* re: btrfs: add tracing for failed reservations
@ 2015-11-10 9:08 Dan Carpenter
2015-11-10 13:55 ` Jeff Mahoney
0 siblings, 1 reply; 3+ messages in thread
From: Dan Carpenter @ 2015-11-10 9:08 UTC (permalink / raw)
To: jeffm; +Cc: linux-btrfs
[ This is old. I don't know why it's only complaining now. Anyway this
looks like one of those rarely used code paths so it might be a real
bug. ]
Hello Jeff Mahoney,
The patch cab45e22da48: "btrfs: add tracing for failed reservations"
from Oct 16, 2013, leads to the following static checker warning:
fs/btrfs/extent-tree.c:4116 btrfs_alloc_data_chunk_ondemand()
error: we previously assumed 'data_sinfo' could be null (see line 4016)
fs/btrfs/extent-tree.c
4014
4015 data_sinfo = fs_info->data_sinfo;
4016 if (!data_sinfo)
^^^^^^^^^^^
Check for NULL.
4017 goto alloc;
4018
4019 again:
4020 /* make sure we have enough space to handle the data first */
4021 spin_lock(&data_sinfo->lock);
4022 used = data_sinfo->bytes_used + data_sinfo->bytes_reserved +
4023 data_sinfo->bytes_pinned + data_sinfo->bytes_readonly +
4024 data_sinfo->bytes_may_use;
4025
4026 if (used + bytes > data_sinfo->total_bytes) {
4027 struct btrfs_trans_handle *trans;
4028
4029 /*
4030 * if we don't have enough free bytes in this space then we need
4031 * to alloc a new chunk.
4032 */
4033 if (!data_sinfo->full) {
4034 u64 alloc_target;
4035
4036 data_sinfo->force_alloc = CHUNK_ALLOC_FORCE;
4037 spin_unlock(&data_sinfo->lock);
4038 alloc:
We jump to here.
4039 alloc_target = btrfs_get_alloc_profile(root, 1);
4040 /*
4041 * It is ugly that we don't call nolock join
4042 * transaction for the free space inode case here.
4043 * But it is safe because we only do the data space
4044 * reservation for the free space cache in the
4045 * transaction context, the common join transaction
4046 * just increase the counter of the current transaction
4047 * handler, doesn't try to acquire the trans_lock of
4048 * the fs.
4049 */
4050 trans = btrfs_join_transaction(root);
4051 if (IS_ERR(trans))
4052 return PTR_ERR(trans);
4053
4054 ret = do_chunk_alloc(trans, root->fs_info->extent_root,
4055 alloc_target,
4056 CHUNK_ALLOC_NO_FORCE);
4057 btrfs_end_transaction(trans, root);
4058 if (ret < 0) {
4059 if (ret != -ENOSPC)
4060 return ret;
4061 else {
4062 have_pinned_space = 1;
4063 goto commit_trans;
The btrfs_end_transaction() call fails.
4064 }
4065 }
4066
4067 if (!data_sinfo)
4068 data_sinfo = fs_info->data_sinfo;
4069
4070 goto again;
4071 }
4072
4073 /*
4074 * If we don't have enough pinned space to deal with this
4075 * allocation, and no removed chunk in current transaction,
4076 * don't bother committing the transaction.
4077 */
4078 have_pinned_space = percpu_counter_compare(
4079 &data_sinfo->total_bytes_pinned,
4080 used + bytes - data_sinfo->total_bytes);
4081 spin_unlock(&data_sinfo->lock);
4082
4083 /* commit the current transaction and try again */
4084 commit_trans:
We jump to here.
4085 if (need_commit &&
4086 !atomic_read(&root->fs_info->open_ioctl_trans)) {
4087 need_commit--;
4088
4089 if (need_commit > 0)
4090 btrfs_wait_ordered_roots(fs_info, -1);
4091
4092 trans = btrfs_join_transaction(root);
4093 if (IS_ERR(trans))
4094 return PTR_ERR(trans);
4095 if (have_pinned_space >= 0 ||
4096 test_bit(BTRFS_TRANS_HAVE_FREE_BGS,
4097 &trans->transaction->flags) ||
4098 need_commit > 0) {
4099 ret = btrfs_commit_transaction(trans, root);
4100 if (ret)
4101 return ret;
4102 /*
4103 * make sure that all running delayed iput are
4104 * done
4105 */
4106 down_write(&root->fs_info->delayed_iput_sem);
4107 up_write(&root->fs_info->delayed_iput_sem);
4108 goto again;
4109 } else {
4110 btrfs_end_transaction(trans, root);
4111 }
4112 }
4113
4114 trace_btrfs_space_reservation(root->fs_info,
4115 "space_info:enospc",
4116 data_sinfo->flags, bytes, 1);
^^^^^^^^^^^^^^^^^
Potential NULL deref.
4117 return -ENOSPC;
regards,
dan carpenter
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: btrfs: add tracing for failed reservations
2015-11-10 9:08 btrfs: add tracing for failed reservations Dan Carpenter
@ 2015-11-10 13:55 ` Jeff Mahoney
0 siblings, 0 replies; 3+ messages in thread
From: Jeff Mahoney @ 2015-11-10 13:55 UTC (permalink / raw)
To: Dan Carpenter; +Cc: linux-btrfs
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Hash: SHA1
On 11/10/15 4:08 AM, Dan Carpenter wrote:
> [ This is old. I don't know why it's only complaining now. Anyway
> this looks like one of those rarely used code paths so it might be
> a real bug. ]
>
> Hello Jeff Mahoney,
>
> The patch cab45e22da48: "btrfs: add tracing for failed
> reservations" from Oct 16, 2013, leads to the following static
> checker warning:
>
> fs/btrfs/extent-tree.c:4116 btrfs_alloc_data_chunk_ondemand()
> error: we previously assumed 'data_sinfo' could be null (see line
> 4016)
Thanks, Dan. The analysis certainly looks correct. The combination
of not having a data block group and having tracing enabled would be
pretty rare, but it's definitely a bug.
I'll post a patch shortly.
- -Jeff
> fs/btrfs/extent-tree.c 4014 4015 data_sinfo =
> fs_info->data_sinfo; 4016 if (!data_sinfo) ^^^^^^^^^^^
> Check for NULL.
>
> 4017 goto alloc; 4018 4019 again: 4020 /* make
> sure we have enough space to handle the data first */ 4021
> spin_lock(&data_sinfo->lock); 4022 used =
> data_sinfo->bytes_used + data_sinfo->bytes_reserved + 4023
> data_sinfo->bytes_pinned + data_sinfo->bytes_readonly + 4024
> data_sinfo->bytes_may_use; 4025 4026 if (used + bytes >
> data_sinfo->total_bytes) { 4027 struct
> btrfs_trans_handle *trans; 4028 4029 /* 4030 * if
> we don't have enough free bytes in this space then we need 4031
> * to alloc a new chunk. 4032 */ 4033 if
> (!data_sinfo->full) { 4034 u64 alloc_target; 4035 4036
> data_sinfo->force_alloc = CHUNK_ALLOC_FORCE; 4037
> spin_unlock(&data_sinfo->lock); 4038 alloc:
>
> We jump to here.
>
> 4039 alloc_target =
> btrfs_get_alloc_profile(root, 1); 4040 /*
> 4041 * It is ugly that we don't call
> nolock join 4042 * transaction for the
> free space inode case here. 4043 * But
> it is safe because we only do the data space 4044 * reservation for
> the free space cache in the 4045 * transaction context, the common
> join transaction 4046 * just increase the counter of the current
> transaction 4047 * handler, doesn't try to acquire the trans_lock
> of 4048 * the fs. 4049 */ 4050 trans =
> btrfs_join_transaction(root); 4051 if (IS_ERR(trans)) 4052
> return PTR_ERR(trans); 4053 4054 ret =
> do_chunk_alloc(trans, root->fs_info->extent_root, 4055
> alloc_target, 4056 CHUNK_ALLOC_NO_FORCE); 4057
> btrfs_end_transaction(trans, root); 4058 if (ret < 0) { 4059
> if (ret != -ENOSPC) 4060
> return ret; 4061 else { 4062
> have_pinned_space = 1; 4063 goto commit_trans;
>
> The btrfs_end_transaction() call fails.
>
> 4064 } 4065 } 4066 4067
> if (!data_sinfo) 4068 data_sinfo = fs_info->data_sinfo; 4069 4070
> goto again; 4071 } 4072 4073 /*
> 4074 * If we don't have enough pinned space to
> deal with this 4075 * allocation, and no removed
> chunk in current transaction, 4076 * don't
> bother committing the transaction. 4077 */ 4078
> have_pinned_space = percpu_counter_compare( 4079
> &data_sinfo->total_bytes_pinned, 4080
> used + bytes - data_sinfo->total_bytes); 4081
> spin_unlock(&data_sinfo->lock); 4082 4083 /*
> commit the current transaction and try again */ 4084 commit_trans:
>
> We jump to here.
>
> 4085 if (need_commit && 4086
> !atomic_read(&root->fs_info->open_ioctl_trans)) { 4087
> need_commit--; 4088 4089 if (need_commit
> > 0) 4090 btrfs_wait_ordered_roots(fs_info, -1); 4091 4092 trans =
> btrfs_join_transaction(root); 4093 if (IS_ERR(trans)) 4094
> return PTR_ERR(trans); 4095 if
> (have_pinned_space
>> = 0 || 4096
> test_bit(BTRFS_TRANS_HAVE_FREE_BGS, 4097
> &trans->transaction->flags) || 4098 need_commit > 0) { 4099
> ret = btrfs_commit_transaction(trans, root); 4100 if (ret) 4101
> return ret; 4102 /* 4103 * make
> sure that all running delayed iput are 4104 * done 4105
> */ 4106 down_write(&root->fs_info->delayed_iput_sem); 4107
> up_write(&root->fs_info->delayed_iput_sem); 4108 goto again; 4109
> } else { 4110 btrfs_end_transaction(trans, root); 4111 } 4112
> } 4113 4114 trace_btrfs_space_reservation(root->fs_info, 4115
> "space_info:enospc", 4116 data_sinfo->flags, bytes, 1);
> ^^^^^^^^^^^^^^^^^ Potential NULL deref.
>
> 4117 return -ENOSPC;
>
> regards, dan carpenter
>
- --
Jeff Mahoney
SUSE Labs
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^ permalink raw reply [flat|nested] 3+ messages in thread
* re: btrfs: add tracing for failed reservations
@ 2013-11-13 20:01 Dan Carpenter
0 siblings, 0 replies; 3+ messages in thread
From: Dan Carpenter @ 2013-11-13 20:01 UTC (permalink / raw)
To: jeffm; +Cc: linux-btrfs
Hello Jeff Mahoney,
This is a semi-automatic email about new static checker warnings.
The patch cab45e22da48: "btrfs: add tracing for failed reservations"
from Oct 16, 2013, leads to the following Smatch complaint:
fs/btrfs/extent-tree.c:3710 btrfs_check_data_free_space()
error: we previously assumed 'data_sinfo' could be null (see line 3629)
fs/btrfs/extent-tree.c
3628 data_sinfo = fs_info->data_sinfo;
3629 if (!data_sinfo)
^^^^^^^^^^^
Existing check.
3630 goto alloc;
3631
3632 again:
3633 /* make sure we have enough space to handle the data first */
3634 spin_lock(&data_sinfo->lock);
3635 used = data_sinfo->bytes_used + data_sinfo->bytes_reserved +
3636 data_sinfo->bytes_pinned + data_sinfo->bytes_readonly +
3637 data_sinfo->bytes_may_use;
3638
3639 if (used + bytes > data_sinfo->total_bytes) {
3640 struct btrfs_trans_handle *trans;
3641
3642 /*
3643 * if we don't have enough free bytes in this space then we need
3644 * to alloc a new chunk.
3645 */
3646 if (!data_sinfo->full && alloc_chunk) {
3647 u64 alloc_target;
3648
3649 data_sinfo->force_alloc = CHUNK_ALLOC_FORCE;
3650 spin_unlock(&data_sinfo->lock);
3651 alloc:
3652 alloc_target = btrfs_get_alloc_profile(root, 1);
3653 /*
3654 * It is ugly that we don't call nolock join
3655 * transaction for the free space inode case here.
3656 * But it is safe because we only do the data space
3657 * reservation for the free space cache in the
3658 * transaction context, the common join transaction
3659 * just increase the counter of the current transaction
3660 * handler, doesn't try to acquire the trans_lock of
3661 * the fs.
3662 */
3663 trans = btrfs_join_transaction(root);
3664 if (IS_ERR(trans))
3665 return PTR_ERR(trans);
3666
3667 ret = do_chunk_alloc(trans, root->fs_info->extent_root,
3668 alloc_target,
3669 CHUNK_ALLOC_NO_FORCE);
3670 btrfs_end_transaction(trans, root);
3671 if (ret < 0) {
3672 if (ret != -ENOSPC)
3673 return ret;
3674 else
3675 goto commit_trans;
^^^^^^^^^^^^^^^^^
Imagine we hit this goto and data_sinfo is NULL.
3676 }
3677
3678 if (!data_sinfo)
3679 data_sinfo = fs_info->data_sinfo;
3680
3681 goto again;
3682 }
3683
3684 /*
3685 * If we don't have enough pinned space to deal with this
3686 * allocation don't bother committing the transaction.
3687 */
3688 if (percpu_counter_compare(&data_sinfo->total_bytes_pinned,
3689 bytes) < 0)
3690 committed = 1;
3691 spin_unlock(&data_sinfo->lock);
3692
3693 /* commit the current transaction and try again */
3694 commit_trans:
3695 if (!committed &&
3696 !atomic_read(&root->fs_info->open_ioctl_trans)) {
3697 committed = 1;
3698
3699 trans = btrfs_join_transaction(root);
3700 if (IS_ERR(trans))
3701 return PTR_ERR(trans);
3702 ret = btrfs_commit_transaction(trans, root);
3703 if (ret)
3704 return ret;
3705 goto again;
3706 }
3707
3708 trace_btrfs_space_reservation(root->fs_info,
3709 "space_info:enospc",
3710 data_sinfo->flags, bytes, 1);
^^^^^^^^^^^^^^^^^
Patch introduces an unchecked dereference.
3711 return -ENOSPC;
3712 }
regards,
dan carpenter
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-11-10 13:55 ` Jeff Mahoney
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