fs_devices and %devices to represent the
struct btrfs_fs_devices and the struct btrfs_device. So follow the same
scheme here too. No functional changes.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:47 +02:00
Anand Jain
9c6d173ea6 btrfs: extend locked section when adding a new device in device_list_add
Make sure the device_list_lock is held the whole time:

* when the device is being looked up
* new device is initialized and put to the list
* the list counters are updated (fs_devices::opened, fs_devices::total_devices)

Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:46 +02:00
Anand Jain
4306a97449 btrfs: do btrfs_free_stale_devices outside of device_list_add
btrfs_free_stale_devices() looks for device path reused for another
filesystem, and deletes the older fs_devices::device entry.

In preparation to handle locking in device_list_add, move
btrfs_free_stale_devices outside as these two functions serve a
different purpose.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:46 +02:00
Nikolay Borisov
959b1c0467 btrfs: close devices without offloading to a temporary list
Since commit 88c14590cd ("btrfs: use RCU in btrfs_show_devname for
device list traversal") btrfs_show_devname no longer takes
device_list_mutex. As such the deadlock that 0ccd05285e ("btrfs: fix a
possible umount deadlock") aimed to fix no longer exists, we can free
the devices immediatelly and remove the code that does the pending work.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:46 +02:00
Qu Wenruo
621567a28c btrfs: Remove unused function btrfs_account_dev_extents_size
This function is not used since the alloc_start parameter has been
obsoleted in commit 0d0c71b317 ("btrfs: obsolete and remove
mount option alloc_start").

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:46 +02:00
Anand Jain
b4993e64f7 btrfs: fix in-memory value of total_devices after seed device deletion
In case of deleting the seed device the %cur_devices (seed) and the
%fs_devices (parent) are different. Now, as the parent
fs_devices::total_devices also maintains the total number of devices
including the seed device, so decrement its in-memory value for the
successful seed delete. We are already updating its corresponding
on-disk btrfs_super_block::number_devices value.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:45 +02:00
David Sterba
d7f663fa3f btrfs: prune unused includes
Remove includes if none of the interfaces and exports is used in the
given source file.

Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:43 +02:00
Anand Jain
694c51fb2e btrfs: drop unnecessary variable in btrfs_init_new_device
There is only usage of the declared devices variable, instead use its
value directly.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:42 +02:00
Anand Jain
5da54bc138 btrfs: use a temporary variable for fs_devices in btrfs_init_new_device
There are many instances of the %fs_info->fs_devices pointer
dereferences, use a temporary variable instead.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:42 +02:00
Qu Wenruo
fce466eab7 btrfs: tree-checker: Verify block_group_item
A crafted image with invalid block group items could make free space cache
code to cause panic.

We could detect such invalid block group item by checking:
1) Item size
   Known fixed value.
2) Block group size (key.offset)
   We have an upper limit on block group item (10G)
3) Chunk objectid
   Known fixed value.
4) Type
   Only 4 valid type values, DATA, METADATA, SYSTEM and DATA|METADATA.
   No more than 1 bit set for profile type.
5) Used space
   No more than the block group size.

This should allow btrfs to detect and refuse to mount the crafted image.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199849
Reported-by: Xu Wen <wen.xu@gatech.edu>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:41 +02:00
Nikolay Borisov
43a7e99db6 btrfs: Remove fs_info from btrfs_force_chunk_alloc
It can be referenced from the passed transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:38 +02:00
Nikolay Borisov
451a2c1303 btrfs: Remove fs_info from check_system_chunk
It can be referenced from trans since the function is always called
within a transaction.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:36 +02:00
Nikolay Borisov
c216b2039a btrfs: Remove fs_info from btrfs_alloc_chunk
It can be referenced from trans since the function is always called
within a transaction.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:36 +02:00
Nikolay Borisov
5a98ec0141 btrfs: Remove fs_info from btrfs_remove_block_group
This function is always called with a valid transaction handle from
where we can reference fs_info. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:34 +02:00
Nikolay Borisov
e7e02096d9 btrfs: Remove fs_info from btrfs_make_block_group
This function is always called with a valid transaction handle from
where we can reference the fs_info. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06 13:12:34 +02:00
David Sterba
20c5bbc640 btrfs: restore uuid_mutex in btrfs_open_devices
Commit 542c5908ab ("btrfs: replace uuid_mutex by
device_list_mutex in btrfs_open_devices") switched to device_list_mutex
as we need that for the device list traversal, but we also need
uuid_mutex to protect access to fs_devices::opened to be consistent with
other users of that.

Fixes: 542c5908ab ("btrfs: replace uuid_mutex by device_list_mutex in btrfs_open_devices")
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-07-13 14:55:46 +02:00
Lu Fengqi
cdb345a877 btrfs: Remove fs_info argument from btrfs_uuid_tree_add
This function always takes a transaction handle which contains a
reference to the fs_info. Use that and remove the extra argument.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-30 16:46:52 +02:00
Anand Jain
6dac13f8e2 btrfs: add prefix "balance:" for log messages
Kernel logs are very important for the forensic investigations of the
issues in general make it easy to use it. This patch adds 'balance:'
prefix so that it can be easily searched.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:38 +02:00
Anand Jain
d9a071f008 btrfs: use common variable for fs_devices in btrfs_destroy_dev_replace_tgtdev
Use a local btrfs_fs_devices variable to access the structure.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:18 +02:00
Anand Jain
ab5c2f65de btrfs: drop uuid_mutex in btrfs_destroy_dev_replace_tgtdev
Delete the uuid_mutex lock here as this thread accesses the
btrfs_fs_devices::devices only (counters or called functions do a list
traversal). And the device_list_mutex lock is already taken.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:17 +02:00
Anand Jain
542c5908ab btrfs: replace uuid_mutex by device_list_mutex in btrfs_open_devices
btrfs_open_devices() is using the uuid_mutex, but as btrfs_open_devices
is just limited to openning all the devices under for given fsid, so we
don't need uuid_mutex.

Instead it should hold the device_list_mutex as it updates the members
of the btrfs_fs_devices and btrfs_device and not the whole fs_devs list.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:15 +02:00
Anand Jain
3dd0f7a364 btrfs: document uuid_mutex uasge in read_chunk_tree
read_chunk_tree() calls read_one_dev(), but for seed device we have
to search the fs_uuids list, so we need the uuid_mutex. Add a comment
comment, so that we can improve this part.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:14 +02:00
Anand Jain
41a52a0f1b btrfs: use existing cur_devices, cleanup btrfs_rm_device
Instead of de-referencing the device->fs_devices use cur_devices
which points to the same fs_devices and does not change.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:13 +02:00
Anand Jain
b6ed73bcb1 btrfs: reduce uuid_mutex critical section while scanning devices
The generic block device lookup or cleanup does not need the uuid mutex,
that's only for the device_list_add.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:23:12 +02:00
David Sterba
6fcf6e2bff btrfs: remove redundant btrfs_balance_control::fs_info
The fs_info is always available from the context so we don't need to
store it in the structure.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:30 +02:00
Nikolay Borisov
63a9c7b9ce btrfs: Remove devid parameter from btrfs_rmap_block
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: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:29 +02:00
Gu Jinxiang
0338dff6e0 btrfs: do reverse path readahead in btrfs_shrink_device
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: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:28 +02:00
Anand Jain
f9fbcaa2a3 btrfs: move btrfs_raid_mindev_errorvalues to btrfs_raid_attr table
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: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:27 +02:00
Anand Jain
41a6e8913c btrfs: move btrfs_raid_group values to btrfs_raid_attr table
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: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:27 +02:00
Anand Jain
ed23467b18 btrfs: move btrfs_raid_type_names values to btrfs_raid_attr table
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: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:27 +02:00
David Sterba
833aae18fc btrfs: open code set_balance_control
The helper is quite simple and I'd like to see the locking in the
caller.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:26 +02:00
David Sterba
1354e1a13e btrfs: use mutex in btrfs_resume_balance_async
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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:26 +02:00
David Sterba
008ef0969d btrfs: drop lock parameter from update_ioctl_balance_args and rename
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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:26 +02:00
David Sterba
cf7d20f447 btrfs: move and comment read-only check in btrfs_cancel_balance
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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:26 +02:00
David Sterba
3009a62f3b btrfs: track running balance in a simpler way
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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:25 +02:00
David Sterba
dccdb07bc9 btrfs: kill btrfs_fs_info::volume_mutex
Mutual exclusion of device add/rm and balance was done by the volume
mutex up to version 3.7. The commit 5ac00addc7 ("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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:25 +02:00
David Sterba
a0fecc2371 btrfs: remove wrong use of volume_mutex from btrfs_dev_replace_start
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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:25 +02:00
David Sterba
149196a2ae btrfs: cleanup helpers that reset balance state
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: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28 18:07:25 +02:00