Date: Fri, 17 Nov 2023 17:35:04 -0500 From: Garrett Wollman <wollman@bimajority.org> To: Mike Karels <mike@karels.net> Cc: freebsd-stable@freebsd.org Subject: Re: NFS exports of ZFS snapshots broken Message-ID: <25943.60056.880614.452966@hergotha.csail.mit.edu> In-Reply-To: <E5F6DD43-6CF9-44E3-A008-2EBEA287BA40@karels.net> References: <25943.54632.572766.121032@hergotha.csail.mit.edu> <E5F6DD43-6CF9-44E3-A008-2EBEA287BA40@karels.net>
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<<On Fri, 17 Nov 2023 15:57:42 -0600, Mike Karels <mike@karels.net> said: > I have not run into this, so I tried it just now. I had no problem. > The server is 13.2, fully patched, the client is up-to-date -current, > and the mount is v4. On my 13.2 client and 13-stable server, I see: 25034 ls CALL open(0x237d32f9a000,0x120004<O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC>) 25034 ls NAMI "/mnt/tools/.zfs/snapshot/weekly-2023-45" 25034 ls RET open 4 25034 ls CALL fcntl(0x4,F_ISUNIONSTACK,0x0) 25034 ls RET fcntl 0 25034 ls CALL getdirentries(0x4,0x237d32faa000,0x1000,0x237d32fa7028) 25034 ls RET getdirentries -1 errno 5 Input/output error 25034 ls CALL close(0x4) 25034 ls RET close 0 25034 ls CALL exit(0) Certainly a libc bug here that getdirentries(2) returning [EIO] results in ls(1) returning EXIT_SUCCESS, but the [EIO] error is consistent across both FreeBSD and Linux clients. Looking at this from the RPC side: (PUTFH, GETATTR, LOOKUP(snapshotname), GETFH, GETATTR) [NFS4_OK for all ops] (PUTFH, GETATTR) [NFS4_OK, NFS4_OK] (PUTFH, ACCESS(0x3f), GETATTR) [NFS4_OK, NFS4_OK, rights = 0x03, NFS4_OK] (PUTFH, GETATTR, LOOKUPP, GETFH, GETATTR) [NFS4_OK, NFS4_OK, NFS4ERR_NOFILEHANDLE] and at this point the [EIO] is returned. It seems that clients always do a LOOKUPP before calling READDIR, and this is failing when the subject file handle is the snapshot. The client is perfectly able to *traverse into* the snapshot: if I try to list a subdirectory I know exists in the snapshot, the client is able to LOOKUP(dirname) just fine, but LOOKUPP still fails with NFS4ERR_NOFILEHANDLE *on the subndirectory*. -GAWollman
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