NFS: Switch to using mapping->private_lock for page writeback lookups.

Switch from using the inode->i_lock for this to avoid contention with
other metadata manipulation.

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

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 12479c25028ea81e4cfa13074b92212fde7e7cd6..86670282386901ee29f17424497342bb0da316b4 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -172,18 +172,18 @@ nfs_page_private_request(struct page *page)
 static struct nfs_page *
 nfs_page_find_private_request(struct page *page)
 {
-       struct inode *inode = page_file_mapping(page)->host;
+       struct address_space *mapping = page_file_mapping(page);
        struct nfs_page *req;
 
        if (!PagePrivate(page))
                return NULL;
-       spin_lock(&inode->i_lock);
+       spin_lock(&mapping->private_lock);
        req = nfs_page_private_request(page);
        if (req) {
                WARN_ON_ONCE(req->wb_head != req);
                kref_get(&req->wb_kref);
        }
-       spin_unlock(&inode->i_lock);
+       spin_unlock(&mapping->private_lock);
        return req;
 }
 
@@ -743,6 +743,7 @@ out_err:
  */
 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 {
+       struct address_space *mapping = page_file_mapping(req->wb_page);
        struct nfs_inode *nfsi = NFS_I(inode);
 
        WARN_ON_ONCE(req->wb_this_page != req);
@@ -750,19 +751,23 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
        /* Lock the request! */
        nfs_lock_request(req);
 
-       spin_lock(&inode->i_lock);
-       if (!nfs_have_writebacks(inode) &&
-           NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
-               inode->i_version++;
        /*
         * Swap-space should not get truncated. Hence no need to plug the race
         * with invalidate/truncate.
         */
+       spin_lock(&mapping->private_lock);
+       if (!nfs_have_writebacks(inode) &&
+           NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE)) {
+               spin_lock(&inode->i_lock);
+               inode->i_version++;
+               spin_unlock(&inode->i_lock);
+       }
        if (likely(!PageSwapCache(req->wb_page))) {
                set_bit(PG_MAPPED, &req->wb_flags);
                SetPagePrivate(req->wb_page);
                set_page_private(req->wb_page, (unsigned long)req);
        }
+       spin_unlock(&mapping->private_lock);
        atomic_long_inc(&nfsi->nrequests);
        /* this a head request for a page group - mark it as having an
         * extra reference so sub groups can follow suit.
@@ -770,7 +775,6 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
         * adding subrequests. */
        WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
        kref_get(&req->wb_kref);
-       spin_unlock(&inode->i_lock);
 }
 
 /*
@@ -778,7 +782,8 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
  */
 static void nfs_inode_remove_request(struct nfs_page *req)
 {
-       struct inode *inode = d_inode(req->wb_context->dentry);
+       struct address_space *mapping = page_file_mapping(req->wb_page);
+       struct inode *inode = mapping->host;
        struct nfs_inode *nfsi = NFS_I(inode);
        struct nfs_page *head;
 
@@ -786,13 +791,13 @@ static void nfs_inode_remove_request(struct nfs_page *req)
        if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
                head = req->wb_head;
 
-               spin_lock(&inode->i_lock);
+               spin_lock(&mapping->private_lock);
                if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
                        set_page_private(head->wb_page, 0);
                        ClearPagePrivate(head->wb_page);
                        clear_bit(PG_MAPPED, &head->wb_flags);
                }
-               spin_unlock(&inode->i_lock);
+               spin_unlock(&mapping->private_lock);
        }
 
        if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))