From: Dave Kleikamp <dave.kleikamp@oracle.com>
To: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
"Maxim V. Patlasov" <mpatlasov@parallels.com>,
Zach Brown <zab@zabbo.net>,
Dave Kleikamp <dave.kleikamp@oracle.com>
Subject: [PATCH V8 08/33] iov_iter: add bvec support
Date: Thu, 25 Jul 2013 12:50:34 -0500 [thread overview]
Message-ID: <1374774659-13121-9-git-send-email-dave.kleikamp@oracle.com> (raw)
In-Reply-To: <1374774659-13121-1-git-send-email-dave.kleikamp@oracle.com>
From: Zach Brown <zab@zabbo.net>
This adds a set of iov_iter_ops calls which work with memory which is
specified by an array of bio_vec structs instead of an array of iovec
structs.
The big difference is that the pages referenced by the bio_vec elements
are pinned. They don't need to be faulted in and we can always use
kmap_atomic() to map them one at a time.
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Zach Brown <zab@zabbo.net>
---
fs/iov-iter.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 19 ++++++++
2 files changed, 148 insertions(+)
diff --git a/fs/iov-iter.c b/fs/iov-iter.c
index 59f9556..5624e36 100644
--- a/fs/iov-iter.c
+++ b/fs/iov-iter.c
@@ -5,6 +5,7 @@
#include <linux/hardirq.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
+#include <linux/bio.h>
static size_t __iovec_copy_to_user(char *vaddr, const struct iovec *iov,
size_t base, size_t bytes, int atomic)
@@ -109,6 +110,134 @@ success:
return copied;
}
+#ifdef CONFIG_BLOCK
+/*
+ * As an easily verifiable first pass, we implement all the methods that
+ * copy data to and from bvec pages with one function. We implement it
+ * all with kmap_atomic().
+ */
+static size_t bvec_copy_tofrom_page(struct iov_iter *iter, struct page *page,
+ unsigned long page_offset, size_t bytes,
+ int topage)
+{
+ struct bio_vec *bvec = (struct bio_vec *)iter->data;
+ size_t bvec_offset = iter->iov_offset;
+ size_t remaining = bytes;
+ void *bvec_map;
+ void *page_map;
+ size_t copy;
+
+ page_map = kmap_atomic(page);
+
+ BUG_ON(bytes > iter->count);
+ while (remaining) {
+ BUG_ON(bvec->bv_len == 0);
+ BUG_ON(bvec_offset >= bvec->bv_len);
+ copy = min(remaining, bvec->bv_len - bvec_offset);
+ bvec_map = kmap_atomic(bvec->bv_page);
+ if (topage)
+ memcpy(page_map + page_offset,
+ bvec_map + bvec->bv_offset + bvec_offset,
+ copy);
+ else
+ memcpy(bvec_map + bvec->bv_offset + bvec_offset,
+ page_map + page_offset,
+ copy);
+ kunmap_atomic(bvec_map);
+ remaining -= copy;
+ bvec_offset += copy;
+ page_offset += copy;
+ if (bvec_offset == bvec->bv_len) {
+ bvec_offset = 0;
+ bvec++;
+ }
+ }
+
+ kunmap_atomic(page_map);
+
+ return bytes;
+}
+
+static size_t ii_bvec_copy_to_user_atomic(struct page *page, struct iov_iter *i,
+ unsigned long offset, size_t bytes)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 0);
+}
+static size_t ii_bvec_copy_to_user(struct page *page, struct iov_iter *i,
+ unsigned long offset, size_t bytes,
+ int check_access)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 0);
+}
+static size_t ii_bvec_copy_from_user_atomic(struct page *page,
+ struct iov_iter *i,
+ unsigned long offset, size_t bytes)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 1);
+}
+static size_t ii_bvec_copy_from_user(struct page *page, struct iov_iter *i,
+ unsigned long offset, size_t bytes)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 1);
+}
+
+/*
+ * bio_vecs have a stricter structure than iovecs that might have
+ * come from userspace. There are no zero length bio_vec elements.
+ */
+static void ii_bvec_advance(struct iov_iter *i, size_t bytes)
+{
+ struct bio_vec *bvec = (struct bio_vec *)i->data;
+ size_t offset = i->iov_offset;
+ size_t delta;
+
+ BUG_ON(i->count < bytes);
+ while (bytes) {
+ BUG_ON(bvec->bv_len == 0);
+ BUG_ON(bvec->bv_len <= offset);
+ delta = min(bytes, bvec->bv_len - offset);
+ offset += delta;
+ i->count -= delta;
+ bytes -= delta;
+ if (offset == bvec->bv_len) {
+ bvec++;
+ offset = 0;
+ }
+ }
+
+ i->data = (unsigned long)bvec;
+ i->iov_offset = offset;
+}
+
+/*
+ * pages pointed to by bio_vecs are always pinned.
+ */
+static int ii_bvec_fault_in_readable(struct iov_iter *i, size_t bytes)
+{
+ return 0;
+}
+
+static size_t ii_bvec_single_seg_count(const struct iov_iter *i)
+{
+ const struct bio_vec *bvec = (struct bio_vec *)i->data;
+ if (i->nr_segs == 1)
+ return i->count;
+ else
+ return min(i->count, bvec->bv_len - i->iov_offset);
+}
+
+struct iov_iter_ops ii_bvec_ops = {
+ .ii_copy_to_user_atomic = ii_bvec_copy_to_user_atomic,
+ .ii_copy_to_user = ii_bvec_copy_to_user,
+ .ii_copy_from_user_atomic = ii_bvec_copy_from_user_atomic,
+ .ii_copy_from_user = ii_bvec_copy_from_user,
+ .ii_advance = ii_bvec_advance,
+ .ii_fault_in_readable = ii_bvec_fault_in_readable,
+ .ii_single_seg_count = ii_bvec_single_seg_count,
+};
+EXPORT_SYMBOL(ii_bvec_ops);
+#endif /* CONFIG_BLOCK */
+
static size_t __iovec_copy_from_user(char *vaddr, const struct iovec *iov,
size_t base, size_t bytes, int atomic)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 96120d5..c2cd17c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -349,6 +349,25 @@ static inline size_t iov_iter_single_seg_count(const struct iov_iter *i)
return i->ops->ii_single_seg_count(i);
}
+#ifdef CONFIG_BLOCK
+extern struct iov_iter_ops ii_bvec_ops;
+
+struct bio_vec;
+static inline void iov_iter_init_bvec(struct iov_iter *i,
+ struct bio_vec *bvec,
+ unsigned long nr_segs,
+ size_t count, size_t written)
+{
+ i->ops = &ii_bvec_ops;
+ i->data = (unsigned long)bvec;
+ i->nr_segs = nr_segs;
+ i->iov_offset = 0;
+ i->count = count + written;
+
+ iov_iter_advance(i, written);
+}
+#endif
+
extern struct iov_iter_ops ii_iovec_ops;
static inline void iov_iter_init(struct iov_iter *i,
--
1.8.3.4
next prev parent reply other threads:[~2013-07-25 17:50 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-25 17:50 [PATCH V8 00/33] loop: Issue O_DIRECT aio using bio_vec Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 01/33] iov_iter: move into its own file Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 02/33] iov_iter: iov_iter_copy_from_user() should use non-atomic copy Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 03/33] iov_iter: add copy_to_user support Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 04/33] iov_iter: add __iovec_copy_to_user() Dave Kleikamp
[not found] ` <1374774659-13121-1-git-send-email-dave.kleikamp-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2013-07-25 17:50 ` [PATCH V8 05/33] fuse: convert fuse to use iov_iter_copy_[to|from]_user Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 06/33] iov_iter: hide iovec details behind ops function pointers Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 07/33] iov_iter: ii_iovec_copy_to_user should pre-fault user pages Dave Kleikamp
2013-07-25 17:50 ` Dave Kleikamp [this message]
2013-07-25 17:50 ` [PATCH V8 09/33] iov_iter: add a shorten call Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 10/33] iov_iter: let callers extract iovecs and bio_vecs Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 11/33] dio: Convert direct_IO to use iov_iter Dave Kleikamp
2013-08-23 15:48 ` Geert Uytterhoeven
2013-07-25 17:50 ` [PATCH V8 12/33] dio: add bio_vec support to __blockdev_direct_IO() Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 13/33] fs: pull iov_iter use higher up the stack Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 14/33] aio: add aio_kernel_() interface Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 15/33] aio: add aio support for iov_iter arguments Dave Kleikamp
2013-08-21 13:55 ` Benjamin LaHaise
2013-08-30 20:05 ` Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 16/33] bio: add bvec_length(), like iov_length() Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 17/33] loop: use aio to perform io on the underlying file Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 18/33] fs: create file_readable() and file_writable() functions Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 19/33] fs: use read_iter and write_iter rather than aio_read and aio_write Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 20/33] fs: add read_iter and write_iter to several file systems Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 21/33] ocfs2: add support for read_iter and write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 22/33] ext4: " Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 23/33] nfs: add support for read_iter, write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 24/33] nfs: simplify swap Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 25/33] btrfs: add support for read_iter and write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 26/33] block_dev: add support for read_iter, write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 27/33] xfs: add support for read_iter and write_iter Dave Kleikamp
2013-07-26 11:51 ` Dave Chinner
2013-07-25 17:50 ` [PATCH V8 28/33] gfs2: Convert aio_read/write ops to read/write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 29/33] udf: convert file ops from aio_read/write " Dave Kleikamp
2013-07-25 21:34 ` Jan Kara
2013-07-25 17:50 ` [PATCH V8 30/33] afs: add support for read_iter and write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 31/33] ecrpytfs: Convert aio_read/write ops to read/write_iter Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 32/33] ubifs: convert file ops from aio_read/write " Dave Kleikamp
2013-07-25 17:50 ` [PATCH V8 33/33] tmpfs: add support for read_iter and write_iter Dave Kleikamp
2013-07-30 21:28 ` [PATCH V8 00/33] loop: Issue O_DIRECT aio using bio_vec Andrew Morton
2013-07-31 0:43 ` Dave Chinner
2013-07-31 6:40 ` Sedat Dilek
2013-07-31 8:41 ` Sedat Dilek
2013-07-31 11:22 ` Sedat Dilek
2013-07-31 9:51 ` Maxim Patlasov
2013-08-01 8:58 ` Christoph Hellwig
2013-08-01 13:04 ` Dave Kleikamp
2013-08-02 10:48 ` Christoph Hellwig
2013-08-20 13:00 ` Christoph Hellwig
2013-08-20 19:13 ` Dave Kleikamp
2013-08-21 0:14 ` Stephen Rothwell
2013-08-21 5:35 ` Sedat Dilek
2013-08-20 22:46 ` Andrew Morton
2013-08-21 13:02 ` Benjamin LaHaise
2013-08-21 16:30 ` Dave Kleikamp
2013-08-21 16:39 ` Benjamin LaHaise
2013-08-21 17:12 ` Dave Kleikamp
2013-08-21 19:30 ` Andrew Morton
2013-08-21 20:24 ` Benjamin LaHaise
2013-10-14 15:07 ` Christoph Hellwig
2013-10-14 21:29 ` Benjamin LaHaise
2013-10-15 16:55 ` Christoph Hellwig
2013-10-15 17:14 ` Benjamin LaHaise
2013-10-15 17:18 ` Christoph Hellwig
2013-10-15 17:53 ` Dave Kleikamp
2014-12-31 20:38 ` Sedat Dilek
2014-12-31 21:52 ` Dave Kleikamp
2014-12-31 22:35 ` Sedat Dilek
2015-01-01 0:52 ` Ming Lei
2015-01-05 19:24 ` Maxim Patlasov
2015-01-06 13:18 ` Ming Lei
2015-01-10 16:51 ` Ming Lei
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