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nfscl: Fix another deadlock related to the NFSv4 clientID lock

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Without this patch, it is possible to hang the NFSv4 client,
when a rename/remove is being done on a file where the client
holds a delegation, if pNFS is being used.  For a delegation
to be returned, dirty data blocks must be flushed to the NFSv4
server.  When pNFS is in use, a shared lock on the clientID
must be acquired while doing a write to the DS(s).
However, if rename/remove is doing the delegation return
an exclusive lock will be acquired on the clientID, preventing
the write to the DS(s) from acquiring a shared lock on the clientID.

This patch stops rename/remove from doing a delegation return
if pNFS is enabled.  Since doing delegation return in the same
compound as rename/remove is only an optimization, not doing
so should not cause problems.

This problem was detected during a recent NFSv4 interoperability
testing event held by the IETF working group.

MFC after:	1 week
This commit is contained in:
Rick Macklem 2021-10-12 17:21:01 -07:00
parent 19e008e7f7
commit b82168e657
1 changed files with 4 additions and 0 deletions
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4
sys/fs/nfsclient/nfs_clstate.c
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@ -4607,6 +4607,8 @@ nfscl_removedeleg(vnode_t vp, NFSPROC_T *p, nfsv4stateid_t *stp)
int igotlock = 0, triedrecall = 0, needsrecall, retcnt = 0, islept;
nmp = VFSTONFS(vp->v_mount);
if (NFSHASPNFS(nmp))
return (retcnt);
NFSLOCKMNT(nmp);
if ((nmp->nm_privflag & NFSMNTP_DELEGISSUED) == 0) {
NFSUNLOCKMNT(nmp);
@ -4712,6 +4714,8 @@ nfscl_renamedeleg(vnode_t fvp, nfsv4stateid_t *fstp, int *gotfdp, vnode_t tvp,
nmp = VFSTONFS(fvp->v_mount);
*gotfdp = 0;
*gottdp = 0;
if (NFSHASPNFS(nmp))
return (retcnt);
NFSLOCKCLSTATE();
/*
* Loop around waiting for: