O_APPEND handling there hadn't been completely fixed by Pavel's
patch; it checks the right value, but it's racy - we can't really
do that until i_mutex has been taken.

Fix by switching to __generic_file_aio_write() (open-coding
generic_file_aio_write(), actually) and pulling mutex_lock() above
inode_size_read().

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ceph_osdc_put_request(ERR_PTR(-error)) oopses.  What we want there
is break, not goto out.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

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

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

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

always equal to &iocb->ki_pos.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

same story - it's &iocb->ki_pos in all cases
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

It's always equal to &iocb->ki_pos, where iocb is the value of the 1st
argument.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

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

sg_iovec array passed to it can be const
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

(casts are due to misannotations in lustre; it uses iovec where kvec would be
correct type; too much noise to properly annotate right now).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

saner variable names, update linuxdoc comments, etc.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

we can calculate that in the caller just fine, TYVM
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... makes passing the amount of pages unnecessary
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and trim the fuck out of process_vm_rw_pages() argument list.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... rather than open-coding those.  As a side benefit, we get much saner
loop calling those; we can just feed entire pages, instead of the "copy
would span the iovec boundary, let's do it in two loop iterations" mess.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

instead of keeping its pieces in separate variables and passing
pointers to all of them...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

instead of passing vector size (by value) and index (by reference),
pass the number of elements remaining.  That's all we care about
in these functions by that point.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

lift iov one more level out - from process_vm_rw_single_vec to
process_vm_rw_core().  Same story as with the previous commit.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

move iov to caller's stack frame; the value we assign to it on the
next call of process_vm_rw_pages() is equal to the value it had
when the last time we were leaving process_vm_rw_pages().

drop lvec argument of process_vm_rw_pages() - it's not used anymore.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

we want to massage it to use of iov_iter.  This one is an equivalent
transformation - just introduce a local variable mirroring
lvec + *lvec_current.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and don't skip on sanity checks.  It's *not* a hot path, TYVM
(a couple of calls per a.out execve(), for pity sake) and headers of
random a.out binary are not to be trusted.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

... we are doing them on adjacent parts of file, so what happens is that
each subsequent call works to rebuild the iov_iter to exact state it
had been abandoned in by previous one.  Just keep it through the entire
cifs_iovec_read().  And use copy_page_to_iter() instead of doing
kmap/copy_to_user/kunmap manually...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

I've switched the sanity checks on iovec to rw_copy_check_uvector();
we might need to do a local analog, if any behaviour differences are
not actually bugfixes here...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

... by that point the request we'd just resent is in the
head of the list anyway.  Just return to the beginning of
the loop body...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

generic_file_aio_read() was looping over the target iovec, with loop over
(source) pages nested inside that.  Just set an iov_iter up and pass *that*
to do_generic_file_aio_read().  With copy_page_to_iter() doing all work
of mapping and copying a page to iovec and advancing iov_iter.

Switch shmem_file_aio_read() to the same and kill file_read_actor(), while
we are at it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

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

... it does that itself (via kmap_atomic())
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

all pipe_buffer_operations have the same instances of those...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>