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Date:      Mon, 19 Dec 2016 05:55:12 +0000
From:      Colin Percival <cperciva@tarsnap.com>
To:        Rick Macklem <rmacklem@uoguelph.ca>
Cc:        "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org>
Subject:   Re: ESTALE after cwd deleted by same NFS client
Message-ID:  <0100015915a5eb1d-65f1e4a1-549d-47a4-9aaf-3ba9f191ec44-000000@email.amazonses.com>
In-Reply-To: <010001590945e9b3-015a4d05-2646-44ba-9db9-415e8b9119dd-000000@email.amazonses.com>
References:  <01000158f023675b-41b35a73-4428-4937-853b-62db4fb9b984-000000@email.amazonses.com> <20161212054233.GU8460@kduck.kaduk.org> <01000158f1abc081-d4eddc58-3b4b-41dd-aa1e-0157d2fad812-000000@email.amazonses.com> <20161212163603.GV8460@kduck.kaduk.org> <YQBPR01MB018054EE62DEFDC73784AD9BDD9B0@YQBPR01MB0180.CANPRD01.PROD.OUTLOOK.COM> <01000158fc3da2c5-c13da088-e7b9-4ac0-ac01-ec49a275dd24-000000@email.amazonses.com> <YTXPR01MB0189ACD940B7D399A6855CB8DD9A0@YTXPR01MB0189.CANPRD01.PROD.OUTLOOK.COM> <YTXPR01MB01891CB02D5D7BA46579F1BFDD9D0@YTXPR01MB0189.CANPRD01.PROD.OUTLOOK.COM> <010001590945e9b3-015a4d05-2646-44ba-9db9-415e8b9119dd-000000@email.amazonses.com>

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On 12/16/16 12:14, Colin Percival wrote:
> making this change in nfs_lookup
>> --- sys/fs/nfsclient/nfs_clvnops.c      (revision 310132)
>> +++ sys/fs/nfsclient/nfs_clvnops.c      (working copy)
>> @@ -1144,7 +1144,7 @@
>>                         *vpp = NULLVP;
>>                 }
>>  
>> -               if (error != ENOENT) {
>> +               if (error != ENOENT && error != ESTALE) {
>>                         if (NFS_ISV4(dvp))
>>                                 error = nfscl_maperr(td, error, (uid_t)0,
>>                                     (gid_t)0);
> 
> fixes the case I described above (for some definition of "fixes" -- I'm not
> sure if this is the correct way of handling ESTALE here?) but I'm still seeing
> ESTALEs from buildworld's cleandir so I think there must be some other place
> where something odd is happening.

Further information: In addition to the "lookup relative to a directory which
has been deleted out from underneath us" case which causes ESTALE to land in
nfs_lookup, the cleandir step of buildworld results in ESTALE being returned
by nfsrpc_getattr into nfs_getattr (landing ultimately in getcwd), and ESTALE
being returned by nfsrpc_accessrpc into nfs34_access_otw (landing ultimately
in stat and lstat).

In UFS there are checks for effnlink == 0 which result in e.g. ufs_lookup
returning ENOENT; would it make sense to add NREMOVED to struct nfsnode.n_flag
and check this in the appropriate nfs_* calls?

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid



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