Merge pull request #1307 from trapexit/readme

Add NFS options to remote filesystems section of readme

README.md

@@ -2054,11 +2054,15 @@ generally recommended to use SMB when possible till situations
 change. That said issues should still be reported. NFS is not really
 recommended but it isn't unsupported.
 
-When exporting mergerfs via NFS ensure to set the following config:
+mergerfs settings:
 * noforget
 * inodecalc=path-hash
 * export-support=false (only available in v2.40.0 and above)
 
+NFS export settings:
+* fsid=UUID
+* no\_root\_squash
+
 `noforget` is needed because NFS uses the `name_to_handle_at` and
 `open_by_handle_at` functions which allow a program to keep a
 reference to a file without technically having it open in the typical
@@ -2093,6 +2097,16 @@ Also see [Kernel Issues &
 Bugs](https://github.com/trapexit/mergerfs/wiki/Kernel-Issues-&-Bugs)
 for more details.
 
+`fsid=UUID` is needed because FUSE filesystems don't have different
+`st_dev` values which can cause issues when exporting. The easiest
+thing to do is set each mergerfs export `fsid` to some random
+value. An easy way to generate a random value is to use the command
+line tool `uuidgen` or through a website such as
+[uuidgenerator.net](https://www.uuidgenerator.net/).
+
+`no_root_squash` is not strictly necessary but can lead to confusing
+permission and ownership issues.
+
 
 ## SMB / CIFS
 

man/mergerfs.1

@@ -2591,9 +2591,10 @@ use SMB when possible till situations change.
 That said issues should still be reported.
 NFS is not really recommended but it isn\[cq]t unsupported.
 .PP
-When exporting mergerfs via NFS ensure to set the following config: *
-noforget * inodecalc=path-hash * export-support=false (only available in
-v2.40.0 and above)
+mergerfs settings: * noforget * inodecalc=path-hash *
+export-support=false (only available in v2.40.0 and above)
+.PP
+NFS export settings: * fsid=UUID * no_root_squash
 .PP
 \f[C]noforget\f[R] is needed because NFS uses the
 \f[C]name_to_handle_at\f[R] and \f[C]open_by_handle_at\f[R] functions
@@ -2635,6 +2636,17 @@ appropriate details.
 Also see Kernel Issues &
 Bugs (https://github.com/trapexit/mergerfs/wiki/Kernel-Issues-&-Bugs)
 for more details.
+.PP
+\f[C]fsid=UUID\f[R] is needed because FUSE filesystems don\[cq]t have
+different \f[C]st_dev\f[R] values which can cause issues when exporting.
+The easiest thing to do is set each mergerfs export \f[C]fsid\f[R] to
+some random value.
+An easy way to generate a random value is to use the command line tool
+\f[C]uuidgen\f[R] or through a website such as
+uuidgenerator.net (https://www.uuidgenerator.net/).
+.PP
+\f[C]no_root_squash\f[R] is not strictly necessary but can lead to
+confusing permission and ownership issues.
 .SS SMB / CIFS
 .PP
 SMB (https://en.wikipedia.org/wiki/Server_Message_Block) is a protocol