On Fri, Oct 10, 2014 at 04:24:26PM +0800, Miao Xie wrote:
> On Fri, 10 Oct 2014 15:13:31 +0800, Eryu Guan wrote:
> > On Thu, Sep 25, 2014 at 06:28:14PM +0800, Eryu Guan wrote:
> >> device replace could fail due to another running scrub process, but this
> >> failure doesn't get returned to userspace.
> >>
> >> The following steps could reproduce this issue
> >>
> >> mkfs -t btrfs -f /dev/sdb1 /dev/sdb2
> >> mount /dev/sdb1 /mnt/btrfs
> >> while true; do
> >> btrfs scrub start -B /mnt/btrfs >/dev/null 2>&1
> >> done &
> >> btrfs replace start -Bf /dev/sdb2 /dev/sdb3 /mnt/btrfs
> >> # if this replace succeeded, do the following and repeat until
> >> # you see this log in dmesg
> >> # BTRFS: btrfs_scrub_dev(/dev/sdb2, 2, /dev/sdb3) failed -115
> >> #btrfs replace start -Bf /dev/sdb3 /dev/sdb2 /mnt/btrfs
> >>
> >> # once you see the error log in dmesg, check return value of
> >> # replace
> >> echo $?
> >>
> >> Also only WARN_ON if the return code is not -EINPROGRESS.
> >>
> >> Signed-off-by: Eryu Guan <guane...@gmail.com>
> >
> > Ping, any comments on this patch?
> >
> > Thanks,
> > Eryu
> >> ---
> >> fs/btrfs/dev-replace.c | 8 +++++---
> >> 1 file changed, 5 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
> >> index eea26e1..44d32ab 100644
> >> --- a/fs/btrfs/dev-replace.c
> >> +++ b/fs/btrfs/dev-replace.c
> >> @@ -418,9 +418,11 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
> >> &dev_replace->scrub_progress, 0, 1);
> >>
> >> ret = btrfs_dev_replace_finishing(root->fs_info, ret);
> >> - WARN_ON(ret);
> >> + /* don't warn if EINPROGRESS, someone else might be running scrub */
> >> + if (ret != -EINPROGRESS)
> >> + WARN_ON(ret);
>
> picky comment
>
> I prefer WARN_ON(ret && ret != -EINPROGRESS).
Yes, this is simpler :)
>
> >>
> >> - return 0;
> >> + return ret;
>
> here we will return -EINPROGRESS if scrub is running, I think it better that
> we assign some special number to args->result, and then return 0, just like
> the case the device replace is running.
Seems that requires a new result type, say,
#define BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS 3
and assign this result to args->result if btrfs_scrub_dev() returned
-EINPROGRESS
But I don't think returning 0 unconditionally is a good idea, since
btrfs_dev_replace_finishing() could return other errors too, that way
these errors will be lost, and userspace still won't catch the
errors ($? is 0)
What I'm thinking about is something like:
ret = btrfs_scrub_dev(...);
ret = btrfs_dev_replace_finishing(root->fs_info, ret);
if (ret == -EINPROGRESS) {
args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
ret = 0;
} else {
WARN_ON(ret);
}
return ret;
What do you think? If no objection I'll work on v2.
Thanks for your review!
Eryu
>
> Thanks
> Miao
>
> >>
> >> leave:
> >> dev_replace->srcdev = NULL;
> >> @@ -538,7 +540,7 @@ static int btrfs_dev_replace_finishing(struct
> >> btrfs_fs_info *fs_info,
> >> btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
> >> mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
> >>
> >> - return 0;
> >> + return scrub_ret;
> >> }
> >>
> >> printk_in_rcu(KERN_INFO
> >> --
> >> 1.8.3.1
> >>
> > --
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>
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