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From: David Howells <dhowells@redhat.com>
To: jlayton@kernel.org, willy@infradead.org
Cc: linux-afs@lists.infradead.org, dhowells@redhat.com,
	linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] afs: Fix afs_write_end() to handle short writes
Date: Mon, 14 Jun 2021 14:20:25 +0100	[thread overview]
Message-ID: <162367682522.460125.5652091227576721609.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <162367681795.460125.11729955608839747375.stgit@warthog.procyon.org.uk>

Fix afs_write_end() to correctly handle a short copy into the intended
write region of the page.  Two things are necessary:

 (1) If the page is not up to date, then we should just return 0
     (ie. indicating a zero-length copy).  The loop in
     generic_perform_write() will go around again, possibly breaking up the
     iterator into discrete chunks.

     This is analogous to commit b9de313cf05fe08fa59efaf19756ec5283af672a
     for ceph.

 (2) The page should not have been set uptodate if it wasn't completely set
     up by netfs_write_begin() (this will be fixed in the next page), so we
     need to set PG_uptodate here in such a case.

Fixes: 3003bbd0697b ("afs: Use the netfs_write_begin() helper")
Reported-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org
---

 fs/afs/write.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/afs/write.c b/fs/afs/write.c
index f68274c39f47..4b3f16ca2810 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -121,6 +121,16 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 	_enter("{%llx:%llu},{%lx}",
 	       vnode->fid.vid, vnode->fid.vnode, page->index);
 
+	len = min_t(size_t, len, thp_size(page) - from);
+	if (!PageUptodate(page)) {
+		if (copied < len) {
+			copied = 0;
+			goto out;
+		}
+
+		SetPageUptodate(page);
+	}
+
 	if (copied == 0)
 		goto out;
 
@@ -135,8 +145,6 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 		write_sequnlock(&vnode->cb_lock);
 	}
 
-	ASSERT(PageUptodate(page));
-
 	if (PagePrivate(page)) {
 		priv = page_private(page);
 		f = afs_page_dirty_from(page, priv);



  reply	other threads:[~2021-06-14 13:21 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14 13:20 [PATCH 1/3] afs: Handle len being extending over page end in write_begin/write_end David Howells
2021-06-14 13:20 ` David Howells [this message]
2021-06-14 13:28   ` [PATCH 2/3] afs: Fix afs_write_end() to handle short writes Matthew Wilcox
2021-06-14 13:37   ` David Howells
2021-06-14 13:46     ` Matthew Wilcox
2021-06-18  3:40       ` Al Viro
2021-06-14 14:04     ` David Howells
2021-06-14 14:37   ` Matthew Wilcox
2021-06-14 15:38   ` David Howells
2021-06-14 15:43     ` Matthew Wilcox
2021-06-14 21:11     ` David Howells
2021-06-14 13:20 ` [PATCH 3/3] netfs: fix test for whether we can skip read when writing beyond EOF David Howells
2021-06-15 17:01   ` Jeff Layton
2021-06-14 13:33 ` David Howells
2021-06-17  7:43 ` [PATCH 1/3] afs: Handle len being extending over page end in write_begin/write_end kernel test robot

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