All places outside of core VFS that checked ->read and ->write for being NULL or
called the methods directly are gone now, so NULL {read,write} with non-NULL
{read,write}_iter will do the right thing in all cases.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and fix the case when the area we are asked to read crosses
a hugepage boundary
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and request the same from the local cache - all filesystems with
anything usable for that support those already.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

do it in ->direct_IO()...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and make it loop
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

just handle it in ->direct_IO()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Don't mess with kmap() - just use ITER_BVEC.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and make it loop until it's done
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We check if ->ki_pos is positive.  However, by that point we have
already done rw_verify_area(), which would have rejected such
unless the file had been one of /dev/mem, /dev/kmem and /proc/kcore.
All of which do not have vectored rw methods, so we would've bailed
out even earlier.

This check had been introduced before rw_verify_area() had been added there
- in fact, it was a subset of checks done on sync paths by rw_verify_area()
(back then the /dev/mem exception didn't exist at all).  The rest of checks
(mandatory locking, etc.) hadn't been added until later.  Unfortunately,
by the time the call of rw_verify_area() got added, the /dev/mem exception
had already appeared, so it wasn't obvious that the older explicit check
downstream had become dead code.  It *is* a dead code, though, since the few
files for which the exception applies do not have ->aio_{read,write}() or
->{read,write}_iter() and for them we won't reach that check anyway.

What's more, even if we ever introduce vectored methods for /dev/mem
and friends, they'll have to cope with negative positions anyway, since
readv(2) and writev(2) are using the same checks as read(2) and write(2) -
i.e. rw_verify_area().

Let's bury it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Way, way back kiocb used to be picked from arrays, so ioctx_alloc()
checked for multiplication overflow when calculating the size of
such array.  By the time fs/aio.c went into the tree (in 2002) they
were already allocated one-by-one by kmem_cache_alloc(), so that
check had already become pointless.  Let's bury it...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

it's actually shorter that way *and* later we'll want iocb in scope
of generic_write_check() caller.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

identical to import_single_range()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We don't need req in either of those.  We don't need nr_segs in caller.
We don't really need len in caller either - iov_iter_count(&iter) will do.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

the only non-trivial detail is that we do it before rw_verify_area(),
so we'd better cap the length ourselves in aio_setup_single_rw()
case (for vectored case rw_copy_check_uvector() will do that for us).
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

get it closer to matching {compat_,}rw_copy_check_uvector().
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We have observed a BUG() crash in fs/attr.c:notify_change(). The crash
occurs during an rsync into a filesystem that is exported via NFS.

1.) fs/attr.c:notify_change() modifies the caller's version of attr.
2.) 6de0ec00 ("VFS: make notify_change pass ATTR_KILL_S*ID to
    setattr operations") introduced a BUG() restriction such that "no
    function will ever call notify_change() with both ATTR_MODE and
    ATTR_KILL_S*ID set". Under some circumstances though, it will have
    assisted in setting the caller's version of attr to this very
    combination.
3.) 27ac0ffe ("locks: break delegations on any attribute
    modification") introduced code to handle breaking
    delegations. This can result in notify_change() being re-called. attr
    _must_ be explicitly reset to avoid triggering the BUG() established
    in #2.
4.) The path that that triggers this is via fs/open.c:chmod_common().
    The combination of attr flags set here and in the first call to
    notify_change() along with a later failed break_deleg_wait()
    results in notify_change() being called again via retry_deleg
    without resetting attr.

Solution is to move retry_deleg in chmod_common() a bit further up to
ensure attr is completely reset.

There are other places where this seemingly could occur, such as
fs/utimes.c:utimes_common(), but the attr flags are not initially
set in such a way to trigger this.

Fixes: 27ac0ffe ("locks: break delegations on any attribute modification")
Reported-by: NEric Meddaugh <etmsys@rit.edu>
Tested-by: NEric Meddaugh <etmsys@rit.edu>
Signed-off-by: NAndrew Elble <aweits@rit.edu>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

On a distributed filesystem it's possible for lookup to discover that a
directory it just found is already cached elsewhere in the directory
heirarchy.  The dcache won't let us keep the directory in both places,
so we have to move the dentry to the new location from the place we
previously had it cached.

If the parent has changed, then this requires all the same locks as we'd
need to do a cross-directory rename.  But we're already in lookup
holding one parent's i_mutex, so it's too late to acquire those locks in
the right order.

The (unreliable) solution in __d_unalias is to trylock() the required
locks and return -EBUSY if it fails.

I see no particular reason for returning -EBUSY, and -ESTALE is already
the result of some other lookup races on NFS.  I think -ESTALE is the
more helpful error return.  It also allows us to take advantage of the
logic Jeff Layton added in c6a94284 "vfs: fix renameat to retry on
ESTALE errors" and ancestors, which hopefully resolves some of these
errors before they're returned to userspace.

I can reproduce these cases using NFS with:

	ssh root@$client '
		mount -olookupcache=pos '$server':'$export' /mnt/
		mkdir /mnt/TO
		mkdir /mnt/DIR
		touch /mnt/DIR/test.txt
		while true; do
			strace -e open cat /mnt/DIR/test.txt 2>&1 | grep EBUSY
		done
	'
	ssh root@$server '
		while true; do
			mv $export/DIR $export/TO/DIR
			mv $export/TO/DIR $export/DIR
		done
	'

It also helps to add some other concurrent use of the directory on the
client (e.g., "ls /mnt/TO").  And you can replace the server-side mv's
by client-side mv's that are repeatedly killed.  (If the client is
interrupted while waiting for the RENAME response then it's left with a
dentry that has to go under one parent or the other, but it doesn't yet
know which.)
Acked-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAnton Altaparmakov <anton@tuxera.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

For one thing, LOOKUP_DIRECTORY will be dealt with in do_last().
For another, name can be an empty string, but not NULL - no callers
pass that and it would oops immediately if they would.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

just make const char iname[] the last member and compare name->name with
name->iname instead of checking name->separate

We need to make sure that out-of-line name doesn't end up allocated adjacent
to struct filename refering to it; fortunately, it's easy to achieve - just
allocate that struct filename with one byte in ->iname[], so that ->iname[0]
will be inside the same object and thus have an address different from that
of out-of-line name [spotted by Boqun Feng <boqun.feng@gmail.com>]
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This is needed if user space wants to know supported bnep features
by kernel, e.g. if kernel supports sending response to bnep setup
control message. By now there is no possibility to know supported
features by kernel in case of bnep. Ioctls allows only to add connection,
delete connection, get connection list, get connection info. Adding
connection if it's possible (establishing network device connection) is
equivalent to starting bnep session. Bnep session handles data queue of
transmit, receive messages over bnep channel. It means that if we add
connection the received/transmitted data will be parsed immediately. In
case of get bnep features we want to know before session start, if we
should leave setup data on socket queue and let kernel to handle with it,
or in case of no setup handling support, if we should pull this message
and handle setup response within user space.
Signed-off-by: NGrzegorz Kolodziejczyk <grzegorz.kolodziejczyk@tieto.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This should cover the set emitted by viced and the volume server.
Signed-off-by: NNathaniel Wesley Filardo <nwf@cs.jhu.edu>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

afs_send_empty_reply() doesn't require an iovec array with which to initialise
the msghdr, but can pass NULL instead.
Suggested-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Coverity reports a warning due to unitialized attr structure in one
code path.

Reported by Coverity (CID 728535)
Signed-off-by: NSteve French <smfrench@gmail.com>
Reviewed-by: NJeff Layton <jlayton@samba.org>