From: Andreas Gruenbacher <agruenba@redhat.com>
To: cluster-devel@redhat.com
Cc: kvm-ppc@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>,
Jan Kara <jack@suse.cz>,
Andreas Gruenbacher <agruenba@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH v9 16/17] iov_iter: Introduce nofault flag to disable page faults
Date: Tue, 2 Nov 2021 13:29:44 +0100 [thread overview]
Message-ID: <20211102122945.117744-17-agruenba@redhat.com> (raw)
In-Reply-To: <20211102122945.117744-1-agruenba@redhat.com>
Introduce a new nofault flag to indicate to iov_iter_get_pages not to
fault in user pages.
This is implemented by passing the FOLL_NOFAULT flag to get_user_pages,
which causes get_user_pages to fail when it would otherwise fault in a
page. We'll use the ->nofault flag to prevent iomap_dio_rw from faulting
in pages when page faults are not allowed.
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 25d1c24fd829..6350354f97e9 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -35,6 +35,7 @@ struct iov_iter_state {
struct iov_iter {
u8 iter_type;
+ bool nofault;
bool data_source;
size_t iov_offset;
size_t count;
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index ac9a87e727a3..66a740e6e153 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -513,6 +513,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
WARN_ON(direction & ~(READ | WRITE));
*i = (struct iov_iter) {
.iter_type = ITER_IOVEC,
+ .nofault = false,
.data_source = direction,
.iov = iov,
.nr_segs = nr_segs,
@@ -1527,13 +1528,17 @@ 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->nofault)
+ gup_flags |= FOLL_NOFAULT;
+
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;
@@ -1649,15 +1654,20 @@ 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->nofault)
+ gup_flags |= FOLL_NOFAULT;
+
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;
--
2.31.1
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next prev parent reply other threads:[~2021-11-02 12:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-02 12:29 [Ocfs2-devel] [PATCH v9 00/17] gfs2: Fix mmap + page fault deadlocks Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 01/17] iov_iter: Fix iov_iter_get_pages{, _alloc} page fault return value Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 02/17] powerpc/kvm: Fix kvm_use_magic_page Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 03/17] gup: Turn fault_in_pages_{readable, writeable} into fault_in_{readable, writeable} Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 04/17] iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable Andreas Gruenbacher
2021-11-04 18:22 ` Catalin Marinas
2021-11-04 20:31 ` Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 05/17] iov_iter: Introduce fault_in_iov_iter_writeable Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 06/17] gfs2: Add wrapper for iomap_file_buffered_write Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 07/17] gfs2: Clean up function may_grant Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 08/17] gfs2: Introduce flag for glock holder auto-demotion Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 09/17] gfs2: Move the inode glock locking to gfs2_file_buffered_write Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 10/17] gfs2: Eliminate ip->i_gh Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 11/17] gfs2: Fix mmap + page fault deadlocks for buffered I/O Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 12/17] iomap: Fix iomap_dio_rw return value for user copies Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 13/17] iomap: Support partial direct I/O on user copy failures Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 14/17] iomap: Add done_before argument to iomap_dio_rw Andreas Gruenbacher
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 15/17] gup: Introduce FOLL_NOFAULT flag to disable page faults Andreas Gruenbacher
2021-11-02 12:29 ` Andreas Gruenbacher [this message]
2021-11-02 12:29 ` [Ocfs2-devel] [PATCH v9 17/17] gfs2: Fix mmap + page fault deadlocks for direct I/O Andreas Gruenbacher
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