On 6/19/20 8:56 PM, J. Bruce Fields wrote:
> On Sat, Jun 20, 2020 at 11:49:57AM +1000, Dave Chinner wrote:
...
>> However, other people have different opinions on this matter (and we
>> know that from the people who considered XFS v4 -> v5 going slower
>> because iversion a major regression), and so we must acknowledge
>> those opinions even if we don't agree with them.
>
> Do you have any of those reports handy? Were there numbers?
I can't answer that but did a little digging. MS_I_VERSION as an option
appeared here:
commit 7a224228ed79d587ece2304869000aad1b8e97dd
Author: Jean Noel Cordenner <jean-noel.cordenner@xxxxxxxx>
Date: Mon Jan 28 23:58:27 2008 -0500
vfs: Add 64 bit i_version support
The i_version field of the inode is changed to be a 64-bit counter that
is set on every inode creation and that is incremented every time the
inode data is modified (similarly to the "ctime" time-stamp).
The aim is to fulfill a NFSv4 requirement for rfc3530.
This first part concerns the vfs, it converts the 32-bit i_version in
the generic inode to a 64-bit, a flag is added in the super block in
order to check if the feature is enabled and the i_version is
incremented in the vfs.
Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
Signed-off-by: Jean Noel Cordenner <jean-noel.cordenner@xxxxxxxx>
Signed-off-by: Kalpak Shah <kalpak@xxxxxxxxxxxxx>
and ext4's Opt_i_version mount option appeared here:
commit 25ec56b518257a56d2ff41a941d288e4b5ff9488
Author: Jean Noel Cordenner <jean-noel.cordenner@xxxxxxxx>
Date: Mon Jan 28 23:58:27 2008 -0500
ext4: Add inode version support in ext4
This patch adds 64-bit inode version support to ext4. The lower 32 bits
are stored in the osd1.linux1.l_i_version field while the high 32 bits
are stored in the i_version_hi field newly created in the ext4_inode.
This field is incremented in case the ext4_inode is large enough. A
i_version mount option has been added to enable the feature.
Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
Signed-off-by: Andreas Dilger <adilger@xxxxxxxxxxxxx>
Signed-off-by: Kalpak Shah <kalpak@xxxxxxxxxxxxx>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jean Noel Cordenner <jean-noel.cordenner@xxxxxxxx>
so the optional enablement was there on day one, without any real explanation
of why.
-Eric
