NFSv4: Fix up mirror allocation

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>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index de9066a92c0d27cb9e397233fb5b92116c8dc127..b7d193e2a2432cc666728d6fbbb0739223557b5f 100644 (file)
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -714,9 +714,6 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
                     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;
@@ -732,21 +729,9 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
        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);
 
@@ -865,32 +850,52 @@ static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
        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;
+       unsigned int mirror_count = 1;
 
-       if (!pgio->pg_ops->pg_get_mirror_count)
-               return 0;
-
-       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;
 }
 
 /*