From: Jens Axboe <axboe@kernel.dk>
To: linux-fsdevel@vger.kernel.org
Cc: torvalds@linux-foundation.org, brauner@kernel.org,
viro@zeniv.linux.org.uk, Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 11/11] iov_iter: import single vector iovecs as ITER_UBUF
Date: Thu, 30 Mar 2023 10:47:02 -0600 [thread overview]
Message-ID: <20230330164702.1647898-12-axboe@kernel.dk> (raw)
In-Reply-To: <20230330164702.1647898-1-axboe@kernel.dk>
Add a special case to __import_iovec(), which imports a single segment
iovec as an ITER_UBUF rather than an ITER_IOVEC. ITER_UBUF is cheaper
to iterate than ITER_IOVEC, and for a single segment iovec, there's no
point in using a segmented iterator.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
lib/iov_iter.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index f411bda1171f..3e6c9bcfa612 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1784,6 +1784,30 @@ struct iovec *iovec_from_user(const struct iovec __user *uvec,
return iov;
}
+/*
+ * Single segment iovec supplied by the user, import it as ITER_UBUF.
+ */
+static ssize_t __import_iovec_ubuf(int type, const struct iovec __user *uvec,
+ struct iovec **iovp, struct iov_iter *i,
+ bool compat)
+{
+ struct iovec *iov = *iovp;
+ ssize_t ret;
+
+ if (compat)
+ ret = copy_compat_iovec_from_user(iov, uvec, 1);
+ else
+ ret = copy_iovec_from_user(iov, uvec, 1);
+ if (unlikely(ret))
+ return ret;
+
+ ret = import_ubuf(type, iov->iov_base, iov->iov_len, i);
+ if (unlikely(ret))
+ return ret;
+ *iovp = NULL;
+ return i->count;
+}
+
ssize_t __import_iovec(int type, const struct iovec __user *uvec,
unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
struct iov_iter *i, bool compat)
@@ -1792,6 +1816,9 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec,
unsigned long seg;
struct iovec *iov;
+ if (nr_segs == 1)
+ return __import_iovec_ubuf(type, uvec, iovp, i, compat);
+
iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
if (IS_ERR(iov)) {
*iovp = NULL;
--
2.39.2
next prev parent reply other threads:[~2023-03-30 16:48 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 16:46 [PATCHSET v6b 0/11] Turn single segment imports into ITER_UBUF Jens Axboe
2023-03-30 16:46 ` [PATCH 01/11] block: ensure bio_alloc_map_data() deals with ITER_UBUF correctly Jens Axboe
2023-03-30 16:46 ` [PATCH 02/11] iov_iter: add iter_iovec() helper Jens Axboe
2023-03-30 16:46 ` [PATCH 03/11] IB/hfi1: check for user backed iterator, not specific iterator type Jens Axboe
2023-03-30 16:46 ` [PATCH 04/11] IB/qib: " Jens Axboe
2023-03-30 16:46 ` [PATCH 05/11] ALSA: pcm: " Jens Axboe
2023-03-30 16:46 ` [PATCH 06/11] iov_iter: add iter_iov_addr() and iter_iov_len() helpers Jens Axboe
2023-03-30 16:46 ` [PATCH 07/11] iov_iter: remove iov_iter_iovec() Jens Axboe
2023-03-30 16:46 ` [PATCH 08/11] iov_iter: set nr_segs = 1 for ITER_UBUF Jens Axboe
2023-03-30 16:47 ` [PATCH 09/11] iov_iter: overlay struct iovec and ubuf/len Jens Axboe
2023-03-30 16:47 ` [PATCH 10/11] iov_iter: convert import_single_range() to ITER_UBUF Jens Axboe
2023-03-30 16:47 ` Jens Axboe [this message]
2023-03-30 17:11 ` [PATCHSET v6b 0/11] Turn single segment imports into ITER_UBUF Linus Torvalds
2023-03-30 17:33 ` Jens Axboe
2023-03-30 21:53 ` Linus Torvalds
2023-03-30 22:18 ` Jens Axboe
2023-04-02 22:22 ` Jens Axboe
2023-04-02 23:37 ` Linus Torvalds
-- strict thread matches above, loose matches on Subject: below --
2023-03-29 18:40 [PATCHSET v6 " Jens Axboe
2023-03-29 18:40 ` [PATCH 11/11] iov_iter: import single vector iovecs as ITER_UBUF Jens Axboe
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