On Thu, Mar 14, 2024 at 8:26 PM Qu Wenruo quwenruo.btrfs@gmx.com wrote:

在 2024/3/15 03:47, Filipe Manana 写道:

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On Thu, Mar 14, 2024 at 9:54 AM Qu Wenruo wqu@suse.com wrote:

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Currently when we increase the device statistics, it would always lead to an error message in the kernel log.

I would argue this behavior is not ideal:

• It would flood the dmesg and bury real important messages One common scenario is scrub. If scrub hit some errors, it would cause both scrub and btrfs_dev_stat_inc_and_print() to print error messages.

  And in that case, btrfs_dev_stat_inc_and_print() is completely useless.

• The results of btrfs_dev_stat_inc_and_print() is mostly for history monitoring, doesn't has enough details

  If we trigger the errors during regular read, such messages from btrfs_dev_stat_inc_and_print() won't help us to locate the cause either.

The real usage for the btrfs device statistics is for some user space daemon to check if there is any new errors, acting like some checks on SMART, thus we don't really need/want those messages in dmesg.

This patch would reduce the log level to debug (disabled by default) for btrfs_dev_stat_inc_and_print(). For users really want to utilize btrfs devices statistics, they should go check "btrfs device stats" periodically, and we should focus the kernel error messages to more important things.

Not sure if this is the right thing to do.

In the scrub context it can be annoying for sure. Other cases I'm not so sure about, because having error messages in dmesg/syslog may help notice issues more quickly.

For non-scrub cases, I'd argue we already have enough output:

No matter if the error is fixed or not, every time a mirror got csum mismatch or other errors, we already have error message output:

Data: btrfs_print_data_csum_error() Meta: btrfs_validate_extent_buffer()

For repaired ones, we have extra output from bio layer for both metadata and data: btrfs_repair_io_failure()

So I'd say the dev_stat ones are already duplicated.

Ok, I suppose it's fine then.

Reviewed-by: Filipe Manana fdmanana@suse.com

Thanks.

Thanks, Qu

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CC: stable@vger.kernel.org Signed-off-by: Qu Wenruo wqu@suse.com

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fs/btrfs/volumes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e49935a54da0..126145950ed3 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7828,7 +7828,7 @@ void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index)

     if (!dev->dev_stats_valid)
             return;

•   btrfs_err_rl_in_rcu(dev->fs_info,
  

•   btrfs_debug_rl_in_rcu(dev->fs_info,
             "bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u",
                        btrfs_dev_name(dev),
                        btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
  

-- 2.44.0