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