Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 923 insertions, 0 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
new file mode 100644
index 000000000000..d19d07c49ad3
--- /dev/null
+++ b/fs/block_dev.c
@@ -0,0 +1,923 @@
+/*
+ *  linux/fs/block_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
+ */
+
+#include <linux/config.h>
+#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/devfs_fs_kernel.h>
+#include <linux/smp_lock.h>
+#include <linux/highmem.h>
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/mount.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <asm/uaccess.h>
+
+struct bdev_inode {
+        struct block_device bdev;
+        struct inode vfs_inode;
+};
+
+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, dirty or not.. */
+static void kill_bdev(struct block_device *bdev)
+{
+        invalidate_bdev(bdev, 1);
+        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 || (size & (size-1)))
+                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)
+{
+        int bits = 9; /* 2^9 = 512 */
+
+        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;
+        for (size >>= 10; size; size >>= 1)
+                ++bits;
+        sb->s_blocksize_bits = bits;
+        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,
+                unsigned long max_blocks, struct buffer_head *bh, int create)
+{
+        sector_t end_block = max_block(I_BDEV(inode));
+
+        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_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
+{
+        return block_prepare_write(page, from, to, blkdev_get_block);
+}
+
+static int blkdev_commit_write(struct file *file, struct page *page, unsigned from, unsigned to)
+{
+        return block_commit_write(page, from, to);
+}
+
+/*
+ * private llseek:
+ * for a block special file file->f_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;
+
+        down(&bd_inode->i_sem);
+        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;
+        }
+        up(&bd_inode->i_sem);
+        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 kmem_cache_t * bdev_cachep;
+
+static struct inode *bdev_alloc_inode(struct super_block *sb)
+{
+        struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, SLAB_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, kmem_cache_t * cachep, unsigned long flags)
+{
+        struct bdev_inode *ei = (struct bdev_inode *) foo;
+        struct block_device *bdev = &ei->bdev;
+
+        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+            SLAB_CTOR_CONSTRUCTOR)
+        {
+                memset(bdev, 0, sizeof(*bdev));
+                sema_init(&bdev->bd_sem, 1);
+                sema_init(&bdev->bd_mount_sem, 1);
+                INIT_LIST_HEAD(&bdev->bd_inodes);
+                INIT_LIST_HEAD(&bdev->bd_list);
+                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 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 struct super_block *bd_get_sb(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576);
+}
+
+static struct file_system_type bd_type = {
+        .name           = "bdev",
+        .get_sb         = bd_get_sb,
+        .kill_sb        = kill_anon_super,
+};
+
+static struct vfsmount *bd_mnt;
+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_PANIC,
+                        init_once, NULL);
+        err = register_filesystem(&bd_type);
+        if (err)
+                panic("Cannot register bdev pseudo-fs");
+        bd_mnt = kern_mount(&bd_type);
+        err = PTR_ERR(bd_mnt);
+        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 list_head *p;
+        long ret = 0;
+        spin_lock(&bdev_lock);
+        list_for_each(p, &all_bdevs) {
+                struct block_device *bdev;
+                bdev = list_entry(p, struct block_device, 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 && igrab(bdev->bd_inode)) {
+                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)
+                        __bd_forget(inode);
+                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)
+{
+        spin_lock(&bdev_lock);
+        if (inode->i_bdev)
+                __bd_forget(inode);
+        spin_unlock(&bdev_lock);
+}
+
+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);
+
+/*
+ * 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, unsigned mode)
+{
+        struct block_device *bdev = bdget(dev);
+        int err = -ENOMEM;
+        int flags = mode & FMODE_WRITE ? O_RDWR : O_RDONLY;
+        if (bdev)
+                err = blkdev_get(bdev, mode, flags);
+        return err ? ERR_PTR(err) : bdev;
+}
+
+EXPORT_SYMBOL(open_by_devnum);
+
+/*
+ * 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;
+
+        if (__invalidate_device(bdev, 0))
+                printk("VFS: busy inodes on changed media.\n");
+
+        if (bdops->revalidate_disk)
+                bdops->revalidate_disk(bdev->bd_disk);
+        if (bdev->bd_disk->minors > 1)
+                bdev->bd_invalidated = 1;
+        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 do_open(struct block_device *bdev, struct file *file)
+{
+        struct module *owner = NULL;
+        struct gendisk *disk;
+        int ret = -ENXIO;
+        int part;
+
+        file->f_mapping = bdev->bd_inode->i_mapping;
+        lock_kernel();
+        disk = get_gendisk(bdev->bd_dev, &part);
+        if (!disk) {
+                unlock_kernel();
+                bdput(bdev);
+                return ret;
+        }
+        owner = disk->fops->owner;
+
+        down(&bdev->bd_sem);
+        if (!bdev->bd_openers) {
+                bdev->bd_disk = disk;
+                bdev->bd_contains = bdev;
+                if (!part) {
+                        struct backing_dev_info *bdi;
+                        if (disk->fops->open) {
+                                ret = disk->fops->open(bdev->bd_inode, file);
+                                if (ret)
+                                        goto out_first;
+                        }
+                        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 hd_struct *p;
+                        struct block_device *whole;
+                        whole = bdget_disk(disk, 0);
+                        ret = -ENOMEM;
+                        if (!whole)
+                                goto out_first;
+                        ret = blkdev_get(whole, file->f_mode, file->f_flags);
+                        if (ret)
+                                goto out_first;
+                        bdev->bd_contains = whole;
+                        down(&whole->bd_sem);
+                        whole->bd_part_count++;
+                        p = disk->part[part - 1];
+                        bdev->bd_inode->i_data.backing_dev_info =
+                           whole->bd_inode->i_data.backing_dev_info;
+                        if (!(disk->flags & GENHD_FL_UP) || !p || !p->nr_sects) {
+                                whole->bd_part_count--;
+                                up(&whole->bd_sem);
+                                ret = -ENXIO;
+                                goto out_first;
+                        }
+                        kobject_get(&p->kobj);
+                        bdev->bd_part = p;
+                        bd_set_size(bdev, (loff_t) p->nr_sects << 9);
+                        up(&whole->bd_sem);
+                }
+        } else {
+                put_disk(disk);
+                module_put(owner);
+                if (bdev->bd_contains == bdev) {
+                        if (bdev->bd_disk->fops->open) {
+                                ret = bdev->bd_disk->fops->open(bdev->bd_inode, file);
+                                if (ret)
+                                        goto out;
+                        }
+                        if (bdev->bd_invalidated)
+                                rescan_partitions(bdev->bd_disk, bdev);
+                } else {
+                        down(&bdev->bd_contains->bd_sem);
+                        bdev->bd_contains->bd_part_count++;
+                        up(&bdev->bd_contains->bd_sem);
+                }
+        }
+        bdev->bd_openers++;
+        up(&bdev->bd_sem);
+        unlock_kernel();
+        return 0;
+
+out_first:
+        bdev->bd_disk = NULL;
+        bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+        if (bdev != bdev->bd_contains)
+                blkdev_put(bdev->bd_contains);
+        bdev->bd_contains = NULL;
+        put_disk(disk);
+        module_put(owner);
+out:
+        up(&bdev->bd_sem);
+        unlock_kernel();
+        if (ret)
+                bdput(bdev);
+        return ret;
+}
+
+int blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags)
+{
+        /*
+         * This crockload is due to bad choice of ->open() type.
+         * It will go away.
+         * For now, block device ->open() routine must _not_
+         * examine anything in 'inode' argument except ->i_rdev.
+         */
+        struct file fake_file = {};
+        struct dentry fake_dentry = {};
+        fake_file.f_mode = mode;
+        fake_file.f_flags = flags;
+        fake_file.f_dentry = &fake_dentry;
+        fake_dentry.d_inode = bdev->bd_inode;
+
+        return do_open(bdev, &fake_file);
+}
+
+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;
+
+        bdev = bd_acquire(inode);
+
+        res = do_open(bdev, filp);
+        if (res)
+                return res;
+
+        if (!(filp->f_flags & O_EXCL) )
+                return 0;
+
+        if (!(res = bd_claim(bdev, filp)))
+                return 0;
+
+        blkdev_put(bdev);
+        return res;
+}
+
+int blkdev_put(struct block_device *bdev)
+{
+        int ret = 0;
+        struct inode *bd_inode = bdev->bd_inode;
+        struct gendisk *disk = bdev->bd_disk;
+
+        down(&bdev->bd_sem);
+        lock_kernel();
+        if (!--bdev->bd_openers) {
+                sync_blockdev(bdev);
+                kill_bdev(bdev);
+        }
+        if (bdev->bd_contains == bdev) {
+                if (disk->fops->release)
+                        ret = disk->fops->release(bd_inode, NULL);
+        } else {
+                down(&bdev->bd_contains->bd_sem);
+                bdev->bd_contains->bd_part_count--;
+                up(&bdev->bd_contains->bd_sem);
+        }
+        if (!bdev->bd_openers) {
+                struct module *owner = disk->fops->owner;
+
+                put_disk(disk);
+                module_put(owner);
+
+                if (bdev->bd_contains != bdev) {
+                        kobject_put(&bdev->bd_part->kobj);
+                        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) {
+                        blkdev_put(bdev->bd_contains);
+                }
+                bdev->bd_contains = NULL;
+        }
+        unlock_kernel();
+        up(&bdev->bd_sem);
+        bdput(bdev);
+        return ret;
+}
+
+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);
+}
+
+static ssize_t blkdev_file_write(struct file *file, const char __user *buf,
+                                   size_t count, loff_t *ppos)
+{
+        struct iovec local_iov = { .iov_base = (void __user *)buf, .iov_len = count };
+
+        return generic_file_write_nolock(file, &local_iov, 1, ppos);
+}
+
+static ssize_t blkdev_file_aio_write(struct kiocb *iocb, const char __user *buf,
+                                   size_t count, loff_t pos)
+{
+        struct iovec local_iov = { .iov_base = (void __user *)buf, .iov_len = count };
+
+        return generic_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
+}
+
+static int block_ioctl(struct inode *inode, struct file *file, unsigned cmd,
+                        unsigned long arg)
+{
+        return blkdev_ioctl(file->f_mapping->host, file, cmd, arg);
+}
+
+struct address_space_operations def_blk_aops = {
+        .readpage       = blkdev_readpage,
+        .writepage      = blkdev_writepage,
+        .sync_page      = block_sync_page,
+        .prepare_write  = blkdev_prepare_write,
+        .commit_write   = blkdev_commit_write,
+        .writepages     = generic_writepages,
+        .direct_IO      = blkdev_direct_IO,
+};
+
+struct file_operations def_blk_fops = {
+        .open           = blkdev_open,
+        .release        = blkdev_close,
+        .llseek         = block_llseek,
+        .read           = generic_file_read,
+        .write          = blkdev_file_write,
+        .aio_read       = generic_file_aio_read,
+        .aio_write      = blkdev_file_aio_write, 
+        .mmap           = generic_file_mmap,
+        .fsync          = block_fsync,
+        .ioctl          = block_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl   = compat_blkdev_ioctl,
+#endif
+        .readv          = generic_file_readv,
+        .writev         = generic_file_write_nolock,
+        .sendfile       = generic_file_sendfile,
+};
+
+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->bd_inode, NULL, 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 @path in the current
+ * namespace if possible and return it.  Return ERR_PTR(error)
+ * otherwise.
+ */
+struct block_device *lookup_bdev(const char *path)
+{
+        struct block_device *bdev;
+        struct inode *inode;
+        struct nameidata nd;
+        int error;
+
+        if (!path || !*path)
+                return ERR_PTR(-EINVAL);
+
+        error = path_lookup(path, LOOKUP_FOLLOW, &nd);
+        if (error)
+                return ERR_PTR(error);
+
+        inode = nd.dentry->d_inode;
+        error = -ENOTBLK;
+        if (!S_ISBLK(inode->i_mode))
+                goto fail;
+        error = -EACCES;
+        if (nd.mnt->mnt_flags & MNT_NODEV)
+                goto fail;
+        error = -ENOMEM;
+        bdev = bd_acquire(inode);
+        if (!bdev)
+                goto fail;
+out:
+        path_release(&nd);
+        return bdev;
+fail:
+        bdev = ERR_PTR(error);
+        goto out;
+}
+
+/**
+ * open_bdev_excl  -  open a block device by name and set it up for use
+ *
+ * @path:       special file representing the block device
+ * @flags:      %MS_RDONLY for opening read-only
+ * @holder:     owner for exclusion
+ *
+ * Open the blockdevice described by the special file at @path, claim it
+ * for the @holder.
+ */
+struct block_device *open_bdev_excl(const char *path, int flags, void *holder)
+{
+        struct block_device *bdev;
+        mode_t mode = FMODE_READ;
+        int error = 0;
+
+        bdev = lookup_bdev(path);
+        if (IS_ERR(bdev))
+                return bdev;
+
+        if (!(flags & MS_RDONLY))
+                mode |= FMODE_WRITE;
+        error = blkdev_get(bdev, mode, 0);
+        if (error)
+                return ERR_PTR(error);
+        error = -EACCES;
+        if (!(flags & MS_RDONLY) && bdev_read_only(bdev))
+                goto blkdev_put;
+        error = bd_claim(bdev, holder);
+        if (error)
+                goto blkdev_put;
+
+        return bdev;
+        
+blkdev_put:
+        blkdev_put(bdev);
+        return ERR_PTR(error);
+}
+
+EXPORT_SYMBOL(open_bdev_excl);
+
+/**
+ * close_bdev_excl  -  release a blockdevice openen by open_bdev_excl()
+ *
+ * @bdev:       blockdevice to close
+ *
+ * This is the counterpart to open_bdev_excl().
+ */
+void close_bdev_excl(struct block_device *bdev)
+{
+        bd_release(bdev);
+        blkdev_put(bdev);
+}
+
+EXPORT_SYMBOL(close_bdev_excl);