linux-kernel - [RFC PATCH v3 1/7] direct-io: don't dirty ITER

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <5db70228c7a288ffb8f87a3e4995cf7584e6a56c.1418173063.git.osandov@osandov.com>
Date:	Tue,  9 Dec 2014 17:45:42 -0800
From:	Omar Sandoval <osandov@...ndov.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	Christoph Hellwig <hch@...radead.org>,
	David Sterba <dsterba@...e.cz>, linux-btrfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Omar Sandoval <osandov@...ndov.com>,
	Ming Lei <ming.lei@...onical.com>
Subject: [RFC PATCH v3 1/7] direct-io: don't dirty ITER_BVEC pages on read

Reads through the iov_iter infrastructure for kernel pages shouldn't be
dirtied by the direct I/O code.

This is based on Dave Kleikamp's and Ming Lei's previously posted
patches.

Cc: Ming Lei <ming.lei@...onical.com>
Acked-by: Dave Kleikamp <dave.kleikamp@...cle.com>
Signed-off-by: Omar Sandoval <osandov@...ndov.com>
---
 fs/direct-io.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index e181b6b..e542ce4 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -120,6 +120,7 @@ struct dio {
 	spinlock_t bio_lock;		/* protects BIO fields below */
 	int page_errors;		/* errno from get_user_pages() */
 	int is_async;			/* is IO async ? */
+	int should_dirty;		/* should we mark read pages dirty? */
 	bool defer_completion;		/* defer AIO completion to workqueue? */
 	int io_error;			/* IO error in completion path */
 	unsigned long refcount;		/* direct_io_worker() and bios */
@@ -392,7 +393,7 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
 	dio->refcount++;
 	spin_unlock_irqrestore(&dio->bio_lock, flags);
 
-	if (dio->is_async && dio->rw == READ)
+	if (dio->is_async && dio->rw == READ && dio->should_dirty)
 		bio_set_pages_dirty(bio);
 
 	if (sdio->submit_io)
@@ -463,13 +464,13 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio)
 	if (!uptodate)
 		dio->io_error = -EIO;
 
-	if (dio->is_async && dio->rw == READ) {
+	if (dio->is_async && dio->rw == READ && dio->should_dirty) {
 		bio_check_pages_dirty(bio);	/* transfers ownership */
 	} else {
 		bio_for_each_segment_all(bvec, bio, i) {
 			struct page *page = bvec->bv_page;
 
-			if (dio->rw == READ && !PageCompound(page))
+			if (dio->rw == READ && !PageCompound(page) && dio->should_dirty)
 				set_page_dirty_lock(page);
 			page_cache_release(page);
 		}
@@ -1177,6 +1178,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 
 	dio->inode = inode;
 	dio->rw = rw;
+	dio->should_dirty = !(iter->type & ITER_BVEC);
 
 	/*
 	 * For AIO O_(D)SYNC writes we need to defer completions to a workqueue
-- 
2.1.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/