[PATCH] NFS: Make searching and waiting on busy writeback requests more efficient.

 Basically copies the VFS's method for tracking writebacks and applies
 it to the struct nfs_page.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 80777f9..356a33b 100644 (file)
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -112,6 +112,33 @@ void nfs_unlock_request(struct nfs_page *req)
 }
 
 /**
+ * nfs_set_page_writeback_locked - Lock a request for writeback
+ * @req:
+ */
+int nfs_set_page_writeback_locked(struct nfs_page *req)
+{
+       struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
+
+       if (!nfs_lock_request(req))
+               return 0;
+       radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
+       return 1;
+}
+
+/**
+ * nfs_clear_page_writeback - Unlock request and wake up sleepers
+ */
+void nfs_clear_page_writeback(struct nfs_page *req)
+{
+       struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
+
+       spin_lock(&nfsi->req_lock);
+       radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
+       spin_unlock(&nfsi->req_lock);
+       nfs_unlock_request(req);
+}
+
+/**
  * nfs_clear_request - Free up all resources allocated to the request
  * @req:
  *
@@ -301,7 +328,7 @@ nfs_scan_list(struct list_head *head, struct list_head *dst,
                if (req->wb_index > idx_end)
                        break;
 
-               if (!nfs_lock_request(req))
+               if (!nfs_set_page_writeback_locked(req))
                        continue;
                nfs_list_remove_request(req);
                nfs_list_add_request(req, dst);

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index a0042fb..6f866b8 100644 (file)
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -173,7 +173,6 @@ static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
        if (len < PAGE_CACHE_SIZE)
                memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
 
-       nfs_lock_request(new);
        nfs_list_add_request(new, &one_request);
        nfs_pagein_one(&one_request, inode);
        return 0;
@@ -185,7 +184,6 @@ static void nfs_readpage_release(struct nfs_page *req)
 
        nfs_clear_request(req);
        nfs_release_request(req);
-       nfs_unlock_request(req);
 
        dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
                        req->wb_context->dentry->d_inode->i_sb->s_id,
@@ -553,7 +551,6 @@ readpage_async_filler(void *data, struct page *page)
        }
        if (len < PAGE_CACHE_SIZE)
                memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
-       nfs_lock_request(new);
        nfs_list_add_request(new, desc->head);
        return 0;
 }

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 79b621a..58a39b0 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -503,13 +503,12 @@ nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int
 
        spin_lock(&nfsi->req_lock);
        next = idx_start;
-       while (radix_tree_gang_lookup(&nfsi->nfs_page_tree, (void **)&req, next, 1)) {
+       while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
                if (req->wb_index > idx_end)
                        break;
 
                next = req->wb_index + 1;
-               if (!NFS_WBACK_BUSY(req))
-                       continue;
+               BUG_ON(!NFS_WBACK_BUSY(req));
 
                atomic_inc(&req->wb_count);
                spin_unlock(&nfsi->req_lock);
@@ -821,7 +820,7 @@ out:
 #else
        nfs_inode_remove_request(req);
 #endif
-       nfs_unlock_request(req);
+       nfs_clear_page_writeback(req);
 }
 
 static inline int flush_task_priority(int how)
@@ -952,7 +951,7 @@ out_bad:
                nfs_writedata_free(data);
        }
        nfs_mark_request_dirty(req);
-       nfs_unlock_request(req);
+       nfs_clear_page_writeback(req);
        return -ENOMEM;
 }
 
@@ -1002,7 +1001,7 @@ static int nfs_flush_one(struct list_head *head, struct inode *inode, int how)
                struct nfs_page *req = nfs_list_entry(head->next);
                nfs_list_remove_request(req);
                nfs_mark_request_dirty(req);
-               nfs_unlock_request(req);
+               nfs_clear_page_writeback(req);
        }
        return -ENOMEM;
 }
@@ -1029,7 +1028,7 @@ nfs_flush_list(struct list_head *head, int wpages, int how)
                req = nfs_list_entry(head->next);
                nfs_list_remove_request(req);
                nfs_mark_request_dirty(req);
-               nfs_unlock_request(req);
+               nfs_clear_page_writeback(req);
        }
        return error;
 }
@@ -1121,7 +1120,7 @@ static void nfs_writeback_done_full(struct nfs_write_data *data, int status)
                nfs_inode_remove_request(req);
 #endif
        next:
-               nfs_unlock_request(req);
+               nfs_clear_page_writeback(req);
        }
 }
 
@@ -1278,7 +1277,7 @@ nfs_commit_list(struct list_head *head, int how)
                req = nfs_list_entry(head->next);
                nfs_list_remove_request(req);
                nfs_mark_request_commit(req);
-               nfs_unlock_request(req);
+               nfs_clear_page_writeback(req);
        }
        return -ENOMEM;
 }
@@ -1324,7 +1323,7 @@ nfs_commit_done(struct rpc_task *task)
                dprintk(" mismatch\n");
                nfs_mark_request_dirty(req);
        next:
-               nfs_unlock_request(req);
+               nfs_clear_page_writeback(req);
                res++;
        }
        sub_page_state(nr_unstable,res);

diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 39e4895..db40e45 100644 (file)
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -20,6 +20,11 @@
 #include <asm/atomic.h>
 
 /*
+ * Valid flags for the radix tree
+ */
+#define NFS_PAGE_TAG_WRITEBACK 1
+
+/*
  * Valid flags for a dirty buffer
  */
 #define PG_BUSY                        0
@@ -62,6 +67,9 @@ extern        int nfs_coalesce_requests(struct list_head *, struct list_head *,
                                  unsigned int);
 extern  int nfs_wait_on_request(struct nfs_page *);
 extern void nfs_unlock_request(struct nfs_page *req);
+extern  int nfs_set_page_writeback_locked(struct nfs_page *req);
+extern  void nfs_clear_page_writeback(struct nfs_page *req);
+
 
 /*
  * Lock the page of an asynchronous request without incrementing the wb_count
@@ -96,10 +104,6 @@ nfs_list_remove_request(struct nfs_page *req)
 {
        if (list_empty(&req->wb_list))
                return;
-       if (!NFS_WBACK_BUSY(req)) {
-               printk(KERN_ERR "NFS: unlocked request attempted removed from list!\n");
-               BUG();
-       }
        list_del_init(&req->wb_list);
        req->wb_list_head = NULL;
 }