Patch "fs: fix data invalidation in the cleancache during direct IO" has been added to the 4.11-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    fs: fix data invalidation in the cleancache during direct IO

to the 4.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fs-fix-data-invalidation-in-the-cleancache-during-direct-io.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 55635ba76ef91f26b418702ace5e6287eb727f6a Mon Sep 17 00:00:00 2001
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
Date: Wed, 3 May 2017 14:55:59 -0700
Subject: fs: fix data invalidation in the cleancache during direct IO

From: Andrey Ryabinin <aryabinin@virtuozzo.com>

commit 55635ba76ef91f26b418702ace5e6287eb727f6a upstream.

Patch series "Properly invalidate data in the cleancache", v2.

We've noticed that after direct IO write, buffered read sometimes gets
stale data which is coming from the cleancache.  The reason for this is
that some direct write hooks call call invalidate_inode_pages2[_range]()
conditionally iff mapping->nrpages is not zero, so we may not invalidate
data in the cleancache.

Another odd thing is that we check only for ->nrpages and don't check
for ->nrexceptional, but invalidate_inode_pages2[_range] also
invalidates exceptional entries as well.  So we invalidate exceptional
entries only if ->nrpages != 0? This doesn't feel right.

 - Patch 1 fixes direct IO writes by removing ->nrpages check.
 - Patch 2 fixes similar case in invalidate_bdev().
     Note: I only fixed conditional cleancache_invalidate_inode() here.
       Do we also need to add ->nrexceptional check in into invalidate_bdev()?

 - Patches 3-4: some optimizations.

This patch (of 4):

Some direct IO write fs hooks call invalidate_inode_pages2[_range]()
conditionally iff mapping->nrpages is not zero.  This can't be right,
because invalidate_inode_pages2[_range]() also invalidate data in the
cleancache via cleancache_invalidate_inode() call.  So if page cache is
empty but there is some data in the cleancache, buffered read after
direct IO write would get stale data from the cleancache.

Also it doesn't feel right to check only for ->nrpages because
invalidate_inode_pages2[_range] invalidates exceptional entries as well.

Fix this by calling invalidate_inode_pages2[_range]() regardless of
nrpages state.

Note: nfs,cifs,9p doesn't need similar fix because the never call
cleancache_get_page() (nor directly, nor via mpage_readpage[s]()), so
they are not affected by this bug.

Fixes: c515e1fd361c ("mm/fs: add hooks to support cleancache")
Link: http://lkml.kernel.org/r/20170424164135.22350-2-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/iomap.c   |   20 +++++++++-----------
 mm/filemap.c |   26 +++++++++++---------------
 2 files changed, 20 insertions(+), 26 deletions(-)

--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -887,16 +887,14 @@ iomap_dio_rw(struct kiocb *iocb, struct
 		flags |= IOMAP_WRITE;
 	}
 
-	if (mapping->nrpages) {
-		ret = filemap_write_and_wait_range(mapping, start, end);
-		if (ret)
-			goto out_free_dio;
-
-		ret = invalidate_inode_pages2_range(mapping,
-				start >> PAGE_SHIFT, end >> PAGE_SHIFT);
-		WARN_ON_ONCE(ret);
-		ret = 0;
-	}
+	ret = filemap_write_and_wait_range(mapping, start, end);
+	if (ret)
+		goto out_free_dio;
+
+	ret = invalidate_inode_pages2_range(mapping,
+			start >> PAGE_SHIFT, end >> PAGE_SHIFT);
+	WARN_ON_ONCE(ret);
+	ret = 0;
 
 	inode_dio_begin(inode);
 
@@ -951,7 +949,7 @@ iomap_dio_rw(struct kiocb *iocb, struct
 	 * one is a pretty crazy thing to do, so we don't support it 100%.  If
 	 * this invalidation fails, tough, the write still worked...
 	 */
-	if (iov_iter_rw(iter) == WRITE && mapping->nrpages) {
+	if (iov_iter_rw(iter) == WRITE) {
 		int err = invalidate_inode_pages2_range(mapping,
 				start >> PAGE_SHIFT, end >> PAGE_SHIFT);
 		WARN_ON_ONCE(err);
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2719,18 +2719,16 @@ generic_file_direct_write(struct kiocb *
 	 * about to write.  We do this *before* the write so that we can return
 	 * without clobbering -EIOCBQUEUED from ->direct_IO().
 	 */
-	if (mapping->nrpages) {
-		written = invalidate_inode_pages2_range(mapping,
+	written = invalidate_inode_pages2_range(mapping,
 					pos >> PAGE_SHIFT, end);
-		/*
-		 * If a page can not be invalidated, return 0 to fall back
-		 * to buffered write.
-		 */
-		if (written) {
-			if (written == -EBUSY)
-				return 0;
-			goto out;
-		}
+	/*
+	 * If a page can not be invalidated, return 0 to fall back
+	 * to buffered write.
+	 */
+	if (written) {
+		if (written == -EBUSY)
+			return 0;
+		goto out;
 	}
 
 	data = *from;
@@ -2744,10 +2742,8 @@ generic_file_direct_write(struct kiocb *
 	 * so we don't support it 100%.  If this invalidation
 	 * fails, tough, the write still worked...
 	 */
-	if (mapping->nrpages) {
-		invalidate_inode_pages2_range(mapping,
-					      pos >> PAGE_SHIFT, end);
-	}
+	invalidate_inode_pages2_range(mapping,
+				pos >> PAGE_SHIFT, end);
 
 	if (written > 0) {
 		pos += written;


Patches currently in stable-queue which might be from aryabinin@virtuozzo.com are

queue-4.11/fs-block_dev-always-invalidate-cleancache-in-invalidate_bdev.patch
queue-4.11/mm-prevent-potential-recursive-reclaim-due-to-clearing-pf_memalloc.patch
queue-4.11/fs-fix-data-invalidation-in-the-cleancache-during-direct-io.patch