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    Subject[PATCH 3.16 070/134] NFS: Use GFP_NOIO for two allocations in writeback
    3.16.47-rc1 review patch.  If anyone has any objections, please let me know.

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

    From: Benjamin Coddington <bcodding@redhat.com>

    commit ae97aa524ef495b6276fd26f5d5449fb22975d7c upstream.

    Prevent a deadlock that can occur if we wait on allocations
    that try to write back our pages.

    Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
    Fixes: 00bfa30abe869 ("NFS: Create a common pgio_alloc and pgio_release...")
    Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
    [bwh: Backported to 3.16:
    - Drop changes in nfs_pageio_init()
    - Adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/nfs/pagelist.c | 15 +++++++++++----
    1 file changed, 11 insertions(+), 4 deletions(-)

    --- a/fs/nfs/pagelist.c
    +++ b/fs/nfs/pagelist.c
    @@ -29,13 +29,14 @@
    static struct kmem_cache *nfs_page_cachep;
    static const struct rpc_call_ops nfs_pgio_common_ops;

    -static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
    +static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount,
    + gfp_t gfp_flags)
    {
    p->npages = pagecount;
    if (pagecount <= ARRAY_SIZE(p->page_array))
    p->pagevec = p->page_array;
    else {
    - p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
    + p->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
    if (!p->pagevec)
    p->npages = 0;
    }
    @@ -739,9 +740,12 @@ int nfs_generic_pgio(struct nfs_pageio_d
    struct list_head *head = &desc->pg_list;
    struct nfs_commit_info cinfo;
    unsigned int pagecount, pageused;
    + gfp_t gfp_flags = GFP_KERNEL;

    pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
    - if (!nfs_pgarray_set(&hdr->page_array, pagecount))
    + if (desc->pg_rw_ops->rw_mode == FMODE_WRITE)
    + gfp_flags = GFP_NOIO;
    + if (!nfs_pgarray_set(&hdr->page_array, pagecount, gfp_flags))
    return nfs_pgio_error(desc, hdr);

    nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
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