From: Steve French <stfrench@microsoft.com>
Date: Tue, 23 Feb 2021 15:50:57 -0600
Subject: [PATCH] cifs: Add new mount parameter "acdirmax" to allow caching
 directory metadata
Git-commit: 4c9f948142a550af416a2bfb5e56d29ce29e92cf
References: bsc#1190317
Patch-mainline: v5.12-rc1

nfs and cifs on Linux currently have a mount parameter "actimeo" to control
metadata (attribute) caching but cifs does not have additional mount
parameters to allow distinguishing between caching directory metadata
(e.g. needed to revalidate paths) and that for files.

Add new mount parameter "acdirmax" to allow caching metadata for
directories more loosely than file data.  NFS adjusts metadata
caching from acdirmin to acdirmax (and another two mount parms
for files) but to reduce complexity, it is safer to just introduce
the one mount parm to allow caching directories longer. The
defaults for acdirmax and actimeo (for cifs.ko) are conservative,
1 second (NFS defaults acdirmax to 60 seconds). For many workloads,
setting acdirmax to a higher value is safe and will improve
performance.  This patch leaves unchanged the default values
for caching metadata for files and directories but gives the
user more flexibility in adjusting them safely for their workload
via the new mount parm.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/cifs_fs_sb.h |    3 ++-
 fs/cifs/cifsfs.c     |    3 ++-
 fs/cifs/cifsglob.h   |    3 ++-
 fs/cifs/connect.c    |   18 +++++++++++++++++-
 4 files changed, 23 insertions(+), 4 deletions(-)

--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -64,7 +64,8 @@ struct cifs_sb_info {
 	unsigned int bsize;
 	unsigned int rsize;
 	unsigned int wsize;
-	unsigned long actimeo; /* attribute cache timeout (jiffies) */
+	unsigned long actimeo; /* attribute cache timeout for files (jiffies) */
+	unsigned long acdirmax; /* attribute cache timeout for directories (jiffies) */
 	atomic_t active;
 	kuid_t	mnt_uid;
 	kgid_t	mnt_gid;
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -600,8 +600,9 @@ cifs_show_options(struct seq_file *s, st
 		seq_printf(s, ",snapshot=%llu", tcon->snapshot_time);
 	if (tcon->handle_timeout)
 		seq_printf(s, ",handletimeout=%u", tcon->handle_timeout);
-	/* convert actimeo and display it in seconds */
+	/* convert actimeo and directory attribute timeout and display in seconds */
 	seq_printf(s, ",actimeo=%lu", cifs_sb->actimeo / HZ);
+	seq_printf(s, ",acdirmax=%lu", cifs_sb->acdirmax / HZ);
 
 	return 0;
 }
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -610,7 +610,8 @@ struct smb_vol {
 	unsigned int wsize;
 	unsigned int min_offload;
 	bool sockopt_tcp_nodelay:1;
-	unsigned long actimeo; /* attribute cache timeout (jiffies) */
+	unsigned long actimeo; /* attribute cache timeout for files (jiffies) */
+	unsigned long acdirmax; /* attribute cache timeout for directories (jiffies) */
 	struct smb_version_operations *ops;
 	struct smb_version_values *vals;
 	char *prepath;
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -107,7 +107,7 @@ enum {
 	Opt_cruid, Opt_gid, Opt_file_mode,
 	Opt_dirmode, Opt_port,
 	Opt_min_enc_offload,
-	Opt_blocksize, Opt_rsize, Opt_wsize, Opt_actimeo,
+	Opt_blocksize, Opt_rsize, Opt_wsize, Opt_actimeo, Opt_acdirmax,
 	Opt_echo_interval, Opt_max_credits, Opt_handletimeout,
 	Opt_snapshot,
 
@@ -218,6 +218,7 @@ static const match_table_t cifs_mount_op
 	{ Opt_rsize, "rsize=%s" },
 	{ Opt_wsize, "wsize=%s" },
 	{ Opt_actimeo, "actimeo=%s" },
+	{ Opt_acdirmax, "acdirmax=%s" },
 	{ Opt_handletimeout, "handletimeout=%s" },
 	{ Opt_echo_interval, "echo_interval=%s" },
 	{ Opt_max_credits, "max_credits=%s" },
@@ -1645,6 +1646,7 @@ cifs_parse_mount_options(const char *mou
 	vol->strict_io = true;
 
 	vol->actimeo = CIFS_DEF_ACTIMEO;
+	vol->acdirmax = CIFS_DEF_ACTIMEO;
 
 	/* Most clients set timeout to 0, allows server to use its default */
 	vol->handle_timeout = 0; /* See MS-SMB2 spec section 2.2.14.2.12 */
@@ -2072,6 +2074,18 @@ cifs_parse_mount_options(const char *mou
 				goto cifs_parse_mount_err;
 			}
 			break;
+		case Opt_acdirmax:
+			if (get_option_ul(args, &option)) {
+				cifs_dbg(VFS, "%s: Invalid acdirmax value\n",
+					 __func__);
+				goto cifs_parse_mount_err;
+			}
+			vol->acdirmax = HZ * option;
+			if (vol->acdirmax > CIFS_MAX_ACTIMEO) {
+				cifs_dbg(VFS, "acdirmax too large\n");
+				goto cifs_parse_mount_err;
+			}
+			break;
 		case Opt_handletimeout:
 			if (get_option_ul(args, &option)) {
 				cifs_dbg(VFS, "%s: Invalid handletimeout value\n",
@@ -3610,6 +3624,8 @@ compare_mount_options(struct super_block
 
 	if (old->actimeo != new->actimeo)
 		return 0;
+	if (old->acdirmax != new->acdirmax)
+		return 0;
 
 	return 1;
 }