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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Rohith Surabattula <rohiths@microsoft.com>,
        "Paulo Alcantara (SUSE)" <pc@cjr.nz>,
        Steve French <stfrench@microsoft.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 723/913] Adjust cifssb maximum read size
Date:   Tue,  5 Apr 2022 09:29:45 +0200
Message-Id: <20220405070401.504022314@linuxfoundation.org>
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From: Rohith Surabattula <rohiths@microsoft.com>

[ Upstream commit 06a466565d54a1a42168f9033a062a3f5c40e73b ]

When session gets reconnected during mount then read size in super block fs context
gets set to zero and after negotiate, rsize is not modified which results in
incorrect read with requested bytes as zero. Fixes intermittent failure
of xfstest generic/240

Note that stable requires a different version of this patch which will be
sent to the stable mailing list.

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Acked-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/cifsfs.c |  3 +++
 fs/cifs/file.c   | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 22a1d8156220..ed220daca3e1 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -210,6 +210,9 @@ cifs_read_super(struct super_block *sb)
 	if (rc)
 		goto out_no_root;
 	/* tune readahead according to rsize if readahead size not set on mount */
+	if (cifs_sb->ctx->rsize == 0)
+		cifs_sb->ctx->rsize =
+			tcon->ses->server->ops->negotiate_rsize(tcon, cifs_sb->ctx);
 	if (cifs_sb->ctx->rasize)
 		sb->s_bdi->ra_pages = cifs_sb->ctx->rasize / PAGE_SIZE;
 	else
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 82bbaf8e92b7..b23f6b489bb9 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3734,6 +3734,11 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 				break;
 		}
 
+		if (cifs_sb->ctx->rsize == 0)
+			cifs_sb->ctx->rsize =
+				server->ops->negotiate_rsize(tlink_tcon(open_file->tlink),
+							     cifs_sb->ctx);
+
 		rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->rsize,
 						   &rsize, credits);
 		if (rc)
@@ -4512,6 +4517,11 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
 				break;
 		}
 
+		if (cifs_sb->ctx->rsize == 0)
+			cifs_sb->ctx->rsize =
+				server->ops->negotiate_rsize(tlink_tcon(open_file->tlink),
+							     cifs_sb->ctx);
+
 		rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->rsize,
 						   &rsize, credits);
 		if (rc)
-- 
2.34.1