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[PATCH 4.12 22/22] NFSv4: Fix up mirror allocation

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4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit 14abcb0bf59a30cf65a74f6c6f53974cd7224bc6 upstream.

There are a number of callers of nfs_pageio_complete() that want to
continue using the nfs_pageio_descriptor without needing to call
nfs_pageio_init() again. Examples include nfs_pageio_resend() and
nfs_pageio_cond_complete().

The problem is that nfs_pageio_complete() also calls
nfs_pageio_cleanup_mirroring(), which frees up the array of mirrors.
This can lead to writeback errors, in the next call to
nfs_pageio_setup_mirroring().

Fix by simply moving the allocation of the mirrors to
nfs_pageio_setup_mirroring().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=196709
Reported-by: JianhongYin <yin-jianhong@163.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfs/pagelist.c |   73 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 39 insertions(+), 34 deletions(-)

--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -697,9 +697,6 @@ void nfs_pageio_init(struct nfs_pageio_d
 		     int io_flags,
 		     gfp_t gfp_flags)
 {
-	struct nfs_pgio_mirror *new;
-	int i;
-
 	desc->pg_moreio = 0;
 	desc->pg_inode = inode;
 	desc->pg_ops = pg_ops;
@@ -715,21 +712,9 @@ void nfs_pageio_init(struct nfs_pageio_d
 	desc->pg_mirror_count = 1;
 	desc->pg_mirror_idx = 0;
 
-	if (pg_ops->pg_get_mirror_count) {
-		/* until we have a request, we don't have an lseg and no
-		 * idea how many mirrors there will be */
-		new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
-			      sizeof(struct nfs_pgio_mirror), gfp_flags);
-		desc->pg_mirrors_dynamic = new;
-		desc->pg_mirrors = new;
-
-		for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
-			nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
-	} else {
-		desc->pg_mirrors_dynamic = NULL;
-		desc->pg_mirrors = desc->pg_mirrors_static;
-		nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
-	}
+	desc->pg_mirrors_dynamic = NULL;
+	desc->pg_mirrors = desc->pg_mirrors_static;
+	nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 
@@ -848,32 +833,52 @@ static int nfs_generic_pg_pgios(struct n
 	return ret;
 }
 
+static struct nfs_pgio_mirror *
+nfs_pageio_alloc_mirrors(struct nfs_pageio_descriptor *desc,
+		unsigned int mirror_count)
+{
+	struct nfs_pgio_mirror *ret;
+	unsigned int i;
+
+	kfree(desc->pg_mirrors_dynamic);
+	desc->pg_mirrors_dynamic = NULL;
+	if (mirror_count == 1)
+		return desc->pg_mirrors_static;
+	ret = kmalloc_array(mirror_count, sizeof(*ret), GFP_NOFS);
+	if (ret != NULL) {
+		for (i = 0; i < mirror_count; i++)
+			nfs_pageio_mirror_init(&ret[i], desc->pg_bsize);
+		desc->pg_mirrors_dynamic = ret;
+	}
+	return ret;
+}
+
 /*
  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
  *				by calling the pg_get_mirror_count op
  */
-static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
+static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 				       struct nfs_page *req)
 {
-	int mirror_count = 1;
-
-	if (!pgio->pg_ops->pg_get_mirror_count)
-		return 0;
+	unsigned int mirror_count = 1;
 
-	mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
-
-	if (pgio->pg_error < 0)
-		return pgio->pg_error;
-
-	if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
-		return -EINVAL;
+	if (pgio->pg_ops->pg_get_mirror_count)
+		mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
+	if (mirror_count == pgio->pg_mirror_count || pgio->pg_error < 0)
+		return;
 
-	if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
-		return -EINVAL;
+	if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX) {
+		pgio->pg_error = -EINVAL;
+		return;
+	}
 
+	pgio->pg_mirrors = nfs_pageio_alloc_mirrors(pgio, mirror_count);
+	if (pgio->pg_mirrors == NULL) {
+		pgio->pg_error = -ENOMEM;
+		pgio->pg_mirrors = pgio->pg_mirrors_static;
+		mirror_count = 1;
+	}
 	pgio->pg_mirror_count = mirror_count;
-
-	return 0;
 }
 
 /*

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[PATCH 4.12 00/22] 4.12.13-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 18/22] ARM64: dts: marvell: armada-37xx: Fix GIC maintenance interrupt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 22/22] NFSv4: Fix up mirror allocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 20/22] NFS: Fix 2 use after free issues in the I/O code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 02/22] mtd: nand: hynix: add support for 20nm NAND chips Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 13/22] mm/memory.c: fix mem_cgroup_oom_disable() call missing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 12/22] mm/swapfile.c: fix swapon frontswap_map memory leak on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 06/22] nvme-fabrics: generate spec-compliant UUID NQNs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:10 +0200
  [PATCH 4.12 08/22] rtlwifi: btcoexist: Fix breakage of ant_sel for rtl8723be Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 09/22] radix-tree: must check __radix_tree_preload() return value Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 03/22] mtd: nand: mxc: Fix mxc_v1 ooblayout Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 21/22] NFS: Sync the correct byte range during synchronous writes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 07/22] btrfs: resume qgroup rescan on rw remount Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 10/22] selftests/x86/fsgsbase: Test selectors 1, 2, and 3 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 05/22] mtd: nand: qcom: fix config error for BCH Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.12 04/22] mtd: nand: qcom: fix read failure without complete bootchain Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  Re: [PATCH 4.12 00/22] 4.12.13-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-13 02:20 +0200
  Re: [PATCH 4.12 00/22] 4.12.13-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-13 16:40 +0200

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