[PATCH AUTOSEL 5.16 19/20] Adjust cifssb maximum read size

[Sasha Levin <sashal@kernel.org>]

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 99c51391a48d..d4fa4e3131b4 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -209,6 +209,9 @@ 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 9fee3af83a73..abadc2f86dea 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