Merge branch 'for-3.20/bdi' of git://git.kernel.dk/linux-block

Pull backing device changes from Jens Axboe:
 "This contains a cleanup of how the backing device is handled, in
  preparation for a rework of the life time rules.  In this part, the
  most important change is to split the unrelated nommu mmap flags from
  it, but also removing a backing_dev_info pointer from the
  address_space (and inode), and a cleanup of other various minor bits.

  Christoph did all the work here, I just fixed an oops with pages that
  have a swap backing.  Arnd fixed a missing export, and Oleg killed the
  lustre backing_dev_info from staging.  Last patch was from Al,
  unexporting parts that are now no longer needed outside"

* 'for-3.20/bdi' of git://git.kernel.dk/linux-block:
  Make super_blocks and sb_lock static
  mtd: export new mtd_mmap_capabilities
  fs: make inode_to_bdi() handle NULL inode
  staging/lustre/llite: get rid of backing_dev_info
  fs: remove default_backing_dev_info
  fs: don't reassign dirty inodes to default_backing_dev_info
  nfs: don't call bdi_unregister
  ceph: remove call to bdi_unregister
  fs: remove mapping->backing_dev_info
  fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info
  nilfs2: set up s_bdi like the generic mount_bdev code
  block_dev: get bdev inode bdi directly from the block device
  block_dev: only write bdev inode on close
  fs: introduce f_op->mmap_capabilities for nommu mmap support
  fs: kill BDI_CAP_SWAP_BACKED
  fs: deduplicate noop_backing_dev_info

Documentation/nommu-mmap.txt

@@ -43,12 +43,12 @@ and it's also much more restricted in the latter case:
            even if this was created by another process.
 
          - If possible, the file mapping will be directly on the backing device
-           if the backing device has the BDI_CAP_MAP_DIRECT capability and
+           if the backing device has the NOMMU_MAP_DIRECT capability and
            appropriate mapping protection capabilities. Ramfs, romfs, cramfs
            and mtd might all permit this.
 
 	 - If the backing device device can't or won't permit direct sharing,
-           but does have the BDI_CAP_MAP_COPY capability, then a copy of the
+           but does have the NOMMU_MAP_COPY capability, then a copy of the
            appropriate bit of the file will be read into a contiguous bit of
            memory and any extraneous space beyond the EOF will be cleared
 
@@ -220,7 +220,7 @@ directly (can't be copied).
 
 The file->f_op->mmap() operation will be called to actually inaugurate the
 mapping. It can be rejected at that point. Returning the ENOSYS error will
-cause the mapping to be copied instead if BDI_CAP_MAP_COPY is specified.
+cause the mapping to be copied instead if NOMMU_MAP_COPY is specified.
 
 The vm_ops->close() routine will be invoked when the last mapping on a chardev
 is removed. An existing mapping will be shared, partially or not, if possible
@@ -232,7 +232,7 @@ want to handle it, despite the fact it's got an operation. For instance, it
 might try directing the call to a secondary driver which turns out not to
 implement it. Such is the case for the framebuffer driver which attempts to
 direct the call to the device-specific driver. Under such circumstances, the
-mapping request will be rejected if BDI_CAP_MAP_COPY is not specified, and a
+mapping request will be rejected if NOMMU_MAP_COPY is not specified, and a
 copy mapped otherwise.
 
 IMPORTANT NOTE:

block/blk-core.c

@@ -607,7 +607,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	q->backing_dev_info.ra_pages =
 			(VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 	q->backing_dev_info.state = 0;
-	q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
+	q->backing_dev_info.capabilities = 0;
 	q->backing_dev_info.name = "block";
 	q->node = node_id;
 

drivers/char/mem.c

@@ -287,13 +287,24 @@ static unsigned long get_unmapped_area_mem(struct file *file,
 	return pgoff << PAGE_SHIFT;
 }
 
+/* permit direct mmap, for read, write or exec */
+static unsigned memory_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_DIRECT |
+		NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
+}
+
+static unsigned zero_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_COPY;
+}
+
 /* can't do an in-place private mapping if there's no MMU */
 static inline int private_mapping_ok(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & VM_MAYSHARE;
 }
 #else
-#define get_unmapped_area_mem	NULL
 
 static inline int private_mapping_ok(struct vm_area_struct *vma)
 {
@@ -721,7 +732,10 @@ static const struct file_operations mem_fops = {
 	.write		= write_mem,
 	.mmap		= mmap_mem,
 	.open		= open_mem,
+#ifndef CONFIG_MMU
 	.get_unmapped_area = get_unmapped_area_mem,
+	.mmap_capabilities = memory_mmap_capabilities,
+#endif
 };
 
 #ifdef CONFIG_DEVKMEM
@@ -731,7 +745,10 @@ static const struct file_operations kmem_fops = {
 	.write		= write_kmem,
 	.mmap		= mmap_kmem,
 	.open		= open_kmem,
+#ifndef CONFIG_MMU
 	.get_unmapped_area = get_unmapped_area_mem,
+	.mmap_capabilities = memory_mmap_capabilities,
+#endif
 };
 #endif
 
@@ -760,16 +777,9 @@ static const struct file_operations zero_fops = {
 	.read_iter	= read_iter_zero,
 	.aio_write	= aio_write_zero,
 	.mmap		= mmap_zero,
-};
+#ifndef CONFIG_MMU
-
+	.mmap_capabilities = zero_mmap_capabilities,
-/*
+#endif
- * capabilities for /dev/zero
- * - permits private mappings, "copies" are taken of the source of zeros
- * - no writeback happens
- */
-static struct backing_dev_info zero_bdi = {
-	.name		= "char/mem",
-	.capabilities	= BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
 };
 
 static const struct file_operations full_fops = {
@@ -783,22 +793,22 @@ static const struct memdev {
 	const char *name;
 	umode_t mode;
 	const struct file_operations *fops;
-	struct backing_dev_info *dev_info;
+	fmode_t fmode;
 } devlist[] = {
-	 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
+	 [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
 #ifdef CONFIG_DEVKMEM
-	 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
+	 [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
 #endif
-	 [3] = { "null", 0666, &null_fops, NULL },
+	 [3] = { "null", 0666, &null_fops, 0 },
 #ifdef CONFIG_DEVPORT
-	 [4] = { "port", 0, &port_fops, NULL },
+	 [4] = { "port", 0, &port_fops, 0 },
 #endif
-	 [5] = { "zero", 0666, &zero_fops, &zero_bdi },
+	 [5] = { "zero", 0666, &zero_fops, 0 },
-	 [7] = { "full", 0666, &full_fops, NULL },
+	 [7] = { "full", 0666, &full_fops, 0 },
-	 [8] = { "random", 0666, &random_fops, NULL },
+	 [8] = { "random", 0666, &random_fops, 0 },
-	 [9] = { "urandom", 0666, &urandom_fops, NULL },
+	 [9] = { "urandom", 0666, &urandom_fops, 0 },
 #ifdef CONFIG_PRINTK
-	[11] = { "kmsg", 0644, &kmsg_fops, NULL },
+	[11] = { "kmsg", 0644, &kmsg_fops, 0 },
 #endif
 };
 
@@ -816,12 +826,7 @@ static int memory_open(struct inode *inode, struct file *filp)
 		return -ENXIO;
 
 	filp->f_op = dev->fops;
-	if (dev->dev_info)
+	filp->f_mode |= dev->fmode;
-		filp->f_mapping->backing_dev_info = dev->dev_info;
-
-	/* Is /dev/mem or /dev/kmem ? */
-	if (dev->dev_info == &directly_mappable_cdev_bdi)
-		filp->f_mode |= FMODE_UNSIGNED_OFFSET;
 
 	if (dev->fops->open)
 		return dev->fops->open(inode, filp);
@@ -846,11 +851,6 @@ static struct class *mem_class;
 static int __init chr_dev_init(void)
 {
 	int minor;
-	int err;
-
-	err = bdi_init(&zero_bdi);
-	if (err)
-		return err;
 
 	if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 		printk("unable to get major %d for memory devs\n", MEM_MAJOR);

drivers/char/raw.c

@@ -104,11 +104,9 @@ static int raw_release(struct inode *inode, struct file *filp)
 
 	mutex_lock(&raw_mutex);
 	bdev = raw_devices[minor].binding;
-	if (--raw_devices[minor].inuse == 0) {
+	if (--raw_devices[minor].inuse == 0)
 		/* Here  inode->i_mapping == bdev->bd_inode->i_mapping  */
 		inode->i_mapping = &inode->i_data;
-		inode->i_mapping->backing_dev_info = &default_backing_dev_info;
-	}
 	mutex_unlock(&raw_mutex);
 
 	blkdev_put(bdev, filp->f_mode | FMODE_EXCL);

drivers/mtd/mtdchar.c

@@ -49,7 +49,6 @@ static DEFINE_MUTEX(mtd_mutex);
  */
 struct mtd_file_info {
 	struct mtd_info *mtd;
-	struct inode *ino;
 	enum mtd_file_modes mode;
 };
 
@@ -59,10 +58,6 @@ static loff_t mtdchar_lseek(struct file *file, loff_t offset, int orig)
 	return fixed_size_llseek(file, offset, orig, mfi->mtd->size);
 }
 
-static int count;
-static struct vfsmount *mnt;
-static struct file_system_type mtd_inodefs_type;
-
 static int mtdchar_open(struct inode *inode, struct file *file)
 {
 	int minor = iminor(inode);
@@ -70,7 +65,6 @@ static int mtdchar_open(struct inode *inode, struct file *file)
 	int ret = 0;
 	struct mtd_info *mtd;
 	struct mtd_file_info *mfi;
-	struct inode *mtd_ino;
 
 	pr_debug("MTD_open\n");
 
@@ -78,10 +72,6 @@ static int mtdchar_open(struct inode *inode, struct file *file)
 	if ((file->f_mode & FMODE_WRITE) && (minor & 1))
 		return -EACCES;
 
-	ret = simple_pin_fs(&mtd_inodefs_type, &mnt, &count);
-	if (ret)
-		return ret;
-
 	mutex_lock(&mtd_mutex);
 	mtd = get_mtd_device(NULL, devnum);
 
@@ -95,43 +85,26 @@ static int mtdchar_open(struct inode *inode, struct file *file)
 		goto out1;
 	}
 
-	mtd_ino = iget_locked(mnt->mnt_sb, devnum);
-	if (!mtd_ino) {
-		ret = -ENOMEM;
-		goto out1;
-	}
-	if (mtd_ino->i_state & I_NEW) {
-		mtd_ino->i_private = mtd;
-		mtd_ino->i_mode = S_IFCHR;
-		mtd_ino->i_data.backing_dev_info = mtd->backing_dev_info;
-		unlock_new_inode(mtd_ino);
-	}
-	file->f_mapping = mtd_ino->i_mapping;
-
 	/* You can't open it RW if it's not a writeable device */
 	if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
 		ret = -EACCES;
-		goto out2;
+		goto out1;
 	}
 
 	mfi = kzalloc(sizeof(*mfi), GFP_KERNEL);
 	if (!mfi) {
 		ret = -ENOMEM;
-		goto out2;
+		goto out1;
 	}
-	mfi->ino = mtd_ino;
 	mfi->mtd = mtd;
 	file->private_data = mfi;
 	mutex_unlock(&mtd_mutex);
 	return 0;
 
-out2:
-	iput(mtd_ino);
 out1:
 	put_mtd_device(mtd);
 out:
 	mutex_unlock(&mtd_mutex);
-	simple_release_fs(&mnt, &count);
 	return ret;
 } /* mtdchar_open */
 
@@ -148,12 +121,9 @@ static int mtdchar_close(struct inode *inode, struct file *file)
 	if ((file->f_mode & FMODE_WRITE))
 		mtd_sync(mtd);
 
-	iput(mfi->ino);
-
 	put_mtd_device(mtd);
 	file->private_data = NULL;
 	kfree(mfi);
-	simple_release_fs(&mnt, &count);
 
 	return 0;
 } /* mtdchar_close */
@@ -1117,6 +1087,13 @@ static unsigned long mtdchar_get_unmapped_area(struct file *file,
 	ret = mtd_get_unmapped_area(mtd, len, offset, flags);
 	return ret == -EOPNOTSUPP ? -ENODEV : ret;
 }
+
+static unsigned mtdchar_mmap_capabilities(struct file *file)
+{
+	struct mtd_file_info *mfi = file->private_data;
+
+	return mtd_mmap_capabilities(mfi->mtd);
+}
 #endif
 
 /*
@@ -1160,27 +1137,10 @@ static const struct file_operations mtd_fops = {
 	.mmap		= mtdchar_mmap,
 #ifndef CONFIG_MMU
 	.get_unmapped_area = mtdchar_get_unmapped_area,
+	.mmap_capabilities = mtdchar_mmap_capabilities,
 #endif
 };
 
-static const struct super_operations mtd_ops = {
-	.drop_inode = generic_delete_inode,
-	.statfs = simple_statfs,
-};
-
-static struct dentry *mtd_inodefs_mount(struct file_system_type *fs_type,
-				int flags, const char *dev_name, void *data)
-{
-	return mount_pseudo(fs_type, "mtd_inode:", &mtd_ops, NULL, MTD_INODE_FS_MAGIC);
-}
-
-static struct file_system_type mtd_inodefs_type = {
-       .name = "mtd_inodefs",
-       .mount = mtd_inodefs_mount,
-       .kill_sb = kill_anon_super,
-};
-MODULE_ALIAS_FS("mtd_inodefs");
-
 int __init init_mtdchar(void)
 {
 	int ret;
@@ -1193,23 +1153,11 @@ int __init init_mtdchar(void)
 		return ret;
 	}
 
-	ret = register_filesystem(&mtd_inodefs_type);
-	if (ret) {
-		pr_err("Can't register mtd_inodefs filesystem, error %d\n",
-		       ret);
-		goto err_unregister_chdev;
-	}
-
-	return ret;
-
-err_unregister_chdev:
-	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
 	return ret;
 }
 
 void __exit cleanup_mtdchar(void)
 {
-	unregister_filesystem(&mtd_inodefs_type);
 	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
 }
 

drivers/mtd/mtdconcat.c

@@ -732,8 +732,6 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
 
 	concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 
-	concat->mtd.backing_dev_info = subdev[0]->backing_dev_info;
-
 	concat->subdev[0] = subdev[0];
 
 	for (i = 1; i < num_devs; i++) {
@@ -761,14 +759,6 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
 				    subdev[i]->flags & MTD_WRITEABLE;
 		}
 
-		/* only permit direct mapping if the BDIs are all the same
-		 * - copy-mapping is still permitted
-		 */
-		if (concat->mtd.backing_dev_info !=
-		    subdev[i]->backing_dev_info)
-			concat->mtd.backing_dev_info =
-				&default_backing_dev_info;
-
 		concat->mtd.size += subdev[i]->size;
 		concat->mtd.ecc_stats.badblocks +=
 			subdev[i]->ecc_stats.badblocks;

drivers/mtd/mtdcore.c

@@ -43,33 +43,7 @@
 
 #include "mtdcore.h"
 
-/*
+static struct backing_dev_info mtd_bdi = {
- * backing device capabilities for non-mappable devices (such as NAND flash)
- * - permits private mappings, copies are taken of the data
- */
-static struct backing_dev_info mtd_bdi_unmappable = {
-	.capabilities	= BDI_CAP_MAP_COPY,
-};
-
-/*
- * backing device capabilities for R/O mappable devices (such as ROM)
- * - permits private mappings, copies are taken of the data
- * - permits non-writable shared mappings
- */
-static struct backing_dev_info mtd_bdi_ro_mappable = {
-	.capabilities	= (BDI_CAP_MAP_COPY | BDI_CAP_MAP_DIRECT |
-			   BDI_CAP_EXEC_MAP | BDI_CAP_READ_MAP),
-};
-
-/*
- * backing device capabilities for writable mappable devices (such as RAM)
- * - permits private mappings, copies are taken of the data
- * - permits non-writable shared mappings
- */
-static struct backing_dev_info mtd_bdi_rw_mappable = {
-	.capabilities	= (BDI_CAP_MAP_COPY | BDI_CAP_MAP_DIRECT |
-			   BDI_CAP_EXEC_MAP | BDI_CAP_READ_MAP |
-			   BDI_CAP_WRITE_MAP),
 };
 
 static int mtd_cls_suspend(struct device *dev, pm_message_t state);
@@ -365,6 +339,23 @@ static struct device_type mtd_devtype = {
 	.release	= mtd_release,
 };
 
+#ifndef CONFIG_MMU
+unsigned mtd_mmap_capabilities(struct mtd_info *mtd)
+{
+	switch (mtd->type) {
+	case MTD_RAM:
+		return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | NOMMU_MAP_EXEC |
+			NOMMU_MAP_READ | NOMMU_MAP_WRITE;
+	case MTD_ROM:
+		return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | NOMMU_MAP_EXEC |
+			NOMMU_MAP_READ;
+	default:
+		return NOMMU_MAP_COPY;
+	}
+}
+EXPORT_SYMBOL_GPL(mtd_mmap_capabilities);
+#endif
+
 /**
  *	add_mtd_device - register an MTD device
  *	@mtd: pointer to new MTD device info structure
@@ -380,19 +371,7 @@ int add_mtd_device(struct mtd_info *mtd)
 	struct mtd_notifier *not;
 	int i, error;
 
-	if (!mtd->backing_dev_info) {
+	mtd->backing_dev_info = &mtd_bdi;
-		switch (mtd->type) {
-		case MTD_RAM:
-			mtd->backing_dev_info = &mtd_bdi_rw_mappable;
-			break;
-		case MTD_ROM:
-			mtd->backing_dev_info = &mtd_bdi_ro_mappable;
-			break;
-		default:
-			mtd->backing_dev_info = &mtd_bdi_unmappable;
-			break;
-		}
-	}
 
 	BUG_ON(mtd->writesize == 0);
 	mutex_lock(&mtd_table_mutex);
@@ -1237,17 +1216,9 @@ static int __init init_mtd(void)
 	if (ret)
 		goto err_reg;
 
-	ret = mtd_bdi_init(&mtd_bdi_unmappable, "mtd-unmap");
+	ret = mtd_bdi_init(&mtd_bdi, "mtd");
 	if (ret)
-		goto err_bdi1;
+		goto err_bdi;
-
-	ret = mtd_bdi_init(&mtd_bdi_ro_mappable, "mtd-romap");
-	if (ret)
-		goto err_bdi2;
-
-	ret = mtd_bdi_init(&mtd_bdi_rw_mappable, "mtd-rwmap");
-	if (ret)
-		goto err_bdi3;
 
 	proc_mtd = proc_create("mtd", 0, NULL, &mtd_proc_ops);
 
@@ -1260,11 +1231,7 @@ static int __init init_mtd(void)
 out_procfs:
 	if (proc_mtd)
 		remove_proc_entry("mtd", NULL);
-err_bdi3:
+err_bdi:
-	bdi_destroy(&mtd_bdi_ro_mappable);
-err_bdi2:
-	bdi_destroy(&mtd_bdi_unmappable);
-err_bdi1:
 	class_unregister(&mtd_class);
 err_reg:
 	pr_err("Error registering mtd class or bdi: %d\n", ret);
@@ -1277,9 +1244,7 @@ static void __exit cleanup_mtd(void)
 	if (proc_mtd)
 		remove_proc_entry("mtd", NULL);
 	class_unregister(&mtd_class);
-	bdi_destroy(&mtd_bdi_unmappable);
+	bdi_destroy(&mtd_bdi);
-	bdi_destroy(&mtd_bdi_ro_mappable);
-	bdi_destroy(&mtd_bdi_rw_mappable);
 }
 
 module_init(init_mtd);

drivers/mtd/mtdpart.c

@@ -378,7 +378,6 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
 
 	slave->mtd.name = name;
 	slave->mtd.owner = master->owner;
-	slave->mtd.backing_dev_info = master->backing_dev_info;
 
 	/* NOTE:  we don't arrange MTDs as a tree; it'd be error-prone
 	 * to have the same data be in two different partitions.

drivers/staging/lustre/lustre/llite/llite_lib.c

@@ -987,7 +987,7 @@ int ll_fill_super(struct super_block *sb, struct vfsmount *mnt)
 	if (err)
 		goto out_free;
 	lsi->lsi_flags |= LSI_BDI_INITIALIZED;
-	lsi->lsi_bdi.capabilities = BDI_CAP_MAP_COPY;
+	lsi->lsi_bdi.capabilities = 0;
 	err = ll_bdi_register(&lsi->lsi_bdi);
 	if (err)
 		goto out_free;
@@ -1812,10 +1812,6 @@ void ll_read_inode2(struct inode *inode, void *opaque)
 
 	/* OIDEBUG(inode); */
 
-	/* initializing backing dev info. */
-	inode->i_mapping->backing_dev_info = &s2lsi(inode->i_sb)->lsi_bdi;
-
-
 	if (S_ISREG(inode->i_mode)) {
 		struct ll_sb_info *sbi = ll_i2sbi(inode);
 

fs/9p/v9fs.c

@@ -335,7 +335,7 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 	}
 	init_rwsem(&v9ses->rename_sem);
 
-	rc = bdi_setup_and_register(&v9ses->bdi, "9p", BDI_CAP_MAP_COPY);
+	rc = bdi_setup_and_register(&v9ses->bdi, "9p");
 	if (rc) {
 		kfree(v9ses->aname);
 		kfree(v9ses->uname);

fs/afs/volume.c

@@ -106,7 +106,7 @@ struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
 	volume->cell		= params->cell;
 	volume->vid		= vlocation->vldb.vid[params->type];
 
-	ret = bdi_setup_and_register(&volume->bdi, "afs", BDI_CAP_MAP_COPY);
+	ret = bdi_setup_and_register(&volume->bdi, "afs");
 	if (ret)
 		goto error_bdi;
 

fs/aio.c

@@ -165,15 +165,6 @@ static struct vfsmount *aio_mnt;
 static const struct file_operations aio_ring_fops;
 static const struct address_space_operations aio_ctx_aops;
 
-/* Backing dev info for aio fs.
- * -no dirty page accounting or writeback happens
- */
-static struct backing_dev_info aio_fs_backing_dev_info = {
-	.name           = "aiofs",
-	.state          = 0,
-	.capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_MAP_COPY,
-};
-
 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
 {
 	struct qstr this = QSTR_INIT("[aio]", 5);
@@ -185,7 +176,6 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
 
 	inode->i_mapping->a_ops = &aio_ctx_aops;
 	inode->i_mapping->private_data = ctx;
-	inode->i_mapping->backing_dev_info = &aio_fs_backing_dev_info;
 	inode->i_size = PAGE_SIZE * nr_pages;
 
 	path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
@@ -230,9 +220,6 @@ static int __init aio_setup(void)
 	if (IS_ERR(aio_mnt))
 		panic("Failed to create aio fs mount.");
 
-	if (bdi_init(&aio_fs_backing_dev_info))
-		panic("Failed to init aio fs backing dev info.");
-
 	kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 

fs/block_dev.c

@@ -49,23 +49,15 @@ inline struct block_device *I_BDEV(struct inode *inode)
 }
 EXPORT_SYMBOL(I_BDEV);
 
-/*
+static void bdev_write_inode(struct inode *inode)
- * Move the inode from its current bdi to a new bdi.  Make sure the inode
- * is clean before moving so that it doesn't linger on the old bdi.
- */
-static void bdev_inode_switch_bdi(struct inode *inode,
-			struct backing_dev_info *dst)
 {
-	while (true) {
 	spin_lock(&inode->i_lock);
-		if (!(inode->i_state & I_DIRTY)) {
+	while (inode->i_state & I_DIRTY) {
-			inode->i_data.backing_dev_info = dst;
-			spin_unlock(&inode->i_lock);
-			return;
-		}
 		spin_unlock(&inode->i_lock);
 		WARN_ON_ONCE(write_inode_now(inode, true));
+		spin_lock(&inode->i_lock);
 	}
+	spin_unlock(&inode->i_lock);
 }
 
 /* Kill _all_ buffers and pagecache , dirty or not.. */
@@ -584,7 +576,6 @@ struct block_device *bdget(dev_t dev)
 		inode->i_bdev = bdev;
 		inode->i_data.a_ops = &def_blk_aops;
 		mapping_set_gfp_mask(&inode->i_data, GFP_USER);
-		inode->i_data.backing_dev_info = &default_backing_dev_info;
 		spin_lock(&bdev_lock);
 		list_add(&bdev->bd_list, &all_bdevs);
 		spin_unlock(&bdev_lock);
@@ -1145,8 +1136,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 		bdev->bd_queue = disk->queue;
 		bdev->bd_contains = bdev;
 		if (!partno) {
-			struct backing_dev_info *bdi;
-
 			ret = -ENXIO;
 			bdev->bd_part = disk_get_part(disk, partno);
 			if (!bdev->bd_part)
@@ -1172,11 +1161,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 				}
 			}
 
-			if (!ret) {
+			if (!ret)
 				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
-				bdi = blk_get_backing_dev_info(bdev);
-				bdev_inode_switch_bdi(bdev->bd_inode, bdi);
-			}
 
 			/*
 			 * If the device is invalidated, rescan partition
@@ -1203,8 +1189,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 			if (ret)
 				goto out_clear;
 			bdev->bd_contains = whole;
-			bdev_inode_switch_bdi(bdev->bd_inode,
-				whole->bd_inode->i_data.backing_dev_info);
 			bdev->bd_part = disk_get_part(disk, partno);
 			if (!(disk->flags & GENHD_FL_UP) ||
 			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
@@ -1244,7 +1228,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 	bdev->bd_disk = NULL;
 	bdev->bd_part = NULL;
 	bdev->bd_queue = NULL;
-	bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
 	if (bdev != bdev->bd_contains)
 		__blkdev_put(bdev->bd_contains, mode, 1);
 	bdev->bd_contains = NULL;
@@ -1464,11 +1447,11 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
 		WARN_ON_ONCE(bdev->bd_holders);
 		sync_blockdev(bdev);
 		kill_bdev(bdev);
-		/* ->release can cause the old bdi to disappear,
+		/*
-		 * so must switch it out first
+		 * ->release can cause the queue to disappear, so flush all
+		 * dirty data before.
 		 */
-		bdev_inode_switch_bdi(bdev->bd_inode,
+		bdev_write_inode(bdev->bd_inode);
-					&default_backing_dev_info);
 	}
 	if (bdev->bd_contains == bdev) {
 		if (disk->fops->release)

fs/btrfs/disk-io.c

@@ -1715,12 +1715,11 @@ static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
 {
 	int err;
 
-	bdi->capabilities = BDI_CAP_MAP_COPY;
+	err = bdi_setup_and_register(bdi, "btrfs");
-	err = bdi_setup_and_register(bdi, "btrfs", BDI_CAP_MAP_COPY);
 	if (err)
 		return err;
 
-	bdi->ra_pages	= default_backing_dev_info.ra_pages;
+	bdi->ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE;
 	bdi->congested_fn	= btrfs_congested_fn;
 	bdi->congested_data	= info;
 	return 0;
@@ -2319,7 +2318,6 @@ int open_ctree(struct super_block *sb,
 	 */
 	fs_info->btree_inode->i_size = OFFSET_MAX;
 	fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
-	fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
 
 	RB_CLEAR_NODE(&BTRFS_I(fs_info->btree_inode)->rb_node);
 	extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,

fs/btrfs/file.c

@@ -1746,7 +1746,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 
 	mutex_lock(&inode->i_mutex);
 
-	current->backing_dev_info = inode->i_mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 	if (err) {
 		mutex_unlock(&inode->i_mutex);

fs/btrfs/inode.c

@@ -3608,7 +3608,6 @@ static void btrfs_read_locked_inode(struct inode *inode)
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFREG:
 		inode->i_mapping->a_ops = &btrfs_aops;
-		inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 		inode->i_fop = &btrfs_file_operations;
 		inode->i_op = &btrfs_file_inode_operations;
@@ -3623,7 +3622,6 @@ static void btrfs_read_locked_inode(struct inode *inode)
 	case S_IFLNK:
 		inode->i_op = &btrfs_symlink_inode_operations;
 		inode->i_mapping->a_ops = &btrfs_symlink_aops;
-		inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 		break;
 	default:
 		inode->i_op = &btrfs_special_inode_operations;
@@ -6088,7 +6086,6 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 	inode->i_fop = &btrfs_file_operations;
 	inode->i_op = &btrfs_file_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_aops;
-	inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 
 	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
 	if (err)
@@ -9203,7 +9200,6 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 	inode->i_fop = &btrfs_file_operations;
 	inode->i_op = &btrfs_file_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_aops;
-	inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 
 	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
@@ -9247,7 +9243,6 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 
 	inode->i_op = &btrfs_symlink_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_symlink_aops;
-	inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 	inode_set_bytes(inode, name_len);
 	btrfs_i_size_write(inode, name_len);
 	err = btrfs_update_inode(trans, root, inode);
@@ -9459,7 +9454,6 @@ static int btrfs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 	inode->i_op = &btrfs_file_inode_operations;
 
 	inode->i_mapping->a_ops = &btrfs_aops;
-	inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
 	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 
 	ret = btrfs_init_inode_security(trans, inode, dir, NULL);

fs/ceph/file.c

@@ -945,7 +945,7 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	mutex_lock(&inode->i_mutex);
 
 	/* We can write back this queue in page reclaim */
-	current->backing_dev_info = file->f_mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 
 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 	if (err)

fs/ceph/inode.c

@@ -783,8 +783,6 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
 	}
 
 	inode->i_mapping->a_ops = &ceph_aops;
-	inode->i_mapping->backing_dev_info =
-		&ceph_sb_to_client(inode->i_sb)->backing_dev_info;
 
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFIFO:

fs/ceph/super.c

@@ -40,17 +40,6 @@ static void ceph_put_super(struct super_block *s)
 
 	dout("put_super\n");
 	ceph_mdsc_close_sessions(fsc->mdsc);
-
-	/*
-	 * ensure we release the bdi before put_anon_super releases
-	 * the device name.
-	 */
-	if (s->s_bdi == &fsc->backing_dev_info) {
-		bdi_unregister(&fsc->backing_dev_info);
-		s->s_bdi = NULL;
-	}
-
-	return;
 }
 
 static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf)
@@ -910,7 +899,7 @@ static int ceph_register_bdi(struct super_block *sb,
 			>> PAGE_SHIFT;
 	else
 		fsc->backing_dev_info.ra_pages =
-			default_backing_dev_info.ra_pages;
+			VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE;
 
 	err = bdi_register(&fsc->backing_dev_info, NULL, "ceph-%ld",
 			   atomic_long_inc_return(&bdi_seq));
@@ -1002,11 +991,16 @@ static struct dentry *ceph_mount(struct file_system_type *fs_type,
 static void ceph_kill_sb(struct super_block *s)
 {
 	struct ceph_fs_client *fsc = ceph_sb_to_client(s);
+	dev_t dev = s->s_dev;
+
 	dout("kill_sb %p\n", s);
+
 	ceph_mdsc_pre_umount(fsc->mdsc);
-	kill_anon_super(s);    /* will call put_super after sb is r/o */
+	generic_shutdown_super(s);
 	ceph_mdsc_destroy(fsc);
+
 	destroy_fs_client(fsc);
+	free_anon_bdev(dev);
 }
 
 static struct file_system_type ceph_fs_type = {

fs/char_dev.c

@@ -24,27 +24,6 @@
 
 #include "internal.h"
 
-/*
- * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
- * devices
- * - permits shared-mmap for read, write and/or exec
- * - does not permit private mmap in NOMMU mode (can't do COW)
- * - no readahead or I/O queue unplugging required
- */
-struct backing_dev_info directly_mappable_cdev_bdi = {
-	.name = "char",
-	.capabilities	= (
-#ifdef CONFIG_MMU
-		/* permit private copies of the data to be taken */
-		BDI_CAP_MAP_COPY |
-#endif
-		/* permit direct mmap, for read, write or exec */
-		BDI_CAP_MAP_DIRECT |
-		BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
-		/* no writeback happens */
-		BDI_CAP_NO_ACCT_AND_WRITEBACK),
-};
-
 static struct kobj_map *cdev_map;
 
 static DEFINE_MUTEX(chrdevs_lock);
@@ -575,8 +554,6 @@ static struct kobject *base_probe(dev_t dev, int *part, void *data)
 void __init chrdev_init(void)
 {
 	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
-	if (bdi_init(&directly_mappable_cdev_bdi))
-		panic("Failed to init directly mappable cdev bdi");
 }
 
 
@@ -590,4 +567,3 @@ EXPORT_SYMBOL(cdev_del);
 EXPORT_SYMBOL(cdev_add);
 EXPORT_SYMBOL(__register_chrdev);
 EXPORT_SYMBOL(__unregister_chrdev);
-EXPORT_SYMBOL(directly_mappable_cdev_bdi);

fs/cifs/connect.c

@@ -3446,7 +3446,7 @@ cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *volume_info)
 	int referral_walks_count = 0;
 #endif
 
-	rc = bdi_setup_and_register(&cifs_sb->bdi, "cifs", BDI_CAP_MAP_COPY);
+	rc = bdi_setup_and_register(&cifs_sb->bdi, "cifs");
 	if (rc)
 		return rc;
 

fs/cifs/inode.c

@@ -937,8 +937,6 @@ cifs_iget(struct super_block *sb, struct cifs_fattr *fattr)
 			inode->i_flags |= S_NOATIME | S_NOCMTIME;
 		if (inode->i_state & I_NEW) {
 			inode->i_ino = hash;
-			if (S_ISREG(inode->i_mode))
-				inode->i_data.backing_dev_info = sb->s_bdi;
 #ifdef CONFIG_CIFS_FSCACHE
 			/* initialize per-inode cache cookie pointer */
 			CIFS_I(inode)->fscache = NULL;

fs/coda/inode.c

@@ -183,7 +183,7 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 		goto unlock_out;
 	}
 
-	error = bdi_setup_and_register(&vc->bdi, "coda", BDI_CAP_MAP_COPY);
+	error = bdi_setup_and_register(&vc->bdi, "coda");
 	if (error)
 		goto unlock_out;
 

fs/configfs/configfs_internal.h

@@ -70,8 +70,6 @@ extern int configfs_is_root(struct config_item *item);
 
 extern struct inode * configfs_new_inode(umode_t mode, struct configfs_dirent *, struct super_block *);
 extern int configfs_create(struct dentry *, umode_t mode, int (*init)(struct inode *));
-extern int configfs_inode_init(void);
-extern void configfs_inode_exit(void);
 
 extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
 extern int configfs_make_dirent(struct configfs_dirent *,

fs/configfs/inode.c

@@ -50,12 +50,6 @@ static const struct address_space_operations configfs_aops = {
 	.write_end	= simple_write_end,
 };
 
-static struct backing_dev_info configfs_backing_dev_info = {
-	.name		= "configfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
 static const struct inode_operations configfs_inode_operations ={
 	.setattr	= configfs_setattr,
 };
@@ -137,7 +131,6 @@ struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 	if (inode) {
 		inode->i_ino = get_next_ino();
 		inode->i_mapping->a_ops = &configfs_aops;
-		inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 		inode->i_op = &configfs_inode_operations;
 
 		if (sd->s_iattr) {
@@ -283,13 +276,3 @@ void configfs_hash_and_remove(struct dentry * dir, const char * name)
 	}
 	mutex_unlock(&dir->d_inode->i_mutex);
 }
-
-int __init configfs_inode_init(void)
-{
-	return bdi_init(&configfs_backing_dev_info);
-}
-
-void configfs_inode_exit(void)
-{
-	bdi_destroy(&configfs_backing_dev_info);
-}

fs/configfs/mount.c

@@ -145,19 +145,13 @@ static int __init configfs_init(void)
 	if (!config_kobj)
 		goto out2;
 
-	err = configfs_inode_init();
+	err = register_filesystem(&configfs_fs_type);
 	if (err)
 		goto out3;
 
-	err = register_filesystem(&configfs_fs_type);
-	if (err)
-		goto out4;
-
 	return 0;
-out4:
-	pr_err("Unable to register filesystem!\n");
-	configfs_inode_exit();
 out3:
+	pr_err("Unable to register filesystem!\n");
 	kobject_put(config_kobj);
 out2:
 	kmem_cache_destroy(configfs_dir_cachep);
@@ -172,7 +166,6 @@ static void __exit configfs_exit(void)
 	kobject_put(config_kobj);
 	kmem_cache_destroy(configfs_dir_cachep);
 	configfs_dir_cachep = NULL;
-	configfs_inode_exit();
 }
 
 MODULE_AUTHOR("Oracle");

fs/ecryptfs/inode.c

@@ -67,7 +67,6 @@ static int ecryptfs_inode_set(struct inode *inode, void *opaque)
 	inode->i_ino = lower_inode->i_ino;
 	inode->i_version++;
 	inode->i_mapping->a_ops = &ecryptfs_aops;
-	inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
 
 	if (S_ISLNK(inode->i_mode))
 		inode->i_op = &ecryptfs_symlink_iops;

fs/ecryptfs/main.c

@@ -520,7 +520,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
 		goto out;
 	}
 
-	rc = bdi_setup_and_register(&sbi->bdi, "ecryptfs", BDI_CAP_MAP_COPY);
+	rc = bdi_setup_and_register(&sbi->bdi, "ecryptfs");
 	if (rc)
 		goto out1;
 

fs/exofs/inode.c

@@ -1214,7 +1214,6 @@ struct inode *exofs_iget(struct super_block *sb, unsigned long ino)
 		memcpy(oi->i_data, fcb.i_data, sizeof(fcb.i_data));
 	}
 
-	inode->i_mapping->backing_dev_info = sb->s_bdi;
 	if (S_ISREG(inode->i_mode)) {
 		inode->i_op = &exofs_file_inode_operations;
 		inode->i_fop = &exofs_file_operations;
@@ -1314,7 +1313,6 @@ struct inode *exofs_new_inode(struct inode *dir, umode_t mode)
 
 	set_obj_2bcreated(oi);
 
-	inode->i_mapping->backing_dev_info = sb->s_bdi;
 	inode_init_owner(inode, dir, mode);
 	inode->i_ino = sbi->s_nextid++;
 	inode->i_blkbits = EXOFS_BLKSHIFT;

fs/exofs/super.c

@@ -836,7 +836,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 		goto free_sbi;
 	}
 
-	ret = bdi_setup_and_register(&sbi->bdi, "exofs", BDI_CAP_MAP_COPY);
+	ret = bdi_setup_and_register(&sbi->bdi, "exofs");
 	if (ret) {
 		EXOFS_DBGMSG("Failed to bdi_setup_and_register\n");
 		dput(sb->s_root);

fs/ext2/ialloc.c

@@ -170,7 +170,7 @@ static void ext2_preread_inode(struct inode *inode)
 	struct ext2_group_desc * gdp;
 	struct backing_dev_info *bdi;
 
-	bdi = inode->i_mapping->backing_dev_info;
+	bdi = inode_to_bdi(inode);
 	if (bdi_read_congested(bdi))
 		return;
 	if (bdi_write_congested(bdi))

fs/ext4/super.c

@@ -334,7 +334,7 @@ static void save_error_info(struct super_block *sb, const char *func,
 static int block_device_ejected(struct super_block *sb)
 {
 	struct inode *bd_inode = sb->s_bdev->bd_inode;
-	struct backing_dev_info *bdi = bd_inode->i_mapping->backing_dev_info;
+	struct backing_dev_info *bdi = inode_to_bdi(bd_inode);
 
 	return bdi->dev == NULL;
 }

fs/fs-writeback.c

@@ -66,15 +66,21 @@ int writeback_in_progress(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL(writeback_in_progress);
 
-static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
+struct backing_dev_info *inode_to_bdi(struct inode *inode)
 {
-	struct super_block *sb = inode->i_sb;
+	struct super_block *sb;
 
+	if (!inode)
+		return &noop_backing_dev_info;
+
+	sb = inode->i_sb;
+#ifdef CONFIG_BLOCK
 	if (sb_is_blkdev_sb(sb))
-		return inode->i_mapping->backing_dev_info;
+		return blk_get_backing_dev_info(I_BDEV(inode));
-
+#endif
 	return sb->s_bdi;
 }
+EXPORT_SYMBOL_GPL(inode_to_bdi);
 
 static inline struct inode *wb_inode(struct list_head *head)
 {

fs/fuse/file.c

@@ -1159,7 +1159,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	mutex_lock(&inode->i_mutex);
 
 	/* We can write back this queue in page reclaim */
-	current->backing_dev_info = mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 
 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 	if (err)
@@ -1464,7 +1464,7 @@ static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
 {
 	struct inode *inode = req->inode;
 	struct fuse_inode *fi = get_fuse_inode(inode);
-	struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
+	struct backing_dev_info *bdi = inode_to_bdi(inode);
 	int i;
 
 	list_del(&req->writepages_entry);
@@ -1658,7 +1658,7 @@ static int fuse_writepage_locked(struct page *page)
 	req->end = fuse_writepage_end;
 	req->inode = inode;
 
-	inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
+	inc_bdi_stat(inode_to_bdi(inode), BDI_WRITEBACK);
 	inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
 
 	spin_lock(&fc->lock);
@@ -1768,7 +1768,7 @@ static bool fuse_writepage_in_flight(struct fuse_req *new_req,
 
 	if (old_req->num_pages == 1 && (old_req->state == FUSE_REQ_INIT ||
 					old_req->state == FUSE_REQ_PENDING)) {
-		struct backing_dev_info *bdi = page->mapping->backing_dev_info;
+		struct backing_dev_info *bdi = inode_to_bdi(page->mapping->host);
 
 		copy_highpage(old_req->pages[0], page);
 		spin_unlock(&fc->lock);
@@ -1872,7 +1872,7 @@ static int fuse_writepages_fill(struct page *page,
 	req->page_descs[req->num_pages].offset = 0;
 	req->page_descs[req->num_pages].length = PAGE_SIZE;
 
-	inc_bdi_stat(page->mapping->backing_dev_info, BDI_WRITEBACK);
+	inc_bdi_stat(inode_to_bdi(inode), BDI_WRITEBACK);
 	inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
 
 	err = 0;

fs/fuse/inode.c

@@ -308,7 +308,6 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 		if (!fc->writeback_cache || !S_ISREG(attr->mode))
 			inode->i_flags |= S_NOCMTIME;
 		inode->i_generation = generation;
-		inode->i_data.backing_dev_info = &fc->bdi;
 		fuse_init_inode(inode, attr);
 		unlock_new_inode(inode);
 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {

fs/gfs2/aops.c

@@ -289,7 +289,7 @@ static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 		if (!clear_page_dirty_for_io(page))
 			goto continue_unlock;
 
-		trace_wbc_writepage(wbc, mapping->backing_dev_info);
+		trace_wbc_writepage(wbc, inode_to_bdi(inode));
 
 		ret = __gfs2_jdata_writepage(page, wbc);
 		if (unlikely(ret)) {

fs/gfs2/glock.c

@@ -768,7 +768,6 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 		mapping->flags = 0;
 		mapping_set_gfp_mask(mapping, GFP_NOFS);
 		mapping->private_data = NULL;
-		mapping->backing_dev_info = s->s_bdi;
 		mapping->writeback_index = 0;
 	}
 

fs/gfs2/ops_fstype.c

@@ -112,7 +112,6 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
 	mapping->flags = 0;
 	mapping_set_gfp_mask(mapping, GFP_NOFS);
 	mapping->private_data = NULL;
-	mapping->backing_dev_info = sb->s_bdi;
 	mapping->writeback_index = 0;
 
 	spin_lock_init(&sdp->sd_log_lock);

fs/gfs2/super.c

@@ -743,7 +743,7 @@ static int gfs2_write_inode(struct inode *inode, struct writeback_control *wbc)
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
 	struct address_space *metamapping = gfs2_glock2aspace(ip->i_gl);
-	struct backing_dev_info *bdi = metamapping->backing_dev_info;
+	struct backing_dev_info *bdi = inode_to_bdi(metamapping->host);
 	int ret = 0;
 
 	if (wbc->sync_mode == WB_SYNC_ALL)

fs/hugetlbfs/inode.c

@@ -62,12 +62,6 @@ static inline struct hugetlbfs_inode_info *HUGETLBFS_I(struct inode *inode)
 	return container_of(inode, struct hugetlbfs_inode_info, vfs_inode);
 }
 
-static struct backing_dev_info hugetlbfs_backing_dev_info = {
-	.name		= "hugetlbfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
 int sysctl_hugetlb_shm_group;
 
 enum {
@@ -498,7 +492,6 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb,
 		lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
 				&hugetlbfs_i_mmap_rwsem_key);
 		inode->i_mapping->a_ops = &hugetlbfs_aops;
-		inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inode->i_mapping->private_data = resv_map;
 		info = HUGETLBFS_I(inode);
@@ -1032,10 +1025,6 @@ static int __init init_hugetlbfs_fs(void)
 		return -ENOTSUPP;
 	}
 
-	error = bdi_init(&hugetlbfs_backing_dev_info);
-	if (error)
-		return error;
-
 	error = -ENOMEM;
 	hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
 					sizeof(struct hugetlbfs_inode_info),
@@ -1071,7 +1060,6 @@ static int __init init_hugetlbfs_fs(void)
  out:
 	kmem_cache_destroy(hugetlbfs_inode_cachep);
  out2:
-	bdi_destroy(&hugetlbfs_backing_dev_info);
 	return error;
 }
 
@@ -1091,7 +1079,6 @@ static void __exit exit_hugetlbfs_fs(void)
 	for_each_hstate(h)
 		kern_unmount(hugetlbfs_vfsmount[i++]);
 	unregister_filesystem(&hugetlbfs_fs_type);
-	bdi_destroy(&hugetlbfs_backing_dev_info);
 }
 
 module_init(init_hugetlbfs_fs)

fs/inode.c

@@ -170,20 +170,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 	atomic_set(&mapping->i_mmap_writable, 0);
 	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
 	mapping->private_data = NULL;
-	mapping->backing_dev_info = &default_backing_dev_info;
 	mapping->writeback_index = 0;
-
-	/*
-	 * If the block_device provides a backing_dev_info for client
-	 * inodes then use that.  Otherwise the inode share the bdev's
-	 * backing_dev_info.
-	 */
-	if (sb->s_bdev) {
-		struct backing_dev_info *bdi;
-
-		bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
-		mapping->backing_dev_info = bdi;
-	}
 	inode->i_private = NULL;
 	inode->i_mapping = mapping;
 	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */

fs/kernfs/inode.c

@@ -24,12 +24,6 @@ static const struct address_space_operations kernfs_aops = {
 	.write_end	= simple_write_end,
 };
 
-static struct backing_dev_info kernfs_bdi = {
-	.name		= "kernfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
 static const struct inode_operations kernfs_iops = {
 	.permission	= kernfs_iop_permission,
 	.setattr	= kernfs_iop_setattr,
@@ -40,12 +34,6 @@ static const struct inode_operations kernfs_iops = {
 	.listxattr	= kernfs_iop_listxattr,
 };
 
-void __init kernfs_inode_init(void)
-{
-	if (bdi_init(&kernfs_bdi))
-		panic("failed to init kernfs_bdi");
-}
-
 static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
 {
 	static DEFINE_MUTEX(iattr_mutex);
@@ -298,7 +286,6 @@ static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
 	kernfs_get(kn);
 	inode->i_private = kn;
 	inode->i_mapping->a_ops = &kernfs_aops;
-	inode->i_mapping->backing_dev_info = &kernfs_bdi;
 	inode->i_op = &kernfs_iops;
 
 	set_default_inode_attr(inode, kn->mode);

fs/kernfs/kernfs-internal.h

@@ -88,7 +88,6 @@ int kernfs_iop_removexattr(struct dentry *dentry, const char *name);
 ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf,
 			    size_t size);
 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size);
-void kernfs_inode_init(void);
 
 /*
  * dir.c

fs/kernfs/mount.c

@@ -246,5 +246,4 @@ void __init kernfs_init(void)
 	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
 					      sizeof(struct kernfs_node),
 					      0, SLAB_PANIC, NULL);
-	kernfs_inode_init();
 }

fs/ncpfs/inode.c

@@ -267,7 +267,6 @@ ncp_iget(struct super_block *sb, struct ncp_entry_info *info)
 	if (inode) {
 		atomic_set(&NCP_FINFO(inode)->opened, info->opened);
 
-		inode->i_mapping->backing_dev_info = sb->s_bdi;
 		inode->i_ino = info->ino;
 		ncp_set_attr(inode, info);
 		if (S_ISREG(inode->i_mode)) {
@@ -560,7 +559,7 @@ static int ncp_fill_super(struct super_block *sb, void *raw_data, int silent)
 	server = NCP_SBP(sb);
 	memset(server, 0, sizeof(*server));
 
-	error = bdi_setup_and_register(&server->bdi, "ncpfs", BDI_CAP_MAP_COPY);
+	error = bdi_setup_and_register(&server->bdi, "ncpfs");
 	if (error)
 		goto out_fput;
 

fs/nfs/filelayout/filelayout.c

@@ -1002,7 +1002,7 @@ filelayout_mark_request_commit(struct nfs_page *req,
 	spin_unlock(cinfo->lock);
 	if (!cinfo->dreq) {
 		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
+		inc_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
 			     BDI_RECLAIMABLE);
 		__mark_inode_dirty(req->wb_context->dentry->d_inode,
 				   I_DIRTY_DATASYNC);

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -1366,7 +1366,7 @@ ff_layout_mark_request_commit(struct nfs_page *req,
 	spin_unlock(cinfo->lock);
 	if (!cinfo->dreq) {
 		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
+		inc_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
 			     BDI_RECLAIMABLE);
 		__mark_inode_dirty(req->wb_context->dentry->d_inode,
 				   I_DIRTY_DATASYNC);

fs/nfs/inode.c

@@ -388,7 +388,6 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr, st
 		if (S_ISREG(inode->i_mode)) {
 			inode->i_fop = NFS_SB(sb)->nfs_client->rpc_ops->file_ops;
 			inode->i_data.a_ops = &nfs_file_aops;
-			inode->i_data.backing_dev_info = &NFS_SB(sb)->backing_dev_info;
 		} else if (S_ISDIR(inode->i_mode)) {
 			inode->i_op = NFS_SB(sb)->nfs_client->rpc_ops->dir_inode_ops;
 			inode->i_fop = &nfs_dir_operations;

fs/nfs/internal.h

@@ -430,7 +430,6 @@ int  nfs_show_options(struct seq_file *, struct dentry *);
 int  nfs_show_devname(struct seq_file *, struct dentry *);
 int  nfs_show_path(struct seq_file *, struct dentry *);
 int  nfs_show_stats(struct seq_file *, struct dentry *);
-void nfs_put_super(struct super_block *);
 int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
 
 /* write.c */

fs/nfs/nfs4super.c

@@ -53,7 +53,6 @@ static const struct super_operations nfs4_sops = {
 	.destroy_inode	= nfs_destroy_inode,
 	.write_inode	= nfs4_write_inode,
 	.drop_inode	= nfs_drop_inode,
-	.put_super	= nfs_put_super,
 	.statfs		= nfs_statfs,
 	.evict_inode	= nfs4_evict_inode,
 	.umount_begin	= nfs_umount_begin,

fs/nfs/super.c

@@ -311,7 +311,6 @@ const struct super_operations nfs_sops = {
 	.destroy_inode	= nfs_destroy_inode,
 	.write_inode	= nfs_write_inode,
 	.drop_inode	= nfs_drop_inode,
-	.put_super	= nfs_put_super,
 	.statfs		= nfs_statfs,
 	.evict_inode	= nfs_evict_inode,
 	.umount_begin	= nfs_umount_begin,
@@ -2572,7 +2571,7 @@ struct dentry *nfs_fs_mount_common(struct nfs_server *server,
 		error = nfs_bdi_register(server);
 		if (error) {
 			mntroot = ERR_PTR(error);
-			goto error_splat_bdi;
+			goto error_splat_super;
 		}
 		server->super = s;
 	}
@@ -2604,9 +2603,6 @@ struct dentry *nfs_fs_mount_common(struct nfs_server *server,
 	dput(mntroot);
 	mntroot = ERR_PTR(error);
 error_splat_super:
-	if (server && !s->s_root)
-		bdi_unregister(&server->backing_dev_info);
-error_splat_bdi:
 	deactivate_locked_super(s);
 	goto out;
 }
@@ -2653,28 +2649,20 @@ struct dentry *nfs_fs_mount(struct file_system_type *fs_type,
 }
 EXPORT_SYMBOL_GPL(nfs_fs_mount);
 
-/*
- * Ensure that we unregister the bdi before kill_anon_super
- * releases the device name
- */
-void nfs_put_super(struct super_block *s)
-{
-	struct nfs_server *server = NFS_SB(s);
-
-	bdi_unregister(&server->backing_dev_info);
-}
-EXPORT_SYMBOL_GPL(nfs_put_super);
-
 /*
  * Destroy an NFS2/3 superblock
  */
 void nfs_kill_super(struct super_block *s)
 {
 	struct nfs_server *server = NFS_SB(s);
+	dev_t dev = s->s_dev;
+
+	generic_shutdown_super(s);
 
-	kill_anon_super(s);
 	nfs_fscache_release_super_cookie(s);
+
 	nfs_free_server(server);
+	free_anon_bdev(dev);
 }
 EXPORT_SYMBOL_GPL(nfs_kill_super);
 

fs/nfs/write.c

@@ -791,7 +791,7 @@ nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
 	spin_unlock(cinfo->lock);
 	if (!cinfo->dreq) {
 		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
+		inc_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
 			     BDI_RECLAIMABLE);
 		__mark_inode_dirty(req->wb_context->dentry->d_inode,
 				   I_DIRTY_DATASYNC);
@@ -858,7 +858,7 @@ static void
 nfs_clear_page_commit(struct page *page)
 {
 	dec_zone_page_state(page, NR_UNSTABLE_NFS);
-	dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
+	dec_bdi_stat(inode_to_bdi(page_file_mapping(page)->host), BDI_RECLAIMABLE);
 }
 
 /* Called holding inode (/cinfo) lock */
@@ -1607,7 +1607,7 @@ void nfs_retry_commit(struct list_head *page_list,
 		nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
 		if (!cinfo->dreq) {
 			dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-			dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
+			dec_bdi_stat(inode_to_bdi(page_file_mapping(req->wb_page)->host),
 				     BDI_RECLAIMABLE);
 		}
 		nfs_unlock_and_release_request(req);

fs/nilfs2/gcinode.c

@@ -172,7 +172,6 @@ int nilfs_init_gcinode(struct inode *inode)
 	inode->i_mode = S_IFREG;
 	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 	inode->i_mapping->a_ops = &empty_aops;
-	inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
 
 	ii->i_flags = 0;
 	nilfs_bmap_init_gc(ii->i_bmap);

fs/nilfs2/mdt.c

@@ -429,7 +429,6 @@ int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
 
 	inode->i_mode = S_IFREG;
 	mapping_set_gfp_mask(inode->i_mapping, gfp_mask);
-	inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
 
 	inode->i_op = &def_mdt_iops;
 	inode->i_fop = &def_mdt_fops;
@@ -457,13 +456,12 @@ int nilfs_mdt_setup_shadow_map(struct inode *inode,
 			       struct nilfs_shadow_map *shadow)
 {
 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
-	struct backing_dev_info *bdi = inode->i_sb->s_bdi;
 
 	INIT_LIST_HEAD(&shadow->frozen_buffers);
 	address_space_init_once(&shadow->frozen_data);
-	nilfs_mapping_init(&shadow->frozen_data, inode, bdi);
+	nilfs_mapping_init(&shadow->frozen_data, inode);
 	address_space_init_once(&shadow->frozen_btnodes);
-	nilfs_mapping_init(&shadow->frozen_btnodes, inode, bdi);
+	nilfs_mapping_init(&shadow->frozen_btnodes, inode);
 	mi->mi_shadow = shadow;
 	return 0;
 }

fs/nilfs2/page.c

@@ -461,14 +461,12 @@ unsigned nilfs_page_count_clean_buffers(struct page *page,
 	return nc;
 }
 
-void nilfs_mapping_init(struct address_space *mapping, struct inode *inode,
+void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
-			struct backing_dev_info *bdi)
 {
 	mapping->host = inode;
 	mapping->flags = 0;
 	mapping_set_gfp_mask(mapping, GFP_NOFS);
 	mapping->private_data = NULL;
-	mapping->backing_dev_info = bdi;
 	mapping->a_ops = &empty_aops;
 }
 

fs/nilfs2/page.h

@@ -57,8 +57,7 @@ int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
 void nilfs_copy_back_pages(struct address_space *, struct address_space *);
 void nilfs_clear_dirty_page(struct page *, bool);
 void nilfs_clear_dirty_pages(struct address_space *, bool);
-void nilfs_mapping_init(struct address_space *mapping, struct inode *inode,
+void nilfs_mapping_init(struct address_space *mapping, struct inode *inode);
-			struct backing_dev_info *bdi);
 unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 					    sector_t start_blk,

fs/nilfs2/super.c

@@ -166,7 +166,7 @@ struct inode *nilfs_alloc_inode(struct super_block *sb)
 	ii->i_state = 0;
 	ii->i_cno = 0;
 	ii->vfs_inode.i_version = 1;
-	nilfs_mapping_init(&ii->i_btnode_cache, &ii->vfs_inode, sb->s_bdi);
+	nilfs_mapping_init(&ii->i_btnode_cache, &ii->vfs_inode);
 	return &ii->vfs_inode;
 }
 
@@ -1057,7 +1057,6 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct the_nilfs *nilfs;
 	struct nilfs_root *fsroot;
-	struct backing_dev_info *bdi;
 	__u64 cno;
 	int err;
 
@@ -1077,8 +1076,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_time_gran = 1;
 	sb->s_max_links = NILFS_LINK_MAX;
 
-	bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
+	sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
-	sb->s_bdi = bdi ? : &default_backing_dev_info;
 
 	err = load_nilfs(nilfs, sb);
 	if (err)

fs/ntfs/file.c

@@ -19,6 +19,7 @@
  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <linux/backing-dev.h>
 #include <linux/buffer_head.h>
 #include <linux/gfp.h>
 #include <linux/pagemap.h>
@@ -2091,7 +2092,7 @@ static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
 	count = iov_length(iov, nr_segs);
 	pos = *ppos;
 	/* We can write back this queue in page reclaim. */
-	current->backing_dev_info = mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 	written = 0;
 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 	if (err)

fs/ocfs2/dlmfs/dlmfs.c

@@ -390,12 +390,6 @@ static void dlmfs_evict_inode(struct inode *inode)
 	ip->ip_conn = NULL;
 }
 
-static struct backing_dev_info dlmfs_backing_dev_info = {
-	.name		= "ocfs2-dlmfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
 static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 {
 	struct inode *inode = new_inode(sb);
@@ -404,7 +398,6 @@ static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 	if (inode) {
 		inode->i_ino = get_next_ino();
 		inode_init_owner(inode, NULL, mode);
-		inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inc_nlink(inode);
 
@@ -428,7 +421,6 @@ static struct inode *dlmfs_get_inode(struct inode *parent,
 
 	inode->i_ino = get_next_ino();
 	inode_init_owner(inode, parent, mode);
-	inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 
 	ip = DLMFS_I(inode);
@@ -643,10 +635,6 @@ static int __init init_dlmfs_fs(void)
 	int status;
 	int cleanup_inode = 0, cleanup_worker = 0;
 
-	status = bdi_init(&dlmfs_backing_dev_info);
-	if (status)
-		return status;
-
 	dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
 				sizeof(struct dlmfs_inode_private),
 				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
@@ -673,7 +661,6 @@ static int __init init_dlmfs_fs(void)
 			kmem_cache_destroy(dlmfs_inode_cache);
 		if (cleanup_worker)
 			destroy_workqueue(user_dlm_worker);
-		bdi_destroy(&dlmfs_backing_dev_info);
 	} else
 		printk("OCFS2 User DLM kernel interface loaded\n");
 	return status;
@@ -693,7 +680,6 @@ static void __exit exit_dlmfs_fs(void)
 	rcu_barrier();
 	kmem_cache_destroy(dlmfs_inode_cache);
 
-	bdi_destroy(&dlmfs_backing_dev_info);
 }
 
 MODULE_AUTHOR("Oracle");

fs/ocfs2/file.c

@@ -2363,7 +2363,7 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
 			goto out_dio;
 		}
 	} else {
-		current->backing_dev_info = file->f_mapping->backing_dev_info;
+		current->backing_dev_info = inode_to_bdi(inode);
 		written = generic_perform_write(file, from, *ppos);
 		if (likely(written >= 0))
 			iocb->ki_pos = *ppos + written;

fs/ramfs/file-nommu.c

@@ -34,7 +34,14 @@ static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
 						   unsigned long flags);
 static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma);
 
+static unsigned ramfs_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_DIRECT | NOMMU_MAP_COPY | NOMMU_MAP_READ |
+		NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
+}
+
 const struct file_operations ramfs_file_operations = {
+	.mmap_capabilities	= ramfs_mmap_capabilities,
 	.mmap			= ramfs_nommu_mmap,
 	.get_unmapped_area	= ramfs_nommu_get_unmapped_area,
 	.read			= new_sync_read,

fs/ramfs/inode.c

@@ -50,14 +50,6 @@ static const struct address_space_operations ramfs_aops = {
 	.set_page_dirty	= __set_page_dirty_no_writeback,
 };
 
-static struct backing_dev_info ramfs_backing_dev_info = {
-	.name		= "ramfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK |
-			  BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
-			  BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
-};
-
 struct inode *ramfs_get_inode(struct super_block *sb,
 				const struct inode *dir, umode_t mode, dev_t dev)
 {
@@ -67,7 +59,6 @@ struct inode *ramfs_get_inode(struct super_block *sb,
 		inode->i_ino = get_next_ino();
 		inode_init_owner(inode, dir, mode);
 		inode->i_mapping->a_ops = &ramfs_aops;
-		inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
 		mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
 		mapping_set_unevictable(inode->i_mapping);
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
@@ -267,19 +258,9 @@ static struct file_system_type ramfs_fs_type = {
 int __init init_ramfs_fs(void)
 {
 	static unsigned long once;
-	int err;
 
 	if (test_and_set_bit(0, &once))
 		return 0;
-
+	return register_filesystem(&ramfs_fs_type);
-	err = bdi_init(&ramfs_backing_dev_info);
-	if (err)
-		return err;
-
-	err = register_filesystem(&ramfs_fs_type);
-	if (err)
-		bdi_destroy(&ramfs_backing_dev_info);
-
-	return err;
 }
 fs_initcall(init_ramfs_fs);

fs/romfs/mmap-nommu.c

@@ -70,6 +70,15 @@ static int romfs_mmap(struct file *file, struct vm_area_struct *vma)
 	return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
 }
 
+static unsigned romfs_mmap_capabilities(struct file *file)
+{
+	struct mtd_info *mtd = file_inode(file)->i_sb->s_mtd;
+
+	if (!mtd)
+		return NOMMU_MAP_COPY;
+	return mtd_mmap_capabilities(mtd);
+}
+
 const struct file_operations romfs_ro_fops = {
 	.llseek			= generic_file_llseek,
 	.read			= new_sync_read,
@@ -77,4 +86,5 @@ const struct file_operations romfs_ro_fops = {
 	.splice_read		= generic_file_splice_read,
 	.mmap			= romfs_mmap,
 	.get_unmapped_area	= romfs_get_unmapped_area,
+	.mmap_capabilities	= romfs_mmap_capabilities,
 };

fs/romfs/super.c

@@ -355,9 +355,6 @@ static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
 	case ROMFH_REG:
 		i->i_fop = &romfs_ro_fops;
 		i->i_data.a_ops = &romfs_aops;
-		if (i->i_sb->s_mtd)
-			i->i_data.backing_dev_info =
-				i->i_sb->s_mtd->backing_dev_info;
 		if (nextfh & ROMFH_EXEC)
 			mode |= S_IXUGO;
 		break;

fs/super.c

@@ -36,8 +36,8 @@
 #include "internal.h"
 
 
-LIST_HEAD(super_blocks);
+static LIST_HEAD(super_blocks);
-DEFINE_SPINLOCK(sb_lock);
+static DEFINE_SPINLOCK(sb_lock);
 
 static char *sb_writers_name[SB_FREEZE_LEVELS] = {
 	"sb_writers",
@@ -185,8 +185,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
 	}
 	init_waitqueue_head(&s->s_writers.wait);
 	init_waitqueue_head(&s->s_writers.wait_unfrozen);
+	s->s_bdi = &noop_backing_dev_info;
 	s->s_flags = flags;
-	s->s_bdi = &default_backing_dev_info;
 	INIT_HLIST_NODE(&s->s_instances);
 	INIT_HLIST_BL_HEAD(&s->s_anon);
 	INIT_LIST_HEAD(&s->s_inodes);
@@ -863,10 +863,7 @@ EXPORT_SYMBOL(free_anon_bdev);
 
 int set_anon_super(struct super_block *s, void *data)
 {
-	int error = get_anon_bdev(&s->s_dev);
+	return get_anon_bdev(&s->s_dev);
-	if (!error)
-		s->s_bdi = &noop_backing_dev_info;
-	return error;
 }
 
 EXPORT_SYMBOL(set_anon_super);
@@ -1111,7 +1108,6 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
 	sb = root->d_sb;
 	BUG_ON(!sb);
 	WARN_ON(!sb->s_bdi);
-	WARN_ON(sb->s_bdi == &default_backing_dev_info);
 	sb->s_flags |= MS_BORN;
 
 	error = security_sb_kern_mount(sb, flags, secdata);

fs/ubifs/dir.c

@@ -108,8 +108,6 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, const struct inode *dir,
 	inode->i_mtime = inode->i_atime = inode->i_ctime =
 			 ubifs_current_time(inode);
 	inode->i_mapping->nrpages = 0;
-	/* Disable readahead */
-	inode->i_mapping->backing_dev_info = &c->bdi;
 
 	switch (mode & S_IFMT) {
 	case S_IFREG:

fs/ubifs/super.c

@@ -156,9 +156,6 @@ struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
 	if (err)
 		goto out_invalid;
 
-	/* Disable read-ahead */
-	inode->i_mapping->backing_dev_info = &c->bdi;
-
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFREG:
 		inode->i_mapping->a_ops = &ubifs_file_address_operations;
@@ -2017,7 +2014,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
 	 * Read-ahead will be disabled because @c->bdi.ra_pages is 0.
 	 */
 	c->bdi.name = "ubifs",
-	c->bdi.capabilities = BDI_CAP_MAP_COPY;
+	c->bdi.capabilities = 0;
 	err  = bdi_init(&c->bdi);
 	if (err)
 		goto out_close;

fs/xfs/xfs_file.c

@@ -735,7 +735,7 @@ xfs_file_buffered_aio_write(
 
 	iov_iter_truncate(from, count);
 	/* We can write back this queue in page reclaim */
-	current->backing_dev_info = mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 
 write_retry:
 	trace_xfs_file_buffered_write(ip, count, iocb->ki_pos, 0);

include/linux/backing-dev.h

@@ -106,6 +106,8 @@ struct backing_dev_info {
 #endif
 };
 
+struct backing_dev_info *inode_to_bdi(struct inode *inode);
+
 int __must_check bdi_init(struct backing_dev_info *bdi);
 void bdi_destroy(struct backing_dev_info *bdi);
 
@@ -114,7 +116,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 		const char *fmt, ...);
 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 void bdi_unregister(struct backing_dev_info *bdi);
-int __must_check bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
+int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
 			enum wb_reason reason);
 void bdi_start_background_writeback(struct backing_dev_info *bdi);
@@ -228,46 +230,17 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
  * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
  * BDI_CAP_NO_WRITEBACK:   Don't write pages back
  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
- *
- * These flags let !MMU mmap() govern direct device mapping vs immediate
- * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
- *
- * BDI_CAP_MAP_COPY:       Copy can be mapped (MAP_PRIVATE)
- * BDI_CAP_MAP_DIRECT:     Can be mapped directly (MAP_SHARED)
- * BDI_CAP_READ_MAP:       Can be mapped for reading
- * BDI_CAP_WRITE_MAP:      Can be mapped for writing
- * BDI_CAP_EXEC_MAP:       Can be mapped for execution
- *
- * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
- *
  * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
  */
 #define BDI_CAP_NO_ACCT_DIRTY	0x00000001
 #define BDI_CAP_NO_WRITEBACK	0x00000002
-#define BDI_CAP_MAP_COPY	0x00000004
+#define BDI_CAP_NO_ACCT_WB	0x00000004
-#define BDI_CAP_MAP_DIRECT	0x00000008
+#define BDI_CAP_STABLE_WRITES	0x00000008
-#define BDI_CAP_READ_MAP	0x00000010
+#define BDI_CAP_STRICTLIMIT	0x00000010
-#define BDI_CAP_WRITE_MAP	0x00000020
-#define BDI_CAP_EXEC_MAP	0x00000040
-#define BDI_CAP_NO_ACCT_WB	0x00000080
-#define BDI_CAP_SWAP_BACKED	0x00000100
-#define BDI_CAP_STABLE_WRITES	0x00000200
-#define BDI_CAP_STRICTLIMIT	0x00000400
-
-#define BDI_CAP_VMFLAGS \
-	(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
 
 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
 	(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
 
-#if defined(VM_MAYREAD) && \
-	(BDI_CAP_READ_MAP != VM_MAYREAD || \
-	 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
-	 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
-#error please change backing_dev_info::capabilities flags
-#endif
-
-extern struct backing_dev_info default_backing_dev_info;
 extern struct backing_dev_info noop_backing_dev_info;
 
 int writeback_in_progress(struct backing_dev_info *bdi);
@@ -329,24 +302,14 @@ static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
 				      BDI_CAP_NO_WRITEBACK));
 }
 
-static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
-{
-	return bdi->capabilities & BDI_CAP_SWAP_BACKED;
-}
-
 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
 {
-	return bdi_cap_writeback_dirty(mapping->backing_dev_info);
+	return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
 }
 
 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
 {
-	return bdi_cap_account_dirty(mapping->backing_dev_info);
+	return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
-}
-
-static inline bool mapping_cap_swap_backed(struct address_space *mapping)
-{
-	return bdi_cap_swap_backed(mapping->backing_dev_info);
 }
 
 static inline int bdi_sched_wait(void *word)

include/linux/cdev.h

@@ -30,6 +30,4 @@ void cdev_del(struct cdev *);
 
 void cd_forget(struct inode *);
 
-extern struct backing_dev_info directly_mappable_cdev_bdi;
-
 #endif

include/linux/fs.h

@@ -34,6 +34,7 @@
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
 
+struct backing_dev_info;
 struct export_operations;
 struct hd_geometry;
 struct iovec;
@@ -394,7 +395,6 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned copied,
 				struct page *page, void *fsdata);
 
-struct backing_dev_info;
 struct address_space {
 	struct inode		*host;		/* owner: inode, block_device */
 	struct radix_tree_root	page_tree;	/* radix tree of all pages */
@@ -408,7 +408,6 @@ struct address_space {
 	pgoff_t			writeback_index;/* writeback starts here */
 	const struct address_space_operations *a_ops;	/* methods */
 	unsigned long		flags;		/* error bits/gfp mask */
-	struct backing_dev_info *backing_dev_info; /* device readahead, etc */
 	spinlock_t		private_lock;	/* for use by the address_space */
 	struct list_head	private_list;	/* ditto */
 	void			*private_data;	/* ditto */
@@ -1201,8 +1200,6 @@ struct mm_struct;
 #define UMOUNT_NOFOLLOW	0x00000008	/* Don't follow symlink on umount */
 #define UMOUNT_UNUSED	0x80000000	/* Flag guaranteed to be unused */
 
-extern struct list_head super_blocks;
-extern spinlock_t sb_lock;
 
 /* Possible states of 'frozen' field */
 enum {
@@ -1519,6 +1516,26 @@ struct block_device_operations;
 #define HAVE_COMPAT_IOCTL 1
 #define HAVE_UNLOCKED_IOCTL 1
 
+/*
+ * These flags let !MMU mmap() govern direct device mapping vs immediate
+ * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
+ *
+ * NOMMU_MAP_COPY:	Copy can be mapped (MAP_PRIVATE)
+ * NOMMU_MAP_DIRECT:	Can be mapped directly (MAP_SHARED)
+ * NOMMU_MAP_READ:	Can be mapped for reading
+ * NOMMU_MAP_WRITE:	Can be mapped for writing
+ * NOMMU_MAP_EXEC:	Can be mapped for execution
+ */
+#define NOMMU_MAP_COPY		0x00000001
+#define NOMMU_MAP_DIRECT	0x00000008
+#define NOMMU_MAP_READ		VM_MAYREAD
+#define NOMMU_MAP_WRITE		VM_MAYWRITE
+#define NOMMU_MAP_EXEC		VM_MAYEXEC
+
+#define NOMMU_VMFLAGS \
+	(NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC)
+
+
 struct iov_iter;
 
 struct file_operations {
@@ -1553,6 +1570,9 @@ struct file_operations {
 	long (*fallocate)(struct file *file, int mode, loff_t offset,
 			  loff_t len);
 	void (*show_fdinfo)(struct seq_file *m, struct file *f);
+#ifndef CONFIG_MMU
+	unsigned (*mmap_capabilities)(struct file *);
+#endif
 };
 
 struct inode_operations {

include/linux/mtd/mtd.h

@@ -408,4 +408,6 @@ static inline int mtd_is_bitflip_or_eccerr(int err) {
 	return mtd_is_bitflip(err) || mtd_is_eccerr(err);
 }
 
+unsigned mtd_mmap_capabilities(struct mtd_info *mtd);
+
 #endif /* __MTD_MTD_H__ */

include/trace/events/writeback.h

@@ -47,7 +47,7 @@ TRACE_EVENT(writeback_dirty_page,
 
 	TP_fast_assign(
 		strncpy(__entry->name,
-			mapping ? dev_name(mapping->backing_dev_info->dev) : "(unknown)", 32);
+			mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32);
 		__entry->ino = mapping ? mapping->host->i_ino : 0;
 		__entry->index = page->index;
 	),
@@ -72,7 +72,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
 	),
 
 	TP_fast_assign(
-		struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
+		struct backing_dev_info *bdi = inode_to_bdi(inode);
 
 		/* may be called for files on pseudo FSes w/ unregistered bdi */
 		strncpy(__entry->name,
@@ -116,7 +116,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
 
 	TP_fast_assign(
 		strncpy(__entry->name,
-			dev_name(inode->i_mapping->backing_dev_info->dev), 32);
+			dev_name(inode_to_bdi(inode)->dev), 32);
 		__entry->ino		= inode->i_ino;
 		__entry->sync_mode	= wbc->sync_mode;
 	),
@@ -156,10 +156,8 @@ DECLARE_EVENT_CLASS(writeback_work_class,
 		__field(int, reason)
 	),
 	TP_fast_assign(
-		struct device *dev = bdi->dev;
+		strncpy(__entry->name,
-		if (!dev)
+			bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
-			dev = default_backing_dev_info.dev;
-		strncpy(__entry->name, dev_name(dev), 32);
 		__entry->nr_pages = work->nr_pages;
 		__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
 		__entry->sync_mode = work->sync_mode;

mm/backing-dev.c

@@ -14,19 +14,10 @@
 
 static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
 
-struct backing_dev_info default_backing_dev_info = {
-	.name		= "default",
-	.ra_pages	= VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
-	.state		= 0,
-	.capabilities	= BDI_CAP_MAP_COPY,
-};
-EXPORT_SYMBOL_GPL(default_backing_dev_info);
-
 struct backing_dev_info noop_backing_dev_info = {
 	.name		= "noop",
 	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
 };
-EXPORT_SYMBOL_GPL(noop_backing_dev_info);
 
 static struct class *bdi_class;
 
@@ -40,17 +31,6 @@ LIST_HEAD(bdi_list);
 /* bdi_wq serves all asynchronous writeback tasks */
 struct workqueue_struct *bdi_wq;
 
-static void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
-{
-	if (wb1 < wb2) {
-		spin_lock(&wb1->list_lock);
-		spin_lock_nested(&wb2->list_lock, 1);
-	} else {
-		spin_lock(&wb2->list_lock);
-		spin_lock_nested(&wb1->list_lock, 1);
-	}
-}
-
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -264,9 +244,6 @@ static int __init default_bdi_init(void)
 	if (!bdi_wq)
 		return -ENOMEM;
 
-	err = bdi_init(&default_backing_dev_info);
-	if (!err)
-		bdi_register(&default_backing_dev_info, NULL, "default");
 	err = bdi_init(&noop_backing_dev_info);
 
 	return err;
@@ -355,19 +332,19 @@ EXPORT_SYMBOL(bdi_register_dev);
  */
 static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 {
-	if (!bdi_cap_writeback_dirty(bdi))
+	/* Make sure nobody queues further work */
+	spin_lock_bh(&bdi->wb_lock);
+	if (!test_and_clear_bit(BDI_registered, &bdi->state)) {
+		spin_unlock_bh(&bdi->wb_lock);
 		return;
+	}
+	spin_unlock_bh(&bdi->wb_lock);
 
 	/*
 	 * Make sure nobody finds us on the bdi_list anymore
 	 */
 	bdi_remove_from_list(bdi);
 
-	/* Make sure nobody queues further work */
-	spin_lock_bh(&bdi->wb_lock);
-	clear_bit(BDI_registered, &bdi->state);
-	spin_unlock_bh(&bdi->wb_lock);
-
 	/*
 	 * Drain work list and shutdown the delayed_work.  At this point,
 	 * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
@@ -375,37 +352,22 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 	 */
 	mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
 	flush_delayed_work(&bdi->wb.dwork);
-	WARN_ON(!list_empty(&bdi->work_list));
-	WARN_ON(delayed_work_pending(&bdi->wb.dwork));
 }
 
 /*
- * This bdi is going away now, make sure that no super_blocks point to it
+ * Called when the device behind @bdi has been removed or ejected.
+ *
+ * We can't really do much here except for reducing the dirty ratio at
+ * the moment.  In the future we should be able to set a flag so that
+ * the filesystem can handle errors at mark_inode_dirty time instead
+ * of only at writeback time.
  */
-static void bdi_prune_sb(struct backing_dev_info *bdi)
-{
-	struct super_block *sb;
-
-	spin_lock(&sb_lock);
-	list_for_each_entry(sb, &super_blocks, s_list) {
-		if (sb->s_bdi == bdi)
-			sb->s_bdi = &default_backing_dev_info;
-	}
-	spin_unlock(&sb_lock);
-}
-
 void bdi_unregister(struct backing_dev_info *bdi)
 {
-	if (bdi->dev) {
+	if (WARN_ON_ONCE(!bdi->dev))
-		bdi_set_min_ratio(bdi, 0);
+		return;
-		trace_writeback_bdi_unregister(bdi);
-		bdi_prune_sb(bdi);
 
-		bdi_wb_shutdown(bdi);
+	bdi_set_min_ratio(bdi, 0);
-		bdi_debug_unregister(bdi);
-		device_unregister(bdi->dev);
-		bdi->dev = NULL;
-	}
 }
 EXPORT_SYMBOL(bdi_unregister);
 
@@ -474,37 +436,19 @@ void bdi_destroy(struct backing_dev_info *bdi)
 {
 	int i;
 
-	/*
+	bdi_wb_shutdown(bdi);
-	 * Splice our entries to the default_backing_dev_info.  This
-	 * condition shouldn't happen.  @wb must be empty at this point and
-	 * dirty inodes on it might cause other issues.  This workaround is
-	 * added by ce5f8e779519 ("writeback: splice dirty inode entries to
-	 * default bdi on bdi_destroy()") without root-causing the issue.
-	 *
-	 * http://lkml.kernel.org/g/1253038617-30204-11-git-send-email-jens.axboe@oracle.com
-	 * http://thread.gmane.org/gmane.linux.file-systems/35341/focus=35350
-	 *
-	 * We should probably add WARN_ON() to find out whether it still
-	 * happens and track it down if so.
-	 */
-	if (bdi_has_dirty_io(bdi)) {
-		struct bdi_writeback *dst = &default_backing_dev_info.wb;
-
-		bdi_lock_two(&bdi->wb, dst);
-		list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
-		list_splice(&bdi->wb.b_io, &dst->b_io);
-		list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
-		spin_unlock(&bdi->wb.list_lock);
-		spin_unlock(&dst->list_lock);
-	}
-
-	bdi_unregister(bdi);
 
+	WARN_ON(!list_empty(&bdi->work_list));
 	WARN_ON(delayed_work_pending(&bdi->wb.dwork));
 
+	if (bdi->dev) {
+		bdi_debug_unregister(bdi);
+		device_unregister(bdi->dev);
+		bdi->dev = NULL;
+	}
+
 	for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
 		percpu_counter_destroy(&bdi->bdi_stat[i]);
-
 	fprop_local_destroy_percpu(&bdi->completions);
 }
 EXPORT_SYMBOL(bdi_destroy);
@@ -513,13 +457,12 @@ EXPORT_SYMBOL(bdi_destroy);
  * For use from filesystems to quickly init and register a bdi associated
  * with dirty writeback
  */
-int bdi_setup_and_register(struct backing_dev_info *bdi, char *name,
+int bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
-			   unsigned int cap)
 {
 	int err;
 
 	bdi->name = name;
-	bdi->capabilities = cap;
+	bdi->capabilities = 0;
 	err = bdi_init(bdi);
 	if (err)
 		return err;

mm/fadvise.c

@@ -73,7 +73,7 @@ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
 	else
 		endbyte--;		/* inclusive */
 
-	bdi = mapping->backing_dev_info;
+	bdi = inode_to_bdi(mapping->host);
 
 	switch (advice) {
 	case POSIX_FADV_NORMAL:
@@ -113,7 +113,7 @@ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
 	case POSIX_FADV_NOREUSE:
 		break;
 	case POSIX_FADV_DONTNEED:
-		if (!bdi_write_congested(mapping->backing_dev_info))
+		if (!bdi_write_congested(bdi))
 			__filemap_fdatawrite_range(mapping, offset, endbyte,
 						   WB_SYNC_NONE);
 

mm/filemap.c

@@ -211,7 +211,7 @@ void __delete_from_page_cache(struct page *page, void *shadow)
 	 */
 	if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
 		dec_zone_page_state(page, NR_FILE_DIRTY);
-		dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
+		dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE);
 	}
 }
 
@@ -2564,7 +2564,7 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	size_t		count = iov_iter_count(from);
 
 	/* We can write back this queue in page reclaim */
-	current->backing_dev_info = mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 	if (err)
 		goto out;

mm/filemap_xip.c

@@ -9,6 +9,7 @@
  */
 
 #include <linux/fs.h>
+#include <linux/backing-dev.h>
 #include <linux/pagemap.h>
 #include <linux/export.h>
 #include <linux/uio.h>
@@ -409,7 +410,7 @@ xip_file_write(struct file *filp, const char __user *buf, size_t len,
 	count = len;
 
 	/* We can write back this queue in page reclaim */
-	current->backing_dev_info = mapping->backing_dev_info;
+	current->backing_dev_info = inode_to_bdi(inode);
 
 	ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
 	if (ret)

mm/madvise.c

@@ -222,19 +222,22 @@ static long madvise_willneed(struct vm_area_struct *vma,
 	struct file *file = vma->vm_file;
 
 #ifdef CONFIG_SWAP
-	if (!file || mapping_cap_swap_backed(file->f_mapping)) {
+	if (!file) {
 		*prev = vma;
-		if (!file)
 		force_swapin_readahead(vma, start, end);
-		else
+		return 0;
+	}
+
+	if (shmem_mapping(file->f_mapping)) {
+		*prev = vma;
 		force_shm_swapin_readahead(vma, start, end,
 					file->f_mapping);
 		return 0;
 	}
-#endif
+#else
-
 	if (!file)
 		return -EBADF;
+#endif
 
 	if (file->f_mapping->a_ops->get_xip_mem) {
 		/* no bad return value, but ignore advice */

mm/nommu.c

@@ -980,9 +980,6 @@ static int validate_mmap_request(struct file *file,
 		return -EOVERFLOW;
 
 	if (file) {
-		/* validate file mapping requests */
-		struct address_space *mapping;
-
 		/* files must support mmap */
 		if (!file->f_op->mmap)
 			return -ENODEV;
@@ -991,28 +988,22 @@ static int validate_mmap_request(struct file *file,
 		 * - we support chardevs that provide their own "memory"
 		 * - we support files/blockdevs that are memory backed
 		 */
-		mapping = file->f_mapping;
+		if (file->f_op->mmap_capabilities) {
-		if (!mapping)
+			capabilities = file->f_op->mmap_capabilities(file);
-			mapping = file_inode(file)->i_mapping;
+		} else {
-
-		capabilities = 0;
-		if (mapping && mapping->backing_dev_info)
-			capabilities = mapping->backing_dev_info->capabilities;
-
-		if (!capabilities) {
 			/* no explicit capabilities set, so assume some
 			 * defaults */
 			switch (file_inode(file)->i_mode & S_IFMT) {
 			case S_IFREG:
 			case S_IFBLK:
-				capabilities = BDI_CAP_MAP_COPY;
+				capabilities = NOMMU_MAP_COPY;
 				break;
 
 			case S_IFCHR:
 				capabilities =
-					BDI_CAP_MAP_DIRECT |
+					NOMMU_MAP_DIRECT |
-					BDI_CAP_READ_MAP |
+					NOMMU_MAP_READ |
-					BDI_CAP_WRITE_MAP;
+					NOMMU_MAP_WRITE;
 				break;
 
 			default:
@@ -1023,9 +1014,9 @@ static int validate_mmap_request(struct file *file,
 		/* eliminate any capabilities that we can't support on this
 		 * device */
 		if (!file->f_op->get_unmapped_area)
-			capabilities &= ~BDI_CAP_MAP_DIRECT;
+			capabilities &= ~NOMMU_MAP_DIRECT;
 		if (!file->f_op->read)
-			capabilities &= ~BDI_CAP_MAP_COPY;
+			capabilities &= ~NOMMU_MAP_COPY;
 
 		/* The file shall have been opened with read permission. */
 		if (!(file->f_mode & FMODE_READ))
@@ -1044,29 +1035,29 @@ static int validate_mmap_request(struct file *file,
 			if (locks_verify_locked(file))
 				return -EAGAIN;
 
-			if (!(capabilities & BDI_CAP_MAP_DIRECT))
+			if (!(capabilities & NOMMU_MAP_DIRECT))
 				return -ENODEV;
 
 			/* we mustn't privatise shared mappings */
-			capabilities &= ~BDI_CAP_MAP_COPY;
+			capabilities &= ~NOMMU_MAP_COPY;
 		} else {
 			/* we're going to read the file into private memory we
 			 * allocate */
-			if (!(capabilities & BDI_CAP_MAP_COPY))
+			if (!(capabilities & NOMMU_MAP_COPY))
 				return -ENODEV;
 
 			/* we don't permit a private writable mapping to be
 			 * shared with the backing device */
 			if (prot & PROT_WRITE)
-				capabilities &= ~BDI_CAP_MAP_DIRECT;
+				capabilities &= ~NOMMU_MAP_DIRECT;
 		}
 
-		if (capabilities & BDI_CAP_MAP_DIRECT) {
+		if (capabilities & NOMMU_MAP_DIRECT) {
-			if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
+			if (((prot & PROT_READ)  && !(capabilities & NOMMU_MAP_READ))  ||
-			    ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
+			    ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
-			    ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
+			    ((prot & PROT_EXEC)  && !(capabilities & NOMMU_MAP_EXEC))
 			    ) {
-				capabilities &= ~BDI_CAP_MAP_DIRECT;
+				capabilities &= ~NOMMU_MAP_DIRECT;
 				if (flags & MAP_SHARED) {
 					printk(KERN_WARNING
 					       "MAP_SHARED not completely supported on !MMU\n");
@@ -1083,21 +1074,21 @@ static int validate_mmap_request(struct file *file,
 		} else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 			/* handle implication of PROT_EXEC by PROT_READ */
 			if (current->personality & READ_IMPLIES_EXEC) {
-				if (capabilities & BDI_CAP_EXEC_MAP)
+				if (capabilities & NOMMU_MAP_EXEC)
 					prot |= PROT_EXEC;
 			}
 		} else if ((prot & PROT_READ) &&
 			 (prot & PROT_EXEC) &&
-			 !(capabilities & BDI_CAP_EXEC_MAP)
+			 !(capabilities & NOMMU_MAP_EXEC)
 			 ) {
 			/* backing file is not executable, try to copy */
-			capabilities &= ~BDI_CAP_MAP_DIRECT;
+			capabilities &= ~NOMMU_MAP_DIRECT;
 		}
 	} else {
 		/* anonymous mappings are always memory backed and can be
 		 * privately mapped
 		 */
-		capabilities = BDI_CAP_MAP_COPY;
+		capabilities = NOMMU_MAP_COPY;
 
 		/* handle PROT_EXEC implication by PROT_READ */
 		if ((prot & PROT_READ) &&
@@ -1129,7 +1120,7 @@ static unsigned long determine_vm_flags(struct file *file,
 	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 	/* vm_flags |= mm->def_flags; */
 
-	if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
+	if (!(capabilities & NOMMU_MAP_DIRECT)) {
 		/* attempt to share read-only copies of mapped file chunks */
 		vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 		if (file && !(prot & PROT_WRITE))
@@ -1138,7 +1129,7 @@ static unsigned long determine_vm_flags(struct file *file,
 		/* overlay a shareable mapping on the backing device or inode
 		 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 		 * romfs/cramfs */
-		vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
+		vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
 		if (flags & MAP_SHARED)
 			vm_flags |= VM_SHARED;
 	}
@@ -1191,7 +1182,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
 	 * shared mappings on devices or memory
 	 * - VM_MAYSHARE will be set if it may attempt to share
 	 */
-	if (capabilities & BDI_CAP_MAP_DIRECT) {
+	if (capabilities & NOMMU_MAP_DIRECT) {
 		ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 		if (ret == 0) {
 			/* shouldn't return success if we're not sharing */
@@ -1380,7 +1371,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 			if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
 			    !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
 				/* new mapping is not a subset of the region */
-				if (!(capabilities & BDI_CAP_MAP_DIRECT))
+				if (!(capabilities & NOMMU_MAP_DIRECT))
 					goto sharing_violation;
 				continue;
 			}
@@ -1419,7 +1410,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 		 * - this is the hook for quasi-memory character devices to
 		 *   tell us the location of a shared mapping
 		 */
-		if (capabilities & BDI_CAP_MAP_DIRECT) {
+		if (capabilities & NOMMU_MAP_DIRECT) {
 			addr = file->f_op->get_unmapped_area(file, addr, len,
 							     pgoff, flags);
 			if (IS_ERR_VALUE(addr)) {
@@ -1431,10 +1422,10 @@ unsigned long do_mmap_pgoff(struct file *file,
 				 * the mapping so we'll have to attempt to copy
 				 * it */
 				ret = -ENODEV;
-				if (!(capabilities & BDI_CAP_MAP_COPY))
+				if (!(capabilities & NOMMU_MAP_COPY))
 					goto error_just_free;
 
-				capabilities &= ~BDI_CAP_MAP_DIRECT;
+				capabilities &= ~NOMMU_MAP_DIRECT;
 			} else {
 				vma->vm_start = region->vm_start = addr;
 				vma->vm_end = region->vm_end = addr + len;
@@ -1445,7 +1436,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 	vma->vm_region = region;
 
 	/* set up the mapping
-	 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
+	 * - the region is filled in if NOMMU_MAP_DIRECT is still set
 	 */
 	if (file && vma->vm_flags & VM_SHARED)
 		ret = do_mmap_shared_file(vma);

mm/page-writeback.c

@@ -1351,7 +1351,7 @@ static void balance_dirty_pages(struct address_space *mapping,
 	unsigned long task_ratelimit;
 	unsigned long dirty_ratelimit;
 	unsigned long pos_ratio;
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
+	struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
 	bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT;
 	unsigned long start_time = jiffies;
 
@@ -1574,7 +1574,7 @@ DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0;
  */
 void balance_dirty_pages_ratelimited(struct address_space *mapping)
 {
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
+	struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
 	int ratelimit;
 	int *p;
 
@@ -1929,7 +1929,7 @@ int write_cache_pages(struct address_space *mapping,
 			if (!clear_page_dirty_for_io(page))
 				goto continue_unlock;
 
-			trace_wbc_writepage(wbc, mapping->backing_dev_info);
+			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
 			ret = (*writepage)(page, wbc, data);
 			if (unlikely(ret)) {
 				if (ret == AOP_WRITEPAGE_ACTIVATE) {
@@ -2094,10 +2094,12 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)
 	trace_writeback_dirty_page(page, mapping);
 
 	if (mapping_cap_account_dirty(mapping)) {
+		struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+
 		__inc_zone_page_state(page, NR_FILE_DIRTY);
 		__inc_zone_page_state(page, NR_DIRTIED);
-		__inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
+		__inc_bdi_stat(bdi, BDI_RECLAIMABLE);
-		__inc_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED);
+		__inc_bdi_stat(bdi, BDI_DIRTIED);
 		task_io_account_write(PAGE_CACHE_SIZE);
 		current->nr_dirtied++;
 		this_cpu_inc(bdp_ratelimits);
@@ -2156,7 +2158,7 @@ void account_page_redirty(struct page *page)
 	if (mapping && mapping_cap_account_dirty(mapping)) {
 		current->nr_dirtied--;
 		dec_zone_page_state(page, NR_DIRTIED);
-		dec_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED);
+		dec_bdi_stat(inode_to_bdi(mapping->host), BDI_DIRTIED);
 	}
 }
 EXPORT_SYMBOL(account_page_redirty);
@@ -2298,7 +2300,7 @@ int clear_page_dirty_for_io(struct page *page)
 		 */
 		if (TestClearPageDirty(page)) {
 			dec_zone_page_state(page, NR_FILE_DIRTY);
-			dec_bdi_stat(mapping->backing_dev_info,
+			dec_bdi_stat(inode_to_bdi(mapping->host),
 					BDI_RECLAIMABLE);
 			return 1;
 		}
@@ -2316,7 +2318,7 @@ int test_clear_page_writeback(struct page *page)
 
 	memcg = mem_cgroup_begin_page_stat(page);
 	if (mapping) {
-		struct backing_dev_info *bdi = mapping->backing_dev_info;
+		struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
 		unsigned long flags;
 
 		spin_lock_irqsave(&mapping->tree_lock, flags);
@@ -2351,7 +2353,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 
 	memcg = mem_cgroup_begin_page_stat(page);
 	if (mapping) {
-		struct backing_dev_info *bdi = mapping->backing_dev_info;
+		struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
 		unsigned long flags;
 
 		spin_lock_irqsave(&mapping->tree_lock, flags);
@@ -2405,12 +2407,7 @@ EXPORT_SYMBOL(mapping_tagged);
  */
 void wait_for_stable_page(struct page *page)
 {
-	struct address_space *mapping = page_mapping(page);
+	if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host)))
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
-
-	if (!bdi_cap_stable_pages_required(bdi))
-		return;
-
 		wait_on_page_writeback(page);
 }
 EXPORT_SYMBOL_GPL(wait_for_stable_page);

mm/readahead.c

@@ -27,7 +27,7 @@
 void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
 {
-	ra->ra_pages = mapping->backing_dev_info->ra_pages;
+	ra->ra_pages = inode_to_bdi(mapping->host)->ra_pages;
 	ra->prev_pos = -1;
 }
 EXPORT_SYMBOL_GPL(file_ra_state_init);
@@ -541,7 +541,7 @@ page_cache_async_readahead(struct address_space *mapping,
 	/*
 	 * Defer asynchronous read-ahead on IO congestion.
 	 */
-	if (bdi_read_congested(mapping->backing_dev_info))
+	if (bdi_read_congested(inode_to_bdi(mapping->host)))
 		return;
 
 	/* do read-ahead */

mm/shmem.c

@@ -191,11 +191,6 @@ static const struct inode_operations shmem_dir_inode_operations;
 static const struct inode_operations shmem_special_inode_operations;
 static const struct vm_operations_struct shmem_vm_ops;
 
-static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
-};
-
 static LIST_HEAD(shmem_swaplist);
 static DEFINE_MUTEX(shmem_swaplist_mutex);
 
@@ -765,11 +760,11 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 		goto redirty;
 
 	/*
-	 * shmem_backing_dev_info's capabilities prevent regular writeback or
+	 * Our capabilities prevent regular writeback or sync from ever calling
-	 * sync from ever calling shmem_writepage; but a stacking filesystem
+	 * shmem_writepage; but a stacking filesystem might use ->writepage of
-	 * might use ->writepage of its underlying filesystem, in which case
+	 * its underlying filesystem, in which case tmpfs should write out to
-	 * tmpfs should write out to swap only in response to memory pressure,
+	 * swap only in response to memory pressure, and not for the writeback
-	 * and not for the writeback threads or sync.
+	 * threads or sync.
 	 */
 	if (!wbc->for_reclaim) {
 		WARN_ON_ONCE(1);	/* Still happens? Tell us about it! */
@@ -1415,7 +1410,6 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		inode->i_ino = get_next_ino();
 		inode_init_owner(inode, dir, mode);
 		inode->i_blocks = 0;
-		inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inode->i_generation = get_seconds();
 		info = SHMEM_I(inode);
@@ -1461,7 +1455,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 
 bool shmem_mapping(struct address_space *mapping)
 {
-	return mapping->backing_dev_info == &shmem_backing_dev_info;
+	return mapping->host->i_sb->s_op == &shmem_ops;
 }
 
 #ifdef CONFIG_TMPFS
@@ -3225,10 +3219,6 @@ int __init shmem_init(void)
 	if (shmem_inode_cachep)
 		return 0;
 
-	error = bdi_init(&shmem_backing_dev_info);
-	if (error)
-		goto out4;
-
 	error = shmem_init_inodecache();
 	if (error)
 		goto out3;
@@ -3252,8 +3242,6 @@ int __init shmem_init(void)
 out2:
 	shmem_destroy_inodecache();
 out3:
-	bdi_destroy(&shmem_backing_dev_info);
-out4:
 	shm_mnt = ERR_PTR(error);
 	return error;
 }

mm/swap.c

@@ -1138,8 +1138,6 @@ void __init swap_setup(void)
 #ifdef CONFIG_SWAP
 	int i;
 
-	if (bdi_init(swapper_spaces[0].backing_dev_info))
-		panic("Failed to init swap bdi");
 	for (i = 0; i < MAX_SWAPFILES; i++)
 		spin_lock_init(&swapper_spaces[i].tree_lock);
 #endif

mm/swap_state.c

@@ -32,17 +32,11 @@ static const struct address_space_operations swap_aops = {
 #endif
 };
 
-static struct backing_dev_info swap_backing_dev_info = {
-	.name		= "swap",
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
-};
-
 struct address_space swapper_spaces[MAX_SWAPFILES] = {
 	[0 ... MAX_SWAPFILES - 1] = {
 		.page_tree	= RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
 		.i_mmap_writable = ATOMIC_INIT(0),
 		.a_ops		= &swap_aops,
-		.backing_dev_info = &swap_backing_dev_info,
 	}
 };
 

mm/truncate.c

@@ -112,7 +112,7 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
 		struct address_space *mapping = page->mapping;
 		if (mapping && mapping_cap_account_dirty(mapping)) {
 			dec_zone_page_state(page, NR_FILE_DIRTY);
-			dec_bdi_stat(mapping->backing_dev_info,
+			dec_bdi_stat(inode_to_bdi(mapping->host),
 					BDI_RECLAIMABLE);
 			if (account_size)
 				task_io_account_cancelled_write(account_size);

mm/vmscan.c

@@ -500,7 +500,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
 	}
 	if (mapping->a_ops->writepage == NULL)
 		return PAGE_ACTIVATE;
-	if (!may_write_to_queue(mapping->backing_dev_info, sc))
+	if (!may_write_to_queue(inode_to_bdi(mapping->host), sc))
 		return PAGE_KEEP;
 
 	if (clear_page_dirty_for_io(page)) {
@@ -879,7 +879,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 */
 		mapping = page_mapping(page);
 		if (((dirty || writeback) && mapping &&
-		     bdi_write_congested(mapping->backing_dev_info)) ||
+		     bdi_write_congested(inode_to_bdi(mapping->host))) ||
 		    (writeback && PageReclaim(page)))
 			nr_congested++;
 

security/security.c

@@ -726,16 +726,15 @@ static inline unsigned long mmap_prot(struct file *file, unsigned long prot)
 		return prot | PROT_EXEC;
 	/*
 	 * ditto if it's not on noexec mount, except that on !MMU we need
-	 * BDI_CAP_EXEC_MMAP (== VM_MAYEXEC) in this case
+	 * NOMMU_MAP_EXEC (== VM_MAYEXEC) in this case
 	 */
 	if (!(file->f_path.mnt->mnt_flags & MNT_NOEXEC)) {
 #ifndef CONFIG_MMU
-		unsigned long caps = 0;
+		if (file->f_op->mmap_capabilities) {
-		struct address_space *mapping = file->f_mapping;
+			unsigned caps = file->f_op->mmap_capabilities(file);
-		if (mapping && mapping->backing_dev_info)
+			if (!(caps & NOMMU_MAP_EXEC))
-			caps = mapping->backing_dev_info->capabilities;
-		if (!(caps & BDI_CAP_EXEC_MAP))
 				return prot;
+		}
 #endif
 		return prot | PROT_EXEC;
 	}