From: Amir Goldstein <amir73il@gmail.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Allison Henderson <allison.henderson@oracle.com>,
linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH 00/17] Parent Pointers V3
Date: Sat, 21 Oct 2017 10:34:30 +0300 [thread overview]
Message-ID: <CAOQ4uxjQk_82RxzSKWT+UeepkKXtrXbVmNW2wz6Mngq=UX+XZg@mail.gmail.com> (raw)
In-Reply-To: <20171020224157.GS3666@dastard>
On Sat, Oct 21, 2017 at 1:41 AM, Dave Chinner <david@fromorbit.com> wrote:
> On Thu, Oct 19, 2017 at 07:11:50AM +0300, Amir Goldstein wrote:
>> On Thu, Oct 19, 2017 at 1:55 AM, Allison Henderson
>> <allison.henderson@oracle.com> wrote:
>> > Hi all,
>> >
>> > This is the third version of parent pointer attributes for xfs.
>> > I've integrated the suggestions made since v2, mostly moving the
>> > attr buffers in the xfs_attr_log_item to pointers that point to
>> > xfs_attr_item. I've also implementing the recovery routines for
>> > the xfs_attr_log_format. If I missed anything please point it
>> > out. As always, comments and feedback are appreciated. Thank
>> > you!
>> >
>>
>> A minor comment about the cover letter.
>> All designated reviewers must know exactly what "parent pointers" are for,
>> but it could be useful to add some context in the cover letter about the purpose
>> of this work for the sake of other readers on the list. Useful to refer to the
>> upcoming scrub support patches.
>>
>> BTW, not sure if this was mentioned in the previous lifetime of those
>> patches, but parent pointers can be used to implement exportfs operation
>> xfs_fs_fh_to_parent() for "non-connectable" file handles (FILEID_INO32_GEN)
>> and to implement xfs_fs_get_name(), which would make reconnect_path()
>> *much* more efficient.
>
> However, XFS only uses FILEID_INO32_GEN for directories
> because they have known parents. For them, we implement ->get_parent()
> and that means reconnect_path just does ->lookup("..") to find the
> parents and doesn't need anything special.
>
> We use FILEID_INO32_GEN_PARENT for all other types of files to
> encode the ino # + generation of the parent inode into the handle.
> That means for any non-dir file handle, our implemention of
> ->fh_to_parent will get us the parent info as efficiently as
> possible.
We only encode FILEID_INO32_GEN_PARENT when we are asked for
a "connectable" file handle, which is NOT the case with name_to_handle_at(2)
and is the case with nfsd on when NFS share is exported with subtree_check
options, which AFAIK, is the less common case.
The question is, when we encode a non-connectable file handle
(FILEID_INO32_GEN), will nfsd benefit from getting a connected file handle
after decode? (result may always be connected if dentry is already in cache).
>
> IOWs, parent pointers won't actually speed up filehandle ->
> dentry reconnection on XFS at all because we already encode parent
> pointers into the filehandles that need them....
Look at default implementation of ->get_name() in expfs.c and you will
see why I wrote that xfs_fs_get_name() would make reconnect_path()
*much* more efficient, even for directories.
Cheers,
Amir.
next prev parent reply other threads:[~2017-10-21 7:34 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-18 22:55 [PATCH 00/17] Parent Pointers V3 Allison Henderson
2017-10-18 22:55 ` [PATCH 01/17] Add helper functions xfs_attr_set_args and xfs_attr_remove_args Allison Henderson
2017-10-19 20:03 ` Darrick J. Wong
2017-10-21 1:14 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 02/17] Set up infastructure for deferred attribute operations Allison Henderson
2017-10-19 19:02 ` Darrick J. Wong
2017-10-21 1:08 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 03/17] Add xfs_attr_set_defered and xfs_attr_remove_defered Allison Henderson
2017-10-19 19:13 ` Darrick J. Wong
2017-10-21 1:08 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 04/17] Remove all strlen calls in all xfs_attr_* functions for attr names Allison Henderson
2017-10-19 19:15 ` Darrick J. Wong
2017-10-21 1:10 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 05/17] xfs: get directory offset when adding directory name Allison Henderson
2017-10-18 22:55 ` [PATCH 06/17] xfs: get directory offset when removing " Allison Henderson
2017-10-19 19:17 ` Darrick J. Wong
2017-10-21 1:11 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 07/17] xfs: get directory offset when replacing a " Allison Henderson
2017-10-18 22:55 ` [PATCH 08/17] xfs: add parent pointer support to attribute code Allison Henderson
2017-10-18 22:55 ` [PATCH 09/17] xfs: define parent pointer xattr format Allison Henderson
2017-10-18 22:55 ` [PATCH 10/17] :xfs: extent transaction reservations for parent attributes Allison Henderson
2017-10-19 18:24 ` Darrick J. Wong
[not found] ` <8680e0c1-ada8-06e3-e397-61a5076030be@oracle.com>
2017-10-20 23:45 ` Darrick J. Wong
2017-10-21 0:12 ` Allison Henderson
2017-10-21 1:07 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 11/17] Add the extra space requirements for parent pointer attributes when calculating the minimum log size during mkfs Allison Henderson
2017-10-19 18:13 ` Darrick J. Wong
2017-10-21 1:07 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 12/17] xfs: parent pointer attribute creation Allison Henderson
2017-10-19 19:36 ` Darrick J. Wong
[not found] ` <9185d3e8-4b41-b2d8-294b-934f7d3409f0@oracle.com>
2017-10-21 0:03 ` Darrick J. Wong
2017-10-21 1:11 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 13/17] xfs: add parent attributes to link Allison Henderson
2017-10-19 19:40 ` Darrick J. Wong
2017-10-21 1:12 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 14/17] xfs: remove parent pointers in unlink Allison Henderson
2017-10-19 19:43 ` Darrick J. Wong
2017-10-21 1:12 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 15/17] xfs_bmap_add_attrfork(): re-add error handling from set_attrforkoff() call Allison Henderson
2017-10-19 19:43 ` Darrick J. Wong
2017-10-21 1:13 ` Allison Henderson
2017-10-18 22:55 ` [PATCH 16/17] Add parent pointers to rename Allison Henderson
2017-10-18 22:55 ` [PATCH 17/17] Add the parent pointer support to the superblock version 5 Allison Henderson
2017-10-19 3:57 ` Amir Goldstein
2017-10-19 20:06 ` Darrick J. Wong
2017-10-20 3:18 ` Amir Goldstein
2017-10-19 19:45 ` Darrick J. Wong
2017-10-21 1:13 ` Allison Henderson
2017-10-19 4:11 ` [PATCH 00/17] Parent Pointers V3 Amir Goldstein
2017-10-20 3:22 ` Amir Goldstein
2017-10-21 1:06 ` Allison Henderson
2017-10-20 22:41 ` Dave Chinner
2017-10-21 7:34 ` Amir Goldstein [this message]
2017-10-22 23:27 ` Dave Chinner
2017-10-23 4:30 ` Amir Goldstein
2017-10-23 5:32 ` Dave Chinner
2017-10-23 6:48 ` Amir Goldstein
2017-10-23 8:40 ` Dave Chinner
2017-10-23 9:06 ` Amir Goldstein
2017-10-23 17:14 ` Darrick J. Wong
2017-10-23 19:20 ` Amir Goldstein
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