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a855fbe692
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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
..
tests btrfs: fix missing delalloc new bit for new delalloc ranges 2020-11-13 22:15:59 +01:00
acl.c btrfs: cleanup btrfs_setxattr_trans and drop transaction parameter 2019-04-29 19:02:44 +02:00
async-thread.c Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
async-thread.h Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
backref.c btrfs: add a helper to read the tree_root commit root for backref lookup 2020-10-26 15:04:57 +01:00
backref.h btrfs: rename BTRFS_ROOT_REF_COWS to BTRFS_ROOT_SHAREABLE 2020-05-25 11:25:35 +02:00
block-group.c btrfs: drop the path before adding block group sysfs files 2020-10-26 15:01:34 +01:00
block-group.h btrfs: convert block group refcount to refcount_t 2020-07-27 12:55:42 +02:00
block-rsv.c btrfs: print the block rsv type when we fail our reservation 2020-11-05 13:02:05 +01:00
block-rsv.h btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
btrfs_inode.h btrfs: rename BTRFS_INODE_ORDERED_DATA_CLOSE flag 2020-10-07 12:18:00 +02:00
check-integrity.c btrfs: check-integrity: remove unnecessary failure messages during memory allocation 2020-07-27 12:55:21 +02:00
check-integrity.h btrfs: remove btrfsic_submit_bh() 2020-03-23 17:01:39 +01:00
compression.c btrfs: compression: move declarations to header 2020-10-07 12:06:55 +02:00
compression.h btrfs: compression: move declarations to header 2020-10-07 12:06:55 +02:00
ctree.c btrfs: cleanup cow block on error 2020-10-07 12:17:59 +02:00
ctree.h btrfs: fix lockdep splat when enabling and disabling qgroups 2020-11-23 21:16:43 +01:00
delalloc-space.c btrfs: add btrfs_reserve_data_bytes and use it 2020-10-07 12:06:52 +02:00
delalloc-space.h btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
delayed-inode.c btrfs: sink total_data parameter in setup_items_for_insert 2020-10-07 12:13:18 +02:00
delayed-inode.h btrfs: delayed-inode: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
delayed-ref.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
delayed-ref.h btrfs: migrate the delayed refs rsv code 2019-07-04 17:26:17 +02:00
dev-replace.c btrfs: dev-replace: fail mount if we don't have replace item with target device 2020-11-05 13:03:31 +01:00
dev-replace.h btrfs: add __pure attribute to functions 2019-11-18 12:46:52 +01:00
dir-item.c btrfs: remove unused parameter fs_info from btrfs_extend_item 2019-04-29 19:02:50 +02:00
discard.c btrfs: discard: add missing put when grabbing block group from unused list 2020-07-07 16:06:28 +02:00
discard.h btrfs: discard: Use the correct style for SPDX License Identifier 2020-04-20 17:43:42 +02:00
disk-io.c btrfs: add a helper to read the tree_root commit root for backref lookup 2020-10-26 15:04:57 +01:00
disk-io.h btrfs: add a helper to read the tree_root commit root for backref lookup 2020-10-26 15:04:57 +01:00
export.c btrfs: simplify iget helpers 2020-05-25 11:25:37 +02:00
export.h btrfs: export helpers for subvolume name/id resolution 2020-03-23 17:01:42 +01:00
extent_io.c btrfs: remove struct extent_io_ops 2020-10-07 12:13:25 +02:00
extent_io.h btrfs: remove struct extent_io_ops 2020-10-07 12:13:25 +02:00
extent_map.c Btrfs: fix race between using extent maps and merging them 2020-02-12 17:16:46 +01:00
extent_map.h btrfs: remove extent_map::bdev 2019-11-18 23:43:44 +01:00
extent-io-tree.h btrfs: remove struct extent_io_ops 2020-10-07 12:13:25 +02:00
extent-tree.c btrfs: tree-checker: fix incorrect printk format 2020-10-26 15:02:30 +01:00
file-item.c btrfs: make btrfs_find_ordered_sum take btrfs_inode 2020-10-07 12:12:19 +02:00
file.c btrfs: fix missing delalloc new bit for new delalloc ranges 2020-11-13 22:15:59 +01:00
free-space-cache.c btrfs: free-space-cache: use unaligned helpers to access data 2020-10-07 12:13:23 +02:00
free-space-cache.h btrfs: let btrfs_return_cluster_to_free_space() return void 2020-07-27 12:55:21 +02:00
free-space-tree.c btrfs: block-group: fix free-space bitmap threshold 2020-08-27 13:37:54 +02:00
free-space-tree.h btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
inode-item.c btrfs: Make btrfs_find_name_in_ext_backref return struct btrfs_inode_extref 2019-09-09 14:59:16 +02:00
inode-map.c btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
inode-map.h
inode.c btrfs: fix missing delalloc new bit for new delalloc ranges 2020-11-13 22:15:59 +01:00
ioctl.c btrfs: fix potential overflow in cluster_pages_for_defrag on 32bit arch 2020-11-05 13:01:42 +01:00
Kconfig btrfs: switch to iomap for direct IO 2020-10-07 12:06:57 +02:00
locking.c btrfs: add nesting tags to the locking helpers 2020-10-07 12:12:16 +02:00
locking.h btrfs: introduce BTRFS_NESTING_NEW_ROOT for adding new roots 2020-10-07 12:12:17 +02:00
lzo.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00
Makefile Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
misc.h btrfs: rename tree_entry to rb_simple_node and export it 2020-05-25 11:25:19 +02:00
ordered-data.c btrfs: remove inode argument from btrfs_start_ordered_extent 2020-10-07 12:13:22 +02:00
ordered-data.h btrfs: remove inode argument from btrfs_start_ordered_extent 2020-10-07 12:13:22 +02:00
orphan.c
print-tree.c btrfs: pretty print leaked root name 2020-10-07 12:12:20 +02:00
print-tree.h btrfs: pretty print leaked root name 2020-10-07 12:12:20 +02:00
props.c btrfs: simplify iget helpers 2020-05-25 11:25:37 +02:00
props.h btrfs: delete unused function btrfs_set_prop_trans 2019-04-29 19:02:54 +02:00
qgroup.c btrfs: fix lockdep splat when enabling and disabling qgroups 2020-11-23 21:16:43 +01:00
qgroup.h btrfs: qgroup: export qgroups in sysfs 2020-07-27 12:55:37 +02:00
raid56.c btrfs: raid56: remove out label in __raid56_parity_recover 2020-07-27 12:55:44 +02:00
raid56.h btrfs: constify map parameter for nr_parity_stripes and nr_data_stripes 2019-07-01 13:34:58 +02:00
rcu-string.h btrfs: rcu-string: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
reada.c btrfs: fix readahead hang and use-after-free after removing a device 2020-10-26 15:03:59 +01:00
ref-verify.c btrfs: ref-verify: fix memory leak in btrfs_ref_tree_mod 2020-11-05 13:03:39 +01:00
ref-verify.h btrfs: ref-verify: Use btrfs_ref to refactor btrfs_ref_tree_mod() 2019-04-29 19:02:49 +02:00
reflink.c btrfs: reschedule when cloning lots of extents 2020-10-07 12:13:22 +02:00
reflink.h Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
relocation.c btrfs: fix min reserved size calculation in merge_reloc_root 2020-11-05 13:02:07 +01:00
root-tree.c btrfs: qgroup: fix qgroup meta rsv leak for subvolume operations 2020-10-07 12:12:13 +02:00
scrub.c btrfs: scrub: update message regarding read-only status 2020-11-05 13:02:58 +01:00
send.c btrfs: send, recompute reference path after orphanization of a directory 2020-10-07 12:13:23 +02:00
send.h btrfs: send: avoid copying file data 2020-10-07 12:13:17 +02:00
space-info.c btrfs: kill the RCU protection for fs_info->space_info 2020-10-07 12:13:19 +02:00
space-info.h btrfs: add btrfs_reserve_data_bytes and use it 2020-10-07 12:06:52 +02:00
struct-funcs.c btrfs: use unaligned helpers for stack and header set/get helpers 2020-10-07 12:13:23 +02:00
super.c btrfs: kill the RCU protection for fs_info->space_info 2020-10-07 12:13:19 +02:00
sysfs.c btrfs: do not create raid sysfs entries under any locks 2020-10-07 12:13:19 +02:00
sysfs.h btrfs: split and refactor btrfs_sysfs_remove_devices_dir 2020-10-07 12:12:21 +02:00
transaction.c btrfs: introduce BTRFS_NESTING_COW for cow'ing blocks 2020-10-07 12:12:16 +02:00
transaction.h btrfs: dio iomap DSYNC workaround 2020-10-07 12:06:57 +02:00
tree-checker.c btrfs: tree-checker: add missing returns after data_ref alignment checks 2020-11-23 21:16:21 +01:00
tree-checker.h btrfs: get fs_info from eb in btrfs_check_chunk_valid 2019-04-29 19:02:39 +02:00
tree-defrag.c btrfs: remove unused btrfs_root::defrag_trans_start 2020-07-27 12:55:28 +02:00
tree-log.c btrfs: reschedule if necessary when logging directory items 2020-10-07 12:13:19 +02:00
tree-log.h btrfs: make fast fsyncs wait only for writeback 2020-10-07 12:06:56 +02:00
ulist.c
ulist.h
uuid-tree.c btrfs: simplify root lookup by id 2020-05-25 11:25:36 +02:00
volumes.c btrfs: don't access possibly stale fs_info data for printing duplicate device 2020-11-23 21:16:12 +01:00
volumes.h btrfs: convert data_seqcount to seqcount_mutex_t 2020-10-27 15:11:51 +01:00
xattr.c Btrfs: fix failure to persist compression property xattr deletion on fsync 2019-06-17 16:37:17 +02:00
xattr.h btrfs: cleanup btrfs_setxattr_trans and drop transaction parameter 2019-04-29 19:02:44 +02:00
zlib.c btrfs: use larger zlib buffer for s390 hardware compression 2020-01-31 10:30:40 -08:00
zstd.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00