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willscott / go-nfs

golang NFSv3 server
Apache License 2.0
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Symbolic Links Cause Stale NFS File Handles #127

Closed t0rr3sp3dr0 closed 9 months ago

t0rr3sp3dr0 commented 9 months ago

When I list a mounted directory that contains symbolic links on macOS, I get Stale NFS file handle errors. Bellow, *.app are symbolic links to directories using their absolute paths.

pedro@Pedros-MacBook-Pro ~ % ls -@Oahl ~/Applications                                                                    
total 2924
dr-xr-xr-x@   5 root   wheel  -  160B 31 Dec  1969 .
    com.apple.FinderInfo      32B 
drwxr-x---+ 103 pedro  staff  -  3.2K 30 Dec 21:02 ..
-rw-rw-rw-    1 root   wheel  -  1.4M 30 Dec 21:35 .VolumeIcon.icns
-rw-rw-rw-    1 root   wheel  -  406B 30 Dec 21:35 ._.

ls: /Users/pedro/Applications/IntelliJ IDEA CE.app: Stale NFS file handle
lrwxr-xr-x    1 root   wheel  -  116B 31 Dec  1969 IntelliJ IDEA CE.app

ls: /Users/pedro/Applications/Sublime Text.app: Stale NFS file handle
lrwxr-xr-x    1 root   wheel  -   91B 31 Dec  1969 Sublime Text.app

ls: /Users/pedro/Applications/Visual Studio Code.app: Stale NFS file handle
lrwxr-xr-x    1 root   wheel  -  105B 31 Dec  1969 Visual Studio Code.app
pedro@Pedros-MacBook-Pro ~ % ls -@Oahl ~/Applications
ls: IntelliJ IDEA CE.app: Stale NFS file handle
ls: Sublime Text.app: Stale NFS file handle
ls: Visual Studio Code.app: Stale NFS file handle
total 2921
dr-xr-xr-x@   5 root   wheel  -  160B 31 Dec  1969 .
    com.apple.FinderInfo      32B 
drwxr-x---+ 103 pedro  staff  -  3.2K 30 Dec 21:02 ..
-rw-rw-rw-    1 root   wheel  -  1.4M 30 Dec 21:38 .VolumeIcon.icns
-rw-rw-rw-    1 root   wheel  -  406B 30 Dec 21:38 ._.
ls: fts_read: Stale NFS file handle

I'm also getting this error message from the NFS client: nfs loadattrcache vnode changed type, was 5 now 2. Meaning that the vnode type was VLNK and now is VDIR.

I've added some logging, and my FS implementation is indeed returning different vnode types for those files. But that's because the NFS library is calling billy.Filesystem#ReadDir, that "If the entry denotes a symbolic link, Info reports the information about the link itself, not the link's target.", and then it calls billy.Filesystem#Stat instead of billy.Filesystem#Lstat. So the vnode type will always change.

This patch addressed my problem: https://github.com/t0rr3sp3dr0/go-nfs/commit/7d4f8290f183abd44a6211fe9e6980a6f2583863

But I'm not sure if changing the implementation of tryStat to always use billy.Filesystem#Lstat is something we can do. I think we need a tryLstat and move to this new function on a case-by-case basis.

willscott commented 9 months ago

Forgot to close this earlier, but merged in your fix. that makes sense.