pNFS: Don't allocate more pages than we need to fit a layoutget response

For the 'files' and 'flexfiles' layout types, we do not expect the reply
to be any larger than 4k. The block and scsi layout types are a little more
greedy, so we keep allocating the maximum response size for now.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

4 files changed, 10 insertions, 0 deletions

diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index d175724ff566..61f46facb39c 100644
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -1164,6 +1164,7 @@ static struct pnfs_layoutdriver_type filelayout_type = {
         .id                     = LAYOUT_NFSV4_1_FILES,
         .name                   = "LAYOUT_NFSV4_1_FILES",
         .owner                  = THIS_MODULE,
+        .max_layoutget_response = 4096, /* 1 page or so... */
         .alloc_layout_hdr       = filelayout_alloc_layout_hdr,
         .free_layout_hdr        = filelayout_free_layout_hdr,
         .alloc_lseg             = filelayout_alloc_lseg,
diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index cae43333ef16..86bcba40ca61 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -2356,6 +2356,7 @@ static struct pnfs_layoutdriver_type flexfilelayout_type = {
         .name                   = "LAYOUT_FLEX_FILES",
         .owner                  = THIS_MODULE,
         .flags                  = PNFS_LAYOUTGET_ON_OPEN,
+        .max_layoutget_response = 4096, /* 1 page or so... */
         .set_layoutdriver       = ff_layout_set_layoutdriver,
         .alloc_layout_hdr       = ff_layout_alloc_layout_hdr,
         .free_layout_hdr        = ff_layout_free_layout_hdr,
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 6b5b2d36f502..c5672c02afd6 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -991,6 +991,7 @@ pnfs_alloc_init_layoutget_args(struct inode *ino,
            gfp_t gfp_flags)
 {
         struct nfs_server *server = pnfs_find_server(ino, ctx);
+        size_t max_reply_sz = server->pnfs_curr_ld->max_layoutget_response;
         size_t max_pages = max_response_pages(server);
         struct nfs4_layoutget *lgp;
 
@@ -1000,6 +1001,12 @@ pnfs_alloc_init_layoutget_args(struct inode *ino,
         if (lgp == NULL)
                 return NULL;
 
+        if (max_reply_sz) {
+                size_t npages = (max_reply_sz + PAGE_SIZE - 1) >> PAGE_SHIFT;
+                if (npages < max_pages)
+                        max_pages = npages;
+        }
+
         lgp->args.layout.pages = nfs4_alloc_pages(max_pages, gfp_flags);
         if (!lgp->args.layout.pages) {
                 kfree(lgp);
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index ece367ebde69..e2e9fcd5341d 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -125,6 +125,7 @@ struct pnfs_layoutdriver_type {
         struct module *owner;
         unsigned flags;
         unsigned max_deviceinfo_size;
+        unsigned max_layoutget_response;
 
         int (*set_layoutdriver) (struct nfs_server *, const struct nfs_fh *);
         int (*clear_layoutdriver) (struct nfs_server *);