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git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf
https://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
https://git.kernel.org/brauner/man-pages/c/1d7b902e2875a1ff342e036a9f866a995640aea8
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
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git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux
Pull more nfsd updates from Chuck Lever:
"Here are a few additional NFSD commits for the merge window:
Optimization:
- Cork the socket while there are queued replies
Fixes:
- DRC shutdown ordering
- svc_rdma_accept() lockdep splat"
* tag 'nfsd-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
SUNRPC: Further clean up svc_tcp_sendmsg()
SUNRPC: Remove redundant socket flags from svc_tcp_sendmsg()
SUNRPC: Use TCP_CORK to optimise send performance on the server
svcrdma: Hold private mutex while invoking rdma_accept()
nfsd: register pernet ops last, unregister first
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Pull core block updates from Jens Axboe:
"Another nice round of removing more code than what is added, mostly
due to Christoph's relentless pursuit of tech debt removal/cleanups.
This pull request contains:
- Two series of BFQ improvements (Paolo, Jan, Jia)
- Block iov_iter improvements (Pavel)
- bsg error path fix (Pan)
- blk-mq scheduler improvements (Jan)
- -EBUSY discard fix (Jan)
- bvec allocation improvements (Ming, Christoph)
- bio allocation and init improvements (Christoph)
- Store bdev pointer in bio instead of gendisk + partno (Christoph)
- Block trace point cleanups (Christoph)
- hard read-only vs read-only split (Christoph)
- Block based swap cleanups (Christoph)
- Zoned write granularity support (Damien)
- Various fixes/tweaks (Chunguang, Guoqing, Lei, Lukas, Huhai)"
* tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-block: (104 commits)
mm: simplify swapdev_block
sd_zbc: clear zone resources for non-zoned case
block: introduce blk_queue_clear_zone_settings()
zonefs: use zone write granularity as block size
block: introduce zone_write_granularity limit
block: use blk_queue_set_zoned in add_partition()
nullb: use blk_queue_set_zoned() to setup zoned devices
nvme: cleanup zone information initialization
block: document zone_append_max_bytes attribute
block: use bi_max_vecs to find the bvec pool
md/raid10: remove dead code in reshape_request
block: mark the bio as cloned in bio_iov_bvec_set
block: set BIO_NO_PAGE_REF in bio_iov_bvec_set
block: remove a layer of indentation in bio_iov_iter_get_pages
block: turn the nr_iovecs argument to bio_alloc* into an unsigned short
block: remove the 1 and 4 vec bvec_slabs entries
block: streamline bvec_alloc
block: factor out a bvec_alloc_gfp helper
block: move struct biovec_slab to bio.c
block: reuse BIO_INLINE_VECS for integrity bvecs
...
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These pernet operations may depend on stuff set up or torn down in the
module init/exit functions. And they may be called at any time in
between. So it makes more sense for them to be the last to be
registered in the init function, and the first to be unregistered in the
exit function.
In particular, without this, the drc slab is being destroyed before all
the per-net drcs are shut down, resulting in an "Objects remaining in
nfsd_drc on __kmem_cache_shutdown()" warning in exit_nfsd.
Reported-by: Zhi Li <yieli@redhat.com>
Fixes: 3ba75830ce17 "nfsd4: drc containerization"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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In the typical case of v4 and an i_version-supporting filesystem, we can
skip a stat which is only required to fake up a change attribute from
ctime.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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When exporting NFS, we may as well use the real change attribute
returned by the original server instead of faking up a change attribute
from the ctime.
Note we can't do that by setting I_VERSION--that would also turn on the
logic in iversion.h which treats the lower bit specially, and that
doesn't make sense for NFS.
So instead we define a new export operation for filesystems like NFS
that want to manage the change attribute themselves.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Currently NFSv4_2 SSC helper, nfs_ssc, incorrectly uses GRACE_PERIOD
as its config. Fix by adding new config NFS_V4_2_SSC_HELPER which
depends on NFS_V4_2 and is automatically selected when NFSD_V4 is
enabled. Also removed the file name from a comment in nfs_ssc.c.
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I'm not sure why we're writing this out the hard way in so many places.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The set_client() was already taken care of by process_open1().
The comments here are mostly redundant with the code.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Every caller is setting this argument to false, so we don't need it.
Also cut this comment a bit and remove an unnecessary warning.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I think this unusual use of struct compound_state could cause confusion.
It's not that much more complicated just to open-code this stateid
lookup.
The only change in behavior should be a different error return in the
case the copy is using a source stateid that is a revoked delegation,
but I doubt that matters.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[ cel: squashed in fix reported by Coverity ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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This'll be useful elsewhere.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I think this is a better name, and I'm going to reuse elsewhere the code
that does the lookup itself.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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You can take the single-exit thing too far, I think.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Similarly, this STALE_CLIENTID check is already handled by:
nfs4_preprocess_confirmed_seqid_op()->
nfs4_preprocess_seqid_op()->
nfsd4_lookup_stateid()->
set_client()->
STALE_CLIENTID()
(This may cause it to return a different error in some cases where
there are multiple things wrong; pynfs test SEQ10 regressed on this
commit because of that, but I think that's the test's fault, and I've
fixed it separately.)
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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This STALE_CLIENTID check is redundant with the one in
lookup_clientid().
There's a difference in behavior is in case of memory allocation
failure, which I think isn't a big deal.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Collect some nfsd stats per export in addition to the global stats.
A new nfsdfs export_stats file is created. It uses the same ops as the
exports file to iterate the export entries and we use the file's name to
determine the reported info per export. For example:
$ cat /proc/fs/nfsd/export_stats
# Version 1.1
# Path Client Start-time
# Stats
/test localhost 92
fh_stale: 0
io_read: 9
io_write: 1
Every export entry reports the start time when stats collection
started, so stats collecting scripts can know if stats where reset
between samples.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfsd stats counters can be updated by concurrent nfsd threads without any
protection.
Convert some nfsd_stats and nfsd_net struct members to use percpu counters.
The longest_chain* members of struct nfsd_net remain unprotected.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Commit 501cb1849f86 ("nfsd: rip out the raparms cache") removed the
code that updates read-ahead cache stats counters,
commit 8bbfa9f3889b ("knfsd: remove the nfsd thread busy histogram")
removed code that updates the thread busy stats counters back in 2009
and code that updated filehandle cache stats was removed back in 2002.
Remove the unused stats counters from nfsd_stats struct and print
hardcoded zeros in /proc/net/rpc/nfsd.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Since the ACL GETATTR procedure is the same as the normal GETATTR
procedure, simply re-use nfssvc_decode_fhandleargs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Now that the argument decoders for NFSv2 and NFSv3 use the
xdr_stream mechanism, the version-specific length checking logic in
nfsd_dispatch() is no longer necessary.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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As an additional clean up, move code not related to XDR decoding
into readdir's .pc_func call out.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add a helper similar to nfsd3_init_dirlist_pages().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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If the code that sets up the sink buffer for nfsd_readlink() is
moved adjacent to the nfsd_readlink() call site that uses it, then
the only argument is a file handle, and the fhandle decoder can be
used instead.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The code that sets up rq_vec is refactored so that it is now
adjacent to the nfsd_read() call site where it is used.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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This commit removes the last usage of the original decode_sattr3(),
so it is removed as a clean-up.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Similar to the WRITE decoder, code that checks the sanity of the
payload size is re-wired to work with xdr_stream infrastructure.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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As an additional clean up, neither nfsd3_proc_readdir() nor
nfsd3_proc_readdirplus() make use of the dircount argument, so
remove it from struct nfsd3_readdirargs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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