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[Patch v3 14/19] CIFS: SMBD: Deregister memory on finishing SMB write

From Long Li <longli@exchange.microsoft.com>
Newsgroups linux.kernel
Subject [Patch v3 14/19] CIFS: SMBD: Deregister memory on finishing SMB write
Date 2017-08-29 21:40 +0200
Message-ID <ujUwG-6Me-37@gated-at.bofh.it> (permalink)
References <ujUwF-6Me-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Long Li <longli@microsoft.com>

On write I/O finish, deregister the memory region if this was for a RDMA read.
If remote invalidation is not used, the call to smbd_deregister_mr will do
local invalidation and possibly wait. Memory region is normally deregistered
in MID callback as soon as it's used. There are situations where the MID may
not be created on I/O failure, under which memory region is deregistered when
write data context is released.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/cifssmb.c |  6 ++++++
 fs/cifs/smb2pdu.c | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index fbb0d4c..6e1de21 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -43,6 +43,7 @@
 #include "cifs_unicode.h"
 #include "cifs_debug.h"
 #include "fscache.h"
+#include "smbdirect.h"
 
 #ifdef CONFIG_CIFS_POSIX
 static struct {
@@ -1905,6 +1906,11 @@ cifs_writedata_release(struct kref *refcount)
 	struct cifs_writedata *wdata = container_of(refcount,
 					struct cifs_writedata, refcount);
 
+	if (wdata->mr) {
+		smbd_deregister_mr(wdata->mr);
+		wdata->mr = NULL;
+	}
+
 	if (wdata->cfile)
 		cifsFileInfo_put(wdata->cfile);
 
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 5581afd..5551053 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2666,6 +2666,18 @@ smb2_writev_callback(struct mid_q_entry *mid)
 		break;
 	}
 
+	/*
+	 * If this wdata has a memory registered, the MR can be freed
+	 * The number of MRs available is limited, it's important to recover
+	 * used MR as soon as I/O is finished. Hold MR longer in the later
+	 * I/O process can possibly result in I/O deadlock due to lack of MR
+	 * to send request on I/O retry
+	 */
+	if (wdata->mr) {
+		smbd_deregister_mr(wdata->mr);
+		wdata->mr = NULL;
+	}
+
 	if (wdata->result)
 		cifs_stats_fail_inc(tcon, SMB2_WRITE_HE);
 
-- 
2.7.4

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Thread

[Patch v3 00/19] CIFS: Implement SMB Direct Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 07/19] CIFS: SMBD: Destroy SMBDirect session on shutdown or umount Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 04/19] CIFS: SMBD: Add SMBDirect transport to SMB connection and Makefile Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
    Re: [Patch v3 04/19] CIFS: SMBD: Add SMBDirect transport to SMB  connection and Makefile Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 01:20 +0200
      RE: [Patch v3 04/19] CIFS: SMBD: Add SMBDirect transport to SMB  connection and Makefile Long Li <longli@microsoft.com> - 2017-08-30 01:20 +0200
  [Patch v3 09/19] CIFS: SMBD: Receive data from SMBDirect Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 01/19] CIFS: Add rdma mount option Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
    Re: [Patch v3 01/19] CIFS: Add rdma mount option Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 00:40 +0200
      RE: [Patch v3 01/19] CIFS: Add rdma mount option Long Li <longli@microsoft.com> - 2017-08-30 01:00 +0200
  [Patch v3 11/19] CIFS: SMBD: Define memory registration for I/O data Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
    Re: [Patch v3 11/19] CIFS: SMBD: Define memory registration for I/O data Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 02:50 +0200
      RE: [Patch v3 11/19] CIFS: SMBD: Define memory registration for I/O  data Long Li <longli@microsoft.com> - 2017-08-30 04:20 +0200
  [Patch v3 12/19] CIFS: SMBD: Fix the definition for SMB2_CHANNEL_RDMA_V1_INVALIDATE Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
    Re: [Patch v3 12/19] CIFS: SMBD: Fix the definition for SMB2_CHANNEL_RDMA_V1_INVALIDATE Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 03:00 +0200
      RE: [Patch v3 12/19] CIFS: SMBD: Fix the definition for  SMB2_CHANNEL_RDMA_V1_INVALIDATE Long Li <longli@microsoft.com> - 2017-08-30 04:20 +0200
  [Patch v3 10/19] CIFS: SMBD: Send data through SMBDirect Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 19/19] CIFS: SMBD: Add SMBDirect debug counters Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 17/19] CIFS: SMBD: Implement SMB read via RDMA write through memory registration Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 14/19] CIFS: SMBD: Deregister memory on finishing SMB write Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 08/19] CIFS: SMBD: Set SMBDirect maximum read or write size for I/O Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 18/19] CIFS: SMBD: Deregister memory when finishing SMB read Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 06/19] CIFS: SMBD: Reconnect to SMBDirect session Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
    Re: [Patch v3 06/19] CIFS: SMBD: Reconnect to SMBDirect session Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 01:30 +0200
      RE: [Patch v3 06/19] CIFS: SMBD: Reconnect to SMBDirect session Long Li <longli@microsoft.com> - 2017-08-30 01:40 +0200
  [Patch v3 15/19] CIFS: SMBD: Add parameter rdata to smb2_new_read_req Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 13/19] CIFS: SMBD: Implement SMB write via RDMA read through memory registration Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
  [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport constants Long Li <longli@exchange.microsoft.com> - 2017-08-29 21:40 +0200
    Re: [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport constants Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 00:50 +0200
      RE: [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport  constants Long Li <longli@microsoft.com> - 2017-08-30 01:10 +0200
        Re: [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport constants Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 20:20 +0200
          RE: [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport  constants Long Li <longli@microsoft.com> - 2017-08-30 20:30 +0200
            Re: [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport constants Pavel Shilovsky <piastryyy@gmail.com> - 2017-08-30 20:40 +0200
              Re: [Patch v3 02/19] CIFS: SMBD: Add SMBDirect protocol and transport constants Steve French <smfrench@gmail.com> - 2017-09-01 17:50 +0200
  RE: [Patch v3 00/19] CIFS: Implement SMB Direct Long Li <longli@microsoft.com> - 2017-08-30 20:50 +0200

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