Re: [REGRESSION]: cephfs: file corruption when reading content via in-kernel ceph client

[Christian Ebner <c.ebner@proxmox.com>]

On 9/6/24 18:22, David Howells wrote:
> 
> Are they using local caching with cachefiles?
> 
> David

Hi David,

if you are referring to [0] than no, there is no such caching layer active.

Output of
```
$ cat /proc/fs/fscache/{caches,cookies,requests,stats,volumes}
CACHE    REF   VOLS  OBJS  ACCES S NAME
======== ===== ===== ===== ===== = ===============
COOKIE   VOLUME   REF ACT ACC S FL DEF
======== ======== === === === = == ================
REQUEST  OR REF FL ERR  OPS COVERAGE
======== == === == ==== === =========
Netfs  : DR=0 RA=140 RF=0 WB=0 WBZ=0
Netfs  : BW=0 WT=0 DW=0 WP=0
Netfs  : ZR=0 sh=0 sk=0
Netfs  : DL=548 ds=548 df=0 di=0
Netfs  : RD=0 rs=0 rf=0
Netfs  : UL=0 us=0 uf=0
Netfs  : WR=0 ws=0 wf=0
Netfs  : rr=0 sr=0 wsc=0
-- FS-Cache statistics --
Cookies: n=0 v=0 vcol=0 voom=0
Acquire: n=0 ok=0 oom=0
LRU    : n=0 exp=0 rmv=0 drp=0 at=0
Invals : n=0
Updates: n=0 rsz=0 rsn=0
Relinqs: n=0 rtr=0 drop=0
NoSpace: nwr=0 ncr=0 cull=0
IO     : rd=0 wr=0 mis=0
VOLUME   REF   nCOOK ACC FL CACHE           KEY
======== ===== ===== === == =============== ================
```

Also, disabling caching by stetting `client_cache_size` to 0 and 
`client_oc` to false as found in [1] did not change the corrupted read 
behavior.

[0] https://www.kernel.org/doc/html/latest/filesystems/caching/fscache.html
[1] 
https://docs.ceph.com/en/latest/cephfs/client-config-ref/#client-config-reference

Regards,
Chris