From: Andreas Gruenbacher <agruenba@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
"Darrick J. Wong" <djwong@kernel.org>
Cc: Jan Kara <jack@suse.cz>,
Andreas Gruenbacher <agruenba@redhat.com>,
linux-kernel@vger.kernel.org, cluster-devel@redhat.com,
linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH v5 11/12] iov_iter: Introduce noio flag to disable page faults
Date: Tue, 3 Aug 2021 21:18:17 +0200 [thread overview]
Message-ID: <20210803191818.993968-12-agruenba@redhat.com> (raw)
In-Reply-To: <20210803191818.993968-1-agruenba@redhat.com>
Introduce a new noio flag to indicate to get_user_pages to use the
FOLL_FAST_ONLY flag. This will cause get_user_pages to fail when it
would otherwise fault in a page.
Currently, the noio flag is only checked in iov_iter_get_pages and
iov_iter_get_pages_alloc. This is enough for iomaop_dio_rw, but it
may make sense to check for this flag in other contexts as well.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
include/linux/uio.h | 1 +
lib/iov_iter.c | 20 +++++++++++++++-----
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index ffa431aeb067..679e48454497 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -29,6 +29,7 @@ enum iter_type {
struct iov_iter {
u8 iter_type;
+ bool noio;
bool data_source;
size_t iov_offset;
size_t count;
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 4ffc76801eaa..66f0c9362bb5 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -519,6 +519,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
WARN_ON(direction & ~(READ | WRITE));
*i = (struct iov_iter) {
.iter_type = ITER_IOVEC,
+ .noio = false,
.data_source = direction,
.iov = iov,
.nr_segs = nr_segs,
@@ -1529,13 +1530,17 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
return 0;
if (likely(iter_is_iovec(i))) {
+ unsigned int gup_flags = 0;
unsigned long addr;
+ if (iov_iter_rw(i) != WRITE)
+ gup_flags |= FOLL_WRITE;
+ if (i->noio)
+ gup_flags |= FOLL_FAST_ONLY;
+
addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
n = DIV_ROUND_UP(len, PAGE_SIZE);
- res = get_user_pages_fast(addr, n,
- iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0,
- pages);
+ res = get_user_pages_fast(addr, n, gup_flags, pages);
if (unlikely(res <= 0))
return res;
return (res == n ? len : res * PAGE_SIZE) - *start;
@@ -1651,15 +1656,20 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
return 0;
if (likely(iter_is_iovec(i))) {
+ unsigned int gup_flags = 0;
unsigned long addr;
+ if (iov_iter_rw(i) != WRITE)
+ gup_flags |= FOLL_WRITE;
+ if (i->noio)
+ gup_flags |= FOLL_FAST_ONLY;
+
addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
n = DIV_ROUND_UP(len, PAGE_SIZE);
p = get_pages_array(n);
if (!p)
return -ENOMEM;
- res = get_user_pages_fast(addr, n,
- iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p);
+ res = get_user_pages_fast(addr, n, gup_flags, p);
if (unlikely(res <= 0)) {
kvfree(p);
*pages = NULL;
--
2.26.3
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next prev parent reply other threads:[~2021-08-03 19:19 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-03 19:18 [Ocfs2-devel] [PATCH v5 00/12] gfs2: Fix mmap + page fault deadlocks Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 01/12] iov_iter: Fix iov_iter_get_pages{, _alloc} page fault return value Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 02/12] powerpc/kvm: Fix kvm_use_magic_page Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 03/12] Turn fault_in_pages_{readable, writeable} into fault_in_{readable, writeable} Andreas Gruenbacher
2021-08-03 19:43 ` Linus Torvalds
2021-08-03 20:57 ` Al Viro
2021-08-03 21:38 ` Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 04/12] Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 05/12] iov_iter: Introduce fault_in_iov_iter_writeable Andreas Gruenbacher
2021-08-04 15:24 ` Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 06/12] gfs2: Add wrapper for iomap_file_buffered_write Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 07/12] gfs2: Fix mmap + page fault deadlocks for buffered I/O Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 08/12] iomap: Fix iomap_dio_rw return value for user copies Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 09/12] iomap: Support restarting direct I/O requests after user copy failures Andreas Gruenbacher
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 10/12] iomap: Add done_before argument to iomap_dio_rw Andreas Gruenbacher
2021-08-03 19:18 ` Andreas Gruenbacher [this message]
2021-08-03 19:18 ` [Ocfs2-devel] [PATCH v5 12/12] gfs2: Fix mmap + page fault deadlocks for direct I/O Andreas Gruenbacher
2021-08-03 19:45 ` [Ocfs2-devel] [PATCH v5 00/12] gfs2: Fix mmap + page fault deadlocks Linus Torvalds
2021-08-16 19:14 ` Andreas Gruenbacher
2021-08-18 21:49 ` Linus Torvalds
2021-08-19 19:40 ` Andreas Gruenbacher
2021-08-19 20:14 ` Linus Torvalds
2021-08-19 21:39 ` Andreas Gruenbacher
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