2:33 a.m.
On 2/5/20 3:21 PM, des(a)vmware.com wrote:
According to page 112 in RFC 7530, NFSv4 read operation should be
allowed on a open state with share access OPEN4_SHARE_ACCESS_WRITE to accommodate clients
whose write implementation may unavoidably do reads (e.g., due to buffer cache
constraints).
This condition is taken care in normal flow in nfs4_read() in here:
https://github.com/nfs-ganesha/nfs-ganesha/blob/next/src/Protocols/NFS/nf...
RFC doesn't clearly state if the same applies even in case of
delegations. So I am not sure about it though logically it may make
sense to allow reads if its the same client.
Nevertheless, we do need below block. In case there is delegation
granted, READs are performed using delegation state and there is no open
state and hence shall bypass share_access checks below. Maybe we can
check for sdeleg->share_deny instead of sdeleg->share_access in this
block to verify if ACCESS_READ is denied.
Thanks,
Soumya
But if the open has granted a write delegation(OPEN_DELEGATE_WRITE),
then the check for deleg state in nfs4_read() does not allow Read op as per RFC mentioned
above but return NFS4ERR_BAD_STATEID.
https://github.com/nfs-ganesha/nfs-ganesha/blob/next/src/Protocols/NFS/nf...
case STATE_TYPE_DELEG:
/* Check if the delegation state allows READ or
* if the open share state allows READ access
* in case of WRITE delegation */
sdeleg = &state_found->state_data.deleg;
if (!((sdeleg->sd_type & OPEN_DELEGATE_READ) ||
(sdeleg->share_access & OPEN4_SHARE_ACCESS_READ))) {
/* Invalid delegation for this operation. */
LogDebug(COMPONENT_STATE,
"Delegation type:%d state:%d",
sdeleg->sd_type,
sdeleg->sd_state);
res_READ4->status = NFS4ERR_BAD_STATEID;
goto out;
}
state_open = NULL;
break;
The ubuntu nfs client when it wants to write data, always opens file with
OPEN4_SHARE_ACCESS_WRITE and not OPEN4_SHARE_ACCESS_BOTH like other linux clients, so with
delegation enabled if we just do "echo data > file.txt ; cat file.txt", it
hangs forever with read op getting NFS4ERR_BAD_STATEID and client retrying forever.
I feel this whole block under 'case STATE_TYPE_DELEG' is not needed at all, as
the share access check will anyway happen below and we need not check the delegation state
while doing read operation.
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