linux.git/fs/btrfs/relocation.c, branch v5.3

btrfs: migrate the delalloc space stuff to it's own home

2019-07-04T15:26:17+00:00

We have code for data and metadata reservations for delalloc.  There's
quite a bit of code here, and it's used in a lot of places so I've
separated it out to it's own file.  inode.c and file.c are already
pretty large, and this code is complicated enough to live in its own
space.

Signed-off-by: Josef Bacik 
Signed-off-by: David Sterba

btrfs: reloc: Also queue orphan reloc tree for cleanup to avoid BUG_ON()

2019-05-28T16:54:10+00:00

[BUG]
When a fs has orphan reloc tree along with unfinished balance:
  ...
        item 16 key (TREE_RELOC ROOT_ITEM FS_TREE) itemoff 12090 itemsize 439
                generation 12 root_dirid 256 bytenr 300400640 level 1 refs 0 <<<
                lastsnap 8 byte_limit 0 bytes_used 1359872 flags 0x0(none)
                uuid 7c48d938-33a3-4aae-ab19-6e5c9d406e46
        item 17 key (BALANCE TEMPORARY_ITEM 0) itemoff 11642 itemsize 448
                temporary item objectid BALANCE offset 0
                balance status flags 14

Then at mount time, we can hit the following kernel BUG_ON():
  BTRFS info (device dm-3): relocating block group 298844160 flags metadata|dup
  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/relocation.c:1413!
  invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 1 PID: 897 Comm: btrfs-balance Tainted: G           O      5.2.0-rc1-custom #15
  RIP: 0010:create_reloc_root+0x1eb/0x200 [btrfs]
  Call Trace:
   btrfs_init_reloc_root+0x96/0xb0 [btrfs]
   record_root_in_trans+0xb2/0xe0 [btrfs]
   btrfs_record_root_in_trans+0x55/0x70 [btrfs]
   select_reloc_root+0x7e/0x230 [btrfs]
   do_relocation+0xc4/0x620 [btrfs]
   relocate_tree_blocks+0x592/0x6a0 [btrfs]
   relocate_block_group+0x47b/0x5d0 [btrfs]
   btrfs_relocate_block_group+0x183/0x2f0 [btrfs]
   btrfs_relocate_chunk+0x4e/0xe0 [btrfs]
   btrfs_balance+0x864/0xfa0 [btrfs]
   balance_kthread+0x3b/0x50 [btrfs]
   kthread+0x123/0x140
   ret_from_fork+0x27/0x50

[CAUSE]
In btrfs, reloc trees are used to record swapped tree blocks during
balance.
Reloc tree either get merged (replace old tree blocks of its parent
subvolume) in next transaction if its ref is 1 (fresh).
Or is already merged and will be cleaned up if its ref is 0 (orphan).

After commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion
after merge_reloc_roots"), reloc tree cleanup is delayed until one block
group is balanced.

Since fresh reloc roots are recorded during merge, as long as there
is no power loss, those orphan reloc roots converted from fresh ones are
handled without problem.

However when power loss happens, orphan reloc roots can be recorded
on-disk, thus at next mount time, we will have orphan reloc roots from
on-disk data directly, and ignored by clean_dirty_subvols() routine.

Then when background balance starts to balance another block group, and
needs to create new reloc root for the same root, btrfs_insert_item()
returns -EEXIST, and trigger that BUG_ON().

[FIX]
For orphan reloc roots, also queue them to rc->dirty_subvol_roots, so
all reloc roots no matter orphan or not, can be cleaned up properly and
avoid above BUG_ON().

And to cooperate with above change, clean_dirty_subvols() will check if
the queued root is a reloc root or a subvol root.
For a subvol root, do the old work, and for a orphan reloc root, clean it
up.

Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
CC: stable@vger.kernel.org # 5.1
Signed-off-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: extent-tree: Use btrfs_ref to refactor btrfs_free_extent()

2019-04-29T17:02:49+00:00

Similar to btrfs_inc_extent_ref(), use btrfs_ref to replace the long
parameter list and the confusing @owner parameter.

Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: extent-tree: Use btrfs_ref to refactor btrfs_inc_extent_ref()

2019-04-29T17:02:49+00:00

Use the new btrfs_ref structure and replace parameter list to clean up
the usage of owner and level to distinguish the extent types.

Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: get fs_info from block group in lookup_free_space_inode

2019-04-29T17:02:45+00:00

We can read fs_info from the block group cache structure and can drop it
from the parameters.

Signed-off-by: David Sterba

btrfs: Remove redundant inode argument from btrfs_add_ordered_sum

2019-04-29T17:02:40+00:00

Ordered csums are keyed off of a btrfs_ordered_extent, which already has
a reference to the inode. This implies that an explicit inode argument
is redundant. So remove it.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: fix panic during relocation after ENOSPC before writeback happens

2019-04-29T17:02:24+00:00

We've been seeing the following sporadically throughout our fleet

panic: kernel BUG at fs/btrfs/relocation.c:4584!
netversion: 5.0-0
Backtrace:
 #0 [ffffc90003adb880] machine_kexec at ffffffff81041da8
 #1 [ffffc90003adb8c8] __crash_kexec at ffffffff8110396c
 #2 [ffffc90003adb988] crash_kexec at ffffffff811048ad
 #3 [ffffc90003adb9a0] oops_end at ffffffff8101c19a
 #4 [ffffc90003adb9c0] do_trap at ffffffff81019114
 #5 [ffffc90003adba00] do_error_trap at ffffffff810195d0
 #6 [ffffc90003adbab0] invalid_op at ffffffff81a00a9b
    [exception RIP: btrfs_reloc_cow_block+692]
    RIP: ffffffff8143b614  RSP: ffffc90003adbb68  RFLAGS: 00010246
    RAX: fffffffffffffff7  RBX: ffff8806b9c32000  RCX: ffff8806aad00690
    RDX: ffff880850b295e0  RSI: ffff8806b9c32000  RDI: ffff88084f205bd0
    RBP: ffff880849415000   R8: ffffc90003adbbe0   R9: ffff88085ac90000
    R10: ffff8805f7369140  R11: 0000000000000000  R12: ffff880850b295e0
    R13: ffff88084f205bd0  R14: 0000000000000000  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffffc90003adbbb0] __btrfs_cow_block at ffffffff813bf1cd
 #8 [ffffc90003adbc28] btrfs_cow_block at ffffffff813bf4b3
 #9 [ffffc90003adbc78] btrfs_search_slot at ffffffff813c2e6c

The way relocation moves data extents is by creating a reloc inode and
preallocating extents in this inode and then copying the data into these
preallocated extents.  Once we've done this for all of our extents,
we'll write out these dirty pages, which marks the extent written, and
goes into btrfs_reloc_cow_block().  From here we get our current
reloc_control, which _should_ match the reloc_control for the current
block group we're relocating.

However if we get an ENOSPC in this path at some point we'll bail out,
never initiating writeback on this inode.  Not a huge deal, unless we
happen to be doing relocation on a different block group, and this block
group is now rc->stage == UPDATE_DATA_PTRS.  This trips the BUG_ON() in
btrfs_reloc_cow_block(), because we expect to be done modifying the data
inode.  We are in fact done modifying the metadata for the data inode
we're currently using, but not the one from the failed block group, and
thus we BUG_ON().

(This happens when writeback finishes for extents from the previous
group, when we are at btrfs_finish_ordered_io() which updates the data
reloc tree (inode item, drops/adds extent items, etc).)

Fix this by writing out the reloc data inode always, and then breaking
out of the loop after that point to keep from tripping this BUG_ON()
later.

Signed-off-by: Josef Bacik 
Reviewed-by: Filipe Manana 
[ add note from Filipe ]
Signed-off-by: David Sterba

btrfs: reloc: Fix NULL pointer dereference due to expanded reloc_root lifespan

2019-04-29T17:02:22+00:00

Commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after
merge_reloc_roots()") expands the life span of root->reloc_root.

This breaks certain checs of fs_info->reloc_ctl.  Before that commit, if
we have a root with valid reloc_root, then it's ensured to have
fs_info->reloc_ctl.

But now since reloc_root doesn't always mean a valid fs_info->reloc_ctl,
such check is unreliable and can cause the following NULL pointer
dereference:

  BUG: unable to handle kernel NULL pointer dereference at 00000000000005c1
  IP: btrfs_reloc_pre_snapshot+0x20/0x50 [btrfs]
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP PTI
  CPU: 0 PID: 10379 Comm: snapperd Not tainted
  Call Trace:
   create_pending_snapshot+0xd7/0xfc0 [btrfs]
   create_pending_snapshots+0x8e/0xb0 [btrfs]
   btrfs_commit_transaction+0x2ac/0x8f0 [btrfs]
   btrfs_mksubvol+0x561/0x570 [btrfs]
   btrfs_ioctl_snap_create_transid+0x189/0x190 [btrfs]
   btrfs_ioctl_snap_create_v2+0x102/0x150 [btrfs]
   btrfs_ioctl+0x5c9/0x1e60 [btrfs]
   do_vfs_ioctl+0x90/0x5f0
   SyS_ioctl+0x74/0x80
   do_syscall_64+0x7b/0x150
   entry_SYSCALL_64_after_hwframe+0x3d/0xa2
  RIP: 0033:0x7fd7cdab8467

Fix it by explicitly checking fs_info->reloc_ctl other than using the
implied root->reloc_root.

Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Introduce extent_io_tree::owner to distinguish different io_trees

2019-04-29T17:02:18+00:00

Btrfs has the following different extent_io_trees used:

- fs_info::free_extents[2]
- btrfs_inode::io_tree - for both normal inodes and the btree inode
- btrfs_inode::io_failure_tree
- btrfs_transaction::dirty_pages
- btrfs_root::dirty_log_pages

If we want to trace changes in those trees, it will be pretty hard to
distinguish them.

Instead of using hard-to-read pointer address, this patch will introduce
a new member extent_io_tree::owner to track the owner.

This modification needs all the callers of extent_io_tree_init() to
accept a new parameter @owner.

This patch provides the basis for later trace events.

Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Introduce fs_info to extent_io_tree

2019-04-29T17:02:18+00:00

This patch will add a new member fs_info to extent_io_tree.

This provides the basis for later trace events to distinguish the output
between different btrfs filesystems. While this increases the size of
the structure, we want to know the source of the trace events and
passing the fs_info as an argument to all contexts is not possible.

The selftests are now allowed to set it to NULL as they don't use the
tracepoints.

Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba