From: Nikolay Borisov <nborisov@suse.com>
To: Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: qgroup: Fix wrong parameter order for trace events
Date: Wed, 16 Oct 2019 10:37:08 +0300 [thread overview]
Message-ID: <f1976eb6-73d6-623e-5c16-79b036eabcb6@suse.com> (raw)
In-Reply-To: <20191016073149.23244-1-wqu@suse.com>
On 16.10.19 г. 10:31 ч., 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@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
next prev parent reply other threads:[~2019-10-16 7:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 7:31 [PATCH] btrfs: qgroup: Fix wrong parameter order for trace events Qu Wenruo
2019-10-16 7:37 ` Nikolay Borisov [this message]
2019-10-16 18:40 ` David Sterba
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