nfs: add nfs_pgio_current_mirror helper

Let it return current nfs_pgio_mirror in use depending on pg_mirror_count.
For read, we always use pg_mirrors[0], so this effectively gives us freedom
to use pg_mirror_idx to track the actual mirror to read from through out the
IO stack.

Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <loghyr@primarydata.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index e123cfce54ee..b822b1749643 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1731,7 +1731,7 @@ static void
 pnfs_write_through_mds(struct nfs_pageio_descriptor *desc,
                 struct nfs_pgio_header *hdr)
 {
-        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+        struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 
         if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
                 list_splice_tail_init(&hdr->pages, &mirror->pg_list);
@@ -1785,7 +1785,7 @@ EXPORT_SYMBOL_GPL(pnfs_writehdr_free);
 int
 pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
 {
-        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+        struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 
         struct nfs_pgio_header *hdr;
         int ret;
@@ -1846,8 +1846,7 @@ static void
 pnfs_read_through_mds(struct nfs_pageio_descriptor *desc,
                 struct nfs_pgio_header *hdr)
 {
-        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
-
+        struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 
         if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
                 list_splice_tail_init(&hdr->pages, &mirror->pg_list);
@@ -1903,7 +1902,7 @@ EXPORT_SYMBOL_GPL(pnfs_readhdr_free);
 int
 pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
 {
-        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+        struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 
         struct nfs_pgio_header *hdr;
         int ret;