On Apr 25, 2019, at 4:04 PM, J. Bruce Fields <bfields@xxxxxxxxxx> wrote: > > From: "J. Bruce Fields" <bfields@xxxxxxxxxx> > > The following patches expose information about NFSv4 opens held by knfsd > on behalf of NFSv4 clients. Those are currently invisible to userspace, > unlike locks (/proc/locks) and local proccesses' opens (/proc/<pid>/). > > The approach is to add a new directory /proc/fs/nfsd/clients/ with > subdirectories for each active NFSv4 client. Each subdirectory has an > "info" file with some basic information to help identify the client and > an "opens" directory that lists the opens held by that client. > > I got it working by cobbling together some poorly-understood code I > found in libfs, rpc_pipefs and elsewhere. If anyone wants to wade in > and tell me what I've got wrong, they're more than welcome, but at this > stage I'm more curious for feedback on the interface. Is this in procfs, sysfs, or a separate NFSD-specific filesystem? My understanding is that "complex" files are verboten in procfs and sysfs? We've been going through a lengthy process to move files out of procfs into sysfs and debugfs as a result (while trying to maintain some kind of compatibility in the user tools), but if it is possible to use a separate filesystem to hold all of the stats/parameters I'd much rather do that than use debugfs (which has become root-access-only in newer kernels). Cheers, Andreas > I'm also cc'ing people responsible for lsof and util-linux in case they > have any opinions. > > Currently these pseudofiles look like: > > # find /proc/fs/nfsd/clients -type f|xargs tail > ==> /proc/fs/nfsd/clients/3741/opens <== > 5cc0cd36/6debfb50/00000001/00000001 rw -- fd:10:13649 'open id:\x00\x00\x00&\x00\x00\x00\x00\x00\x00\x0b\xb7\x89%\xfc\xef' > 5cc0cd36/6debfb50/00000003/00000001 r- -- fd:10:13650 'open id:\x00\x00\x00&\x00\x00\x00\x00\x00\x00\x0b\xb7\x89%\xfc\xef' > > ==> /proc/fs/nfsd/clients/3741/info <== > clientid: 6debfb505cc0cd36 > address: 192.168.122.36:0 > name: Linux NFSv4.2 test2.fieldses.org > minor version: 2 > > Each line of the "opens" file is tab-delimited and describes one open, > and the fields are stateid, open access bits, deny bits, > major:minor:ino, and open owner. > > So, some random questions: > > - I just copied the major:minor:ino thing from /proc/locks, I > suspect we would have picked something different to identify > inodes if /proc/locks were done now. (Mount id and inode? > Something else?) > > - The open owner is just an opaque blob of binary data, but > clients may choose to include some useful asci-encoded > information, so I'm formatting them as strings with non-ascii > stuff escaped. For example, pynfs usually uses the name of > the test as the open owner. But as you see above, the ascii > content of the Linux client's open owners is less useful. > Also, there's no way I know of to map them back to a file > description or process or anything else useful on the client, > so perhaps they're of limited interest. > > - I'm not sure about the stateid either. I did think it might > be useful just as a unique identifier for each line. > (Actually for that it'd be enough to take just the third of > those four numbers making up the stateid--maybe that would be > better.) > > In the "info" file, the "name" line is the client identifier/client > owner provided by the client, which (like the stateowner) is just opaque > binary data, though as you can see here the Linux client is providing a > readable ascii string. > > There's probably a lot more we could add to that info file eventually. > > Other stuff to add next: > > - nfsd/clients/#/kill that you can write to to revoke all a > client's state if it's wedged somehow. > - lists of locks and delegations; lower priority since most of > that information is already in /proc/locks. > > --b. > > J. Bruce Fields (10): > nfsd: persist nfsd filesystem across mounts > nfsd: rename cl_refcount > nfsd4: use reference count to free client > nfsd: add nfsd/clients directory > nfsd: make client/ directory names small ints > rpc: replace rpc_filelist by tree_descr > nfsd4: add a client info file > nfsd4: add file to display list of client's opens > nfsd: expose some more information about NFSv4 opens > nfsd: add more information to client info file > > fs/nfsd/netns.h | 6 + > fs/nfsd/nfs4state.c | 228 ++++++++++++++++++++++++++++++--- > fs/nfsd/nfsctl.c | 225 +++++++++++++++++++++++++++++++- > fs/nfsd/nfsd.h | 11 ++ > fs/nfsd/state.h | 9 +- > fs/seq_file.c | 17 +++ > include/linux/seq_file.h | 2 + > include/linux/string_helpers.h | 1 + > lib/string_helpers.c | 5 +- > net/sunrpc/rpc_pipe.c | 37 ++---- > 10 files changed, 491 insertions(+), 50 deletions(-) > > -- > 2.20.1 > Cheers, Andreas
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