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From:   trondmy@kernel.org
To:     linux-nfs@vger.kernel.org
Subject: [PATCH v2 2/3] NFS: Don't corrupt the value of pg_bytes_written in nfs_do_recoalesce()
Date:   Tue, 25 May 2021 14:02:40 -0400
Message-Id: <20210525180241.261090-2-trondmy@kernel.org>
In-Reply-To: <20210525180241.261090-1-trondmy@kernel.org>
References: <20210525180241.261090-1-trondmy@kernel.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

The value of mirror->pg_bytes_written should only be updated after a
successful attempt to flush out the requests on the list.

Fixes: a7d42ddb3099 ("nfs: add mirroring support to pgio layer")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/pagelist.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index d35c84af44e0..daf6658517f4 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -1128,17 +1128,16 @@ static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 {
 	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 
-
 	if (!list_empty(&mirror->pg_list)) {
 		int error = desc->pg_ops->pg_doio(desc);
 		if (error < 0)
 			desc->pg_error = error;
-		else
+		if (list_empty(&mirror->pg_list)) {
 			mirror->pg_bytes_written += mirror->pg_count;
-	}
-	if (list_empty(&mirror->pg_list)) {
-		mirror->pg_count = 0;
-		mirror->pg_base = 0;
+			mirror->pg_count = 0;
+			mirror->pg_base = 0;
+			mirror->pg_recoalesce = 0;
+		}
 	}
 }
 
@@ -1228,7 +1227,6 @@ static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
 
 	do {
 		list_splice_init(&mirror->pg_list, &head);
-		mirror->pg_bytes_written -= mirror->pg_count;
 		mirror->pg_count = 0;
 		mirror->pg_base = 0;
 		mirror->pg_recoalesce = 0;
-- 
2.31.1