ACK/Cmt: [SRU][B F J K L][PATCH 0/1] Fix the significant increase in NFS ACCESS operations

[Dimitri John Ledkov]

Acked-by: Dimitri John Ledkov <dimitri.ledkov at canonical.com>

On Fri, 17 Mar 2023 at 02:23, Chengen Du <chengen.du at canonical.com> wrote:
>
> BugLink: https://bugs.launchpad.net/bugs/2009325
>
> SRU Justification:
>
> [Impact]
> When a user logs in and their login time is more recent than the cache's timestamp,
> a new entry is created to replace the original entry in the RB-tree.
> Currently, the timestamp is only set if the entry is not found in the RB-tree.
> This can lead to the timestamp being undefined when the entry already exists,
> potentially causing a significant increase in ACCESS operations if the timestamp is set to zero.
>
> [Fix]
> The fix corrects the timing for assigning the access cache timestamp.
>
> git://git.linux-nfs.org/projects/anna/linux-nfs linux-nfs branch
> 21fd9e8700de86d1169f6336e97d7a74916ed04a (NFS: Correct timing for assigning access cache timestamp)
>

It is actually https://git.linux-nfs.org/?p=anna/linux-nfs.git;a=commit;h=21fd9e8700de86d1169f6336e97d7a74916ed04a
as seen on linux-next (not linux-nfs) branch.

Also this commit already appears without any branch in cel repo at
https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/commit/?id=21fd9e8700de86d1169f6336e97d7a74916ed04a

And in lore there is agreement to submit it for the upcoming -rc.

Normally these are pulled by Linus unmodified, thus imho it is
justified to use `cherry-picked` stanza, although it hasn't yet been
pulled.



> [Test Plan]
> 1. Create some files in an NFS folder from the client side.
> 2. Log out and log back in with the same user.
> 3. Access the existing files in the NFS folder and confirm that the client side only sends one ACCESS operation to the server side.
>
> [Where problems could occur]
> This patch only adjusts the timing for initializing the cache's timestamp,
> which was found to be incorrect in the original code.
> While it does have an impact on NFS-related operations,
> it does not affect any other aspects of the system's logic apart from timestamp initialization.
>
> Chengen Du (1):
>   NFS: Correct timing for assigning access cache timestamp
>
>  fs/nfs/dir.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> --
> 2.37.2
>
>
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-- 
okurrr,

Dimitri