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Subject[PATCH v5 2/2] btrfs: qgroup: fix sleep from invalid context bug in update_qgroup_limit_item()
Date
Syzkaller reported BUG as follows:

BUG: sleeping function called from invalid context at
include/linux/sched/mm.h:274
Call Trace:
<TASK>
dump_stack_lvl+0xcd/0x134
__might_resched.cold+0x222/0x26b
kmem_cache_alloc+0x2e7/0x3c0
update_qgroup_limit_item+0xe1/0x390
btrfs_qgroup_inherit+0x147b/0x1ee0
create_subvol+0x4eb/0x1710
btrfs_mksubvol+0xfe5/0x13f0
__btrfs_ioctl_snap_create+0x2b0/0x430
btrfs_ioctl_snap_create_v2+0x25a/0x520
btrfs_ioctl+0x2a1c/0x5ce0
__x64_sys_ioctl+0x193/0x200
do_syscall_64+0x35/0x80

Fix this by calling qgroup_dirty() on @dstqgroup, and update limit item in
btrfs_run_qgroups() later.

Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
---
fs/btrfs/qgroup.c | 29 ++++++++++++-----------------
1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 9334c3157c22..8f5c52e24430 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2860,6 +2860,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
bool need_rescan = false;
u32 level_size = 0;
u64 nums;
+ bool dirty_dstgrp = false;

/*
* There are only two callers of this function.
@@ -2941,7 +2942,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
dstgroup = add_qgroup_rb(fs_info, objectid);
if (IS_ERR(dstgroup)) {
ret = PTR_ERR(dstgroup);
- goto unlock;
+ goto dirty;
}

if (inherit && inherit->flags & BTRFS_QGROUP_INHERIT_SET_LIMITS) {
@@ -2950,21 +2951,13 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
dstgroup->max_excl = inherit->lim.max_excl;
dstgroup->rsv_rfer = inherit->lim.rsv_rfer;
dstgroup->rsv_excl = inherit->lim.rsv_excl;
-
- ret = update_qgroup_limit_item(trans, dstgroup);
- if (ret) {
- qgroup_mark_inconsistent(fs_info);
- btrfs_info(fs_info,
- "unable to update quota limit for %llu",
- dstgroup->qgroupid);
- goto unlock;
- }
+ dirty_dstgrp = true;
}

if (srcid) {
srcgroup = find_qgroup_rb(fs_info, srcid);
if (!srcgroup)
- goto unlock;
+ goto dirty;

/*
* We call inherit after we clone the root in order to make sure
@@ -2985,20 +2978,20 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
dstgroup->max_excl = srcgroup->max_excl;
dstgroup->rsv_rfer = srcgroup->rsv_rfer;
dstgroup->rsv_excl = srcgroup->rsv_excl;
+ dirty_dstgrp = true;

- qgroup_dirty(fs_info, dstgroup);
qgroup_dirty(fs_info, srcgroup);
}

if (!inherit)
- goto unlock;
+ goto dirty;

i_qgroups = (u64 *)(inherit + 1);
for (i = 0; i < inherit->num_qgroups; ++i) {
if (*i_qgroups) {
ret = add_relation_rb(fs_info, objectid, *i_qgroups);
if (ret)
- goto unlock;
+ goto dirty;
}
++i_qgroups;

@@ -3022,7 +3015,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,

if (!src || !dst) {
ret = -EINVAL;
- goto unlock;
+ goto dirty;
}

dst->rfer = src->rfer - level_size;
@@ -3043,15 +3036,17 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,

if (!src || !dst) {
ret = -EINVAL;
- goto unlock;
+ goto dirty;
}

dst->excl = src->excl + level_size;
dst->excl_cmpr = src->excl_cmpr + level_size;
need_rescan = true;
}
+dirty:
+ if (dirty_dstgrp)
+ qgroup_dirty(fs_info, dstgroup);

-unlock:
spin_unlock(&fs_info->qgroup_lock);
if (!ret)
ret = btrfs_sysfs_add_one_qgroup(fs_info, dstgroup);
--
2.31.1
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