Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

1 files changed, 1377 insertions, 0 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
new file mode 100644
index 0000000..99e0ae1
--- /dev/null
+++ b/fs/block_dev.c
@@ -0,0 +1,1377 @@
+/*
+ *  linux/fs/block_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/fcntl.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/major.h>
+#include <linux/smp_lock.h>
+#include <linux/device_cgroup.h>
+#include <linux/highmem.h>
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/mpage.h>
+#include <linux/mount.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <linux/log2.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+struct bdev_inode {
+	struct block_device bdev;
+	struct inode vfs_inode;
+};
+
+static const struct address_space_operations def_blk_aops;
+
+static inline struct bdev_inode *BDEV_I(struct inode *inode)
+{
+	return container_of(inode, struct bdev_inode, vfs_inode);
+}
+
+inline struct block_device *I_BDEV(struct inode *inode)
+{
+	return &BDEV_I(inode)->bdev;
+}
+
+EXPORT_SYMBOL(I_BDEV);
+
+static sector_t max_block(struct block_device *bdev)
+{
+	sector_t retval = ~((sector_t)0);
+	loff_t sz = i_size_read(bdev->bd_inode);
+
+	if (sz) {
+		unsigned int size = block_size(bdev);
+		unsigned int sizebits = blksize_bits(size);
+		retval = (sz >> sizebits);
+	}
+	return retval;
+}
+
+/* Kill _all_ buffers and pagecache , dirty or not.. */
+static void kill_bdev(struct block_device *bdev)
+{
+	if (bdev->bd_inode->i_mapping->nrpages == 0)
+		return;
+	invalidate_bh_lrus();
+	truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
+}	
+
+int set_blocksize(struct block_device *bdev, int size)
+{
+	/* Size must be a power of two, and between 512 and PAGE_SIZE */
+	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
+		return -EINVAL;
+
+	/* Size cannot be smaller than the size supported by the device */
+	if (size < bdev_hardsect_size(bdev))
+		return -EINVAL;
+
+	/* Don't change the size if it is same as current */
+	if (bdev->bd_block_size != size) {
+		sync_blockdev(bdev);
+		bdev->bd_block_size = size;
+		bdev->bd_inode->i_blkbits = blksize_bits(size);
+		kill_bdev(bdev);
+	}
+	return 0;
+}
+
+EXPORT_SYMBOL(set_blocksize);
+
+int sb_set_blocksize(struct super_block *sb, int size)
+{
+	if (set_blocksize(sb->s_bdev, size))
+		return 0;
+	/* If we get here, we know size is power of two
+	 * and it's value is between 512 and PAGE_SIZE */
+	sb->s_blocksize = size;
+	sb->s_blocksize_bits = blksize_bits(size);
+	return sb->s_blocksize;
+}
+
+EXPORT_SYMBOL(sb_set_blocksize);
+
+int sb_min_blocksize(struct super_block *sb, int size)
+{
+	int minsize = bdev_hardsect_size(sb->s_bdev);
+	if (size < minsize)
+		size = minsize;
+	return sb_set_blocksize(sb, size);
+}
+
+EXPORT_SYMBOL(sb_min_blocksize);
+
+static int
+blkdev_get_block(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	if (iblock >= max_block(I_BDEV(inode))) {
+		if (create)
+			return -EIO;
+
+		/*
+		 * for reads, we're just trying to fill a partial page.
+		 * return a hole, they will have to call get_block again
+		 * before they can fill it, and they will get -EIO at that
+		 * time
+		 */
+		return 0;
+	}
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	set_buffer_mapped(bh);
+	return 0;
+}
+
+static int
+blkdev_get_blocks(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	sector_t end_block = max_block(I_BDEV(inode));
+	unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
+
+	if ((iblock + max_blocks) > end_block) {
+		max_blocks = end_block - iblock;
+		if ((long)max_blocks <= 0) {
+			if (create)
+				return -EIO;	/* write fully beyond EOF */
+			/*
+			 * It is a read which is fully beyond EOF.  We return
+			 * a !buffer_mapped buffer
+			 */
+			max_blocks = 0;
+		}
+	}
+
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	bh->b_size = max_blocks << inode->i_blkbits;
+	if (max_blocks)
+		set_buffer_mapped(bh);
+	return 0;
+}
+
+static ssize_t
+blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+			loff_t offset, unsigned long nr_segs)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+
+	return blockdev_direct_IO_no_locking(rw, iocb, inode, I_BDEV(inode),
+				iov, offset, nr_segs, blkdev_get_blocks, NULL);
+}
+
+static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, blkdev_get_block, wbc);
+}
+
+static int blkdev_readpage(struct file * file, struct page * page)
+{
+	return block_read_full_page(page, blkdev_get_block);
+}
+
+static int blkdev_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	*pagep = NULL;
+	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+				blkdev_get_block);
+}
+
+static int blkdev_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	int ret;
+	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	return ret;
+}
+
+/*
+ * private llseek:
+ * for a block special file file->f_path.dentry->d_inode->i_size is zero
+ * so we compute the size by hand (just as in block_read/write above)
+ */
+static loff_t block_llseek(struct file *file, loff_t offset, int origin)
+{
+	struct inode *bd_inode = file->f_mapping->host;
+	loff_t size;
+	loff_t retval;
+
+	mutex_lock(&bd_inode->i_mutex);
+	size = i_size_read(bd_inode);
+
+	switch (origin) {
+		case 2:
+			offset += size;
+			break;
+		case 1:
+			offset += file->f_pos;
+	}
+	retval = -EINVAL;
+	if (offset >= 0 && offset <= size) {
+		if (offset != file->f_pos) {
+			file->f_pos = offset;
+		}
+		retval = offset;
+	}
+	mutex_unlock(&bd_inode->i_mutex);
+	return retval;
+}
+	
+/*
+ *	Filp is never NULL; the only case when ->fsync() is called with
+ *	NULL first argument is nfsd_sync_dir() and that's not a directory.
+ */
+ 
+static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
+{
+	return sync_blockdev(I_BDEV(filp->f_mapping->host));
+}
+
+/*
+ * pseudo-fs
+ */
+
+static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
+static struct kmem_cache * bdev_cachep __read_mostly;
+
+static struct inode *bdev_alloc_inode(struct super_block *sb)
+{
+	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+	return &ei->vfs_inode;
+}
+
+static void bdev_destroy_inode(struct inode *inode)
+{
+	struct bdev_inode *bdi = BDEV_I(inode);
+
+	bdi->bdev.bd_inode_backing_dev_info = NULL;
+	kmem_cache_free(bdev_cachep, bdi);
+}
+
+static void init_once(void *foo)
+{
+	struct bdev_inode *ei = (struct bdev_inode *) foo;
+	struct block_device *bdev = &ei->bdev;
+
+	memset(bdev, 0, sizeof(*bdev));
+	mutex_init(&bdev->bd_mutex);
+	sema_init(&bdev->bd_mount_sem, 1);
+	INIT_LIST_HEAD(&bdev->bd_inodes);
+	INIT_LIST_HEAD(&bdev->bd_list);
+#ifdef CONFIG_SYSFS
+	INIT_LIST_HEAD(&bdev->bd_holder_list);
+#endif
+	inode_init_once(&ei->vfs_inode);
+}
+
+static inline void __bd_forget(struct inode *inode)
+{
+	list_del_init(&inode->i_devices);
+	inode->i_bdev = NULL;
+	inode->i_mapping = &inode->i_data;
+}
+
+static void bdev_clear_inode(struct inode *inode)
+{
+	struct block_device *bdev = &BDEV_I(inode)->bdev;
+	struct list_head *p;
+	spin_lock(&bdev_lock);
+	while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
+		__bd_forget(list_entry(p, struct inode, i_devices));
+	}
+	list_del_init(&bdev->bd_list);
+	spin_unlock(&bdev_lock);
+}
+
+static const struct super_operations bdev_sops = {
+	.statfs = simple_statfs,
+	.alloc_inode = bdev_alloc_inode,
+	.destroy_inode = bdev_destroy_inode,
+	.drop_inode = generic_delete_inode,
+	.clear_inode = bdev_clear_inode,
+};
+
+static int bd_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
+}
+
+static struct file_system_type bd_type = {
+	.name		= "bdev",
+	.get_sb		= bd_get_sb,
+	.kill_sb	= kill_anon_super,
+};
+
+static struct vfsmount *bd_mnt __read_mostly;
+struct super_block *blockdev_superblock;
+
+void __init bdev_cache_init(void)
+{
+	int err;
+	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
+			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
+				SLAB_MEM_SPREAD|SLAB_PANIC),
+			init_once);
+	err = register_filesystem(&bd_type);
+	if (err)
+		panic("Cannot register bdev pseudo-fs");
+	bd_mnt = kern_mount(&bd_type);
+	if (IS_ERR(bd_mnt))
+		panic("Cannot create bdev pseudo-fs");
+	blockdev_superblock = bd_mnt->mnt_sb;	/* For writeback */
+}
+
+/*
+ * Most likely _very_ bad one - but then it's hardly critical for small
+ * /dev and can be fixed when somebody will need really large one.
+ * Keep in mind that it will be fed through icache hash function too.
+ */
+static inline unsigned long hash(dev_t dev)
+{
+	return MAJOR(dev)+MINOR(dev);
+}
+
+static int bdev_test(struct inode *inode, void *data)
+{
+	return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
+}
+
+static int bdev_set(struct inode *inode, void *data)
+{
+	BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
+	return 0;
+}
+
+static LIST_HEAD(all_bdevs);
+
+struct block_device *bdget(dev_t dev)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+
+	inode = iget5_locked(bd_mnt->mnt_sb, hash(dev),
+			bdev_test, bdev_set, &dev);
+
+	if (!inode)
+		return NULL;
+
+	bdev = &BDEV_I(inode)->bdev;
+
+	if (inode->i_state & I_NEW) {
+		bdev->bd_contains = NULL;
+		bdev->bd_inode = inode;
+		bdev->bd_block_size = (1 << inode->i_blkbits);
+		bdev->bd_part_count = 0;
+		bdev->bd_invalidated = 0;
+		inode->i_mode = S_IFBLK;
+		inode->i_rdev = 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);
+		unlock_new_inode(inode);
+	}
+	return bdev;
+}
+
+EXPORT_SYMBOL(bdget);
+
+long nr_blockdev_pages(void)
+{
+	struct block_device *bdev;
+	long ret = 0;
+	spin_lock(&bdev_lock);
+	list_for_each_entry(bdev, &all_bdevs, bd_list) {
+		ret += bdev->bd_inode->i_mapping->nrpages;
+	}
+	spin_unlock(&bdev_lock);
+	return ret;
+}
+
+void bdput(struct block_device *bdev)
+{
+	iput(bdev->bd_inode);
+}
+
+EXPORT_SYMBOL(bdput);
+ 
+static struct block_device *bd_acquire(struct inode *inode)
+{
+	struct block_device *bdev;
+
+	spin_lock(&bdev_lock);
+	bdev = inode->i_bdev;
+	if (bdev) {
+		atomic_inc(&bdev->bd_inode->i_count);
+		spin_unlock(&bdev_lock);
+		return bdev;
+	}
+	spin_unlock(&bdev_lock);
+
+	bdev = bdget(inode->i_rdev);
+	if (bdev) {
+		spin_lock(&bdev_lock);
+		if (!inode->i_bdev) {
+			/*
+			 * We take an additional bd_inode->i_count for inode,
+			 * and it's released in clear_inode() of inode.
+			 * So, we can access it via ->i_mapping always
+			 * without igrab().
+			 */
+			atomic_inc(&bdev->bd_inode->i_count);
+			inode->i_bdev = bdev;
+			inode->i_mapping = bdev->bd_inode->i_mapping;
+			list_add(&inode->i_devices, &bdev->bd_inodes);
+		}
+		spin_unlock(&bdev_lock);
+	}
+	return bdev;
+}
+
+/* Call when you free inode */
+
+void bd_forget(struct inode *inode)
+{
+	struct block_device *bdev = NULL;
+
+	spin_lock(&bdev_lock);
+	if (inode->i_bdev) {
+		if (inode->i_sb != blockdev_superblock)
+			bdev = inode->i_bdev;
+		__bd_forget(inode);
+	}
+	spin_unlock(&bdev_lock);
+
+	if (bdev)
+		iput(bdev->bd_inode);
+}
+
+int bd_claim(struct block_device *bdev, void *holder)
+{
+	int res;
+	spin_lock(&bdev_lock);
+
+	/* first decide result */
+	if (bdev->bd_holder == holder)
+		res = 0;	 /* already a holder */
+	else if (bdev->bd_holder != NULL)
+		res = -EBUSY; 	 /* held by someone else */
+	else if (bdev->bd_contains == bdev)
+		res = 0;  	 /* is a whole device which isn't held */
+
+	else if (bdev->bd_contains->bd_holder == bd_claim)
+		res = 0; 	 /* is a partition of a device that is being partitioned */
+	else if (bdev->bd_contains->bd_holder != NULL)
+		res = -EBUSY;	 /* is a partition of a held device */
+	else
+		res = 0;	 /* is a partition of an un-held device */
+
+	/* now impose change */
+	if (res==0) {
+		/* note that for a whole device bd_holders
+		 * will be incremented twice, and bd_holder will
+		 * be set to bd_claim before being set to holder
+		 */
+		bdev->bd_contains->bd_holders ++;
+		bdev->bd_contains->bd_holder = bd_claim;
+		bdev->bd_holders++;
+		bdev->bd_holder = holder;
+	}
+	spin_unlock(&bdev_lock);
+	return res;
+}
+
+EXPORT_SYMBOL(bd_claim);
+
+void bd_release(struct block_device *bdev)
+{
+	spin_lock(&bdev_lock);
+	if (!--bdev->bd_contains->bd_holders)
+		bdev->bd_contains->bd_holder = NULL;
+	if (!--bdev->bd_holders)
+		bdev->bd_holder = NULL;
+	spin_unlock(&bdev_lock);
+}
+
+EXPORT_SYMBOL(bd_release);
+
+#ifdef CONFIG_SYSFS
+/*
+ * Functions for bd_claim_by_kobject / bd_release_from_kobject
+ *
+ *     If a kobject is passed to bd_claim_by_kobject()
+ *     and the kobject has a parent directory,
+ *     following symlinks are created:
+ *        o from the kobject to the claimed bdev
+ *        o from "holders" directory of the bdev to the parent of the kobject
+ *     bd_release_from_kobject() removes these symlinks.
+ *
+ *     Example:
+ *        If /dev/dm-0 maps to /dev/sda, kobject corresponding to
+ *        /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
+ *           /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ *           /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ */
+
+static int add_symlink(struct kobject *from, struct kobject *to)
+{
+	if (!from || !to)
+		return 0;
+	return sysfs_create_link(from, to, kobject_name(to));
+}
+
+static void del_symlink(struct kobject *from, struct kobject *to)
+{
+	if (!from || !to)
+		return;
+	sysfs_remove_link(from, kobject_name(to));
+}
+
+/*
+ * 'struct bd_holder' contains pointers to kobjects symlinked by
+ * bd_claim_by_kobject.
+ * It's connected to bd_holder_list which is protected by bdev->bd_sem.
+ */
+struct bd_holder {
+	struct list_head list;	/* chain of holders of the bdev */
+	int count;		/* references from the holder */
+	struct kobject *sdir;	/* holder object, e.g. "/block/dm-0/slaves" */
+	struct kobject *hdev;	/* e.g. "/block/dm-0" */
+	struct kobject *hdir;	/* e.g. "/block/sda/holders" */
+	struct kobject *sdev;	/* e.g. "/block/sda" */
+};
+
+/*
+ * Get references of related kobjects at once.
+ * Returns 1 on success. 0 on failure.
+ *
+ * Should call bd_holder_release_dirs() after successful use.
+ */
+static int bd_holder_grab_dirs(struct block_device *bdev,
+			struct bd_holder *bo)
+{
+	if (!bdev || !bo)
+		return 0;
+
+	bo->sdir = kobject_get(bo->sdir);
+	if (!bo->sdir)
+		return 0;
+
+	bo->hdev = kobject_get(bo->sdir->parent);
+	if (!bo->hdev)
+		goto fail_put_sdir;
+
+	bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
+	if (!bo->sdev)
+		goto fail_put_hdev;
+
+	bo->hdir = kobject_get(bdev->bd_part->holder_dir);
+	if (!bo->hdir)
+		goto fail_put_sdev;
+
+	return 1;
+
+fail_put_sdev:
+	kobject_put(bo->sdev);
+fail_put_hdev:
+	kobject_put(bo->hdev);
+fail_put_sdir:
+	kobject_put(bo->sdir);
+
+	return 0;
+}
+
+/* Put references of related kobjects at once. */
+static void bd_holder_release_dirs(struct bd_holder *bo)
+{
+	kobject_put(bo->hdir);
+	kobject_put(bo->sdev);
+	kobject_put(bo->hdev);
+	kobject_put(bo->sdir);
+}
+
+static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
+{
+	struct bd_holder *bo;
+
+	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
+	if (!bo)
+		return NULL;
+
+	bo->count = 1;
+	bo->sdir = kobj;
+
+	return bo;
+}
+
+static void free_bd_holder(struct bd_holder *bo)
+{
+	kfree(bo);
+}
+
+/**
+ * find_bd_holder - find matching struct bd_holder from the block device
+ *
+ * @bdev:	struct block device to be searched
+ * @bo:		target struct bd_holder
+ *
+ * Returns matching entry with @bo in @bdev->bd_holder_list.
+ * If found, increment the reference count and return the pointer.
+ * If not found, returns NULL.
+ */
+static struct bd_holder *find_bd_holder(struct block_device *bdev,
+					struct bd_holder *bo)
+{
+	struct bd_holder *tmp;
+
+	list_for_each_entry(tmp, &bdev->bd_holder_list, list)
+		if (tmp->sdir == bo->sdir) {
+			tmp->count++;
+			return tmp;
+		}
+
+	return NULL;
+}
+
+/**
+ * add_bd_holder - create sysfs symlinks for bd_claim() relationship
+ *
+ * @bdev:	block device to be bd_claimed
+ * @bo:		preallocated and initialized by alloc_bd_holder()
+ *
+ * Add @bo to @bdev->bd_holder_list, create symlinks.
+ *
+ * Returns 0 if symlinks are created.
+ * Returns -ve if something fails.
+ */
+static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
+{
+	int err;
+
+	if (!bo)
+		return -EINVAL;
+
+	if (!bd_holder_grab_dirs(bdev, bo))
+		return -EBUSY;
+
+	err = add_symlink(bo->sdir, bo->sdev);
+	if (err)
+		return err;
+
+	err = add_symlink(bo->hdir, bo->hdev);
+	if (err) {
+		del_symlink(bo->sdir, bo->sdev);
+		return err;
+	}
+
+	list_add_tail(&bo->list, &bdev->bd_holder_list);
+	return 0;
+}
+
+/**
+ * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
+ *
+ * @bdev:	block device to be bd_claimed
+ * @kobj:	holder's kobject
+ *
+ * If there is matching entry with @kobj in @bdev->bd_holder_list
+ * and no other bd_claim() from the same kobject,
+ * remove the struct bd_holder from the list, delete symlinks for it.
+ *
+ * Returns a pointer to the struct bd_holder when it's removed from the list
+ * and ready to be freed.
+ * Returns NULL if matching claim isn't found or there is other bd_claim()
+ * by the same kobject.
+ */
+static struct bd_holder *del_bd_holder(struct block_device *bdev,
+					struct kobject *kobj)
+{
+	struct bd_holder *bo;
+
+	list_for_each_entry(bo, &bdev->bd_holder_list, list) {
+		if (bo->sdir == kobj) {
+			bo->count--;
+			BUG_ON(bo->count < 0);
+			if (!bo->count) {
+				list_del(&bo->list);
+				del_symlink(bo->sdir, bo->sdev);
+				del_symlink(bo->hdir, bo->hdev);
+				bd_holder_release_dirs(bo);
+				return bo;
+			}
+			break;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * bd_claim_by_kobject - bd_claim() with additional kobject signature
+ *
+ * @bdev:	block device to be claimed
+ * @holder:	holder's signature
+ * @kobj:	holder's kobject
+ *
+ * Do bd_claim() and if it succeeds, create sysfs symlinks between
+ * the bdev and the holder's kobject.
+ * Use bd_release_from_kobject() when relesing the claimed bdev.
+ *
+ * Returns 0 on success. (same as bd_claim())
+ * Returns errno on failure.
+ */
+static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
+				struct kobject *kobj)
+{
+	int err;
+	struct bd_holder *bo, *found;
+
+	if (!kobj)
+		return -EINVAL;
+
+	bo = alloc_bd_holder(kobj);
+	if (!bo)
+		return -ENOMEM;
+
+	mutex_lock(&bdev->bd_mutex);
+
+	err = bd_claim(bdev, holder);
+	if (err)
+		goto fail;
+
+	found = find_bd_holder(bdev, bo);
+	if (found)
+		goto fail;
+
+	err = add_bd_holder(bdev, bo);
+	if (err)
+		bd_release(bdev);
+	else
+		bo = NULL;
+fail:
+	mutex_unlock(&bdev->bd_mutex);
+	free_bd_holder(bo);
+	return err;
+}
+
+/**
+ * bd_release_from_kobject - bd_release() with additional kobject signature
+ *
+ * @bdev:	block device to be released
+ * @kobj:	holder's kobject
+ *
+ * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
+ */
+static void bd_release_from_kobject(struct block_device *bdev,
+					struct kobject *kobj)
+{
+	if (!kobj)
+		return;
+
+	mutex_lock(&bdev->bd_mutex);
+	bd_release(bdev);
+	free_bd_holder(del_bd_holder(bdev, kobj));
+	mutex_unlock(&bdev->bd_mutex);
+}
+
+/**
+ * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
+ *
+ * @bdev:	block device to be claimed
+ * @holder:	holder's signature
+ * @disk:	holder's gendisk
+ *
+ * Call bd_claim_by_kobject() with getting @disk->slave_dir.
+ */
+int bd_claim_by_disk(struct block_device *bdev, void *holder,
+			struct gendisk *disk)
+{
+	return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
+}
+EXPORT_SYMBOL_GPL(bd_claim_by_disk);
+
+/**
+ * bd_release_from_disk - wrapper function for bd_release_from_kobject()
+ *
+ * @bdev:	block device to be claimed
+ * @disk:	holder's gendisk
+ *
+ * Call bd_release_from_kobject() and put @disk->slave_dir.
+ */
+void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
+{
+	bd_release_from_kobject(bdev, disk->slave_dir);
+	kobject_put(disk->slave_dir);
+}
+EXPORT_SYMBOL_GPL(bd_release_from_disk);
+#endif
+
+/*
+ * Tries to open block device by device number.  Use it ONLY if you
+ * really do not have anything better - i.e. when you are behind a
+ * truly sucky interface and all you are given is a device number.  _Never_
+ * to be used for internal purposes.  If you ever need it - reconsider
+ * your API.
+ */
+struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
+{
+	struct block_device *bdev = bdget(dev);
+	int err = -ENOMEM;
+	if (bdev)
+		err = blkdev_get(bdev, mode);
+	return err ? ERR_PTR(err) : bdev;
+}
+
+EXPORT_SYMBOL(open_by_devnum);
+
+/**
+ * flush_disk - invalidates all buffer-cache entries on a disk
+ *
+ * @bdev:      struct block device to be flushed
+ *
+ * Invalidates all buffer-cache entries on a disk. It should be called
+ * when a disk has been changed -- either by a media change or online
+ * resize.
+ */
+static void flush_disk(struct block_device *bdev)
+{
+	if (__invalidate_device(bdev)) {
+		char name[BDEVNAME_SIZE] = "";
+
+		if (bdev->bd_disk)
+			disk_name(bdev->bd_disk, 0, name);
+		printk(KERN_WARNING "VFS: busy inodes on changed media or "
+		       "resized disk %s\n", name);
+	}
+
+	if (!bdev->bd_disk)
+		return;
+	if (disk_partitionable(bdev->bd_disk))
+		bdev->bd_invalidated = 1;
+}
+
+/**
+ * check_disk_size_change - checks for disk size change and adjusts bdev size.
+ * @disk: struct gendisk to check
+ * @bdev: struct bdev to adjust.
+ *
+ * This routine checks to see if the bdev size does not match the disk size
+ * and adjusts it if it differs.
+ */
+void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
+{
+	loff_t disk_size, bdev_size;
+
+	disk_size = (loff_t)get_capacity(disk) << 9;
+	bdev_size = i_size_read(bdev->bd_inode);
+	if (disk_size != bdev_size) {
+		char name[BDEVNAME_SIZE];
+
+		disk_name(disk, 0, name);
+		printk(KERN_INFO
+		       "%s: detected capacity change from %lld to %lld\n",
+		       name, bdev_size, disk_size);
+		i_size_write(bdev->bd_inode, disk_size);
+		flush_disk(bdev);
+	}
+}
+EXPORT_SYMBOL(check_disk_size_change);
+
+/**
+ * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
+ * @disk: struct gendisk to be revalidated
+ *
+ * This routine is a wrapper for lower-level driver's revalidate_disk
+ * call-backs.  It is used to do common pre and post operations needed
+ * for all revalidate_disk operations.
+ */
+int revalidate_disk(struct gendisk *disk)
+{
+	struct block_device *bdev;
+	int ret = 0;
+
+	if (disk->fops->revalidate_disk)
+		ret = disk->fops->revalidate_disk(disk);
+
+	bdev = bdget_disk(disk, 0);
+	if (!bdev)
+		return ret;
+
+	mutex_lock(&bdev->bd_mutex);
+	check_disk_size_change(disk, bdev);
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	return ret;
+}
+EXPORT_SYMBOL(revalidate_disk);
+
+/*
+ * This routine checks whether a removable media has been changed,
+ * and invalidates all buffer-cache-entries in that case. This
+ * is a relatively slow routine, so we have to try to minimize using
+ * it. Thus it is called only upon a 'mount' or 'open'. This
+ * is the best way of combining speed and utility, I think.
+ * People changing diskettes in the middle of an operation deserve
+ * to lose :-)
+ */
+int check_disk_change(struct block_device *bdev)
+{
+	struct gendisk *disk = bdev->bd_disk;
+	struct block_device_operations * bdops = disk->fops;
+
+	if (!bdops->media_changed)
+		return 0;
+	if (!bdops->media_changed(bdev->bd_disk))
+		return 0;
+
+	flush_disk(bdev);
+	if (bdops->revalidate_disk)
+		bdops->revalidate_disk(bdev->bd_disk);
+	return 1;
+}
+
+EXPORT_SYMBOL(check_disk_change);
+
+void bd_set_size(struct block_device *bdev, loff_t size)
+{
+	unsigned bsize = bdev_hardsect_size(bdev);
+
+	bdev->bd_inode->i_size = size;
+	while (bsize < PAGE_CACHE_SIZE) {
+		if (size & bsize)
+			break;
+		bsize <<= 1;
+	}
+	bdev->bd_block_size = bsize;
+	bdev->bd_inode->i_blkbits = blksize_bits(bsize);
+}
+EXPORT_SYMBOL(bd_set_size);
+
+static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
+
+/*
+ * bd_mutex locking:
+ *
+ *  mutex_lock(part->bd_mutex)
+ *    mutex_lock_nested(whole->bd_mutex, 1)
+ */
+
+static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
+{
+	struct gendisk *disk;
+	int ret;
+	int partno;
+	int perm = 0;
+
+	if (mode & FMODE_READ)
+		perm |= MAY_READ;
+	if (mode & FMODE_WRITE)
+		perm |= MAY_WRITE;
+	/*
+	 * hooks: /n/, see "layering violations".
+	 */
+	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
+	if (ret != 0) {
+		bdput(bdev);
+		return ret;
+	}
+
+	lock_kernel();
+
+	ret = -ENXIO;
+	disk = get_gendisk(bdev->bd_dev, &partno);
+	if (!disk)
+		goto out_unlock_kernel;
+
+	mutex_lock_nested(&bdev->bd_mutex, for_part);
+	if (!bdev->bd_openers) {
+		bdev->bd_disk = disk;
+		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)
+				goto out_clear;
+
+			if (disk->fops->open) {
+				ret = disk->fops->open(bdev, mode);
+				if (ret)
+					goto out_clear;
+			}
+			if (!bdev->bd_openers) {
+				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
+				bdi = blk_get_backing_dev_info(bdev);
+				if (bdi == NULL)
+					bdi = &default_backing_dev_info;
+				bdev->bd_inode->i_data.backing_dev_info = bdi;
+			}
+			if (bdev->bd_invalidated)
+				rescan_partitions(disk, bdev);
+		} else {
+			struct block_device *whole;
+			whole = bdget_disk(disk, 0);
+			ret = -ENOMEM;
+			if (!whole)
+				goto out_clear;
+			BUG_ON(for_part);
+			ret = __blkdev_get(whole, mode, 1);
+			if (ret)
+				goto out_clear;
+			bdev->bd_contains = whole;
+			bdev->bd_inode->i_data.backing_dev_info =
+			   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) {
+				ret = -ENXIO;
+				goto out_clear;
+			}
+			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
+		}
+	} else {
+		put_disk(disk);
+		module_put(disk->fops->owner);
+		disk = NULL;
+		if (bdev->bd_contains == bdev) {
+			if (bdev->bd_disk->fops->open) {
+				ret = bdev->bd_disk->fops->open(bdev, mode);
+				if (ret)
+					goto out_unlock_bdev;
+			}
+			if (bdev->bd_invalidated)
+				rescan_partitions(bdev->bd_disk, bdev);
+		}
+	}
+	bdev->bd_openers++;
+	if (for_part)
+		bdev->bd_part_count++;
+	mutex_unlock(&bdev->bd_mutex);
+	unlock_kernel();
+	return 0;
+
+ out_clear:
+	disk_put_part(bdev->bd_part);
+	bdev->bd_disk = NULL;
+	bdev->bd_part = NULL;
+	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+	if (bdev != bdev->bd_contains)
+		__blkdev_put(bdev->bd_contains, mode, 1);
+	bdev->bd_contains = NULL;
+ out_unlock_bdev:
+	mutex_unlock(&bdev->bd_mutex);
+ out_unlock_kernel:
+	unlock_kernel();
+
+	if (disk)
+		module_put(disk->fops->owner);
+	put_disk(disk);
+	bdput(bdev);
+
+	return ret;
+}
+
+int blkdev_get(struct block_device *bdev, fmode_t mode)
+{
+	return __blkdev_get(bdev, mode, 0);
+}
+EXPORT_SYMBOL(blkdev_get);
+
+static int blkdev_open(struct inode * inode, struct file * filp)
+{
+	struct block_device *bdev;
+	int res;
+
+	/*
+	 * Preserve backwards compatibility and allow large file access
+	 * even if userspace doesn't ask for it explicitly. Some mkfs
+	 * binary needs it. We might want to drop this workaround
+	 * during an unstable branch.
+	 */
+	filp->f_flags |= O_LARGEFILE;
+
+	if (filp->f_flags & O_NDELAY)
+		filp->f_mode |= FMODE_NDELAY;
+	if (filp->f_flags & O_EXCL)
+		filp->f_mode |= FMODE_EXCL;
+	if ((filp->f_flags & O_ACCMODE) == 3)
+		filp->f_mode |= FMODE_WRITE_IOCTL;
+
+	bdev = bd_acquire(inode);
+	if (bdev == NULL)
+		return -ENOMEM;
+
+	filp->f_mapping = bdev->bd_inode->i_mapping;
+
+	res = blkdev_get(bdev, filp->f_mode);
+	if (res)
+		return res;
+
+	if (filp->f_mode & FMODE_EXCL) {
+		res = bd_claim(bdev, filp);
+		if (res)
+			goto out_blkdev_put;
+	}
+
+	return 0;
+
+ out_blkdev_put:
+	blkdev_put(bdev, filp->f_mode);
+	return res;
+}
+
+static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
+{
+	int ret = 0;
+	struct gendisk *disk = bdev->bd_disk;
+	struct block_device *victim = NULL;
+
+	mutex_lock_nested(&bdev->bd_mutex, for_part);
+	lock_kernel();
+	if (for_part)
+		bdev->bd_part_count--;
+
+	if (!--bdev->bd_openers) {
+		sync_blockdev(bdev);
+		kill_bdev(bdev);
+	}
+	if (bdev->bd_contains == bdev) {
+		if (disk->fops->release)
+			ret = disk->fops->release(disk, mode);
+	}
+	if (!bdev->bd_openers) {
+		struct module *owner = disk->fops->owner;
+
+		put_disk(disk);
+		module_put(owner);
+		disk_put_part(bdev->bd_part);
+		bdev->bd_part = NULL;
+		bdev->bd_disk = NULL;
+		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+		if (bdev != bdev->bd_contains)
+			victim = bdev->bd_contains;
+		bdev->bd_contains = NULL;
+	}
+	unlock_kernel();
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	if (victim)
+		__blkdev_put(victim, mode, 1);
+	return ret;
+}
+
+int blkdev_put(struct block_device *bdev, fmode_t mode)
+{
+	return __blkdev_put(bdev, mode, 0);
+}
+EXPORT_SYMBOL(blkdev_put);
+
+static int blkdev_close(struct inode * inode, struct file * filp)
+{
+	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+	if (bdev->bd_holder == filp)
+		bd_release(bdev);
+	return blkdev_put(bdev, filp->f_mode);
+}
+
+static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
+{
+	struct block_device *bdev = I_BDEV(file->f_mapping->host);
+	fmode_t mode = file->f_mode;
+
+	/*
+	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
+	 * to updated it before every ioctl.
+	 */
+	if (file->f_flags & O_NDELAY)
+		mode |= FMODE_NDELAY;
+	else
+		mode &= ~FMODE_NDELAY;
+
+	return blkdev_ioctl(bdev, mode, cmd, arg);
+}
+
+static const struct address_space_operations def_blk_aops = {
+	.readpage	= blkdev_readpage,
+	.writepage	= blkdev_writepage,
+	.sync_page	= block_sync_page,
+	.write_begin	= blkdev_write_begin,
+	.write_end	= blkdev_write_end,
+	.writepages	= generic_writepages,
+	.direct_IO	= blkdev_direct_IO,
+};
+
+const struct file_operations def_blk_fops = {
+	.open		= blkdev_open,
+	.release	= blkdev_close,
+	.llseek		= block_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+  	.aio_read	= generic_file_aio_read,
+  	.aio_write	= generic_file_aio_write_nolock,
+	.mmap		= generic_file_mmap,
+	.fsync		= block_fsync,
+	.unlocked_ioctl	= block_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= compat_blkdev_ioctl,
+#endif
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= generic_file_splice_write,
+};
+
+int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
+{
+	int res;
+	mm_segment_t old_fs = get_fs();
+	set_fs(KERNEL_DS);
+	res = blkdev_ioctl(bdev, 0, cmd, arg);
+	set_fs(old_fs);
+	return res;
+}
+
+EXPORT_SYMBOL(ioctl_by_bdev);
+
+/**
+ * lookup_bdev  - lookup a struct block_device by name
+ * @path:	special file representing the block device
+ *
+ * Get a reference to the blockdevice at @pathname in the current
+ * namespace if possible and return it.  Return ERR_PTR(error)
+ * otherwise.
+ */
+struct block_device *lookup_bdev(const char *pathname)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+	struct path path;
+	int error;
+
+	if (!pathname || !*pathname)
+		return ERR_PTR(-EINVAL);
+
+	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+	if (error)
+		return ERR_PTR(error);
+
+	inode = path.dentry->d_inode;
+	error = -ENOTBLK;
+	if (!S_ISBLK(inode->i_mode))
+		goto fail;
+	error = -EACCES;
+	if (path.mnt->mnt_flags & MNT_NODEV)
+		goto fail;
+	error = -ENOMEM;
+	bdev = bd_acquire(inode);
+	if (!bdev)
+		goto fail;
+out:
+	path_put(&path);
+	return bdev;
+fail:
+	bdev = ERR_PTR(error);
+	goto out;
+}
+EXPORT_SYMBOL(lookup_bdev);
+
+/**
+ * open_bdev_exclusive  -  open a block device by name and set it up for use
+ *
+ * @path:	special file representing the block device
+ * @mode:	FMODE_... combination to pass be used
+ * @holder:	owner for exclusion
+ *
+ * Open the blockdevice described by the special file at @path, claim it
+ * for the @holder.
+ */
+struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *holder)
+{
+	struct block_device *bdev;
+	int error = 0;
+
+	bdev = lookup_bdev(path);
+	if (IS_ERR(bdev))
+		return bdev;
+
+	error = blkdev_get(bdev, mode);
+	if (error)
+		return ERR_PTR(error);
+	error = -EACCES;
+	if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
+		goto blkdev_put;
+	error = bd_claim(bdev, holder);
+	if (error)
+		goto blkdev_put;
+
+	return bdev;
+	
+blkdev_put:
+	blkdev_put(bdev, mode);
+	return ERR_PTR(error);
+}
+
+EXPORT_SYMBOL(open_bdev_exclusive);
+
+/**
+ * close_bdev_exclusive  -  close a blockdevice opened by open_bdev_exclusive()
+ *
+ * @bdev:	blockdevice to close
+ * @mode:	mode, must match that used to open.
+ *
+ * This is the counterpart to open_bdev_exclusive().
+ */
+void close_bdev_exclusive(struct block_device *bdev, fmode_t mode)
+{
+	bd_release(bdev);
+	blkdev_put(bdev, mode);
+}
+
+EXPORT_SYMBOL(close_bdev_exclusive);
+
+int __invalidate_device(struct block_device *bdev)
+{
+	struct super_block *sb = get_super(bdev);
+	int res = 0;
+
+	if (sb) {
+		/*
+		 * no need to lock the super, get_super holds the
+		 * read mutex so the filesystem cannot go away
+		 * under us (->put_super runs with the write lock
+		 * hold).
+		 */
+		shrink_dcache_sb(sb);
+		res = invalidate_inodes(sb);
+		drop_super(sb);
+	}
+	invalidate_bdev(bdev);
+	return res;
+}
+EXPORT_SYMBOL(__invalidate_device);