Commit Graph

27 Commits

Author SHA1 Message Date
Al Viro aa583096d9 copy_from_iter_nocache()
BTW, do we want memcpy_nocache()?

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-08 20:25:23 -05:00
Al Viro abb78f875f new helper: iov_iter_kvec()
initialization of kvec-backed iov_iter

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-08 20:25:23 -05:00
Al Viro a604ec7e9f csum_and_copy_..._iter()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-08 20:25:22 -05:00
Al Viro a280455fa8 iov_iter.c: handle ITER_KVEC directly
... without bothering with copy_..._user()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-08 19:52:00 -05:00
Al Viro 3d4d3e4826 iov_iter.c: convert copy_to_iter() to iterate_and_advance
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:14 -05:00
Al Viro 0dbca9a4b5 iov_iter.c: convert copy_from_iter() to iterate_and_advance
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:13 -05:00
Al Viro d271524a3a iov_iter.c: get rid of bvec_copy_page_{to,from}_iter()
Just have copy_page_{to,from}_iter() fall back to kmap_atomic +
copy_{to,from}_iter() + kunmap_atomic() in ITER_BVEC case.  As
the matter of fact, that's what we want to do for any iov_iter
kind that isn't blocking - e.g. ITER_KVEC will also go that way
once we recognize it on iov_iter.c primitives level

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:13 -05:00
Al Viro 8442fa46cf iov_iter.c: convert iov_iter_zero() to iterate_and_advance
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:12 -05:00
Al Viro 1b17f1f2e5 iov_iter.c: convert iov_iter_get_pages_alloc() to iterate_all_kinds
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:12 -05:00
Al Viro e5393fae3b iov_iter.c: convert iov_iter_get_pages() to iterate_all_kinds
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:11 -05:00
Al Viro e0f2dc4061 iov_iter.c: convert iov_iter_npages() to iterate_all_kinds
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:11 -05:00
Al Viro 7ce2a91e51 iov_iter.c: iterate_and_advance
same as iterate_all_kinds, but iterator is moved to the position past
the last byte we'd handled.

iov_iter_advance() converted to it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:10 -05:00
Al Viro 04a311655b iov_iter.c: macros for iterating over iov_iter
iterate_all_kinds(iter, size, ident, step_iovec, step_bvec)
iterates through the ranges covered by iter (up to size bytes total),
repeating step_iovec or step_bvec for each of those.  ident is
declared in expansion of that thing, either as struct iovec or
struct bvec, and it contains the range we are currently looking
at.  step_bvec should be a void expression, step_iovec - a size_t
one, with non-zero meaning "stop here, that many bytes from this
range left".  In the end, the amount actually handled is stored
in size.

iov_iter_copy_from_user_atomic() and iov_iter_alignment() converted
to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-27 18:44:10 -05:00
Paul Mackerras ad0eab9293 Fix thinko in iov_iter_single_seg_count
The branches of the if (i->type & ITER_BVEC) statement in
iov_iter_single_seg_count() are the wrong way around; if ITER_BVEC is
clear then we use i->bvec, when we should be using i->iov.  This fixes
it.

In my case, the symptom that this caused was that a KVM guest doing
filesystem operations on a virtual disk would result in one of qemu's
threads on the host going into an infinite loop in
generic_perform_write().  The loop would hit the copied == 0 case and
call iov_iter_single_seg_count() to reduce the number of bytes to try
to process, but because of the error, iov_iter_single_seg_count()
would just return i->count and the loop made no progress and continued
forever.

Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-13 13:28:55 -05:00
Matthew Wilcox c35e024800 Add copy_to_iter(), copy_from_iter() and iov_iter_zero()
For DAX, we want to be able to copy between iovecs and kernel addresses
that don't necessarily have a struct page.  This is a fairly simple
rearrangement for bvec iters to kmap the pages outside and pass them in,
but for user iovecs it gets more complicated because we might try various
different ways to kmap the memory.  Duplicating the existing logic works
out best in this case.

We need to be able to write zeroes to an iovec for reads from unwritten
ranges in a file.  This is performed by the new iov_iter_zero() function,
again patterned after the existing code that handles iovec iterators.

[AV: and export the buggers...]

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-10-09 02:39:03 -04:00
Miklos Szeredi 2c80929c4c fuse: honour max_read and max_write in direct_io mode
The third argument of fuse_get_user_pages() "nbytesp" refers to the number of
bytes a caller asked to pack into fuse request. This value may be lesser
than capacity of fuse request or iov_iter.  So fuse_get_user_pages() must
ensure that *nbytesp won't grow.

Now, when helper iov_iter_get_pages() performs all hard work of extracting
pages from iov_iter, it can be done by passing properly calculated
"maxsize" to the helper.

The other caller of iov_iter_get_pages() (dio_refill_pages()) doesn't need
this capability, so pass LONG_MAX as the maxsize argument here.

Fixes: c9c37e2e63 ("fuse: switch to iov_iter_get_pages()")
Reported-by: Werner Baumann <werner.baumann@onlinehome.de>
Tested-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-09-26 21:16:51 -04:00
Al Viro c7f3888ad7 switch iov_iter_get_pages() to passing maximal number of pages
... instead of maximal size.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-08-07 14:40:11 -04:00
Al Viro 62a8067a7f bio_vec-backed iov_iter
New variant of iov_iter - ITER_BVEC in iter->type, backed with
bio_vec array instead of iovec one.  Primitives taught to deal
with such beasts, __swap_write() switched to using that kind
of iov_iter.

Note that bio_vec is just a <page, offset, length> triple - there's
nothing block-specific about it.  I've left the definition where it
was, but took it from under ifdef CONFIG_BLOCK.

Next target: ->splice_write()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:39:45 -04:00
Al Viro 81055e584f optimize copy_page_{to,from}_iter()
if we'd ended up in the end of a segment, jump to the
beginning of the next one (iov_offset = 0, iov++),
rather than having the next primitive deal with that.

Ought to be folded back...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:39:45 -04:00
Al Viro f0d1bec9d5 new helper: copy_page_from_iter()
parallel to copy_page_to_iter().  pipe_write() switched to it (and became
->write_iter()).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:39:42 -04:00
Al Viro 91f79c43d1 new helper: iov_iter_get_pages_alloc()
same as iov_iter_get_pages(), except that pages array is allocated
(kmalloc if possible, vmalloc if that fails) and left for caller to
free.  Lustre and NFS ->direct_IO() switched to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:32:53 -04:00
Al Viro f67da30c1d new helper: iov_iter_npages()
counts the pages covered by iov_iter, up to given limit.
do_block_direct_io() and fuse_iter_npages() switched to
it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:32:52 -04:00
Al Viro 7b2c99d155 new helper: iov_iter_get_pages()
iov_iter_get_pages(iter, pages, maxsize, &start) grabs references pinning
the pages of up to maxsize of (contiguous) data from iter.  Returns the
amount of memory grabbed or -error.  In case of success, the requested
area begins at offset start in pages[0] and runs through pages[1], etc.
Less than requested amount might be returned - either because the contiguous
area in the beginning of iterator is smaller than requested, or because
the kernel failed to pin that many pages.

direct-io.c switched to using iov_iter_get_pages()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:32:50 -04:00
Al Viro 71d8e532b1 start adding the tag to iov_iter
For now, just use the same thing we pass to ->direct_IO() - it's all
iovec-based at the moment.  Pass it explicitly to iov_iter_init() and
account for kvec vs. iovec in there, by the same kludge NFS ->direct_IO()
uses.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:32:49 -04:00
Al Viro 886a391150 new primitive: iov_iter_alignment()
returns the value aligned as badly as the worst remaining segment
in iov_iter is.  Use instead of open-coded equivalents.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:32:47 -04:00
Al Viro e7c24607b5 kill iov_iter_copy_from_user()
all callers can use copy_page_from_iter() and it actually simplifies
them.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06 17:32:42 -04:00
Al Viro 4f18cd317a take iov_iter stuff to mm/iov_iter.c
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-01 23:19:30 -04:00