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refactor the nfs4 server lock code to use last_byte_offset
to compute the last byte covered by the lock. Check for overflow
so that the last byte is set to NFS4_MAX_UINT64 if offset + len
wraps around.
Also, use NFS4_MAX_UINT64 for ~(u64)0 where appropriate.
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Since nfsv4 allows LOCKT without an open, but the ->lock() method is a
file method, we fake up a struct file in the nfsv4 code with just the
fields we need initialized. But we forgot to initialize the file
operations, with the result that LOCKT never results in a call to the
filesystem's ->lock() method (if it exists).
We could just add that one more initialization. But this hack of faking
up a struct file with only some fields initialized seems the kind of
thing that might cause more problems in the future. We should either do
an open and get a real struct file, or make lock-testing an inode (not a
file) method.
This patch does the former.
Reported-by: Marc Eshel <eshel@almaden.ibm.com>
Tested-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Minor cleanup/rewrite of find_stateid. Compile tested.
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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This patch adds server-side support for callbacks other than AUTH_SYS.
Signed-off-by: Olga Kornievskaia <aglo@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Two principals are involved in krb5 authentication: the target, who we
authenticate *to* (normally the name of the server, like
nfs/server.citi.umich.edu@CITI.UMICH.EDU), and the source, we we
authenticate *as* (normally a user, like bfields@UMICH.EDU)
In the case of NFSv4 callbacks, the target of the callback should be the
source of the client's setclientid call, and the source should be the
nfs server's own principal.
Therefore we allow svcgssd to pass down the name of the principal that
just authenticated, so that on setclientid we can store that principal
name with the new client, to be used later on callbacks.
Signed-off-by: Olga Kornievskaia <aglo@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
drivers/net/e1000e/ich8lan.c
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If nfsd was shut down before the grace period ended, we could end up
with a freed object still on grace_list. Thanks to Jeff Moyer for
reporting the resulting list corruption warnings.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Tested-by: Jeff Moyer <jmoyer@redhat.com>
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Using NIPQUAD() with NIPQUAD_FMT, %d.%d.%d.%d or %u.%u.%u.%u
can be replaced with %pI4
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Rewrite grace period code to unify management of grace period across
lockd and nfsd. The current code has lockd and nfsd cooperate to
compute a grace period which is satisfactory to them both, and then
individually enforce it. This creates a slight race condition, since
the enforcement is not coordinated. It's also more complicated than
necessary.
Here instead we have lockd and nfsd each inform common code when they
enter the grace period, and when they're ready to leave the grace
period, and allow normal locking only after both of them are ready to
leave.
We also expect the locks_start_grace()/locks_end_grace() interface here
to be simpler to build on for future cluster/high-availability work,
which may require (for example) putting individual filesystems into
grace, or enforcing grace periods across multiple cluster nodes.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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testing with newpynfs revealed this warning:
Jul 3 07:32:50 buml kernel: writeable file with no mnt_want_write()
Jul 3 07:32:50 buml kernel: ------------[ cut here ]------------
Jul 3 07:32:50 buml kernel: WARNING: at /usr0/export/dev/bhalevy/git/linux-pnfs-bh-nfs41/include/linux/fs.h:855 drop_file_write_access+0x6b/0x7e()
Jul 3 07:32:50 buml kernel: Modules linked in: nfsd auth_rpcgss exportfs nfs lockd nfs_acl sunrpc
Jul 3 07:32:50 buml kernel: Call Trace:
Jul 3 07:32:50 buml kernel: 6eaadc88: [<6002f471>] warn_on_slowpath+0x54/0x8e
Jul 3 07:32:50 buml kernel: 6eaadcc8: [<601b790d>] printk+0xa0/0x793
Jul 3 07:32:50 buml kernel: 6eaadd38: [<601b6205>] __mutex_lock_slowpath+0x1db/0x1ea
Jul 3 07:32:50 buml kernel: 6eaadd68: [<7107d4d5>] nfs4_preprocess_seqid_op+0x2a6/0x31c [nfsd]
Jul 3 07:32:50 buml kernel: 6eaadda8: [<60078dc9>] drop_file_write_access+0x6b/0x7e
Jul 3 07:32:50 buml kernel: 6eaaddc8: [<710804e4>] nfsd4_open_downgrade+0x114/0x1de [nfsd]
Jul 3 07:32:50 buml kernel: 6eaade08: [<71076215>] nfsd4_proc_compound+0x1ba/0x2dc [nfsd]
Jul 3 07:32:50 buml kernel: 6eaade48: [<71068221>] nfsd_dispatch+0xe5/0x1c2 [nfsd]
Jul 3 07:32:50 buml kernel: 6eaade88: [<71312f81>] svc_process+0x3fd/0x714 [sunrpc]
Jul 3 07:32:50 buml kernel: 6eaadea8: [<60039a81>] kernel_sigprocmask+0xf3/0x100
Jul 3 07:32:50 buml kernel: 6eaadee8: [<7106874b>] nfsd+0x182/0x29b [nfsd]
Jul 3 07:32:50 buml kernel: 6eaadf48: [<60021cc9>] run_kernel_thread+0x41/0x4a
Jul 3 07:32:50 buml kernel: 6eaadf58: [<710685c9>] nfsd+0x0/0x29b [nfsd]
Jul 3 07:32:50 buml kernel: 6eaadf98: [<60021cb0>] run_kernel_thread+0x28/0x4a
Jul 3 07:32:50 buml kernel: 6eaadfc8: [<60013829>] new_thread_handler+0x72/0x9c
Jul 3 07:32:50 buml kernel:
Jul 3 07:32:50 buml kernel: ---[ end trace 2426dd7cb2fba3bf ]---
Bruce Fields suggested this (Thanks!):
maybe we need to be doing a mnt_want_write on open_upgrade and mnt_put_write on downgrade?
This patch adds a call to mnt_want_write and file_take_write (which is
doing the actual work).
The counter-calls mnt_drop_write a file_release_write are now being properly
called by drop_file_write_access in the exact path printed by the warning
above.
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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It's not immediately obvious from the code why we're doing this.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Benny Halevy <bhalevy@panasas.com>
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Rename nfsd_permission() specific MAY_* flags to NFSD_MAY_* to make it
clear, that these are not used outside nfsd, and to avoid name and
number space conflicts with the VFS.
[comment from hch: rename MAY_READ, MAY_WRITE and MAY_EXEC as well]
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Several of the nfsd filesystem interfaces allow changes to parameters
that don't have any effect on a running nfsd service. They are only ever
checked when nfsd is started. This patch fixes it so that changes to
those procfiles return -EBUSY if nfsd is already running to make it
clear that changes on the fly don't work.
The patch should also close some relatively harmless races between
changing the info in those interfaces and starting nfsd, since these
variables are being moved under the protection of the nfsd_mutex.
Finally, the nfsv4recoverydir file always returns -EINVAL if read. This
patch fixes it to return the recoverydir path as expected.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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These bit operations don't need to be atomic. They're all done under a
single big mutex anyway.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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The file_lock structure is used both as a heavy-weight representation of
an active lock, with pointers to reference-counted structures, etc., and
as a simple container for parameters that describe a file lock.
The conflicting lock returned from __posix_lock_file is an example of
the latter; so don't call the filesystem or lock manager callbacks when
copying to it. This also saves the need for an unnecessary
locks_init_lock in the nfsv4 server.
Thanks to Trond for pointing out the error.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
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While lease is correctly checked by supplying the type argument to
vfs_setlease(), it's stored with fl_type uninitialized. This breaks the
logic when checking the type of the lease. The fix is to initialize
fl_type.
The old code still happened to function correctly since F_RDLCK is zero,
and we only implement read delegations currently (nor write
delegations). But that's no excuse for not fixing this.
Signed-off-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Add extern to nfsd/nfsd.h
fs/nfsd/nfssvc.c:146:5: warning: symbol 'nfsd_nrthreads' was not declared. Should it be static?
fs/nfsd/nfssvc.c:261:5: warning: symbol 'nfsd_nrpools' was not declared. Should it be static?
fs/nfsd/nfssvc.c:269:5: warning: symbol 'nfsd_get_nrthreads' was not declared. Should it be static?
fs/nfsd/nfssvc.c:281:5: warning: symbol 'nfsd_set_nrthreads' was not declared. Should it be static?
fs/nfsd/export.c:1534:23: warning: symbol 'nfs_exports_op' was not declared. Should it be static?
Add include of auth.h
fs/nfsd/auth.c:27:5: warning: symbol 'nfsd_setuser' was not declared. Should it be static?
Make static, move forward declaration closer to where it's needed.
fs/nfsd/nfs4state.c:1877:1: warning: symbol 'laundromat_main' was not declared. Should it be static?
Make static, forward declaration was already marked static.
fs/nfsd/nfs4idmap.c:206:1: warning: symbol 'idtoname_parse' was not declared. Should it be static?
fs/nfsd/vfs.c:1156:1: warning: symbol 'nfsd_create_setattr' was not declared. Should it be static?
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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This condition is always true.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Pull this common code into a separate function.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Every caller sets this flag, so it's meaningless.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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If someone decides to demote a file from r/w to just
r/o, they can use this same code as __fput().
NFS does just that, and will use this in the next
patch.
AV: drop write access in __fput() only after we evict from file list.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Cc: Erez Zadok <ezk@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J Bruce Fields" <bfields@fieldses.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* Add path_put() functions for releasing a reference to the dentry and
vfsmount of a struct path in the right order
* Switch from path_release(nd) to path_put(&nd->path)
* Rename dput_path() to path_put_conditional()
[akpm@linux-foundation.org: fix cifs]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is the central patch of a cleanup series. In most cases there is no good
reason why someone would want to use a dentry for itself. This series reflects
that fact and embeds a struct path into nameidata.
Together with the other patches of this series
- it enforced the correct order of getting/releasing the reference count on
<dentry,vfsmount> pairs
- it prepares the VFS for stacking support since it is essential to have a
struct path in every place where the stack can be traversed
- it reduces the overall code size:
without patch series:
text data bss dec hex filename
5321639 858418 715768 6895825 6938d1 vmlinux
with patch series:
text data bss dec hex filename
5320026 858418 715768 6894212 693284 vmlinux
This patch:
Switch from nd->{dentry,mnt} to nd->path.{dentry,mnt} everywhere.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix cifs]
[akpm@linux-foundation.org: fix smack]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Document these checks a little better and inline, as suggested by Neil
Brown (note both functions have two callers). Remove an obviously bogus
check while we're there (checking whether unsigned value is negative).
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Neil Brown <neilb@suse.de>
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The failure to return a stateowner from nfs4_preprocess_seqid_op() means
in the case where a lock request is of a type incompatible with an open
(due to, e.g., an application attempting a write lock on a file open for
read), means that fs/nfsd/nfs4xdr.c:ENCODE_SEQID_OP_TAIL() never bumps
the seqid as it should. The client, attempting to close the file
afterwards, then gets an (incorrect) bad sequence id error. Worse, this
prevents the open file from ever being closed, so we leak state.
Thanks to Benny Halevy and Trond Myklebust for analysis, and to Steven
Wilton for the report and extensive data-gathering.
Cc: Benny Halevy <bhalevy@panasas.com>
Cc: Steven Wilton <steven.wilton@team.eftel.com.au>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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When the callback channel fails, we inform the client of that by
returning a cb_path_down error the next time it tries to renew its
lease.
If we wait most of a lease period before deciding that a callback has
failed and that the callback channel is down, then we decrease the
chances that the client will find out in time to do anything about it.
So, mark the channel down as soon as we recognize that an rpc has
failed. However, continue trying to recall delegations anyway, in hopes
it will come back up. This will prevent more delegations from being
given out, and ensure cb_path_down is returned to renew calls earlier,
while still making the best effort to deliver recalls of existing
delegations.
Also fix a couple comments and remove a dprink that doesn't seem likely
to be useful.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Fix various minor style violations.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Declare this variable in the one function where it's used, and clean up
some minor style problems.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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We generate a unique cl_confirm for every new client; so if we've
already checked that this cl_confirm agrees with the cl_confirm of
unconf, then we already know that it does not agree with the cl_confirm
of conf.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Again, the only way conf and unconf can have the same clientid is if
they were created in the "probable callback update" case of setclientid,
in which case we already know that the cl_verifier fields must agree.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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If conf and unconf are both found in the lookup by cl_clientid, then
they share the same cl_clientid. We always create a unique new
cl_clientid field when creating a new client--the only exception is the
"probable callback update" case in setclientid, where we copy the old
cl_clientid from another clientid with the same name.
Therefore two clients with the same cl_client field also always share
the same cl_name field, and a couple of the checks here are redundant.
Thanks to Simon Holm Thøgersen for a compile fix.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Simon Holm Thøgersen <odie@cs.aau.dk>
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Using a counter instead of the nanoseconds value seems more likely to
produce a unique cl_confirm.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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We're supposed to generate a different cl_confirm verifier for each new
client, so these to cl_confirm values should never be the same.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Most of these comments just summarize the code.
The matching of code to the cases described in the RFC may still be
useful, though; add specific section references to make that easier to
follow. Also update references to the outdated RFC 3010.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Our callback code doesn't actually handle concurrent attempts to probe
the callback channel. Some rethinking of the locking may be required.
However, we can also just move the callback probing to this case. Since
this is the only time a client is "confirmed" (and since that can only
happen once in the lifetime of a client), this ensures we only probe
once.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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* 'locks' of git://linux-nfs.org/~bfields/linux:
nfsd: remove IS_ISMNDLCK macro
Rework /proc/locks via seq_files and seq_list helpers
fs/locks.c: use list_for_each_entry() instead of list_for_each()
NFS: clean up explicit check for mandatory locks
AFS: clean up explicit check for mandatory locks
9PFS: clean up explicit check for mandatory locks
GFS2: clean up explicit check for mandatory locks
Cleanup macros for distinguishing mandatory locks
Documentation: move locks.txt in filesystems/
locks: add warning about mandatory locking races
Documentation: move mandatory locking documentation to filesystems/
locks: Fix potential OOPS in generic_setlease()
Use list_first_entry in locks_wake_up_blocks
locks: fix flock_lock_file() comment
Memory shortage can result in inconsistent flocks state
locks: kill redundant local variable
locks: reverse order of posix_locks_conflict() arguments
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The combination of S_ISGID bit set and S_IXGRP bit unset is used to mark the
inode as "mandatory lockable" and there's a macro for this check called
MANDATORY_LOCK(inode). However, fs/locks.c and some filesystems still perform
the explicit i_mode checking. Besides, Andrew pointed out, that this macro is
buggy itself, as it dereferences the inode arg twice.
Convert this macro into static inline function and switch its users to it,
making the code shorter and more readable.
The __mandatory_lock() helper is to be used in places where the IS_MANDLOCK()
for superblock is already known to be true.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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It's not enough to take a reference on the delegation object itself; we
need to ensure that the rpc_client won't go away just as we're about to
make an rpc call.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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If a callback still holds a reference on the client, then it may be
about to perform an rpc call, so it isn't safe to call rpc_shutdown().
(Though rpc_shutdown() does wait for any outstanding rpc's, it can't
know if a new rpc is about to be issued with that client.)
So, wait to shutdown the rpc_client until the reference count on the
client has gone to zero.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Currently there's a race that can cause an oops in generic_setlease.
(In detail: nfsd, when it removes a lease, does so by calling
vfs_setlease() with F_UNLCK and a pointer to the fl_flock field, which
in turn points to nfsd's existing lease; but the first thing the
setlease code does is call time_out_leases(). If the lease happens to
already be beyond the lease break time, that will free the lease and (in
nfsd's release_private callback) set fl_flock to NULL, leading to a NULL
deference soon after in vfs_setlease().)
There are probably other things to fix here too, but it seems inherently
racy to allow either locks.c or nfsd to time out this lease. Instead
just set the fl_break_time to 0 (preventing locks.c from ever timing out
this lock) and leave it up to nfsd's laundromat thread to deal with it.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Each branch of this if-then-else has a bunch of duplicated code that we
could just put at the end.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Acked-by: Neil Brown <neilb@suse.de>
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We have some slabs that the nfs4 server uses to store state objects.
We're currently creating and destroying those slabs whenever the server
is brought up or down. That seems excessive; may as well just do that
in module initialization and exit.
Also add some minor header cleanup. (Thanks to Andrew Morton for that
and a compile fix.)
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Acked-by: Neil Brown <neilb@suse.de>
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To quote a recent mail from Andrew Morton:
Look: if there's a way in which an unprivileged user can trigger
a printk we fix it, end of story.
OK. I assume that goes double for printk()s that might be triggered by
random hosts on the internet. So, disable some printk()s that look like
they could be triggered by malfunctioning or malicious clients. For
now, just downgrade them to dprintk()s.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Acked-by: Neil Brown <neilb@suse.de>
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Benny Halevy suggested renaming cmp_* to same_* to make the meaning of
the return value clearer.
Fix some nearby style deviations while we're at it, including a small
swath of creative indentation in nfs4_preprocess_seqid_op().
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Acked-by: Neil Brown <neilb@suse.de>
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Slab destructors were no longer supported after Christoph's
c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been
BUGs for both slab and slub, and slob never supported them
either.
This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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We've been using the convention that vfs_foo is the function that calls
a filesystem-specific foo method if it exists, or falls back on a
generic method if it doesn't; thus vfs_foo is what is called when some
other part of the kernel (normally lockd or nfsd) wants to get a lock,
whereas foo is what filesystems call to use the underlying local
functionality as part of their lock implementation.
So rename setlease to vfs_setlease (which will call a
filesystem-specific setlease after a later patch) and __setlease to
setlease.
Also, vfs_setlease need only be GPL-exported as long as it's only needed
by lockd and nfsd.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
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One more incremental delegation policy improvement: don't give out a
delegation on a file if conflicting access has previously required that a
delegation be revoked on that file. (In practice we'll forget about the
conflict when the struct nfs4_file is removed on close, so this is of limited
use for now, though it should at least solve a temporary problem with
self-conflicts on write opens from the same client.)
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Our original NFSv4 delegation policy was to give out a read delegation on any
open when it was possible to.
Since the lifetime of a delegation isn't limited to that of an open, a client
may quite reasonably hang on to a delegation as long as it has the inode
cached. This becomes an obvious problem the first time a client's inode cache
approaches the size of the server's total memory.
Our first quick solution was to add a hard-coded limit. This patch makes a
mild incremental improvement by varying that limit according to the server's
total memory size, allowing at most 4 delegations per megabyte of RAM.
My quick back-of-the-envelope calculation finds that in the worst case (where
every delegation is for a different inode), a delegation could take about
1.5K, which would make the worst case usage about 6% of memory. The new limit
works out to be about the same as the old on a 1-gig server.
[akpm@linux-foundation.org: Don't needlessly bloat vmlinux]
[akpm@linux-foundation.org: Make it right for highmem machines]
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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