Please discard this patch.
It's sent out by accident.
The correct one is only sent to btrfs mail list.
Thanks,
Qu
On 2019/10/17 上午10:23, Qu Wenruo wrote:
> [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
> qgroup_meta_reserve: 9c7f6acc-b342-4037-bc47-7f6e4d2232d7: refroot=5(FS_TREE) type=0x258792 diff=2
>
> Since we're in qgroup_meta_reserve() trace event, the @type should never
> be DATA, while diff must be aligned to sectorsize (4K in this case).
>
> Only UUID and refroot is correct.
>
> [CAUSE]
> There are two causes for this bug:
>
> - Bad parameter order
> For trace event btrfs:qgroup_meta_reserve, we're passing wrong
> parameters.
>
> The correct parameters are:
> struct btrfs_root, s64 diff, int type.
>
> However the used order is:
> struct btrfs_root, int type, s64 diff.
>
> - @type is not even assigned
> What I was doing !? /facepalm
>
> [FIX]
> Fix the super stupid bug.
>
> Now everything works fine:
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PERTRANS diff=81920
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=16384
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=0
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=16384
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=-16384
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=16384
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=-16384
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=16384
> qgroup_meta_reserve: 0477ad60-9aeb-4040-8a03-1900844d46ba: refroot=5(FS_TREE) type=META_PREALLOC diff=-16384
>
> Fixes: 4ee0d8832c2e ("btrfs: qgroup: Update trace events for metadata reservation")
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> Changelog:
> v2:
> - Use more accurate comment about the fintuning options
> - Use more elegant method to output uuid
> ---
> fs/btrfs/qgroup.c | 4 ++--
> include/trace/events/btrfs.h | 1 +
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index c4bb69941c77..3ad151655eb8 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -3629,7 +3629,7 @@ int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
> return 0;
>
> BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
> - trace_qgroup_meta_reserve(root, type, (s64)num_bytes);
> + trace_qgroup_meta_reserve(root, (s64)num_bytes, type);
> ret = qgroup_reserve(root, num_bytes, enforce, type);
> if (ret < 0)
> return ret;
> @@ -3676,7 +3676,7 @@ void __btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes,
> */
> num_bytes = sub_root_meta_rsv(root, num_bytes, type);
> BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
> - trace_qgroup_meta_reserve(root, type, -(s64)num_bytes);
> + trace_qgroup_meta_reserve(root, -(s64)num_bytes, type);
> btrfs_qgroup_free_refroot(fs_info, root->root_key.objectid,
> num_bytes, type);
> }
> diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
> index 5df604de4f11..0ebcaa153f93 100644
> --- a/include/trace/events/btrfs.h
> +++ b/include/trace/events/btrfs.h
> @@ -1710,6 +1710,7 @@ TRACE_EVENT(qgroup_meta_reserve,
> TP_fast_assign_btrfs(root->fs_info,
> __entry->refroot = root->root_key.objectid;
> __entry->diff = diff;
> + __entry->type = type;
> ),
>
> TP_printk_btrfs("refroot=%llu(%s) type=%s diff=%lld",
>
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