When we add a device we need to add it to sysfs, so instead of using the
btrfs_sysfs_add_devices_dir() fs_devices argument to specify whether to
add a device or all of fs_devices, call the helper function directly
btrfs_sysfs_add_device() and thus make it non-static.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_sysfs_remove_devices_dir() return value is unused declare it as
void.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_sysfs_remove_devices_dir() removes device link and devid kobject
(sysfs entries) for a device or all the devices in the btrfs_fs_devices.
In preparation to remove these sysfs entries for the seed as well, add
a btrfs_sysfs_remove_device() helper function and avoid code
duplication.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_sysfs_add_devices_dir() adds device link and devid kobject
(sysfs entries) for a device or all the devices in the btrfs_fs_devices.
In preparation to add these sysfs entries for the seed as well, add
a btrfs_sysfs_add_device() helper function and avoid code duplication.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

If you replace a seed device in a sprouted fs, it appears to have
successfully replaced the seed device, but if you look closely, it
didn't.  Here is an example.

  $ mkfs.btrfs /dev/sda
  $ btrfstune -S1 /dev/sda
  $ mount /dev/sda /btrfs
  $ btrfs device add /dev/sdb /btrfs
  $ umount /btrfs
  $ btrfs device scan --forget
  $ mount -o device=/dev/sda /dev/sdb /btrfs
  $ btrfs replace start -f /dev/sda /dev/sdc /btrfs
  $ echo $?
  0

  BTRFS info (device sdb): dev_replace from /dev/sda (devid 1) to /dev/sdc started
  BTRFS info (device sdb): dev_replace from /dev/sda (devid 1) to /dev/sdc finished

  $ btrfs fi show
  Label: none  uuid: ab2c88b7-be81-4a7e-9849-c3666e7f9f4f
	  Total devices 2 FS bytes used 256.00KiB
	  devid    1 size 3.00GiB used 520.00MiB path /dev/sdc
	  devid    2 size 3.00GiB used 896.00MiB path /dev/sdb

  Label: none  uuid: 10bd3202-0415-43af-96a8-d5409f310a7e
	  Total devices 1 FS bytes used 128.00KiB
	  devid    1 size 3.00GiB used 536.00MiB path /dev/sda

So as per the replace start command and kernel log replace was successful.
Now let's try to clean mount.

  $ umount /btrfs
  $ btrfs device scan --forget

  $ mount -o device=/dev/sdc /dev/sdb /btrfs
  mount: /btrfs: wrong fs type, bad option, bad superblock on /dev/sdb, missing codepage or helper program, or other error.

  [  636.157517] BTRFS error (device sdc): failed to read chunk tree: -2
  [  636.180177] BTRFS error (device sdc): open_ctree failed

That's because per dev items it is still looking for the original seed
device.

 $ btrfs inspect-internal dump-tree -d /dev/sdb

	item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
		devid 1 total_bytes 3221225472 bytes_used 545259520
		io_align 4096 io_width 4096 sector_size 4096 type 0
		generation 6 start_offset 0 dev_group 0
		seek_speed 0 bandwidth 0
		uuid 59368f50-9af2-4b17-91da-8a783cc418d4  <--- seed uuid
		fsid 10bd3202-0415-43af-96a8-d5409f310a7e  <--- seed fsid
	item 1 key (DEV_ITEMS DEV_ITEM 2) itemoff 16087 itemsize 98
		devid 2 total_bytes 3221225472 bytes_used 939524096
		io_align 4096 io_width 4096 sector_size 4096 type 0
		generation 0 start_offset 0 dev_group 0
		seek_speed 0 bandwidth 0
		uuid 56a0a6bc-4630-4998-8daf-3c3030c4256a  <- sprout uuid
		fsid ab2c88b7-be81-4a7e-9849-c3666e7f9f4f <- sprout fsid

But the replaced target has the following uuid+fsid in its superblock
which doesn't match with the expected uuid+fsid in its devitem.

  $ btrfs in dump-super /dev/sdc | egrep '^generation|dev_item.uuid|dev_item.fsid|devid'
  generation	20
  dev_item.uuid	59368f50-9af2-4b17-91da-8a783cc418d4
  dev_item.fsid	ab2c88b7-be81-4a7e-9849-c3666e7f9f4f [match]
  dev_item.devid	1

So if you provide the original seed device the mount shall be
successful.  Which so long happening in the test case btrfs/163.

  $ btrfs device scan --forget
  $ mount -o device=/dev/sda /dev/sdb /btrfs

Fix in this patch:
If a seed is not sprouted then there is no replacement of it, because of
its read-only filesystem with a read-only device. Similarly, in the case
of a sprouted filesystem, the seed device is still read only. So, mark
it as you can't replace a seed device, you can only add a new device and
then delete the seed device. If replace is attempted then returns
-EINVAL.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Systems booting without the initramfs seems to scan an unusual kind
of device path (/dev/root). And at a later time, the device is updated
to the correct path. We generally print the process name and PID of the
process scanning the device but we don't capture the same information if
the device path is rescanned with a different pathname.

The current message is too long, so drop the unnecessary UUID and add
process name and PID.

While at this also update the duplicate device warning to include the
process name and PID so the messages are consistent

CC: stable@vger.kernel.org # 4.19+
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=89721Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

I'm a actual human being so am incapable of converting u64 to s64 in my
head, so add a helper to get the pretty name of a root objectid and use
that helper to spit out the name for any special roots for leaked roots,
so I don't have to scratch my head and figure out which root I messed up
the refs for.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

/sys/fs/<fsid>/exclusive_operation contains the currently executing
exclusive operation. Add a sysfs_notify() when operation end, so
userspace can be notified of exclusive operation is finished.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Instead of using a flag bit for exclusive operation, use a variable to
store which exclusive operation is being performed.  Introduce an API
to start and finish an exclusive operation.

This would enable another way for tools to check which operation is
running on why starting an exclusive operation failed. The followup
patch adds a sysfs_notify() to alert userspace when the state changes, so
userspace can perform select() on it to get notified of the change.

This would enable us to enqueue a command which will wait for current
exclusive operation to complete before issuing the next exclusive
operation. This has been done synchronously as opposed to a background
process, or else error collection (if any) will become difficult.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ update comments ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

While running btrfs/061, btrfs/073, btrfs/078, or btrfs/178 we hit the
following lockdep splat:

  ======================================================
  WARNING: possible circular locking dependency detected
  5.9.0-rc3+ #4 Not tainted
  ------------------------------------------------------
  kswapd0/100 is trying to acquire lock:
  ffff96ecc22ef4a0 (&delayed_node->mutex){+.+.}-{3:3}, at: __btrfs_release_delayed_node.part.0+0x3f/0x330

  but task is already holding lock:
  ffffffff8dd74700 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #3 (fs_reclaim){+.+.}-{0:0}:
	 fs_reclaim_acquire+0x65/0x80
	 slab_pre_alloc_hook.constprop.0+0x20/0x200
	 kmem_cache_alloc+0x37/0x270
	 alloc_inode+0x82/0xb0
	 iget_locked+0x10d/0x2c0
	 kernfs_get_inode+0x1b/0x130
	 kernfs_get_tree+0x136/0x240
	 sysfs_get_tree+0x16/0x40
	 vfs_get_tree+0x28/0xc0
	 path_mount+0x434/0xc00
	 __x64_sys_mount+0xe3/0x120
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #2 (kernfs_mutex){+.+.}-{3:3}:
	 __mutex_lock+0x7e/0x7e0
	 kernfs_add_one+0x23/0x150
	 kernfs_create_link+0x63/0xa0
	 sysfs_do_create_link_sd+0x5e/0xd0
	 btrfs_sysfs_add_devices_dir+0x81/0x130
	 btrfs_init_new_device+0x67f/0x1250
	 btrfs_ioctl+0x1ef/0x2e20
	 __x64_sys_ioctl+0x83/0xb0
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #1 (&fs_info->chunk_mutex){+.+.}-{3:3}:
	 __mutex_lock+0x7e/0x7e0
	 btrfs_chunk_alloc+0x125/0x3a0
	 find_free_extent+0xdf6/0x1210
	 btrfs_reserve_extent+0xb3/0x1b0
	 btrfs_alloc_tree_block+0xb0/0x310
	 alloc_tree_block_no_bg_flush+0x4a/0x60
	 __btrfs_cow_block+0x11a/0x530
	 btrfs_cow_block+0x104/0x220
	 btrfs_search_slot+0x52e/0x9d0
	 btrfs_insert_empty_items+0x64/0xb0
	 btrfs_insert_delayed_items+0x90/0x4f0
	 btrfs_commit_inode_delayed_items+0x93/0x140
	 btrfs_log_inode+0x5de/0x2020
	 btrfs_log_inode_parent+0x429/0xc90
	 btrfs_log_new_name+0x95/0x9b
	 btrfs_rename2+0xbb9/0x1800
	 vfs_rename+0x64f/0x9f0
	 do_renameat2+0x320/0x4e0
	 __x64_sys_rename+0x1f/0x30
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #0 (&delayed_node->mutex){+.+.}-{3:3}:
	 __lock_acquire+0x119c/0x1fc0
	 lock_acquire+0xa7/0x3d0
	 __mutex_lock+0x7e/0x7e0
	 __btrfs_release_delayed_node.part.0+0x3f/0x330
	 btrfs_evict_inode+0x24c/0x500
	 evict+0xcf/0x1f0
	 dispose_list+0x48/0x70
	 prune_icache_sb+0x44/0x50
	 super_cache_scan+0x161/0x1e0
	 do_shrink_slab+0x178/0x3c0
	 shrink_slab+0x17c/0x290
	 shrink_node+0x2b2/0x6d0
	 balance_pgdat+0x30a/0x670
	 kswapd+0x213/0x4c0
	 kthread+0x138/0x160
	 ret_from_fork+0x1f/0x30

  other info that might help us debug this:

  Chain exists of:
    &delayed_node->mutex --> kernfs_mutex --> fs_reclaim

   Possible unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(fs_reclaim);
				 lock(kernfs_mutex);
				 lock(fs_reclaim);
    lock(&delayed_node->mutex);

   *** DEADLOCK ***

  3 locks held by kswapd0/100:
   #0: ffffffff8dd74700 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30
   #1: ffffffff8dd65c50 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x115/0x290
   #2: ffff96ed2ade30e0 (&type->s_umount_key#36){++++}-{3:3}, at: super_cache_scan+0x38/0x1e0

  stack backtrace:
  CPU: 0 PID: 100 Comm: kswapd0 Not tainted 5.9.0-rc3+ #4
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
  Call Trace:
   dump_stack+0x8b/0xb8
   check_noncircular+0x12d/0x150
   __lock_acquire+0x119c/0x1fc0
   lock_acquire+0xa7/0x3d0
   ? __btrfs_release_delayed_node.part.0+0x3f/0x330
   __mutex_lock+0x7e/0x7e0
   ? __btrfs_release_delayed_node.part.0+0x3f/0x330
   ? __btrfs_release_delayed_node.part.0+0x3f/0x330
   ? lock_acquire+0xa7/0x3d0
   ? find_held_lock+0x2b/0x80
   __btrfs_release_delayed_node.part.0+0x3f/0x330
   btrfs_evict_inode+0x24c/0x500
   evict+0xcf/0x1f0
   dispose_list+0x48/0x70
   prune_icache_sb+0x44/0x50
   super_cache_scan+0x161/0x1e0
   do_shrink_slab+0x178/0x3c0
   shrink_slab+0x17c/0x290
   shrink_node+0x2b2/0x6d0
   balance_pgdat+0x30a/0x670
   kswapd+0x213/0x4c0
   ? _raw_spin_unlock_irqrestore+0x41/0x50
   ? add_wait_queue_exclusive+0x70/0x70
   ? balance_pgdat+0x670/0x670
   kthread+0x138/0x160
   ? kthread_create_worker_on_cpu+0x40/0x40
   ret_from_fork+0x1f/0x30

This happens because we are holding the chunk_mutex at the time of
adding in a new device.  However we only need to hold the
device_list_mutex, as we're going to iterate over the fs_devices
devices.  Move the sysfs init stuff outside of the chunk_mutex to get
rid of this lockdep splat.

CC: stable@vger.kernel.org # 4.4.x: f3cd2c58: btrfs: sysfs, rename device_link add/remove functions
CC: stable@vger.kernel.org # 4.4.x
Reported-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

It's counterintuitive to have a function named btrfs_inode_xxx which
takes a generic inode. Also move the function to btrfs_inode.h so that
it has access to the definition of struct btrfs_inode.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

I've made this change separate since it requires both of the newly added
NESTED flags and I didn't want to slip it into one of those changes.

If we do a double split of a node we can end up doing a
BTRFS_NESTED_SPLIT on level 0, which throws lockdep off because it
appears as a double lock.  Since we're maxed out on subclasses, use
BTRFS_NESTED_NEW_ROOT if we had to do a double split.  This is OK
because we won't have to do a double split if we had to insert a new
root, and the new root would be at a higher level anyway.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The way we add new roots is confusing from a locking perspective for
lockdep.  We generally have the rule that we lock things in order from
highest level to lowest, but in the case of adding a new level to the
tree we actually allocate a new block for the root, which makes the
locking go in reverse.  A similar issue exists for snapshotting, we cow
the original root for the root of a new tree, however they're at the
same level.  Address this by using BTRFS_NESTING_NEW_ROOT for these
operations.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

If we are splitting a leaf/node, we could do something like the
following

lock(leaf)  BTRFS_NESTING_NORMAL
  lock(left) BTRFS_NESTING_LEFT + BTRFS_NESTING_COW
    push from leaf -> left
      reset path to point to left
        split left
          allocate new block, lock block BTRFS_NESTING_SPLIT

at the new block point we need to have a different nesting level,
because we have already used either BTRFS_NESTING_LEFT or
BTRFS_NESTING_RIGHT when pushing items from the original leaf into the
adjacent leaves.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

For similar reasons as BTRFS_NESTING_COW, we need
BTRFS_NESTING_LEFT/RIGHT_COW.  The pattern is this

lock leaf -> BTRFS_NESTING_NORMAL
  cow leaf -> BTRFS_NESTING_COW
    split leaf
      lock left -> BTRFS_NESTING_LEFT
        cow left -> BTRFS_NESTING_LEFT_COW

We need this in order to indicate to lockdep that these locks are
discrete and are being taken in a safe order.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Our lockdep maps are based on rootid+level, however in some cases we
will lock adjacent blocks on the same level, namely in searching forward
or in split/balance.  Because of this lockdep will complain, so we need
a separate subclass to indicate to lockdep that these are different
locks.

lock leaf -> BTRFS_NESTING_NORMAL
  cow leaf -> BTRFS_NESTING_COW
    split leaf
       lock left -> BTRFS_NESTING_LEFT
       lock right -> BTRFS_NESTING_RIGHT

The above graph illustrates the need for this new nesting subclass.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When we COW a block we are holding a lock on the original block, and
then we lock the new COW block.  Because our lockdep maps are based on
root + level, this will make lockdep complain.  We need a way to
indicate a subclass for locking the COW'ed block, so plumb through our
btrfs_lock_nesting from btrfs_cow_block down to the btrfs_init_buffer,
and then introduce BTRFS_NESTING_COW to be used for cow'ing blocks.

The reason I've added all this extra infrastructure is because there
will be need of different nesting classes in follow up patches.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We will need these when we switch to an rwsem, so plumb in the
infrastructure here to use later on.  I violate the 80 character limit
some here because it'll be cleaned up later.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Our current tree locking stuff allows us to recurse with read locks if
we're already holding the write lock.  This is necessary for the space
cache inode, as we could be holding a lock on the root_tree root when we
need to cache a block group, and thus need to be able to read down the
root_tree to read in the inode cache.

We can get away with this in our current locking, but we won't be able
to with a rwsem.  Handle this by purposefully annotating the places
where we require recursion, so that in the future we can maybe come up
with a way to avoid the recursion.  In the case of the free space inode,
this will be superseded by the free space tree.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Nested locking with lockdep and everything else refers to lock hierarchy
within the same lock map.  This is how we indicate the same locks for
different objects are ok to take in a specific order, for our use case
that would be to take the lock on a leaf and then take a lock on an
adjacent leaf.

What ->lock_nested _actually_ refers to is if we happen to already be
holding the write lock on the extent buffer and we're allowing a read
lock to be taken on that extent buffer, which is recursion.  Rename this
so we don't get confused when we switch to a rwsem and have to start
using the _nested helpers.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Instead of opencoding filemap_write_and_wait simply call syncblockdev as
it makes it abundantly clear what's going on and why this is used. No
semantics changes.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Following the refactor of btrfs_free_stale_devices in
7bcb8164 ("btrfs: use device_list_mutex when removing stale devices")
fs_devices are freed after they have been iterated by the inner
list_for_each so the use-after-free fixed by introducing the break in
fd649f10 ("btrfs: Fix use-after-free when cleaning up fs_devs with
a single stale device") is no longer necessary. Just remove it
altogether. No functional changes.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Invert unlocked to locked and exploit the fact it can only ever be
modified if we are adding a new device to a seed filesystem. This allows
to simplify the check in error: label. No semantics changes.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When adding a new device there's a mandatory check to see if a device is
being duplicated to the filesystem it's added to. Since this is a
read-only operations not necessary to take device_list_mutex and can simply
make do with an rcu-readlock.

Using just RCU is safe because there won't be another device add delete
running in parallel as btrfs_init_new_device is called only from
btrfs_ioctl_add_dev.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

[BUG]
With a crafted image, btrfs can panic at btrfs_del_csums():

  kernel BUG at fs/btrfs/ctree.c:3188!
  invalid opcode: 0000 [#1] SMP PTI
  CPU: 0 PID: 1156 Comm: btrfs-transacti Not tainted 5.0.0-rc8+ #9
  RIP: 0010:btrfs_set_item_key_safe+0x16c/0x180
  RSP: 0018:ffff976141257ab8 EFLAGS: 00010202
  RAX: 0000000000000001 RBX: ffff898a6b890930 RCX: 0000000004b70000
  RDX: 0000000000000000 RSI: ffff976141257bae RDI: ffff976141257acf
  RBP: ffff976141257b10 R08: 0000000000001000 R09: ffff9761412579a8
  R10: 0000000000000000 R11: 0000000000000000 R12: ffff976141257abe
  R13: 0000000000000003 R14: ffff898a6a8be578 R15: ffff976141257bae
  FS: 0000000000000000(0000) GS:ffff898a77a00000(0000) knlGS:0000000000000000
  CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f779d9cd624 CR3: 000000022b2b4006 CR4: 00000000000206f0
  Call Trace:
  truncate_one_csum+0xac/0xf0
  btrfs_del_csums+0x24f/0x3a0
  __btrfs_free_extent.isra.72+0x5a7/0xbe0
  __btrfs_run_delayed_refs+0x539/0x1120
  btrfs_run_delayed_refs+0xdb/0x1b0
  btrfs_commit_transaction+0x52/0x950
  ? start_transaction+0x94/0x450
  transaction_kthread+0x163/0x190
  kthread+0x105/0x140
  ? btrfs_cleanup_transaction+0x560/0x560
  ? kthread_destroy_worker+0x50/0x50
  ret_from_fork+0x35/0x40
  Modules linked in:
  ---[ end trace 93bf9db00e6c374e ]---

[CAUSE]
This crafted image has a tricky key order corruption:

  checksum tree key (CSUM_TREE ROOT_ITEM 0)
  node 29741056 level 1 items 14 free 107 generation 19 owner CSUM_TREE
          ...
          key (EXTENT_CSUM EXTENT_CSUM 73785344) block 29757440 gen 19
          key (EXTENT_CSUM EXTENT_CSUM 77594624) block 29753344 gen 19
          ...

  leaf 29757440 items 5 free space 150 generation 19 owner CSUM_TREE
          item 0 key (EXTENT_CSUM EXTENT_CSUM 73785344) itemoff 2323 itemsize 1672
                  range start 73785344 end 75497472 length 1712128
          item 1 key (EXTENT_CSUM EXTENT_CSUM 75497472) itemoff 2319 itemsize 4
                  range start 75497472 end 75501568 length 4096
          item 2 key (EXTENT_CSUM EXTENT_CSUM 75501568) itemoff 579 itemsize 1740
                  range start 75501568 end 77283328 length 1781760
          item 3 key (EXTENT_CSUM EXTENT_CSUM 77283328) itemoff 575 itemsize 4
                  range start 77283328 end 77287424 length 4096
          item 4 key (EXTENT_CSUM EXTENT_CSUM 4120596480) itemoff 275 itemsize 300 <<<
                  range start 4120596480 end 4120903680 length 307200
  leaf 29753344 items 3 free space 1936 generation 19 owner CSUM_TREE
          item 0 key (18446744073457893366 EXTENT_CSUM 77594624) itemoff 2323 itemsize 1672
                  range start 77594624 end 79306752 length 1712128
          ...

Note the item 4 key of leaf 29757440, which is obviously too large, and
even larger than the first key of the next leaf.

However it still follows the key order in that tree block, thus tree
checker is unable to detect it at read time, since tree checker can only
work inside one leaf, thus such complex corruption can't be detected in
advance.

[FIX]
The next time to detect such problem is at tree block merge time,
which is in push_node_left(), balance_node_right(), push_leaf_left() or
push_leaf_right().

Now we check if the key order of the right-most key of the left node is
larger than the left-most key of the right node.

By this we don't need to call the full tree-checker, while still keeping
the key order correct as key order in each node is already checked by
tree checker thus we only need to check the above two slots.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202833Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

[BUG]
With a crafted image, btrfs can panic at insert_inline_extent_backref():

  kernel BUG at fs/btrfs/extent-tree.c:1857!
  invalid opcode: 0000 [#1] SMP PTI
  CPU: 0 PID: 1117 Comm: btrfs-transacti Not tainted 5.0.0-rc8+ #9
  RIP: 0010:insert_inline_extent_backref+0xcc/0xe0
  RSP: 0018:ffffac4dc1287be8 EFLAGS: 00010293
  RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000000001
  RDX: 0000000000001000 RSI: 0000000000000000 RDI: 0000000000000000
  RBP: ffffac4dc1287c28 R08: ffffac4dc1287ab8 R09: ffffac4dc1287ac0
  R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
  R13: ffff8febef88a540 R14: ffff8febeaa7bc30 R15: 0000000000000000
  FS: 0000000000000000(0000) GS:ffff8febf7a00000(0000) knlGS:0000000000000000
  CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f663ace94c0 CR3: 0000000235698006 CR4: 00000000000206f0
  Call Trace:
  ? _cond_resched+0x1a/0x50
  __btrfs_inc_extent_ref.isra.64+0x7e/0x240
  ? btrfs_merge_delayed_refs+0xa5/0x330
  __btrfs_run_delayed_refs+0x653/0x1120
  btrfs_run_delayed_refs+0xdb/0x1b0
  btrfs_commit_transaction+0x52/0x950
  ? start_transaction+0x94/0x450
  transaction_kthread+0x163/0x190
  kthread+0x105/0x140
  ? btrfs_cleanup_transaction+0x560/0x560
  ? kthread_destroy_worker+0x50/0x50
  ret_from_fork+0x35/0x40
  Modules linked in:
  ---[ end trace 2ad8b3de903cf825 ]---

[CAUSE]
Due to extent tree corruption (still valid by itself, but bad cross
ref), we can allocate an extent which is still in extent tree.  The
offending tree block of that case is from csum tree.  The newly
allocated tree block is also for csum tree.

Then we will try to insert a tree block ref for the existing tree block
ref.

For a tree extent item, tree block can never be shared directly by the
same tree twice.  We have such BUG_ON() to prevent such problem, but
this is not a proper error handling.

[FIX]
Replace that BUG_ON() with proper error message and leaf dump for debug
build.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202829Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

__btrfs_free_extent() is doing two things:

1. Reduce the refs number of an extent backref
   Either it's an inline extent backref (inside EXTENT/METADATA item) or
   a keyed extent backref (SHARED_* item).
   We only need to locate that backref line, either reduce the number or
   remove the backref line completely.

2. Update the refs count in EXTENT/METADATA_ITEM

During step 1), we will try to locate the EXTENT/METADATA_ITEM without
triggering another btrfs_search_slot() as fast path.

Only when we fail to locate that item, we will trigger another
btrfs_search_slot() to get that EXTENT/METADATA_ITEM after we
updated/deleted the backref line.

And we have a lot of strict checks on things like refs_to_drop against
extent refs and special case checks for single ref extents.

There are 7 BUG_ON()s, although they're doing correct checks, they can
be triggered by crafted images.

This patch improves the function:

- Introduce two examples to show what __btrfs_free_extent() is doing
  One inline backref case and one keyed case.  Should cover most cases.

- Kill all BUG_ON()s with proper error message and optional leaf dump

- Add comment to show the overall flow

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202819
[ The report triggers one BUG_ON() in __btrfs_free_extent() ]
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Although we have start, len check for extent buffer reader/write (e.g.
read_extent_buffer()), these checks have limitations:

- No overflow check
  Values like start = 1024 len = -1024 can still pass the basic
   (start + len) > eb->len check.

- Checks are not consistent
  For read_extent_buffer() we only check (start + len) against eb->len.
  While for memcmp_extent_buffer() we also check start against eb->len.

- Different error reporting mechanism
  We use WARN() in read_extent_buffer() but BUG() in
  memcpy_extent_buffer().

- Still modify memory if the request is obviously wrong
  In read_extent_buffer() even we find (start + len) > eb->len, we still
  call memset(dst, 0, len), which can easily cause memory access error
  if start + len overflows.

To address above problems, this patch creates a new common function to
check such access, check_eb_range().

- Add overflow check
  This function checks start, start + len against eb->len and overflow
  check.

- Unified checks

- Unified error reports
  Will call WARN() if CONFIG_BTRFS_DEBUG is configured.
  And also do btrfs_warn() message for non-debug build.

- Exit ASAP if check fails
  No more possible memory corruption.

- Add extra comment for @start @len used in those functions as it's
  sometimes confused with the logical addressing instead of a range
  inside the eb space

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202817
[ Inspired by above report, the report itself is already addressed ]
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ use check_add_overflow ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

To avoid duplicating 3 lines of code the error detection logic in
init_tree_roots is somewhat quirky. It first checks for the presence of
any error condition, then checks for the specific condition to perform
any specific actions. That's spurious because directly checking for
each respective error condition and doing the necessary steps is more
obvious. While at it change the -EUCLEAN to -EIO in case the extent
buffer is not read correctly, this is in line with other sites which
return -EIO when the eb couldn't be read.

Additionally it results in smaller code and the code reads
more linearly:

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-95 (-95)
Function                                     old     new   delta
open_ctree                                 17243   17148     -95
Total: Before=113104, After=113009, chg -0.08%
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>