[ceph-users] Re: ln: failed to create hard link 'file name': Read-only file system

enabling the kclient debug logs and

also the mds debug logs

Hi Gregory, thanks for your reply. First a quick update. Here is how I get ln to work after it failed, there seems no timeout: $ ln envs/satwindspy/include/ffi.h mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h ln: failed to create hard link 'mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h': Read-only file system $ ls -l envs/satwindspy/include mambaforge/pkgs/libffi-3.3-h58526e2_2 envs/satwindspy/include: total 7664 -rw-rw-r--. 1 rit rit 959 Mar 5 2021 ares_build.h [...] $ ln envs/satwindspy/include/ffi.h mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h After an ls -l on both directories ln works. To the question: How can I pull out a log from the nfs server? There is nothing in /var/log/messages. I can't reproduce it with simple commands on the NFS client. It seems to occur only when a large number of files/dirs is created. I can make the archive available to you if this helps. Best regards, ================= Frank Schilder AIT Risø Campus Bygning 109, rum S14 ________________________________________ From: Gregory Farnum &lt;gfarnum(a)redhat.com&gt; Sent: Wednesday, March 22, 2023 4:14 PM To: Frank Schilder Cc: ceph-users(a)ceph.io Subject: Re: [ceph-users] Re: ln: failed to create hard link 'file name': Read-only file system Do you have logs of what the nfs server is doing? Managed to reproduce it in terms of direct CephFS ops? On Wed, Mar 22, 2023 at 8:05 AM Frank Schilder <frans@dtu.dk<mailto:frans@dtu.dk>> wrote: I have to correct myself. It also fails on an export with "sync" mode. Here is an strace on the client (strace ln envs/satwindspy/include/ffi.h mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h): [...] stat("mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h", 0x7ffdc5c32820) = -1 ENOENT (No such file or directory) lstat("envs/satwindspy/include/ffi.h", {st_mode=S_IFREG|0664, st_size=13934, ...}) = 0 linkat(AT_FDCWD, "envs/satwindspy/include/ffi.h", AT_FDCWD, "mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h", 0) = -1 EROFS (Read-only file system) [...] write(2, "ln: ", 4ln: ) = 4 write(2, "failed to create hard link 'mamb"..., 80failed to create hard link 'mambaforge/pkgs/libffi-3.3-h58526e2_2/include/ffi.h') = 80 [...] write(2, ": Read-only file system", 23: Read-only file system) = 23 write(2, "\n", 1 ) = 1 lseek(0, 0, SEEK_CUR) = -1 ESPIPE (Illegal seek) close(0) = 0 close(1) = 0 close(2) = 0 exit_group(1) = ? +++ exited with 1 +++ Has anyone advice? Thanks! ================= Frank Schilder AIT Risø Campus Bygning 109, rum S14 ________________________________________ From: Frank Schilder <frans@dtu.dk<mailto:frans@dtu.dk>> Sent: Wednesday, March 22, 2023 2:44 PM To: ceph-users@ceph.io<mailto:ceph-users@ceph.io> Subject: [ceph-users] ln: failed to create hard link 'file name': Read-only file system Hi all, on an NFS re-export of a ceph-fs (kernel client) I observe a very strange error. I'm un-taring a larger package (1.2G) and after some time I get these errors: ln: failed to create hard link 'file name': Read-only file system The strange thing is that this seems only temporary. When I used "ln src dst" for manual testing, the command failed as above. However, after that I tried "ln -v src dst" and this command created the hard link with exactly the same path arguments. During the period when the error occurs, I can't see any FS in read-only mode, neither on the NFS client nor the NFS server. Funny thing is that file creation and write still works, its only the hard-link creation that fails. For details, the set-up is: file-server: mount ceph-fs at /shares/path, export /shares/path as nfs4 to other server other server: mount /shares/path as NFS More precisely, on the file-server: fstab: MON-IPs:/shares/folder /shares/nfs/folder ceph defaults,noshare,name=NAME,secretfile=sec.file,mds_namespace=FS-NAME,_netdev 0 0 exports: /shares/nfs/folder -no_root_squash,rw,async,mountpoint,no_subtree_check DEST-IP On the host at DEST-IP: fstab: FILE-SERVER-IP:/shares/nfs/folder /mnt/folder nfs defaults,_netdev 0 0 Both, the file server and the client server are virtual machines. The file server is on Centos 8 stream (4.18.0-338.el8.x86_64) and the client machine is on AlmaLinux 8 (4.18.0-425.13.1.el8_7.x86_64). When I change the NFS export from "async" to "sync" everything works. However, that's a rather bad workaround and not a solution. Although this looks like an NFS issue, I'm afraid it is a problem with hard links and ceph-fs. It looks like a race with scheduling and executing operations on the ceph-fs kernel mount. Has anyone seen something like that? Thanks and best regards, ================= Frank Schilder AIT Risø Campus Bygning 109, rum S14 _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io<mailto:ceph-users@ceph.io> To unsubscribe send an email to ceph-users-leave@ceph.io<mailto:ceph-users-leave@ceph.io> _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io<mailto:ceph-users@ceph.io> To unsubscribe send an email to ceph-users-leave@ceph.io<mailto:ceph-users-leave@ceph.io> _______________________________________________ ceph-users mailing list -- ceph-users(a)ceph.io To unsubscribe send an email to ceph-users-leave(a)ceph.io