On 04/08/2013 11:22 PM, David Sterba wrote:
On Thu, Mar 21, 2013 at 07:56:44PM +0800, Anand Jain wrote:
We should avoid using non multi-path (mp) path for mp disks
As of now there is no good way (like api) to check that.
A workaround way is to check if the O_EXCL open is unsuccessful.
This is safe since otherwise the BTRFS_IOC_SCAN_DEV ioctl would
fail if the disk-path can not be opened with the flag O_EXCL set.
Agreed. Alternatively we could try to parse the /sys entries.
sorry to confuse you on this David. hope the below
description will clarify..
this patch actually combined two fixes - one as in the
subject here, and the other a small fix which is to check if
the kernel module is loaded.
the later revised patch separated this into two patch-set
- v6: access to backup superblock (dt: 04/05/13)
- [PATCH 0/9] a bunch of miscellaneous bug fixes (dt: 04/05/13)
in the above v6... as indicated I have dropped the
[PATCH] btrfs-progs: make btrfs dev scan multi path aware
since its found that when btrfs is mounted it would open
the dev with O_EXCL as well, so we can't depend on this
workaround.
Further original problem related to the multi-path wasn't
reproducible with my above two patch-sets applied (in the
same order) on top integration-20130321 . IMO I lost the
trigger as I don't think there is any fix related to
multi path. If there is any good reproducible test-case
related to multi-path I would dig further.
The above patch set viz. "v6: access to backup superblock"
and "[PATCH 0/9] a bunch of miscellaneous bug fixes" are
important. They bring a lot of stability around the area
of mkfs, btrfs fi show, btrfs dev scan.
Thanks, Anand
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