From: Goffredo Baroncelli <kreijack@inwind.it>
To: Jeff Mahoney <jeffm@suse.com>
Cc: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [patch 00/13] sysfs publishing patchset
Date: Tue, 29 Oct 2013 22:57:29 +0100 [thread overview]
Message-ID: <52702F49.5060306@inwind.it> (raw)
In-Reply-To: <527019EF.5040608@suse.com>
Hi Jeff
On 2013-10-29 21:26, Jeff Mahoney wrote:
>> This for two reasons:
>> > 1) so it would be possible to show also the disks informations under a
>> > dev/ directory. It would be possible to handle the case that some disks
>> > are registered in btrfs but the related filesystems aren't mounted (like
>> > after a "btrfs dev scan" command)
>> >
>> > 2) it would help the browsing of the /sys/btrfs/ hierarchy: every
>> > directory under /sys/btrfs/fs/ represents a filesystem. With the current
>> > structure not all the directory under /sys/btrfs are related to a
>> > filesystem (like the features/ one, but I am sure that other directories
>> > sooner or later will appear)
> I'd like to define /sys/fs/btrfs/<fsid> as filesystem-specific and
> anything else as btrfs-wide.
I fully agree. My idea was to put under btrfs/dev *only* the device
which are registered in BTRFS by "btrfs dev scan" and/or mount commands.
> This is what ext4 already does with the
> exception that they use block device names instead of fsids. Your device
> use case is interesting, but a tough one to implement well since it is a
> cache that can be wrong as soon as the user decides to mkfs a device
> (either as btrfs or anything else) without calling btrfs dev scan
> afterward.
Right, I never though about this case.
> I wouldn't necessarily oppose such a feature; I just don't
> think it merits moving the primary case of per-filesystem information
> deeper into the hierarchy.
Fortunately the two thing are unrelated. The
/sys/fs/btrfs/dev/<device-uuid>/... hierarchy can live with
/sys/fs/btrfs/<fsid>/... or /sys/fs/btrfs/fs/<fsid>.
BTW, I am playing with your patch. What is the means of the field
<fsid>/allocation/*/disk_total ? In a RAID5 it seems to be the space
available ( == (<number-of-disk> - 1)*<size-of-chunk> ) and not the disk
space consumed ( == <number-of-disk> * <size-of-chunk> ). In fact it
seems that disk_total == total_bytes...
Ok looking at the kernel code (update_space_info() in extent-tree.c) it
seems that the info contained in space_info is bogus in case of
RAID5/RAID6....
--
gpg @keyserver.linux.it: Goffredo Baroncelli (kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
prev parent reply other threads:[~2013-10-29 22:03 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-21 21:19 [patch 00/13] sysfs publishing patchset Jeff Mahoney
2013-10-21 21:19 ` [patch 01/13] btrfs: add ioctls to query/change feature bits online Jeff Mahoney
2013-10-21 21:19 ` [patch 02/13] kobject: export kobj_sysfs_ops Jeff Mahoney
2013-10-22 14:44 ` Jeff Mahoney
2013-10-21 21:19 ` [patch 03/13] btrfs: publish supported featured in sysfs Jeff Mahoney
2013-10-21 21:19 ` [patch 04/13] btrfs: publish per-super attributes " Jeff Mahoney
2013-10-21 21:19 ` [patch 05/13] btrfs: publish per-super features " Jeff Mahoney
2013-10-21 21:19 ` [patch 06/13] btrfs: publish unknown feature bits " Jeff Mahoney
2013-10-21 21:19 ` [patch 07/13] btrfs: add ability to change features via sysfs Jeff Mahoney
2013-10-21 21:19 ` [patch 08/13] btrfs: use feature attribute names to print better error messages Jeff Mahoney
2013-10-21 21:19 ` [patch 09/13] btrfs: add ioctl to export size of global metadata reservation Jeff Mahoney
2013-10-21 21:19 ` [patch 10/13] btrfs: publish allocation data in sysfs Jeff Mahoney
2013-10-29 18:49 ` Jeff Mahoney
2013-10-21 21:19 ` [patch 11/13] btrfs: publish device membership " Jeff Mahoney
2013-10-21 21:19 ` [patch 12/13] btrfs: publish fs label " Jeff Mahoney
2013-10-21 21:19 ` [patch 13/13] btrfs: add tracing for failed reservations Jeff Mahoney
2013-10-22 18:26 ` [patch 00/13] sysfs publishing patchset Josef Bacik
2013-10-22 18:39 ` Jeff Mahoney
2013-10-22 20:43 ` Josef Bacik
2013-10-29 18:25 ` Goffredo Baroncelli
2013-10-29 20:26 ` Jeff Mahoney
2013-10-29 21:57 ` Goffredo Baroncelli [this message]
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