* bindfs over NFS shows the underlying file system
@ 2019-10-11 5:24 Alkis Georgopoulos
2019-10-11 16:47 ` J. Bruce Fields
0 siblings, 1 reply; 3+ messages in thread
From: Alkis Georgopoulos @ 2019-10-11 5:24 UTC (permalink / raw)
To: linux-nfs
I'm not sure if this is an NFS issue, or a bindfs issue, or if I'm not
using the appropriate NFS options.
I export my /home via NFS with:
/home *(rw,async,crossmnt,no_subtree_check,no_root_squash,insecure)
Inside my /home I'm providing a shared folder with a bindfs mount:
bindfs -u 1000 --create-for-user=1000 -g 100 --create-for-group=100
-p 770,af-x /home/share /home/share
I.e. this just sets fixed permissions for anything under /home/share.
And finally I mount /home on some NFS client (or on localhost):
mount -t nfs server:/home /home
The problem is that /home/share on the client doesn't show the bindfs
permissions, but it shows the underlying file system of the server's
/home/share.
The crossmnt NFS option follows submounts with other file systems, but
not with bindfs.
On the other hand, if the bindfs source is on a different file system
than the bindfs target directory, everything works fine (i.e. bindfs
/other/filesystem/share /home/share).
Is there any way to configure either NFS or bindfs, so that this works
when I only have one partition, i.e. when the share is on the same file
system as /home?
If anyone answers, please Cc me as I'm not in the list.
Thank you very much,
Alkis Georgopoulos
LTSP developer
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: bindfs over NFS shows the underlying file system 2019-10-11 5:24 bindfs over NFS shows the underlying file system Alkis Georgopoulos @ 2019-10-11 16:47 ` J. Bruce Fields 2019-10-12 5:03 ` Alkis Georgopoulos 0 siblings, 1 reply; 3+ messages in thread From: J. Bruce Fields @ 2019-10-11 16:47 UTC (permalink / raw) To: Alkis Georgopoulos; +Cc: linux-nfs On Fri, Oct 11, 2019 at 08:24:14AM +0300, Alkis Georgopoulos wrote: > I'm not sure if this is an NFS issue, or a bindfs issue, or if I'm > not using the appropriate NFS options. > > I export my /home via NFS with: > > /home *(rw,async,crossmnt,no_subtree_check,no_root_squash,insecure) > > Inside my /home I'm providing a shared folder with a bindfs mount: > > bindfs -u 1000 --create-for-user=1000 -g 100 > --create-for-group=100 -p 770,af-x /home/share /home/share > > I.e. this just sets fixed permissions for anything under /home/share. > > And finally I mount /home on some NFS client (or on localhost): > > mount -t nfs server:/home /home > > The problem is that /home/share on the client doesn't show the > bindfs permissions, but it shows the underlying file system of the > server's /home/share. > The crossmnt NFS option follows submounts with other file systems, > but not with bindfs. > > On the other hand, if the bindfs source is on a different file > system than the bindfs target directory, everything works fine (i.e. > bindfs /other/filesystem/share /home/share). Huh. I wonder if nfsd is for some reason determining the existence of a mountpoint by comparing some kind of filesystem id and not seeing a change. Looking at the code to remind myself how this works.... nfsd_mountpoint() is using d_mountpoint() and follow_down(), which should be right. Then it's making an upcall to mountd. That's handled by nfs-utils/mountd/cache.c:nfsd_export(). The is_mountpoint() check there is indeed going to return false in your case because it's just comparing inode and device numbers.... But I think that case is only for the "mountpoint" export option. So I think all that matters is that export_matches() does the right thing, and it certainly looks like it does--it should succeed as long as there's a parent directory that's exported with crossmnt. There's some debugging you could try by looking at net/sunrpc/nfsd.*/content or using strace to watch rpc.mountd's reads and writes of net/sunrpc/nfsd.*/channel. What version of nfs-utils are you on? --b. > > Is there any way to configure either NFS or bindfs, so that this > works when I only have one partition, i.e. when the share is on the > same file system as /home? > > If anyone answers, please Cc me as I'm not in the list. > > Thank you very much, > Alkis Georgopoulos > LTSP developer ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: bindfs over NFS shows the underlying file system 2019-10-11 16:47 ` J. Bruce Fields @ 2019-10-12 5:03 ` Alkis Georgopoulos 0 siblings, 0 replies; 3+ messages in thread From: Alkis Georgopoulos @ 2019-10-12 5:03 UTC (permalink / raw) To: linux-nfs Thank you very much for the feedback, I'm testing with Ubuntu 18.04, nfs-common 1:1.3.4-2.1ubuntu5.2. I think this means "nfs utils 1.3.4". I tried explicitly listing all submounts in exports, and specifying an fsid everywhere, and that worked, for example: exports: /home *(fsid=4858dab5b4ac16ad2b7d274698c2532a,rw,async,crossmnt,no_subtree_check,no_root_squash,insecure) /home/share *(fsid=8c1748909cac2548372caead5bab9aa5,rw,async,no_subtree_check,no_root_squash,insecure) ...and the clients only mount /home, and then properly see the bindfs share permissions. But I'd really like to avoid that as in the real scenario there are many submounts which are frequently added/removed, not just /home/share. I'll try to follow your advice for debugging information. On 10/11/19 7:47 PM, J. Bruce Fields wrote: > On Fri, Oct 11, 2019 at 08:24:14AM +0300, Alkis Georgopoulos wrote: >> I'm not sure if this is an NFS issue, or a bindfs issue, or if I'm >> not using the appropriate NFS options. >> >> I export my /home via NFS with: >> >> /home *(rw,async,crossmnt,no_subtree_check,no_root_squash,insecure) >> >> Inside my /home I'm providing a shared folder with a bindfs mount: >> >> bindfs -u 1000 --create-for-user=1000 -g 100 >> --create-for-group=100 -p 770,af-x /home/share /home/share >> >> I.e. this just sets fixed permissions for anything under /home/share. >> >> And finally I mount /home on some NFS client (or on localhost): >> >> mount -t nfs server:/home /home >> >> The problem is that /home/share on the client doesn't show the >> bindfs permissions, but it shows the underlying file system of the >> server's /home/share. >> The crossmnt NFS option follows submounts with other file systems, >> but not with bindfs. >> >> On the other hand, if the bindfs source is on a different file >> system than the bindfs target directory, everything works fine (i.e. >> bindfs /other/filesystem/share /home/share). > > Huh. I wonder if nfsd is for some reason determining the existence of a > mountpoint by comparing some kind of filesystem id and not seeing a > change. Looking at the code to remind myself how this works.... > > nfsd_mountpoint() is using d_mountpoint() and follow_down(), which > should be right. Then it's making an upcall to mountd. That's handled > by nfs-utils/mountd/cache.c:nfsd_export(). > > The is_mountpoint() check there is indeed going to return false in your > case because it's just comparing inode and device numbers.... But I > think that case is only for the "mountpoint" export option. > > So I think all that matters is that export_matches() does the right > thing, and it certainly looks like it does--it should succeed as long as > there's a parent directory that's exported with crossmnt. > > There's some debugging you could try by looking at > net/sunrpc/nfsd.*/content or using strace to watch rpc.mountd's reads > and writes of net/sunrpc/nfsd.*/channel. > > What version of nfs-utils are you on? > > --b. > >> >> Is there any way to configure either NFS or bindfs, so that this >> works when I only have one partition, i.e. when the share is on the >> same file system as /home? >> >> If anyone answers, please Cc me as I'm not in the list. >> >> Thank you very much, >> Alkis Georgopoulos >> LTSP developer ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-10-12 5:03 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-10-11 5:24 bindfs over NFS shows the underlying file system Alkis Georgopoulos 2019-10-11 16:47 ` J. Bruce Fields 2019-10-12 5:03 ` Alkis Georgopoulos
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