[PATCH][SMB3 client] allow deferred close timeout to be configurable

[Steve French <smfrench@gmail.com>]

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Deferred close can be a very useful feature for very safely
allowing caching data for read, and for minimizing the number
of reopens needed for a file that is repeatedly opened and
close but there are workloads where its default (1 second,
similar to actimeo/acregmax) is too small.

Allow the user to configure the amount of time we can
defer sending the final smb3 close when we have a
handle lease on the file (rather than forcing it to depend
on 1 second or actimeo which is often unrelated).

Adds new mount parameter "closetime=" which is the maximum
number of seconds we can wait before sending an SMB3
close when we have a handle lease for it.  Default value
is unchanged at 1 second.

-- 
Thanks,

Steve

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From 464efd4fec1eed5d34a0953c23dea951b9f528b1 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Thu, 11 Aug 2022 00:53:00 -0500
Subject: [PATCH] smb3: allow deferred close timeout to be configurable

Deferred close can be a very useful feature for allowing
caching data for read, and for minimizing the number of
reopens needed for a file that is repeatedly opened and
close but there are workloads where its default (1 second,
similar to actimeo/acregmax) is too small.

Allow the user to configure the amount of time we can
defer sending the final smb3 close when we have a
handle lease on the file (rather than forcing it to depend
on 1 second or actimeo which is often unrelated).

Adds new mount parameter "closetime=" which is the maximum
number of seconds we can wait before sending an SMB3
close when we have a handle lease for it.  Default value
is unchanged at 1 second.

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifsfs.c     | 2 ++
 fs/cifs/connect.c    | 2 ++
 fs/cifs/file.c       | 4 ++--
 fs/cifs/fs_context.c | 9 +++++++++
 fs/cifs/fs_context.h | 3 +++
 5 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 945fb083cea7..af6114e17fb5 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -693,6 +693,8 @@ cifs_show_options(struct seq_file *s, struct dentry *root)
 		seq_printf(s, ",acdirmax=%lu", cifs_sb->ctx->acdirmax / HZ);
 		seq_printf(s, ",acregmax=%lu", cifs_sb->ctx->acregmax / HZ);
 	}
+	if (cifs_sb->ctx->closetimeo != cifs_sb->ctx->acregmax)
+		seq_printf(s, ",closetimeo=%lu", cifs_sb->ctx->closetimeo / HZ);
 
 	if (tcon->ses->chan_max > 1)
 		seq_printf(s, ",multichannel,max_channels=%zu",
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 7f205a9a2de4..9111c025bcb8 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2681,6 +2681,8 @@ compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
 		return 0;
 	if (old->ctx->acdirmax != new->ctx->acdirmax)
 		return 0;
+	if (old->ctx->closetimeo != new->ctx->closetimeo)
+		return 0;
 
 	return 1;
 }
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 42f2639a1a66..2c5eae7d31f4 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -964,12 +964,12 @@ int cifs_close(struct inode *inode, struct file *file)
 				 * So, Increase the ref count to avoid use-after-free.
 				 */
 				if (!mod_delayed_work(deferredclose_wq,
-						&cfile->deferred, cifs_sb->ctx->acregmax))
+						&cfile->deferred, cifs_sb->ctx->closetimeo))
 					cifsFileInfo_get(cfile);
 			} else {
 				/* Deferred close for files */
 				queue_delayed_work(deferredclose_wq,
-						&cfile->deferred, cifs_sb->ctx->acregmax);
+						&cfile->deferred, cifs_sb->ctx->closetimeo);
 				cfile->deferred_close_scheduled = true;
 				spin_unlock(&cinode->deferred_lock);
 				return 0;
diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 8dc0d923ef6a..28a339c57beb 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -147,6 +147,7 @@ const struct fs_parameter_spec smb3_fs_parameters[] = {
 	fsparam_u32("actimeo", Opt_actimeo),
 	fsparam_u32("acdirmax", Opt_acdirmax),
 	fsparam_u32("acregmax", Opt_acregmax),
+	fsparam_u32("closetimeo", Opt_closetimeo),
 	fsparam_u32("echo_interval", Opt_echo_interval),
 	fsparam_u32("max_credits", Opt_max_credits),
 	fsparam_u32("handletimeout", Opt_handletimeout),
@@ -1074,6 +1075,13 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 		}
 		ctx->acdirmax = ctx->acregmax = HZ * result.uint_32;
 		break;
+	case Opt_closetimeo:
+		ctx->closetimeo = HZ * result.uint_32;
+		if (ctx->closetimeo > CIFS_MAX_ACTIMEO) {
+			cifs_errorf(fc, "closetimeo too large\n");
+			goto cifs_parse_mount_err;
+		}
+		break;
 	case Opt_echo_interval:
 		ctx->echo_interval = result.uint_32;
 		break;
@@ -1521,6 +1529,7 @@ int smb3_init_fs_context(struct fs_context *fc)
 
 	ctx->acregmax = CIFS_DEF_ACTIMEO;
 	ctx->acdirmax = CIFS_DEF_ACTIMEO;
+	ctx->closetimeo = CIFS_DEF_ACTIMEO;
 
 	/* Most clients set timeout to 0, allows server to use its default */
 	ctx->handle_timeout = 0; /* See MS-SMB2 spec section 2.2.14.2.12 */
diff --git a/fs/cifs/fs_context.h b/fs/cifs/fs_context.h
index 5f093cb7e9b9..927a5f2f9919 100644
--- a/fs/cifs/fs_context.h
+++ b/fs/cifs/fs_context.h
@@ -125,6 +125,7 @@ enum cifs_param {
 	Opt_actimeo,
 	Opt_acdirmax,
 	Opt_acregmax,
+	Opt_closetimeo,
 	Opt_echo_interval,
 	Opt_max_credits,
 	Opt_snapshot,
@@ -247,6 +248,8 @@ struct smb3_fs_context {
 	/* attribute cache timemout for files and directories in jiffies */
 	unsigned long acregmax;
 	unsigned long acdirmax;
+	/* timeout for deferred close of files in jiffies */
+	unsigned long closetimeo;
 	struct smb_version_operations *ops;
 	struct smb_version_values *vals;
 	char *prepath;
-- 
2.34.1