nfs: Convert to separately allocated bdi

Allocate struct backing_dev_info separately instead of embedding it
inside the superblock. This unifies handling of bdi among users.

CC: Anna Schumaker <anna.schumaker@netapp.com>
CC: linux-nfs@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

4 files changed, 28 insertions, 35 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 390ada8741bc..04d15a0045e3 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -761,9 +761,6 @@ static void nfs_server_set_fsinfo(struct nfs_server *server,
                 server->rsize = NFS_MAX_FILE_IO_SIZE;
         server->rpages = (server->rsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
-        server->backing_dev_info.name = "nfs";
-        server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;
-
         if (server->wsize > max_rpc_payload)
                 server->wsize = max_rpc_payload;
         if (server->wsize > NFS_MAX_FILE_IO_SIZE)
@@ -917,12 +914,6 @@ struct nfs_server *nfs_alloc_server(void)
                 return NULL;
         }
 
-        if (bdi_init(&server->backing_dev_info)) {
-                nfs_free_iostats(server->io_stats);
-                kfree(server);
-                return NULL;
-        }
-
         ida_init(&server->openowner_id);
         ida_init(&server->lockowner_id);
         pnfs_init_server(server);
@@ -953,7 +944,6 @@ void nfs_free_server(struct nfs_server *server)
         ida_destroy(&server->lockowner_id);
         ida_destroy(&server->openowner_id);
         nfs_free_iostats(server->io_stats);
-        bdi_destroy(&server->backing_dev_info);
         kfree(server);
         nfs_release_automount_timer();
         dprintk("<-- nfs_free_server()\n");
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 7b38fedb7e03..9dc65d7ae754 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -139,7 +139,7 @@ struct nfs_mount_request {
 };
 
 struct nfs_mount_info {
-        void (*fill_super)(struct super_block *, struct nfs_mount_info *);
+        int (*fill_super)(struct super_block *, struct nfs_mount_info *);
         int (*set_security)(struct super_block *, struct dentry *, struct nfs_mount_info *);
         struct nfs_parsed_mount_data *parsed;
         struct nfs_clone_mount *cloned;
@@ -407,7 +407,7 @@ struct dentry *nfs_fs_mount(struct file_system_type *, int, const char *, void *
 struct dentry * nfs_xdev_mount_common(struct file_system_type *, int,
                 const char *, struct nfs_mount_info *);
 void nfs_kill_super(struct super_block *);
-void nfs_fill_super(struct super_block *, struct nfs_mount_info *);
+int nfs_fill_super(struct super_block *, struct nfs_mount_info *);
 
 extern struct rpc_stat nfs_rpcstat;
 
@@ -458,7 +458,7 @@ extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
 extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
 
 /* super.c */
-void nfs_clone_super(struct super_block *, struct nfs_mount_info *);
+int nfs_clone_super(struct super_block *, struct nfs_mount_info *);
 void nfs_umount_begin(struct super_block *);
 int  nfs_statfs(struct dentry *, struct kstatfs *);
 int  nfs_show_options(struct seq_file *, struct dentry *);
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 54e0f9f2dd94..8d97aa70407e 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2315,18 +2315,17 @@ inline void nfs_initialise_sb(struct super_block *sb)
                 sb->s_blocksize = nfs_block_bits(server->wsize,
                                                  &sb->s_blocksize_bits);
 
-        sb->s_bdi = &server->backing_dev_info;
-
         nfs_super_set_maxbytes(sb, server->maxfilesize);
 }
 
 /*
  * Finish setting up an NFS2/3 superblock
  */
-void nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
+int nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
 {
         struct nfs_parsed_mount_data *data = mount_info->parsed;
         struct nfs_server *server = NFS_SB(sb);
+        int ret;
 
         sb->s_blocksize_bits = 0;
         sb->s_blocksize = 0;
@@ -2344,13 +2343,21 @@ void nfs_fill_super(struct super_block *sb, struct nfs_mount_info *mount_info)
         }
 
         nfs_initialise_sb(sb);
+
+        ret = super_setup_bdi_name(sb, "%u:%u", MAJOR(server->s_dev),
+                                   MINOR(server->s_dev));
+        if (ret)
+                return ret;
+        sb->s_bdi->ra_pages = server->rpages * NFS_MAX_READAHEAD;
+        return 0;
+
 }
 EXPORT_SYMBOL_GPL(nfs_fill_super);
 
 /*
  * Finish setting up a cloned NFS2/3/4 superblock
  */
-void nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
+int nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
 {
         const struct super_block *old_sb = mount_info->cloned->sb;
         struct nfs_server *server = NFS_SB(sb);
@@ -2370,6 +2377,11 @@ void nfs_clone_super(struct super_block *sb, struct nfs_mount_info *mount_info)
         }
 
         nfs_initialise_sb(sb);
+
+        sb->s_bdi = bdi_get(old_sb->s_bdi);
+        sb->s_iflags |= SB_I_DYNBDI;
+
+        return 0;
 }
 
 static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
@@ -2522,11 +2534,6 @@ static void nfs_get_cache_cookie(struct super_block *sb,
 }
 #endif
 
-static int nfs_bdi_register(struct nfs_server *server)
-{
-        return bdi_register_dev(&server->backing_dev_info, server->s_dev);
-}
-
 int nfs_set_sb_security(struct super_block *s, struct dentry *mntroot,
                         struct nfs_mount_info *mount_info)
 {
@@ -2594,17 +2601,14 @@ struct dentry *nfs_fs_mount_common(struct nfs_server *server,
                 nfs_free_server(server);
                 server = NULL;
         } else {
-                error = nfs_bdi_register(server);
-                if (error) {
-                        mntroot = ERR_PTR(error);
-                        goto error_splat_super;
-                }
                 server->super = s;
         }
 
         if (!s->s_root) {
                 /* initial superblock/root creation */
-                mount_info->fill_super(s, mount_info);
+                error = mount_info->fill_super(s, mount_info);
+                if (error)
+                        goto error_splat_super;
                 nfs_get_cache_cookie(s, mount_info->parsed, mount_info->cloned);
         }
 
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index abb2c8a3be42..cc341fc7fd44 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -263,16 +263,15 @@ int nfs_congestion_kb;
 
 static void nfs_set_page_writeback(struct page *page)
 {
-        struct nfs_server *nfss = NFS_SERVER(page_file_mapping(page)->host);
+        struct inode *inode = page_file_mapping(page)->host;
+        struct nfs_server *nfss = NFS_SERVER(inode);
         int ret = test_set_page_writeback(page);
 
         WARN_ON_ONCE(ret != 0);
 
         if (atomic_long_inc_return(&nfss->writeback) >
-                        NFS_CONGESTION_ON_THRESH) {
-                set_bdi_congested(&nfss->backing_dev_info,
-                                        BLK_RW_ASYNC);
-        }
+                        NFS_CONGESTION_ON_THRESH)
+                set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 }
 
 static void nfs_end_page_writeback(struct nfs_page *req)
@@ -285,7 +284,7 @@ static void nfs_end_page_writeback(struct nfs_page *req)
 
         end_page_writeback(req->wb_page);
         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
-                clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
+                clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 }
 
 
@@ -1808,7 +1807,7 @@ static void nfs_commit_release_pages(struct nfs_commit_data *data)
         }
         nfss = NFS_SERVER(data->inode);
         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
-                clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
+                clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
 
         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
         nfs_commit_end(cinfo.mds);