Commit Graph

295 Commits

Author SHA1 Message Date
Nikolay Borisov 80e9baed72 btrfs: export and rename qgroup_reserve_meta
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-03-02 16:58:30 +01:00
Filipe Manana cb13eea3b4 btrfs: fix transaction leak and crash after RO remount caused by qgroup rescan
If we remount a filesystem in RO mode while the qgroup rescan worker is
running, we can end up having it still running after the remount is done,
and at unmount time we may end up with an open transaction that ends up
never getting committed. If that happens we end up with several memory
leaks and can crash when hardware acceleration is unavailable for crc32c.
Possibly it can lead to other nasty surprises too, due to use-after-free
issues.

The following steps explain how the problem happens.

1) We have a filesystem mounted in RW mode and the qgroup rescan worker is
   running;

2) We remount the filesystem in RO mode, and never stop/pause the rescan
   worker, so after the remount the rescan worker is still running. The
   important detail here is that the rescan task is still running after
   the remount operation committed any ongoing transaction through its
   call to btrfs_commit_super();

3) The rescan is still running, and after the remount completed, the
   rescan worker started a transaction, after it finished iterating all
   leaves of the extent tree, to update the qgroup status item in the
   quotas tree. It does not commit the transaction, it only releases its
   handle on the transaction;

4) A filesystem unmount operation starts shortly after;

5) The unmount task, at close_ctree(), stops the transaction kthread,
   which had not had a chance to commit the open transaction since it was
   sleeping and the commit interval (default of 30 seconds) has not yet
   elapsed since the last time it committed a transaction;

6) So after stopping the transaction kthread we still have the transaction
   used to update the qgroup status item open. At close_ctree(), when the
   filesystem is in RO mode and no transaction abort happened (or the
   filesystem is in error mode), we do not expect to have any transaction
   open, so we do not call btrfs_commit_super();

7) We then proceed to destroy the work queues, free the roots and block
   groups, etc. After that we drop the last reference on the btree inode
   by calling iput() on it. Since there are dirty pages for the btree
   inode, corresponding to the COWed extent buffer for the quotas btree,
   btree_write_cache_pages() is invoked to flush those dirty pages. This
   results in creating a bio and submitting it, which makes us end up at
   btrfs_submit_metadata_bio();

8) At btrfs_submit_metadata_bio() we end up at the if-then-else branch
   that calls btrfs_wq_submit_bio(), because check_async_write() returned
   a value of 1. This value of 1 is because we did not have hardware
   acceleration available for crc32c, so BTRFS_FS_CSUM_IMPL_FAST was not
   set in fs_info->flags;

9) Then at btrfs_wq_submit_bio() we call btrfs_queue_work() against the
   workqueue at fs_info->workers, which was already freed before by the
   call to btrfs_stop_all_workers() at close_ctree(). This results in an
   invalid memory access due to a use-after-free, leading to a crash.

When this happens, before the crash there are several warnings triggered,
since we have reserved metadata space in a block group, the delayed refs
reservation, etc:

  ------------[ cut here ]------------
  WARNING: CPU: 4 PID: 1729896 at fs/btrfs/block-group.c:125 btrfs_put_block_group+0x63/0xa0 [btrfs]
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  CPU: 4 PID: 1729896 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_put_block_group+0x63/0xa0 [btrfs]
  Code: f0 01 00 00 48 39 c2 75 (...)
  RSP: 0018:ffffb270826bbdd8 EFLAGS: 00010206
  RAX: 0000000000000001 RBX: ffff947ed73e4000 RCX: ffff947ebc8b29c8
  RDX: 0000000000000001 RSI: ffffffffc0b150a0 RDI: ffff947ebc8b2800
  RBP: ffff947ebc8b2800 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ed73e4110
  R13: ffff947ed73e4160 R14: ffff947ebc8b2988 R15: dead000000000100
  FS:  00007f15edfea840(0000) GS:ffff9481ad600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f37e2893320 CR3: 0000000138f68001 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   btrfs_free_block_groups+0x17f/0x2f0 [btrfs]
   close_ctree+0x2ba/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f15ee221ee7
  Code: ff 0b 00 f7 d8 64 89 01 48 (...)
  RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
  RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
  R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last  enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace dd74718fef1ed5c6 ]---
  ------------[ cut here ]------------
  WARNING: CPU: 2 PID: 1729896 at fs/btrfs/block-rsv.c:459 btrfs_release_global_block_rsv+0x70/0xc0 [btrfs]
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  CPU: 2 PID: 1729896 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_release_global_block_rsv+0x70/0xc0 [btrfs]
  Code: 48 83 bb b0 03 00 00 00 (...)
  RSP: 0018:ffffb270826bbdd8 EFLAGS: 00010206
  RAX: 000000000033c000 RBX: ffff947ed73e4000 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffffffffc0b0d8c1 RDI: 00000000ffffffff
  RBP: ffff947ebc8b7000 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ed73e4110
  R13: ffff947ed73e5278 R14: dead000000000122 R15: dead000000000100
  FS:  00007f15edfea840(0000) GS:ffff9481aca00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000561a79f76e20 CR3: 0000000138f68006 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   btrfs_free_block_groups+0x24c/0x2f0 [btrfs]
   close_ctree+0x2ba/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f15ee221ee7
  Code: ff 0b 00 f7 d8 64 89 01 (...)
  RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
  RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
  R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last  enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace dd74718fef1ed5c7 ]---
  ------------[ cut here ]------------
  WARNING: CPU: 2 PID: 1729896 at fs/btrfs/block-group.c:3377 btrfs_free_block_groups+0x25d/0x2f0 [btrfs]
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  CPU: 5 PID: 1729896 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_free_block_groups+0x25d/0x2f0 [btrfs]
  Code: ad de 49 be 22 01 00 (...)
  RSP: 0018:ffffb270826bbde8 EFLAGS: 00010206
  RAX: ffff947ebeae1d08 RBX: ffff947ed73e4000 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffff947e9d823ae8 RDI: 0000000000000246
  RBP: ffff947ebeae1d08 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ebeae1c00
  R13: ffff947ed73e5278 R14: dead000000000122 R15: dead000000000100
  FS:  00007f15edfea840(0000) GS:ffff9481ad200000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f1475d98ea8 CR3: 0000000138f68005 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   close_ctree+0x2ba/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f15ee221ee7
  Code: ff 0b 00 f7 d8 64 89 (...)
  RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
  RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
  R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last  enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  ---[ end trace dd74718fef1ed5c8 ]---
  BTRFS info (device sdc): space_info 4 has 268238848 free, is not full
  BTRFS info (device sdc): space_info total=268435456, used=114688, pinned=0, reserved=16384, may_use=0, readonly=65536
  BTRFS info (device sdc): global_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): trans_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): chunk_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): delayed_block_rsv: size 0 reserved 0
  BTRFS info (device sdc): delayed_refs_rsv: size 524288 reserved 0

And the crash, which only happens when we do not have crc32c hardware
acceleration, produces the following trace immediately after those
warnings:

  stack segment: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
  CPU: 2 PID: 1749129 Comm: umount Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:btrfs_queue_work+0x36/0x190 [btrfs]
  Code: 54 55 53 48 89 f3 (...)
  RSP: 0018:ffffb27082443ae8 EFLAGS: 00010282
  RAX: 0000000000000004 RBX: ffff94810ee9ad90 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffff94810ee9ad90 RDI: ffff947ed8ee75a0
  RBP: a56b6b6b6b6b6b6b R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000007 R11: 0000000000000001 R12: ffff947fa9b435a8
  R13: ffff94810ee9ad90 R14: 0000000000000000 R15: ffff947e93dc0000
  FS:  00007f3cfe974840(0000) GS:ffff9481ac600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f1b42995a70 CR3: 0000000127638003 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   btrfs_wq_submit_bio+0xb3/0xd0 [btrfs]
   btrfs_submit_metadata_bio+0x44/0xc0 [btrfs]
   submit_one_bio+0x61/0x70 [btrfs]
   btree_write_cache_pages+0x414/0x450 [btrfs]
   ? kobject_put+0x9a/0x1d0
   ? trace_hardirqs_on+0x1b/0xf0
   ? _raw_spin_unlock_irqrestore+0x3c/0x60
   ? free_debug_processing+0x1e1/0x2b0
   do_writepages+0x43/0xe0
   ? lock_acquired+0x199/0x490
   __writeback_single_inode+0x59/0x650
   writeback_single_inode+0xaf/0x120
   write_inode_now+0x94/0xd0
   iput+0x187/0x2b0
   close_ctree+0x2c6/0x2fa [btrfs]
   generic_shutdown_super+0x6c/0x100
   kill_anon_super+0x14/0x30
   btrfs_kill_super+0x12/0x20 [btrfs]
   deactivate_locked_super+0x31/0x70
   cleanup_mnt+0x100/0x160
   task_work_run+0x68/0xb0
   exit_to_user_mode_prepare+0x1bb/0x1c0
   syscall_exit_to_user_mode+0x4b/0x260
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f3cfebabee7
  Code: ff 0b 00 f7 d8 64 89 01 (...)
  RSP: 002b:00007ffc9c9a05f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 00007f3cfecd1264 RCX: 00007f3cfebabee7
  RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 0000562b6b478000
  RBP: 0000562b6b473a30 R08: 0000000000000000 R09: 00007f3cfec6cbe0
  R10: 0000562b6b479fe0 R11: 0000000000000246 R12: 0000000000000000
  R13: 0000562b6b478000 R14: 0000562b6b473b40 R15: 0000562b6b473c60
  Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
  ---[ end trace dd74718fef1ed5cc ]---

Finally when we remove the btrfs module (rmmod btrfs), there are several
warnings about objects that were allocated from our slabs but were never
freed, consequence of the transaction that was never committed and got
leaked:

  =============================================================================
  BUG btrfs_delayed_ref_head (Tainted: G    B   W        ): Objects remaining in btrfs_delayed_ref_head on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  INFO: Slab 0x0000000094c2ae56 objects=24 used=2 fp=0x000000002bfa2521 flags=0x17fffc000010200
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   slab_err+0xb7/0xdc
   ? lock_acquired+0x199/0x490
   __kmem_cache_shutdown+0x1ac/0x3c0
   ? lock_release+0x20e/0x4c0
   kmem_cache_destroy+0x55/0x120
   btrfs_delayed_ref_exit+0x11/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  INFO: Object 0x0000000050cbdd61 @offset=12104
  INFO: Allocated in btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs] age=1894 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs]
	btrfs_free_tree_block+0x128/0x360 [btrfs]
	__btrfs_cow_block+0x489/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
	btrfs_mount+0x13b/0x3e0 [btrfs]
  INFO: Freed in __btrfs_run_delayed_refs+0x1117/0x1290 [btrfs] age=4292 cpu=2 pid=1729526
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x1117/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	commit_cowonly_roots+0xfb/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	sync_filesystem+0x74/0x90
	generic_shutdown_super+0x22/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  INFO: Object 0x0000000086e9b0ff @offset=12776
  INFO: Allocated in btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs] age=1900 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs]
	btrfs_alloc_tree_block+0x2bf/0x360 [btrfs]
	alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
	__btrfs_cow_block+0x12d/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
  INFO: Freed in __btrfs_run_delayed_refs+0x1117/0x1290 [btrfs] age=3141 cpu=6 pid=1729803
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x1117/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	btrfs_write_dirty_block_groups+0x17d/0x3d0 [btrfs]
	commit_cowonly_roots+0x248/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	close_ctree+0x113/0x2fa [btrfs]
	generic_shutdown_super+0x6c/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  kmem_cache_destroy btrfs_delayed_ref_head: Slab cache still has objects
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   kmem_cache_destroy+0x119/0x120
   btrfs_delayed_ref_exit+0x11/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 0b (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  =============================================================================
  BUG btrfs_delayed_tree_ref (Tainted: G    B   W        ): Objects remaining in btrfs_delayed_tree_ref on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  INFO: Slab 0x0000000011f78dc0 objects=37 used=2 fp=0x0000000032d55d91 flags=0x17fffc000010200
  CPU: 3 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   slab_err+0xb7/0xdc
   ? lock_acquired+0x199/0x490
   __kmem_cache_shutdown+0x1ac/0x3c0
   ? lock_release+0x20e/0x4c0
   kmem_cache_destroy+0x55/0x120
   btrfs_delayed_ref_exit+0x1d/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  INFO: Object 0x000000001a340018 @offset=4408
  INFO: Allocated in btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs] age=1917 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs]
	btrfs_free_tree_block+0x128/0x360 [btrfs]
	__btrfs_cow_block+0x489/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
	btrfs_mount+0x13b/0x3e0 [btrfs]
  INFO: Freed in __btrfs_run_delayed_refs+0x63d/0x1290 [btrfs] age=4167 cpu=4 pid=1729795
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x63d/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	btrfs_commit_transaction+0x60/0xc40 [btrfs]
	create_subvol+0x56a/0x990 [btrfs]
	btrfs_mksubvol+0x3fb/0x4a0 [btrfs]
	__btrfs_ioctl_snap_create+0x119/0x1a0 [btrfs]
	btrfs_ioctl_snap_create+0x58/0x80 [btrfs]
	btrfs_ioctl+0x1a92/0x36f0 [btrfs]
	__x64_sys_ioctl+0x83/0xb0
	do_syscall_64+0x33/0x80
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  INFO: Object 0x000000002b46292a @offset=13648
  INFO: Allocated in btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs] age=1923 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs]
	btrfs_alloc_tree_block+0x2bf/0x360 [btrfs]
	alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
	__btrfs_cow_block+0x12d/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
  INFO: Freed in __btrfs_run_delayed_refs+0x63d/0x1290 [btrfs] age=3164 cpu=6 pid=1729803
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0x63d/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	commit_cowonly_roots+0xfb/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	close_ctree+0x113/0x2fa [btrfs]
	generic_shutdown_super+0x6c/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  kmem_cache_destroy btrfs_delayed_tree_ref: Slab cache still has objects
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   kmem_cache_destroy+0x119/0x120
   btrfs_delayed_ref_exit+0x1d/0x35 [btrfs]
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  =============================================================================
  BUG btrfs_delayed_extent_op (Tainted: G    B   W        ): Objects remaining in btrfs_delayed_extent_op on __kmem_cache_shutdown()
  -----------------------------------------------------------------------------

  INFO: Slab 0x00000000f145ce2f objects=22 used=1 fp=0x00000000af0f92cf flags=0x17fffc000010200
  CPU: 5 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   slab_err+0xb7/0xdc
   ? lock_acquired+0x199/0x490
   __kmem_cache_shutdown+0x1ac/0x3c0
   ? __mutex_unlock_slowpath+0x45/0x2a0
   kmem_cache_destroy+0x55/0x120
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 f5 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  INFO: Object 0x000000004cf95ea8 @offset=6264
  INFO: Allocated in btrfs_alloc_tree_block+0x1e0/0x360 [btrfs] age=1931 cpu=6 pid=1729873
	__slab_alloc.isra.0+0x109/0x1c0
	kmem_cache_alloc+0x7bb/0x830
	btrfs_alloc_tree_block+0x1e0/0x360 [btrfs]
	alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
	__btrfs_cow_block+0x12d/0x5f0 [btrfs]
	btrfs_cow_block+0xf7/0x220 [btrfs]
	btrfs_search_slot+0x62a/0xc40 [btrfs]
	btrfs_del_orphan_item+0x65/0xd0 [btrfs]
	btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
	open_ctree+0x125a/0x18a0 [btrfs]
	btrfs_mount_root.cold+0x13/0xed [btrfs]
	legacy_get_tree+0x30/0x60
	vfs_get_tree+0x28/0xe0
	fc_mount+0xe/0x40
	vfs_kern_mount.part.0+0x71/0x90
	btrfs_mount+0x13b/0x3e0 [btrfs]
  INFO: Freed in __btrfs_run_delayed_refs+0xabd/0x1290 [btrfs] age=3173 cpu=6 pid=1729803
	kmem_cache_free+0x34c/0x3c0
	__btrfs_run_delayed_refs+0xabd/0x1290 [btrfs]
	btrfs_run_delayed_refs+0x81/0x210 [btrfs]
	commit_cowonly_roots+0xfb/0x300 [btrfs]
	btrfs_commit_transaction+0x367/0xc40 [btrfs]
	close_ctree+0x113/0x2fa [btrfs]
	generic_shutdown_super+0x6c/0x100
	kill_anon_super+0x14/0x30
	btrfs_kill_super+0x12/0x20 [btrfs]
	deactivate_locked_super+0x31/0x70
	cleanup_mnt+0x100/0x160
	task_work_run+0x68/0xb0
	exit_to_user_mode_prepare+0x1bb/0x1c0
	syscall_exit_to_user_mode+0x4b/0x260
	entry_SYSCALL_64_after_hwframe+0x44/0xa9
  kmem_cache_destroy btrfs_delayed_extent_op: Slab cache still has objects
  CPU: 3 PID: 1729921 Comm: rmmod Tainted: G    B   W         5.10.0-rc4-btrfs-next-73 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   kmem_cache_destroy+0x119/0x120
   exit_btrfs_fs+0xa/0x59 [btrfs]
   __x64_sys_delete_module+0x194/0x260
   ? fpregs_assert_state_consistent+0x1e/0x40
   ? exit_to_user_mode_prepare+0x55/0x1c0
   ? trace_hardirqs_on+0x1b/0xf0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f693e305897
  Code: 73 01 c3 48 8b 0d f9 (...)
  RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
  RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
  R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
  R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
  BTRFS: state leak: start 30408704 end 30425087 state 1 in tree 1 refs 1

Fix this issue by having the remount path stop the qgroup rescan worker
when we are remounting RO and teach the rescan worker to stop when a
remount is in progress. If later a remount in RW mode happens, we are
already resuming the qgroup rescan worker through the call to
btrfs_qgroup_rescan_resume(), so we do not need to worry about that.

Tested-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-18 14:59:57 +01:00
Qu Wenruo ae5e070eac btrfs: qgroup: don't try to wait flushing if we're already holding a transaction
There is a chance of racing for qgroup flushing which may lead to
deadlock:

	Thread A		|	Thread B
   (not holding trans handle)	|  (holding a trans handle)
--------------------------------+--------------------------------
__btrfs_qgroup_reserve_meta()   | __btrfs_qgroup_reserve_meta()
|- try_flush_qgroup()		| |- try_flush_qgroup()
   |- QGROUP_FLUSHING bit set   |    |
   |				|    |- test_and_set_bit()
   |				|    |- wait_event()
   |- btrfs_join_transaction()	|
   |- btrfs_commit_transaction()|

			!!! DEAD LOCK !!!

Since thread A wants to commit transaction, but thread B is holding a
transaction handle, blocking the commit.
At the same time, thread B is waiting for thread A to finish its commit.

This is just a hot fix, and would lead to more EDQUOT when we're near
the qgroup limit.

The proper fix would be to make all metadata/data reservations happen
without holding a transaction handle.

CC: stable@vger.kernel.org # 5.9+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-18 14:50:07 +01:00
Josef Bacik 1b7ec85ef4 btrfs: pass root owner to read_tree_block
In order to properly set the lockdep class of a newly allocated block we
need to know the owner of the block.  For non-refcounted trees this is
straightforward, we always know in advance what tree we're reading from.
For refcounted trees we don't necessarily know, however all refcounted
trees share the same lockdep class name, tree-<level>.

Fix all the callers of read_tree_block() to pass in the root objectid
we're using.  In places like relocation and backref we could probably
unconditionally use 0, but just in case use the root when we have it,
otherwise use 0 in the cases we don't have the root as it's going to be
a refcounted tree anyway.

This is a preparation patch for further changes.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:07 +01:00
Josef Bacik 182c79fcb8 btrfs: use btrfs_read_node_slot in btrfs_qgroup_trace_subtree
We're open-coding btrfs_read_node_slot() here, replace with the helper.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:07 +01:00
Josef Bacik 3acfbd6a99 btrfs: use btrfs_read_node_slot in qgroup_trace_new_subtree_blocks
We're open-coding btrfs_read_node_slot() here, replace with the helper.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:07 +01:00
Josef Bacik 6b2cb7cb95 btrfs: use btrfs_read_node_slot in qgroup_trace_extent_swap
We're open-coding btrfs_read_node_slot() here, replace with the helper.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:06 +01:00
Josef Bacik b9729ce014 btrfs: locking: rip out path->leave_spinning
We no longer distinguish between blocking and spinning, so rip out all
this code.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:02 +01:00
Josef Bacik ac5887c8e0 btrfs: locking: remove all the blocking helpers
Now that we're using a rw_semaphore we no longer need to indicate if a
lock is blocking or not, nor do we need to flip the entire path from
blocking to spinning.  Remove these helpers and all the places they are
called.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:01 +01:00
Filipe Manana a855fbe692 btrfs: fix lockdep splat when enabling and disabling qgroups
When running test case btrfs/017 from fstests, lockdep reported the
following splat:

  [ 1297.067385] ======================================================
  [ 1297.067708] WARNING: possible circular locking dependency detected
  [ 1297.068022] 5.10.0-rc4-btrfs-next-73 #1 Not tainted
  [ 1297.068322] ------------------------------------------------------
  [ 1297.068629] btrfs/189080 is trying to acquire lock:
  [ 1297.068929] ffff9f2725731690 (sb_internal#2){.+.+}-{0:0}, at: btrfs_quota_enable+0xaf/0xa70 [btrfs]
  [ 1297.069274]
		 but task is already holding lock:
  [ 1297.069868] ffff9f2702b61a08 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_quota_enable+0x3b/0xa70 [btrfs]
  [ 1297.070219]
		 which lock already depends on the new lock.

  [ 1297.071131]
		 the existing dependency chain (in reverse order) is:
  [ 1297.071721]
		 -> #1 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}:
  [ 1297.072375]        lock_acquire+0xd8/0x490
  [ 1297.072710]        __mutex_lock+0xa3/0xb30
  [ 1297.073061]        btrfs_qgroup_inherit+0x59/0x6a0 [btrfs]
  [ 1297.073421]        create_subvol+0x194/0x990 [btrfs]
  [ 1297.073780]        btrfs_mksubvol+0x3fb/0x4a0 [btrfs]
  [ 1297.074133]        __btrfs_ioctl_snap_create+0x119/0x1a0 [btrfs]
  [ 1297.074498]        btrfs_ioctl_snap_create+0x58/0x80 [btrfs]
  [ 1297.074872]        btrfs_ioctl+0x1a90/0x36f0 [btrfs]
  [ 1297.075245]        __x64_sys_ioctl+0x83/0xb0
  [ 1297.075617]        do_syscall_64+0x33/0x80
  [ 1297.075993]        entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [ 1297.076380]
		 -> #0 (sb_internal#2){.+.+}-{0:0}:
  [ 1297.077166]        check_prev_add+0x91/0xc60
  [ 1297.077572]        __lock_acquire+0x1740/0x3110
  [ 1297.077984]        lock_acquire+0xd8/0x490
  [ 1297.078411]        start_transaction+0x3c5/0x760 [btrfs]
  [ 1297.078853]        btrfs_quota_enable+0xaf/0xa70 [btrfs]
  [ 1297.079323]        btrfs_ioctl+0x2c60/0x36f0 [btrfs]
  [ 1297.079789]        __x64_sys_ioctl+0x83/0xb0
  [ 1297.080232]        do_syscall_64+0x33/0x80
  [ 1297.080680]        entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [ 1297.081139]
		 other info that might help us debug this:

  [ 1297.082536]  Possible unsafe locking scenario:

  [ 1297.083510]        CPU0                    CPU1
  [ 1297.084005]        ----                    ----
  [ 1297.084500]   lock(&fs_info->qgroup_ioctl_lock);
  [ 1297.084994]                                lock(sb_internal#2);
  [ 1297.085485]                                lock(&fs_info->qgroup_ioctl_lock);
  [ 1297.085974]   lock(sb_internal#2);
  [ 1297.086454]
		  *** DEADLOCK ***
  [ 1297.087880] 3 locks held by btrfs/189080:
  [ 1297.088324]  #0: ffff9f2725731470 (sb_writers#14){.+.+}-{0:0}, at: btrfs_ioctl+0xa73/0x36f0 [btrfs]
  [ 1297.088799]  #1: ffff9f2702b60cc0 (&fs_info->subvol_sem){++++}-{3:3}, at: btrfs_ioctl+0x1f4d/0x36f0 [btrfs]
  [ 1297.089284]  #2: ffff9f2702b61a08 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_quota_enable+0x3b/0xa70 [btrfs]
  [ 1297.089771]
		 stack backtrace:
  [ 1297.090662] CPU: 5 PID: 189080 Comm: btrfs Not tainted 5.10.0-rc4-btrfs-next-73 #1
  [ 1297.091132] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  [ 1297.092123] Call Trace:
  [ 1297.092629]  dump_stack+0x8d/0xb5
  [ 1297.093115]  check_noncircular+0xff/0x110
  [ 1297.093596]  check_prev_add+0x91/0xc60
  [ 1297.094076]  ? kvm_clock_read+0x14/0x30
  [ 1297.094553]  ? kvm_sched_clock_read+0x5/0x10
  [ 1297.095029]  __lock_acquire+0x1740/0x3110
  [ 1297.095510]  lock_acquire+0xd8/0x490
  [ 1297.095993]  ? btrfs_quota_enable+0xaf/0xa70 [btrfs]
  [ 1297.096476]  start_transaction+0x3c5/0x760 [btrfs]
  [ 1297.096962]  ? btrfs_quota_enable+0xaf/0xa70 [btrfs]
  [ 1297.097451]  btrfs_quota_enable+0xaf/0xa70 [btrfs]
  [ 1297.097941]  ? btrfs_ioctl+0x1f4d/0x36f0 [btrfs]
  [ 1297.098429]  btrfs_ioctl+0x2c60/0x36f0 [btrfs]
  [ 1297.098904]  ? do_user_addr_fault+0x20c/0x430
  [ 1297.099382]  ? kvm_clock_read+0x14/0x30
  [ 1297.099854]  ? kvm_sched_clock_read+0x5/0x10
  [ 1297.100328]  ? sched_clock+0x5/0x10
  [ 1297.100801]  ? sched_clock_cpu+0x12/0x180
  [ 1297.101272]  ? __x64_sys_ioctl+0x83/0xb0
  [ 1297.101739]  __x64_sys_ioctl+0x83/0xb0
  [ 1297.102207]  do_syscall_64+0x33/0x80
  [ 1297.102673]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [ 1297.103148] RIP: 0033:0x7f773ff65d87

This is because during the quota enable ioctl we lock first the mutex
qgroup_ioctl_lock and then start a transaction, and starting a transaction
acquires a fs freeze semaphore (at the VFS level). However, every other
code path, except for the quota disable ioctl path, we do the opposite:
we start a transaction and then lock the mutex.

So fix this by making the quota enable and disable paths to start the
transaction without having the mutex locked, and then, after starting the
transaction, lock the mutex and check if some other task already enabled
or disabled the quotas, bailing with success if that was the case.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-11-23 21:16:43 +01:00
Filipe Manana 7aa6d35984 btrfs: do nofs allocations when adding and removing qgroup relations
When adding or removing a qgroup relation we are doing a GFP_KERNEL
allocation which is not safe because we are holding a transaction
handle open and that can make us deadlock if the allocator needs to
recurse into the filesystem. So just surround those calls with a
nofs context.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-11-23 21:16:40 +01:00
Filipe Manana 3d05cad3c3 btrfs: fix lockdep splat when reading qgroup config on mount
Lockdep reported the following splat when running test btrfs/190 from
fstests:

  [ 9482.126098] ======================================================
  [ 9482.126184] WARNING: possible circular locking dependency detected
  [ 9482.126281] 5.10.0-rc4-btrfs-next-73 #1 Not tainted
  [ 9482.126365] ------------------------------------------------------
  [ 9482.126456] mount/24187 is trying to acquire lock:
  [ 9482.126534] ffffa0c869a7dac0 (&fs_info->qgroup_rescan_lock){+.+.}-{3:3}, at: qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.126647]
		 but task is already holding lock:
  [ 9482.126777] ffffa0c892ebd3a0 (btrfs-quota-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x120 [btrfs]
  [ 9482.126886]
		 which lock already depends on the new lock.

  [ 9482.127078]
		 the existing dependency chain (in reverse order) is:
  [ 9482.127213]
		 -> #1 (btrfs-quota-00){++++}-{3:3}:
  [ 9482.127366]        lock_acquire+0xd8/0x490
  [ 9482.127436]        down_read_nested+0x45/0x220
  [ 9482.127528]        __btrfs_tree_read_lock+0x27/0x120 [btrfs]
  [ 9482.127613]        btrfs_read_lock_root_node+0x41/0x130 [btrfs]
  [ 9482.127702]        btrfs_search_slot+0x514/0xc30 [btrfs]
  [ 9482.127788]        update_qgroup_status_item+0x72/0x140 [btrfs]
  [ 9482.127877]        btrfs_qgroup_rescan_worker+0xde/0x680 [btrfs]
  [ 9482.127964]        btrfs_work_helper+0xf1/0x600 [btrfs]
  [ 9482.128039]        process_one_work+0x24e/0x5e0
  [ 9482.128110]        worker_thread+0x50/0x3b0
  [ 9482.128181]        kthread+0x153/0x170
  [ 9482.128256]        ret_from_fork+0x22/0x30
  [ 9482.128327]
		 -> #0 (&fs_info->qgroup_rescan_lock){+.+.}-{3:3}:
  [ 9482.128464]        check_prev_add+0x91/0xc60
  [ 9482.128551]        __lock_acquire+0x1740/0x3110
  [ 9482.128623]        lock_acquire+0xd8/0x490
  [ 9482.130029]        __mutex_lock+0xa3/0xb30
  [ 9482.130590]        qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.131577]        btrfs_read_qgroup_config+0x43a/0x550 [btrfs]
  [ 9482.132175]        open_ctree+0x1228/0x18a0 [btrfs]
  [ 9482.132756]        btrfs_mount_root.cold+0x13/0xed [btrfs]
  [ 9482.133325]        legacy_get_tree+0x30/0x60
  [ 9482.133866]        vfs_get_tree+0x28/0xe0
  [ 9482.134392]        fc_mount+0xe/0x40
  [ 9482.134908]        vfs_kern_mount.part.0+0x71/0x90
  [ 9482.135428]        btrfs_mount+0x13b/0x3e0 [btrfs]
  [ 9482.135942]        legacy_get_tree+0x30/0x60
  [ 9482.136444]        vfs_get_tree+0x28/0xe0
  [ 9482.136949]        path_mount+0x2d7/0xa70
  [ 9482.137438]        do_mount+0x75/0x90
  [ 9482.137923]        __x64_sys_mount+0x8e/0xd0
  [ 9482.138400]        do_syscall_64+0x33/0x80
  [ 9482.138873]        entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [ 9482.139346]
		 other info that might help us debug this:

  [ 9482.140735]  Possible unsafe locking scenario:

  [ 9482.141594]        CPU0                    CPU1
  [ 9482.142011]        ----                    ----
  [ 9482.142411]   lock(btrfs-quota-00);
  [ 9482.142806]                                lock(&fs_info->qgroup_rescan_lock);
  [ 9482.143216]                                lock(btrfs-quota-00);
  [ 9482.143629]   lock(&fs_info->qgroup_rescan_lock);
  [ 9482.144056]
		  *** DEADLOCK ***

  [ 9482.145242] 2 locks held by mount/24187:
  [ 9482.145637]  #0: ffffa0c8411c40e8 (&type->s_umount_key#44/1){+.+.}-{3:3}, at: alloc_super+0xb9/0x400
  [ 9482.146061]  #1: ffffa0c892ebd3a0 (btrfs-quota-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x120 [btrfs]
  [ 9482.146509]
		 stack backtrace:
  [ 9482.147350] CPU: 1 PID: 24187 Comm: mount Not tainted 5.10.0-rc4-btrfs-next-73 #1
  [ 9482.147788] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  [ 9482.148709] Call Trace:
  [ 9482.149169]  dump_stack+0x8d/0xb5
  [ 9482.149628]  check_noncircular+0xff/0x110
  [ 9482.150090]  check_prev_add+0x91/0xc60
  [ 9482.150561]  ? kvm_clock_read+0x14/0x30
  [ 9482.151017]  ? kvm_sched_clock_read+0x5/0x10
  [ 9482.151470]  __lock_acquire+0x1740/0x3110
  [ 9482.151941]  ? __btrfs_tree_read_lock+0x27/0x120 [btrfs]
  [ 9482.152402]  lock_acquire+0xd8/0x490
  [ 9482.152887]  ? qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.153354]  __mutex_lock+0xa3/0xb30
  [ 9482.153826]  ? qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.154301]  ? qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.154768]  ? qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.155226]  qgroup_rescan_init+0x43/0xf0 [btrfs]
  [ 9482.155690]  btrfs_read_qgroup_config+0x43a/0x550 [btrfs]
  [ 9482.156160]  open_ctree+0x1228/0x18a0 [btrfs]
  [ 9482.156643]  btrfs_mount_root.cold+0x13/0xed [btrfs]
  [ 9482.157108]  ? rcu_read_lock_sched_held+0x5d/0x90
  [ 9482.157567]  ? kfree+0x31f/0x3e0
  [ 9482.158030]  legacy_get_tree+0x30/0x60
  [ 9482.158489]  vfs_get_tree+0x28/0xe0
  [ 9482.158947]  fc_mount+0xe/0x40
  [ 9482.159403]  vfs_kern_mount.part.0+0x71/0x90
  [ 9482.159875]  btrfs_mount+0x13b/0x3e0 [btrfs]
  [ 9482.160335]  ? rcu_read_lock_sched_held+0x5d/0x90
  [ 9482.160805]  ? kfree+0x31f/0x3e0
  [ 9482.161260]  ? legacy_get_tree+0x30/0x60
  [ 9482.161714]  legacy_get_tree+0x30/0x60
  [ 9482.162166]  vfs_get_tree+0x28/0xe0
  [ 9482.162616]  path_mount+0x2d7/0xa70
  [ 9482.163070]  do_mount+0x75/0x90
  [ 9482.163525]  __x64_sys_mount+0x8e/0xd0
  [ 9482.163986]  do_syscall_64+0x33/0x80
  [ 9482.164437]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [ 9482.164902] RIP: 0033:0x7f51e907caaa

This happens because at btrfs_read_qgroup_config() we can call
qgroup_rescan_init() while holding a read lock on a quota btree leaf,
acquired by the previous call to btrfs_search_slot_for_read(), and
qgroup_rescan_init() acquires the mutex qgroup_rescan_lock.

A qgroup rescan worker does the opposite: it acquires the mutex
qgroup_rescan_lock, at btrfs_qgroup_rescan_worker(), and then tries to
update the qgroup status item in the quota btree through the call to
update_qgroup_status_item(). This inversion of locking order
between the qgroup_rescan_lock mutex and quota btree locks causes the
splat.

Fix this simply by releasing and freeing the path before calling
qgroup_rescan_init() at btrfs_read_qgroup_config().

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-11-23 21:16:30 +01:00
Qu Wenruo 6f23277a49 btrfs: qgroup: don't commit transaction when we already hold the handle
[BUG]
When running the following script, btrfs will trigger an ASSERT():

  #/bin/bash
  mkfs.btrfs -f $dev
  mount $dev $mnt
  xfs_io -f -c "pwrite 0 1G" $mnt/file
  sync
  btrfs quota enable $mnt
  btrfs quota rescan -w $mnt

  # Manually set the limit below current usage
  btrfs qgroup limit 512M $mnt $mnt

  # Crash happens
  touch $mnt/file

The dmesg looks like this:

  assertion failed: refcount_read(&trans->use_count) == 1, in fs/btrfs/transaction.c:2022
  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/ctree.h:3230!
  invalid opcode: 0000 [#1] SMP PTI
  RIP: 0010:assertfail.constprop.0+0x18/0x1a [btrfs]
   btrfs_commit_transaction.cold+0x11/0x5d [btrfs]
   try_flush_qgroup+0x67/0x100 [btrfs]
   __btrfs_qgroup_reserve_meta+0x3a/0x60 [btrfs]
   btrfs_delayed_update_inode+0xaa/0x350 [btrfs]
   btrfs_update_inode+0x9d/0x110 [btrfs]
   btrfs_dirty_inode+0x5d/0xd0 [btrfs]
   touch_atime+0xb5/0x100
   iterate_dir+0xf1/0x1b0
   __x64_sys_getdents64+0x78/0x110
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7fb5afe588db

[CAUSE]
In try_flush_qgroup(), we assume we don't hold a transaction handle at
all.  This is true for data reservation and mostly true for metadata.
Since data space reservation always happens before we start a
transaction, and for most metadata operation we reserve space in
start_transaction().

But there is an exception, btrfs_delayed_inode_reserve_metadata().
It holds a transaction handle, while still trying to reserve extra
metadata space.

When we hit EDQUOT inside btrfs_delayed_inode_reserve_metadata(), we
will join current transaction and commit, while we still have
transaction handle from qgroup code.

[FIX]
Let's check current->journal before we join the transaction.

If current->journal is unset or BTRFS_SEND_TRANS_STUB, it means
we are not holding a transaction, thus are able to join and then commit
transaction.

If current->journal is a valid transaction handle, we avoid committing
transaction and just end it

This is less effective than committing current transaction, as it won't
free metadata reserved space, but we may still free some data space
before new data writes.

Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1178634
Fixes: c53e965360 ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-11-13 22:17:57 +01:00
Dan Carpenter f07728d541 btrfs: clean up NULL checks in qgroup_unreserve_range()
Smatch complains that this code dereferences "entry" before checking
whether it's NULL on the next line.  Fortunately, rb_entry() will never
return NULL so it doesn't cause a problem.  We can clean up the NULL
checking a bit to silence the warning and make the code more clear.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-11-05 13:02:20 +01:00
Josef Bacik 5223cc60b4 btrfs: drop the path before adding qgroup items when enabling qgroups
When enabling qgroups we walk the tree_root and then add a qgroup item
for every root that we have.  This creates a lock dependency on the
tree_root and qgroup_root, which results in the following lockdep splat
(with tree locks using rwsem), eg. in tests btrfs/017 or btrfs/022:

  ======================================================
  WARNING: possible circular locking dependency detected
  5.9.0-default+ #1299 Not tainted
  ------------------------------------------------------
  btrfs/24552 is trying to acquire lock:
  ffff9142dfc5f630 (btrfs-quota-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]

  but task is already holding lock:
  ffff9142dfc5d0b0 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #1 (btrfs-root-00){++++}-{3:3}:
	 __lock_acquire+0x3fb/0x730
	 lock_acquire.part.0+0x6a/0x130
	 down_read_nested+0x46/0x130
	 __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]
	 __btrfs_read_lock_root_node+0x3a/0x50 [btrfs]
	 btrfs_search_slot_get_root+0x11d/0x290 [btrfs]
	 btrfs_search_slot+0xc3/0x9f0 [btrfs]
	 btrfs_insert_item+0x6e/0x140 [btrfs]
	 btrfs_create_tree+0x1cb/0x240 [btrfs]
	 btrfs_quota_enable+0xcd/0x790 [btrfs]
	 btrfs_ioctl_quota_ctl+0xc9/0xe0 [btrfs]
	 __x64_sys_ioctl+0x83/0xa0
	 do_syscall_64+0x2d/0x70
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #0 (btrfs-quota-00){++++}-{3:3}:
	 check_prev_add+0x91/0xc30
	 validate_chain+0x491/0x750
	 __lock_acquire+0x3fb/0x730
	 lock_acquire.part.0+0x6a/0x130
	 down_read_nested+0x46/0x130
	 __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]
	 __btrfs_read_lock_root_node+0x3a/0x50 [btrfs]
	 btrfs_search_slot_get_root+0x11d/0x290 [btrfs]
	 btrfs_search_slot+0xc3/0x9f0 [btrfs]
	 btrfs_insert_empty_items+0x58/0xa0 [btrfs]
	 add_qgroup_item.part.0+0x72/0x210 [btrfs]
	 btrfs_quota_enable+0x3bb/0x790 [btrfs]
	 btrfs_ioctl_quota_ctl+0xc9/0xe0 [btrfs]
	 __x64_sys_ioctl+0x83/0xa0
	 do_syscall_64+0x2d/0x70
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  other info that might help us debug this:

   Possible unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(btrfs-root-00);
				 lock(btrfs-quota-00);
				 lock(btrfs-root-00);
    lock(btrfs-quota-00);

   *** DEADLOCK ***

  5 locks held by btrfs/24552:
   #0: ffff9142df431478 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write_file+0x22/0xa0
   #1: ffff9142f9b10cc0 (&fs_info->subvol_sem){++++}-{3:3}, at: btrfs_ioctl_quota_ctl+0x7b/0xe0 [btrfs]
   #2: ffff9142f9b11a08 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_quota_enable+0x3b/0x790 [btrfs]
   #3: ffff9142df431698 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x406/0x510 [btrfs]
   #4: ffff9142dfc5d0b0 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]

  stack backtrace:
  CPU: 1 PID: 24552 Comm: btrfs Not tainted 5.9.0-default+ #1299
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
  Call Trace:
   dump_stack+0x77/0x97
   check_noncircular+0xf3/0x110
   check_prev_add+0x91/0xc30
   validate_chain+0x491/0x750
   __lock_acquire+0x3fb/0x730
   lock_acquire.part.0+0x6a/0x130
   ? __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]
   ? lock_acquire+0xc4/0x140
   ? __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]
   down_read_nested+0x46/0x130
   ? __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]
   __btrfs_tree_read_lock+0x35/0x1c0 [btrfs]
   ? btrfs_root_node+0xd9/0x200 [btrfs]
   __btrfs_read_lock_root_node+0x3a/0x50 [btrfs]
   btrfs_search_slot_get_root+0x11d/0x290 [btrfs]
   btrfs_search_slot+0xc3/0x9f0 [btrfs]
   btrfs_insert_empty_items+0x58/0xa0 [btrfs]
   add_qgroup_item.part.0+0x72/0x210 [btrfs]
   btrfs_quota_enable+0x3bb/0x790 [btrfs]
   btrfs_ioctl_quota_ctl+0xc9/0xe0 [btrfs]
   __x64_sys_ioctl+0x83/0xa0
   do_syscall_64+0x2d/0x70
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fix this by dropping the path whenever we find a root item, add the
qgroup item, and then re-lookup the root item we found and continue
processing roots.

Reported-by: David Sterba <dsterba@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-10-26 15:04:57 +01:00
Randy Dunlap 260db43cd2 btrfs: delete duplicated words + other fixes in comments
Delete repeated words in fs/btrfs/.
{to, the, a, and old}
and change "into 2 part" to "into 2 parts".

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-10-07 12:06:50 +02:00
Qu Wenruo adca4d945c btrfs: qgroup: remove ASYNC_COMMIT mechanism in favor of reserve retry-after-EDQUOT
commit a514d63882 ("btrfs: qgroup: Commit transaction in advance to
reduce early EDQUOT") tries to reduce the early EDQUOT problems by
checking the qgroup free against threshold and tries to wake up commit
kthread to free some space.

The problem of that mechanism is, it can only free qgroup per-trans
metadata space, can't do anything to data, nor prealloc qgroup space.

Now since we have the ability to flush qgroup space, and implemented
retry-after-EDQUOT behavior, such mechanism can be completely replaced.

So this patch will cleanup such mechanism in favor of
retry-after-EDQUOT.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:43 +02:00
Qu Wenruo c53e965360 btrfs: qgroup: try to flush qgroup space when we get -EDQUOT
[PROBLEM]
There are known problem related to how btrfs handles qgroup reserved
space.  One of the most obvious case is the the test case btrfs/153,
which do fallocate, then write into the preallocated range.

  btrfs/153 1s ... - output mismatch (see xfstests-dev/results//btrfs/153.out.bad)
      --- tests/btrfs/153.out     2019-10-22 15:18:14.068965341 +0800
      +++ xfstests-dev/results//btrfs/153.out.bad      2020-07-01 20:24:40.730000089 +0800
      @@ -1,2 +1,5 @@
       QA output created by 153
      +pwrite: Disk quota exceeded
      +/mnt/scratch/testfile2: Disk quota exceeded
      +/mnt/scratch/testfile2: Disk quota exceeded
       Silence is golden
      ...
      (Run 'diff -u xfstests-dev/tests/btrfs/153.out xfstests-dev/results//btrfs/153.out.bad'  to see the entire diff)

[CAUSE]
Since commit c6887cd111 ("Btrfs: don't do nocow check unless we have to"),
we always reserve space no matter if it's COW or not.

Such behavior change is mostly for performance, and reverting it is not
a good idea anyway.

For preallcoated extent, we reserve qgroup data space for it already,
and since we also reserve data space for qgroup at buffered write time,
it needs twice the space for us to write into preallocated space.

This leads to the -EDQUOT in buffered write routine.

And we can't follow the same solution, unlike data/meta space check,
qgroup reserved space is shared between data/metadata.
The EDQUOT can happen at the metadata reservation, so doing NODATACOW
check after qgroup reservation failure is not a solution.

[FIX]
To solve the problem, we don't return -EDQUOT directly, but every time
we got a -EDQUOT, we try to flush qgroup space:

- Flush all inodes of the root
  NODATACOW writes will free the qgroup reserved at run_dealloc_range().
  However we don't have the infrastructure to only flush NODATACOW
  inodes, here we flush all inodes anyway.

- Wait for ordered extents
  This would convert the preallocated metadata space into per-trans
  metadata, which can be freed in later transaction commit.

- Commit transaction
  This will free all per-trans metadata space.

Also we don't want to trigger flush multiple times, so here we introduce
a per-root wait list and a new root status, to ensure only one thread
starts the flushing.

Fixes: c6887cd111 ("Btrfs: don't do nocow check unless we have to")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:42 +02:00
Qu Wenruo 263da812e8 btrfs: qgroup: allow to unreserve range without releasing other ranges
[PROBLEM]
Before this patch, when btrfs_qgroup_reserve_data() fails, we free all
reserved space of the changeset.

For example:
	ret = btrfs_qgroup_reserve_data(inode, changeset, 0, SZ_1M);
	ret = btrfs_qgroup_reserve_data(inode, changeset, SZ_1M, SZ_1M);
	ret = btrfs_qgroup_reserve_data(inode, changeset, SZ_2M, SZ_1M);

If the last btrfs_qgroup_reserve_data() failed, it will release the
entire [0, 3M) range.

This behavior is kind of OK for now, as when we hit -EDQUOT, we normally
go error handling and need to release all reserved ranges anyway.

But this also means the following call is not possible:

	ret = btrfs_qgroup_reserve_data();
	if (ret == -EDQUOT) {
		/* Do something to free some qgroup space */
		ret = btrfs_qgroup_reserve_data();
	}

As if the first btrfs_qgroup_reserve_data() fails, it will free all
reserved qgroup space.

[CAUSE]
This is because we release all reserved ranges when
btrfs_qgroup_reserve_data() fails.

[FIX]
This patch will implement a new function, qgroup_unreserve_range(), to
iterate through the ulist nodes, to find any nodes in the failure range,
and remove the EXTENT_QGROUP_RESERVED bits from the io_tree, and
decrease the extent_changeset::bytes_changed, so that we can revert to
previous state.

This allows later patches to retry btrfs_qgroup_reserve_data() if EDQUOT
happens.

Suggested-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:42 +02:00
Qu Wenruo 49e5fb4621 btrfs: qgroup: export qgroups in sysfs
This patch will add the following sysfs interface:

  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/referenced
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/exclusive
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/max_referenced
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/max_exclusive
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/limit_flags

Which is also available in output of "btrfs qgroup show".

  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_data
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_meta_pertrans
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_meta_prealloc

The last 3 rsv related members are not visible to users, but can be very
useful to debug qgroup limit related bugs.

Also, to avoid '/' used in <qgroup_id>, the separator between qgroup
level and qgroup id is changed to '_'.

The interface is not hidden behind 'debug' as we want this interface to
be included into production build and to provide another way to read the
qgroup information besides the ioctls.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:37 +02:00
Qu Wenruo 06f67c4707 btrfs: use __u16 for the return value of btrfs_qgroup_level()
The qgroup level is limited to u16, so no need to use u64 for it.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:37 +02:00
Nikolay Borisov cfdd459215 btrfs: make btrfs_qgroup_check_reserved_leak take btrfs_inode
vfs_inode is used only for the inode number everything else requires
btrfs_inode.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ use btrfs_ino ]
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:37 +02:00
Nikolay Borisov 7661a3e033 btrfs: make btrfs_qgroup_reserve_data take btrfs_inode
There's only a single use of vfs_inode in a tracepoint so let's take
btrfs_inode directly.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:35 +02:00
Nikolay Borisov 72b7d15bf1 btrfs: make btrfs_qgroup_release_data take btrfs_inode
It just forwards its argument to __btrfs_qgroup_release_data.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:32 +02:00
Nikolay Borisov 8b8a979f1f btrfs: make btrfs_qgroup_free_data take btrfs_inode
It passes btrfs_inode to its callee so change the interface.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:30 +02:00
Nikolay Borisov 8769af96cf btrfs: make __btrfs_qgroup_release_data take btrfs_inode
It uses vfs_inode only for a tracepoint so convert its interface to take
btrfs_inode directly.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:30 +02:00
Nikolay Borisov df2cfd131f btrfs: make qgroup_free_reserved_data take btrfs_inode
It only uses btrfs_inode so can just as easily take it as an argument.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:30 +02:00
Qu Wenruo 5958253cf6 btrfs: qgroup: catch reserved space leaks at unmount time
Before this patch, qgroup completely relies on per-inode extent io tree
to detect reserved data space leak.

However previous bug has already shown how release page before
btrfs_finish_ordered_io() could lead to leak, and since it's
QGROUP_RESERVED bit cleared without triggering qgroup rsv, it can't be
detected by per-inode extent io tree.

So this patch adds another (and hopefully the final) safety net to catch
qgroup data reserved space leak.  At least the new safety net catches
all the leaks during development, so it should be pretty useful in the
real world.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-07-27 12:55:24 +02:00
Qu Wenruo cbab8ade58 btrfs: qgroup: mark qgroup inconsistent if we're inherting snapshot to a new qgroup
[BUG]
For the following operation, qgroup is guaranteed to be screwed up due
to snapshot adding to a new qgroup:

  # mkfs.btrfs -f $dev
  # mount $dev $mnt
  # btrfs qgroup en $mnt
  # btrfs subv create $mnt/src
  # xfs_io -f -c "pwrite 0 1m" $mnt/src/file
  # sync
  # btrfs qgroup create 1/0 $mnt/src
  # btrfs subv snapshot -i 1/0 $mnt/src $mnt/snapshot
  # btrfs qgroup show -prce $mnt/src
  qgroupid         rfer         excl     max_rfer     max_excl parent  child
  --------         ----         ----     --------     -------- ------  -----
  0/5          16.00KiB     16.00KiB         none         none ---     ---
  0/257         1.02MiB     16.00KiB         none         none ---     ---
  0/258         1.02MiB     16.00KiB         none         none 1/0     ---
  1/0             0.00B        0.00B         none         none ---     0/258
	        ^^^^^^^^^^^^^^^^^^^^

[CAUSE]
The problem is in btrfs_qgroup_inherit(), we don't have good enough
check to determine if the new relation would break the existing
accounting.

Unlike btrfs_add_qgroup_relation(), which has proper check to determine
if we can do quick update without a rescan, in btrfs_qgroup_inherit() we
can even assign a snapshot to multiple qgroups.

[FIX]
Fix it by manually marking qgroup inconsistent for snapshot inheritance.

For subvolume creation, since all its extents are exclusively owned, we
don't need to rescan.

In theory, we should call relation check like quick_update_accounting()
when doing qgroup inheritance and inform user about qgroup accounting
inconsistency.

But we don't have good mechanism to relay that back to the user in the
snapshot creation context, thus we can only silently mark the qgroup
inconsistent.

Anyway, user shouldn't use qgroup inheritance during snapshot creation,
and should add qgroup relationship after snapshot creation by 'btrfs
qgroup assign', which has a much better UI to inform user about qgroup
inconsistent and kick in rescan automatically.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-05-25 11:25:29 +02:00
Josef Bacik 8c38938c7b btrfs: move the root freeing stuff into btrfs_put_root
There are a few different ways to free roots, either you allocated them
yourself and you just do

free_extent_buffer(root->node);
free_extent_buffer(root->commit_node);
btrfs_put_root(root);

Which is the pattern for log roots.  Or for snapshots/subvolumes that
are being dropped you simply call btrfs_free_fs_root() which does all
the cleanup for you.

Unify this all into btrfs_put_root(), so that we don't free up things
associated with the root until the last reference is dropped.  This
makes the root freeing code much more significant.

The only caveat is at close_ctree() time we have to free the extent
buffers for all of our main roots (extent_root, chunk_root, etc) because
we have to drop the btree_inode and we'll run into issues if we hold
onto those nodes until ->kill_sb() time.  This will be addressed in the
future when we kill the btree_inode.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-03-23 17:01:59 +01:00
Qu Wenruo daf475c915 btrfs: qgroup: Remove the unnecesaary spin lock for qgroup_rescan_running
After the previous patch, qgroup_rescan_running is protected by
btrfs_fs_info::qgroup_rescan_lock, thus no need for the extra spinlock.

Suggested-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-03-23 17:01:47 +01:00
Qu Wenruo d61acbbf54 btrfs: qgroup: ensure qgroup_rescan_running is only set when the worker is at least queued
[BUG]
There are some reports about btrfs wait forever to unmount itself, with
the following call trace:

  INFO: task umount:4631 blocked for more than 491 seconds.
        Tainted: G               X  5.3.8-2-default #1
  "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  umount          D    0  4631   3337 0x00000000
  Call Trace:
  ([<00000000174adf7a>] __schedule+0x342/0x748)
   [<00000000174ae3ca>] schedule+0x4a/0xd8
   [<00000000174b1f08>] schedule_timeout+0x218/0x420
   [<00000000174af10c>] wait_for_common+0x104/0x1d8
   [<000003ff804d6994>] btrfs_qgroup_wait_for_completion+0x84/0xb0 [btrfs]
   [<000003ff8044a616>] close_ctree+0x4e/0x380 [btrfs]
   [<0000000016fa3136>] generic_shutdown_super+0x8e/0x158
   [<0000000016fa34d6>] kill_anon_super+0x26/0x40
   [<000003ff8041ba88>] btrfs_kill_super+0x28/0xc8 [btrfs]
   [<0000000016fa39f8>] deactivate_locked_super+0x68/0x98
   [<0000000016fcb198>] cleanup_mnt+0xc0/0x140
   [<0000000016d6a846>] task_work_run+0xc6/0x110
   [<0000000016d04f76>] do_notify_resume+0xae/0xb8
   [<00000000174b30ae>] system_call+0xe2/0x2c8

[CAUSE]
The problem happens when we have called qgroup_rescan_init(), but
not queued the worker. It can be caused mostly by error handling.

	Qgroup ioctl thread		|	Unmount thread
----------------------------------------+-----------------------------------
					|
btrfs_qgroup_rescan()			|
|- qgroup_rescan_init()			|
|  |- qgroup_rescan_running = true;	|
|					|
|- trans = btrfs_join_transaction()	|
|  Some error happened			|
|					|
|- btrfs_qgroup_rescan() returns error	|
   But qgroup_rescan_running == true;	|
					| close_ctree()
					| |- btrfs_qgroup_wait_for_completion()
					|    |- running == true;
					|    |- wait_for_completion();

btrfs_qgroup_rescan_worker is never queued, thus no one is going to wake
up close_ctree() and we get a deadlock.

All involved qgroup_rescan_init() callers are:

- btrfs_qgroup_rescan()
  The example above. It's possible to trigger the deadlock when error
  happened.

- btrfs_quota_enable()
  Not possible. Just after qgroup_rescan_init() we queue the work.

- btrfs_read_qgroup_config()
  It's possible to trigger the deadlock. It only init the work, the
  work queueing happens in btrfs_qgroup_rescan_resume().
  Thus if error happened in between, deadlock is possible.

We shouldn't set fs_info->qgroup_rescan_running just in
qgroup_rescan_init(), as at that stage we haven't yet queued qgroup
rescan worker to run.

[FIX]
Set qgroup_rescan_running before queueing the work, so that we ensure
the rescan work is queued when we wait for it.

Fixes: 8d9eddad19 ("Btrfs: fix qgroup rescan worker initialization")
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
[ Change subject and cause analyse, use a smaller fix ]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-03-23 17:01:47 +01:00
Josef Bacik 0024652895 btrfs: rename btrfs_put_fs_root and btrfs_grab_fs_root
We are now using these for all roots, rename them to btrfs_put_root()
and btrfs_grab_root();

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-03-23 17:01:33 +01:00
Josef Bacik 81f096edf0 btrfs: use btrfs_put_fs_root to free roots always
If we are going to track leaked roots we need to free them all the same
way, so don't kfree() roots directly, use btrfs_put_fs_root.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-03-23 17:01:32 +01:00
Jeff Mahoney 81f7eb00ff btrfs: destroy qgroup extent records on transaction abort
We clean up the delayed references when we abort a transaction but we
leave the pending qgroup extent records behind, leaking memory.

This patch destroys the extent records when we destroy the delayed refs
and makes sure ensure they're gone before releasing the transaction.

Fixes: 3368d001ba ("btrfs: qgroup: Record possible quota-related extent for qgroup.")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
[ Rebased to latest upstream, remove to_qgroup() helper, use
  rbtree_postorder_for_each_entry_safe() wrapper ]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-02-19 00:35:54 +01:00
Marcos Paulo de Souza 8a36e408d4 btrfs: qgroup: return ENOTCONN instead of EINVAL when quotas are not enabled
[PROBLEM]
qgroup create/remove code is currently returning EINVAL when the user
tries to create a qgroup on a subvolume without quota enabled. EINVAL is
already being used for too many error scenarios so that is hard to
depict what is the problem.

[FIX]
Currently scrub and balance code return -ENOTCONN when the user tries to
cancel/pause and no scrub or balance is currently running for the
desired subvolume. Do the same here by returning -ENOTCONN  when a user
tries to create/delete/assing/list a qgroup on a subvolume without quota
enabled.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-01-20 16:40:50 +01:00
Marcos Paulo de Souza e3b0edd297 btrfs: qgroup: remove one-time use variables for quota_root checks
Remove some variables that are set only to be checked later, and never
used.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-01-20 16:40:50 +01:00
Johannes Thumshirn 26ef8493e1 btrfs: fix memory leak in qgroup accounting
When running xfstests on the current btrfs I get the following splat from
kmemleak:

unreferenced object 0xffff88821b2404e0 (size 32):
  comm "kworker/u4:7", pid 26663, jiffies 4295283698 (age 8.776s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 10 ff fd 26 82 88 ff ff  ...........&....
    10 ff fd 26 82 88 ff ff 20 ff fd 26 82 88 ff ff  ...&.... ..&....
  backtrace:
    [<00000000f94fd43f>] ulist_alloc+0x25/0x60 [btrfs]
    [<00000000fd023d99>] btrfs_find_all_roots_safe+0x41/0x100 [btrfs]
    [<000000008f17bd32>] btrfs_find_all_roots+0x52/0x70 [btrfs]
    [<00000000b7660afb>] btrfs_qgroup_rescan_worker+0x343/0x680 [btrfs]
    [<0000000058e66778>] btrfs_work_helper+0xac/0x1e0 [btrfs]
    [<00000000f0188930>] process_one_work+0x1cf/0x350
    [<00000000af5f2f8e>] worker_thread+0x28/0x3c0
    [<00000000b55a1add>] kthread+0x109/0x120
    [<00000000f88cbd17>] ret_from_fork+0x35/0x40

This corresponds to:

  (gdb) l *(btrfs_find_all_roots_safe+0x41)
  0x8d7e1 is in btrfs_find_all_roots_safe (fs/btrfs/backref.c:1413).
  1408
  1409            tmp = ulist_alloc(GFP_NOFS);
  1410            if (!tmp)
  1411                    return -ENOMEM;
  1412            *roots = ulist_alloc(GFP_NOFS);
  1413            if (!*roots) {
  1414                    ulist_free(tmp);
  1415                    return -ENOMEM;
  1416            }
  1417

Following the lifetime of the allocated 'roots' ulist, it gets freed
again in btrfs_qgroup_account_extent().

But this does not happen if the function is called with the
'BTRFS_FS_QUOTA_ENABLED' flag cleared, then btrfs_qgroup_account_extent()
does a short leave and directly returns.

Instead of directly returning we should jump to the 'out_free' in order to
free all resources as expected.

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
2020-01-08 17:56:17 +01:00
Nikolay Borisov 37d02592f1 btrfs: Fix error messages in qgroup_rescan_init
The branch of qgroup_rescan_init which is executed from the mount
path prints wrong errors messages. The textual print out in case
BTRFS_QGROUP_STATUS_FLAG_RESCAN/BTRFS_QGROUP_STATUS_FLAG_ON are not
set are transposed. Fix it by exchanging their place.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-12-13 13:29:12 +01:00
David Sterba 32da5386d9 btrfs: rename btrfs_block_group_cache
The type name is misleading, a single entry is named 'cache' while this
normally means a collection of objects. Rename that everywhere. Also the
identifier was quite long, making function prototypes harder to format.

Suggested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-11-18 17:51:51 +01:00
David Sterba 67439dadb0 btrfs: opencode extent_buffer_get
The helper is trivial and we can understand what the atomic_inc on
something named refs does.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-11-18 12:46:54 +01:00
Omar Sandoval a0cac0ec96 btrfs: get rid of unique workqueue helper functions
Commit 9e0af23764 ("Btrfs: fix task hang under heavy compressed
write") worked around the issue that a recycled work item could get a
false dependency on the original work item due to how the workqueue code
guarantees non-reentrancy. It did so by giving different work functions
to different types of work.

However, the fixes in the previous few patches are more complete, as
they prevent a work item from being recycled at all (except for a tiny
window that the kernel workqueue code handles for us). This obsoletes
the previous fix, so we don't need the unique helpers for correctness.
The only other reason to keep them would be so they show up in stack
traces, but they always seem to be optimized to a tail call, so they
don't show up anyways. So, let's just get rid of the extra indirection.

While we're here, rename normal_work_helper() to the more informative
btrfs_work_helper().

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-11-18 12:46:48 +01:00
Omar Sandoval cdc6f1668e btrfs: get rid of unnecessary memset() of work item
Commit fc97fab0ea ("btrfs: Replace fs_info->qgroup_rescan_worker
workqueue with btrfs_workqueue.") converted qgroup_rescan_work to be
initialized with btrfs_init_work(), but it left behind an unnecessary
memset(). Get rid of the memset().

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-11-18 12:46:47 +01:00
Qu Wenruo fd2b007eae btrfs: tracepoints: Fix wrong parameter order for qgroup events
[BUG]
For btrfs:qgroup_meta_reserve event, the trace event can output garbage:

  qgroup_meta_reserve: 9c7f6acc-b342-4037-bc47-7f6e4d2232d7: refroot=5(FS_TREE) type=DATA diff=2

The diff should always be alinged to sector size (4k), so there is
definitely something wrong.

[CAUSE]
For the wrong @diff, it's caused by wrong parameter order.
The correct parameters are:

  struct btrfs_root, s64 diff, int type.

However the parameters used are:

  struct btrfs_root, int type, s64 diff.

Fixes: 4ee0d8832c ("btrfs: qgroup: Update trace events for metadata reservation")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-10-17 14:09:31 +02:00
Qu Wenruo d4e204948f btrfs: qgroup: Fix reserved data space leak if we have multiple reserve calls
[BUG]
The following script can cause btrfs qgroup data space leak:

  mkfs.btrfs -f $dev
  mount $dev -o nospace_cache $mnt

  btrfs subv create $mnt/subv
  btrfs quota en $mnt
  btrfs quota rescan -w $mnt
  btrfs qgroup limit 128m $mnt/subv

  for (( i = 0; i < 3; i++)); do
          # Create 3 64M holes for latter fallocate to fail
          truncate -s 192m $mnt/subv/file
          xfs_io -c "pwrite 64m 4k" $mnt/subv/file > /dev/null
          xfs_io -c "pwrite 128m 4k" $mnt/subv/file > /dev/null
          sync

          # it's supposed to fail, and each failure will leak at least 64M
          # data space
          xfs_io -f -c "falloc 0 192m" $mnt/subv/file &> /dev/null
          rm $mnt/subv/file
          sync
  done

  # Shouldn't fail after we removed the file
  xfs_io -f -c "falloc 0 64m" $mnt/subv/file

[CAUSE]
Btrfs qgroup data reserve code allow multiple reservations to happen on
a single extent_changeset:
E.g:
	btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_1M);
	btrfs_qgroup_reserve_data(inode, &data_reserved, SZ_1M, SZ_2M);
	btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_4M);

Btrfs qgroup code has its internal tracking to make sure we don't
double-reserve in above example.

The only pattern utilizing this feature is in the main while loop of
btrfs_fallocate() function.

However btrfs_qgroup_reserve_data()'s error handling has a bug in that
on error it clears all ranges in the io_tree with EXTENT_QGROUP_RESERVED
flag but doesn't free previously reserved bytes.

This bug has a two fold effect:
- Clearing EXTENT_QGROUP_RESERVED ranges
  This is the correct behavior, but it prevents
  btrfs_qgroup_check_reserved_leak() to catch the leakage as the
  detector is purely EXTENT_QGROUP_RESERVED flag based.

- Leak the previously reserved data bytes.

The bug manifests when N calls to btrfs_qgroup_reserve_data are made and
the last one fails, leaking space reserved in the previous ones.

[FIX]
Also free previously reserved data bytes when btrfs_qgroup_reserve_data
fails.

Fixes: 5247255370 ("btrfs: qgroup: Introduce btrfs_qgroup_reserve_data function")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-09-27 15:24:34 +02:00
Qu Wenruo bab32fc069 btrfs: qgroup: Fix the wrong target io_tree when freeing reserved data space
[BUG]
Under the following case with qgroup enabled, if some error happened
after we have reserved delalloc space, then in error handling path, we
could cause qgroup data space leakage:

From btrfs_truncate_block() in inode.c:

	ret = btrfs_delalloc_reserve_space(inode, &data_reserved,
					   block_start, blocksize);
	if (ret)
		goto out;

 again:
	page = find_or_create_page(mapping, index, mask);
	if (!page) {
		btrfs_delalloc_release_space(inode, data_reserved,
					     block_start, blocksize, true);
		btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, true);
		ret = -ENOMEM;
		goto out;
	}

[CAUSE]
In the above case, btrfs_delalloc_reserve_space() will call
btrfs_qgroup_reserve_data() and mark the io_tree range with
EXTENT_QGROUP_RESERVED flag.

In the error handling path, we have the following call stack:
btrfs_delalloc_release_space()
|- btrfs_free_reserved_data_space()
   |- btrsf_qgroup_free_data()
      |- __btrfs_qgroup_release_data(reserved=@reserved, free=1)
         |- qgroup_free_reserved_data(reserved=@reserved)
            |- clear_record_extent_bits();
            |- freed += changeset.bytes_changed;

However due to a completion bug, qgroup_free_reserved_data() will clear
EXTENT_QGROUP_RESERVED flag in BTRFS_I(inode)->io_failure_tree, other
than the correct BTRFS_I(inode)->io_tree.
Since io_failure_tree is never marked with that flag,
btrfs_qgroup_free_data() will not free any data reserved space at all,
causing a leakage.

This type of error handling can only be triggered by errors outside of
qgroup code. So EDQUOT error from qgroup can't trigger it.

[FIX]
Fix the wrong target io_tree.

Reported-by: Josef Bacik <josef@toxicpanda.com>
Fixes: bc42bda223 ("btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-09-27 15:24:28 +02:00
Filipe Manana 13fc1d271a Btrfs: fix race setting up and completing qgroup rescan workers
There is a race between setting up a qgroup rescan worker and completing
a qgroup rescan worker that can lead to callers of the qgroup rescan wait
ioctl to either not wait for the rescan worker to complete or to hang
forever due to missing wake ups. The following diagram shows a sequence
of steps that illustrates the race.

        CPU 1                                                         CPU 2                                  CPU 3

 btrfs_ioctl_quota_rescan()
  btrfs_qgroup_rescan()
   qgroup_rescan_init()
    mutex_lock(&fs_info->qgroup_rescan_lock)
    spin_lock(&fs_info->qgroup_lock)

    fs_info->qgroup_flags |=
      BTRFS_QGROUP_STATUS_FLAG_RESCAN

    init_completion(
      &fs_info->qgroup_rescan_completion)

    fs_info->qgroup_rescan_running = true

    mutex_unlock(&fs_info->qgroup_rescan_lock)
    spin_unlock(&fs_info->qgroup_lock)

    btrfs_init_work()
     --> starts the worker

                                                        btrfs_qgroup_rescan_worker()
                                                         mutex_lock(&fs_info->qgroup_rescan_lock)

                                                         fs_info->qgroup_flags &=
                                                           ~BTRFS_QGROUP_STATUS_FLAG_RESCAN

                                                         mutex_unlock(&fs_info->qgroup_rescan_lock)

                                                         starts transaction, updates qgroup status
                                                         item, etc

                                                                                                           btrfs_ioctl_quota_rescan()
                                                                                                            btrfs_qgroup_rescan()
                                                                                                             qgroup_rescan_init()
                                                                                                              mutex_lock(&fs_info->qgroup_rescan_lock)
                                                                                                              spin_lock(&fs_info->qgroup_lock)

                                                                                                              fs_info->qgroup_flags |=
                                                                                                                BTRFS_QGROUP_STATUS_FLAG_RESCAN

                                                                                                              init_completion(
                                                                                                                &fs_info->qgroup_rescan_completion)

                                                                                                              fs_info->qgroup_rescan_running = true

                                                                                                              mutex_unlock(&fs_info->qgroup_rescan_lock)
                                                                                                              spin_unlock(&fs_info->qgroup_lock)

                                                                                                              btrfs_init_work()
                                                                                                               --> starts another worker

                                                         mutex_lock(&fs_info->qgroup_rescan_lock)

                                                         fs_info->qgroup_rescan_running = false

                                                         mutex_unlock(&fs_info->qgroup_rescan_lock)

							 complete_all(&fs_info->qgroup_rescan_completion)

Before the rescan worker started by the task at CPU 3 completes, if
another task calls btrfs_ioctl_quota_rescan(), it will get -EINPROGRESS
because the flag BTRFS_QGROUP_STATUS_FLAG_RESCAN is set at
fs_info->qgroup_flags, which is expected and correct behaviour.

However if other task calls btrfs_ioctl_quota_rescan_wait() before the
rescan worker started by the task at CPU 3 completes, it will return
immediately without waiting for the new rescan worker to complete,
because fs_info->qgroup_rescan_running is set to false by CPU 2.

This race is making test case btrfs/171 (from fstests) to fail often:

  btrfs/171 9s ... - output mismatch (see /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad)
      --- tests/btrfs/171.out     2018-09-16 21:30:48.505104287 +0100
      +++ /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad      2019-09-19 02:01:36.938486039 +0100
      @@ -1,2 +1,3 @@
       QA output created by 171
      +ERROR: quota rescan failed: Operation now in progress
       Silence is golden
      ...
      (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/171.out /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad'  to see the entire diff)

That is because the test calls the btrfs-progs commands "qgroup quota
rescan -w", "qgroup assign" and "qgroup remove" in a sequence that makes
calls to the rescan start ioctl fail with -EINPROGRESS (note the "btrfs"
commands 'qgroup assign' and 'qgroup remove' often call the rescan start
ioctl after calling the qgroup assign ioctl,
btrfs_ioctl_qgroup_assign()), since previous waits didn't actually wait
for a rescan worker to complete.

Another problem the race can cause is missing wake ups for waiters,
since the call to complete_all() happens outside a critical section and
after clearing the flag BTRFS_QGROUP_STATUS_FLAG_RESCAN. In the sequence
diagram above, if we have a waiter for the first rescan task (executed
by CPU 2), then fs_info->qgroup_rescan_completion.wait is not empty, and
if after the rescan worker clears BTRFS_QGROUP_STATUS_FLAG_RESCAN and
before it calls complete_all() against
fs_info->qgroup_rescan_completion, the task at CPU 3 calls
init_completion() against fs_info->qgroup_rescan_completion which
re-initilizes its wait queue to an empty queue, therefore causing the
rescan worker at CPU 2 to call complete_all() against an empty queue,
never waking up the task waiting for that rescan worker.

Fix this by clearing BTRFS_QGROUP_STATUS_FLAG_RESCAN and setting
fs_info->qgroup_rescan_running to false in the same critical section,
delimited by the mutex fs_info->qgroup_rescan_lock, as well as doing the
call to complete_all() in that same critical section. This gives the
protection needed to avoid rescan wait ioctl callers not waiting for a
running rescan worker and the lost wake ups problem, since setting that
rescan flag and boolean as well as initializing the wait queue is done
already in a critical section delimited by that mutex (at
qgroup_rescan_init()).

Fixes: 57254b6ebc ("Btrfs: add ioctl to wait for qgroup rescan completion")
Fixes: d2c609b834 ("btrfs: properly track when rescan worker is running")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-09-24 16:38:53 +02:00
Qu Wenruo 73798c465b btrfs: qgroup: Try our best to delete qgroup relations
When we try to delete qgroups, we're pretty cautious, we make sure both
qgroups exist and there is a relationship between them, then try to
delete the relation.

This behavior is OK, but the problem is we need to two relation items,
and if we failed the first item deletion, we error out, leaving the
other relation item in qgroup tree.

Sometimes the error from del_qgroup_relation_item() could just be
-ENOENT, thus we can ignore that error and continue without any problem.

Further more, such cautious behavior makes qgroup relation deletion
impossible for orphan relation items.

This patch will enhance __del_qgroup_relation():
- If both qgroups and their relation items exist
  Go the regular deletion routine and update their accounting if needed.

- If any qgroup or relation item doesn't exist
  Then we still try to delete the orphan items anyway, but don't trigger
  the accounting update.

By this, we try our best to remove relation items, and can handle orphan
relation items properly, while still keep the existing behavior for good
qgroup tree.

Reported-by: Andrei Borzenkov <arvidjaar@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-09-09 14:59:06 +02:00
Josef Bacik aac0023c21 btrfs: move basic block_group definitions to their own header
This is prep work for moving all of the block group cache code into its
own file.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
2019-09-09 14:59:03 +02:00
Qu Wenruo e88439debd btrfs: qgroup: Don't hold qgroup_ioctl_lock in btrfs_qgroup_inherit()
[BUG]
Lockdep will report the following circular locking dependency:

  WARNING: possible circular locking dependency detected
  5.2.0-rc2-custom #24 Tainted: G           O
  ------------------------------------------------------
  btrfs/8631 is trying to acquire lock:
  000000002536438c (&fs_info->qgroup_ioctl_lock#2){+.+.}, at: btrfs_qgroup_inherit+0x40/0x620 [btrfs]

  but task is already holding lock:
  000000003d52cc23 (&fs_info->tree_log_mutex){+.+.}, at: create_pending_snapshot+0x8b6/0xe60 [btrfs]

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #2 (&fs_info->tree_log_mutex){+.+.}:
         __mutex_lock+0x76/0x940
         mutex_lock_nested+0x1b/0x20
         btrfs_commit_transaction+0x475/0xa00 [btrfs]
         btrfs_commit_super+0x71/0x80 [btrfs]
         close_ctree+0x2bd/0x320 [btrfs]
         btrfs_put_super+0x15/0x20 [btrfs]
         generic_shutdown_super+0x72/0x110
         kill_anon_super+0x18/0x30
         btrfs_kill_super+0x16/0xa0 [btrfs]
         deactivate_locked_super+0x3a/0x80
         deactivate_super+0x51/0x60
         cleanup_mnt+0x3f/0x80
         __cleanup_mnt+0x12/0x20
         task_work_run+0x94/0xb0
         exit_to_usermode_loop+0xd8/0xe0
         do_syscall_64+0x210/0x240
         entry_SYSCALL_64_after_hwframe+0x49/0xbe

  -> #1 (&fs_info->reloc_mutex){+.+.}:
         __mutex_lock+0x76/0x940
         mutex_lock_nested+0x1b/0x20
         btrfs_commit_transaction+0x40d/0xa00 [btrfs]
         btrfs_quota_enable+0x2da/0x730 [btrfs]
         btrfs_ioctl+0x2691/0x2b40 [btrfs]
         do_vfs_ioctl+0xa9/0x6d0
         ksys_ioctl+0x67/0x90
         __x64_sys_ioctl+0x1a/0x20
         do_syscall_64+0x65/0x240
         entry_SYSCALL_64_after_hwframe+0x49/0xbe

  -> #0 (&fs_info->qgroup_ioctl_lock#2){+.+.}:
         lock_acquire+0xa7/0x190
         __mutex_lock+0x76/0x940
         mutex_lock_nested+0x1b/0x20
         btrfs_qgroup_inherit+0x40/0x620 [btrfs]
         create_pending_snapshot+0x9d7/0xe60 [btrfs]
         create_pending_snapshots+0x94/0xb0 [btrfs]
         btrfs_commit_transaction+0x415/0xa00 [btrfs]
         btrfs_mksubvol+0x496/0x4e0 [btrfs]
         btrfs_ioctl_snap_create_transid+0x174/0x180 [btrfs]
         btrfs_ioctl_snap_create_v2+0x11c/0x180 [btrfs]
         btrfs_ioctl+0xa90/0x2b40 [btrfs]
         do_vfs_ioctl+0xa9/0x6d0
         ksys_ioctl+0x67/0x90
         __x64_sys_ioctl+0x1a/0x20
         do_syscall_64+0x65/0x240
         entry_SYSCALL_64_after_hwframe+0x49/0xbe

  other info that might help us debug this:

  Chain exists of:
    &fs_info->qgroup_ioctl_lock#2 --> &fs_info->reloc_mutex --> &fs_info->tree_log_mutex

   Possible unsafe locking scenario:

         CPU0                    CPU1
         ----                    ----
    lock(&fs_info->tree_log_mutex);
                                 lock(&fs_info->reloc_mutex);
                                 lock(&fs_info->tree_log_mutex);
    lock(&fs_info->qgroup_ioctl_lock#2);

   *** DEADLOCK ***

  6 locks held by btrfs/8631:
   #0: 00000000ed8f23f6 (sb_writers#12){.+.+}, at: mnt_want_write_file+0x28/0x60
   #1: 000000009fb1597a (&type->i_mutex_dir_key#10/1){+.+.}, at: btrfs_mksubvol+0x70/0x4e0 [btrfs]
   #2: 0000000088c5ad88 (&fs_info->subvol_sem){++++}, at: btrfs_mksubvol+0x128/0x4e0 [btrfs]
   #3: 000000009606fc3e (sb_internal#2){.+.+}, at: start_transaction+0x37a/0x520 [btrfs]
   #4: 00000000f82bbdf5 (&fs_info->reloc_mutex){+.+.}, at: btrfs_commit_transaction+0x40d/0xa00 [btrfs]
   #5: 000000003d52cc23 (&fs_info->tree_log_mutex){+.+.}, at: create_pending_snapshot+0x8b6/0xe60 [btrfs]

[CAUSE]
Due to the delayed subvolume creation, we need to call
btrfs_qgroup_inherit() inside commit transaction code, with a lot of
other mutex hold.
This hell of lock chain can lead to above problem.

[FIX]
On the other hand, we don't really need to hold qgroup_ioctl_lock if
we're in the context of create_pending_snapshot().
As in that context, we're the only one being able to modify qgroup.

All other qgroup functions which needs qgroup_ioctl_lock are either
holding a transaction handle, or will start a new transaction:
  Functions will start a new transaction():
  * btrfs_quota_enable()
  * btrfs_quota_disable()
  Functions hold a transaction handler:
  * btrfs_add_qgroup_relation()
  * btrfs_del_qgroup_relation()
  * btrfs_create_qgroup()
  * btrfs_remove_qgroup()
  * btrfs_limit_qgroup()
  * btrfs_qgroup_inherit() call inside create_subvol()

So we have a higher level protection provided by transaction, thus we
don't need to always hold qgroup_ioctl_lock in btrfs_qgroup_inherit().

Only the btrfs_qgroup_inherit() call in create_subvol() needs to hold
qgroup_ioctl_lock, while the btrfs_qgroup_inherit() call in
create_pending_snapshot() is already protected by transaction.

So the fix is to detect the context by checking
trans->transaction->state.
If we're at TRANS_STATE_COMMIT_DOING, then we're in commit transaction
context and no need to get the mutex.

Reported-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-02 12:30:48 +02:00