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-rw-r--r--kernel/fs/block_dev.c1795
1 files changed, 1795 insertions, 0 deletions
diff --git a/kernel/fs/block_dev.c b/kernel/fs/block_dev.c
new file mode 100644
index 000000000..c7e4163ed
--- /dev/null
+++ b/kernel/fs/block_dev.c
@@ -0,0 +1,1795 @@
+/*
+ * 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/device_cgroup.h>
+#include <linux/highmem.h>
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/magic.h>
+#include <linux/buffer_head.h>
+#include <linux/swap.h>
+#include <linux/pagevec.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 <linux/cleancache.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 void bdev_write_inode(struct inode *inode)
+{
+ spin_lock(&inode->i_lock);
+ while (inode->i_state & I_DIRTY) {
+ 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.. */
+void kill_bdev(struct block_device *bdev)
+{
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+ if (mapping->nrpages == 0 && mapping->nrshadows == 0)
+ return;
+
+ invalidate_bh_lrus();
+ truncate_inode_pages(mapping, 0);
+}
+EXPORT_SYMBOL(kill_bdev);
+
+/* Invalidate clean unused buffers and pagecache. */
+void invalidate_bdev(struct block_device *bdev)
+{
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+ if (mapping->nrpages == 0)
+ return;
+
+ invalidate_bh_lrus();
+ lru_add_drain_all(); /* make sure all lru add caches are flushed */
+ invalidate_mapping_pages(mapping, 0, -1);
+ /* 99% of the time, we don't need to flush the cleancache on the bdev.
+ * But, for the strange corners, lets be cautious
+ */
+ cleancache_invalidate_inode(mapping);
+}
+EXPORT_SYMBOL(invalidate_bdev);
+
+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_logical_block_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_logical_block_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)
+{
+ bh->b_bdev = I_BDEV(inode);
+ bh->b_blocknr = iblock;
+ set_buffer_mapped(bh);
+ return 0;
+}
+
+static ssize_t
+blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+
+ return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset,
+ blkdev_get_block, NULL, NULL,
+ DIO_SKIP_DIO_COUNT);
+}
+
+int __sync_blockdev(struct block_device *bdev, int wait)
+{
+ if (!bdev)
+ return 0;
+ if (!wait)
+ return filemap_flush(bdev->bd_inode->i_mapping);
+ return filemap_write_and_wait(bdev->bd_inode->i_mapping);
+}
+
+/*
+ * Write out and wait upon all the dirty data associated with a block
+ * device via its mapping. Does not take the superblock lock.
+ */
+int sync_blockdev(struct block_device *bdev)
+{
+ return __sync_blockdev(bdev, 1);
+}
+EXPORT_SYMBOL(sync_blockdev);
+
+/*
+ * Write out and wait upon all dirty data associated with this
+ * device. Filesystem data as well as the underlying block
+ * device. Takes the superblock lock.
+ */
+int fsync_bdev(struct block_device *bdev)
+{
+ struct super_block *sb = get_super(bdev);
+ if (sb) {
+ int res = sync_filesystem(sb);
+ drop_super(sb);
+ return res;
+ }
+ return sync_blockdev(bdev);
+}
+EXPORT_SYMBOL(fsync_bdev);
+
+/**
+ * freeze_bdev -- lock a filesystem and force it into a consistent state
+ * @bdev: blockdevice to lock
+ *
+ * If a superblock is found on this device, we take the s_umount semaphore
+ * on it to make sure nobody unmounts until the snapshot creation is done.
+ * The reference counter (bd_fsfreeze_count) guarantees that only the last
+ * unfreeze process can unfreeze the frozen filesystem actually when multiple
+ * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
+ * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
+ * actually.
+ */
+struct super_block *freeze_bdev(struct block_device *bdev)
+{
+ struct super_block *sb;
+ int error = 0;
+
+ mutex_lock(&bdev->bd_fsfreeze_mutex);
+ if (++bdev->bd_fsfreeze_count > 1) {
+ /*
+ * We don't even need to grab a reference - the first call
+ * to freeze_bdev grab an active reference and only the last
+ * thaw_bdev drops it.
+ */
+ sb = get_super(bdev);
+ drop_super(sb);
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return sb;
+ }
+
+ sb = get_active_super(bdev);
+ if (!sb)
+ goto out;
+ if (sb->s_op->freeze_super)
+ error = sb->s_op->freeze_super(sb);
+ else
+ error = freeze_super(sb);
+ if (error) {
+ deactivate_super(sb);
+ bdev->bd_fsfreeze_count--;
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return ERR_PTR(error);
+ }
+ deactivate_super(sb);
+ out:
+ sync_blockdev(bdev);
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return sb; /* thaw_bdev releases s->s_umount */
+}
+EXPORT_SYMBOL(freeze_bdev);
+
+/**
+ * thaw_bdev -- unlock filesystem
+ * @bdev: blockdevice to unlock
+ * @sb: associated superblock
+ *
+ * Unlocks the filesystem and marks it writeable again after freeze_bdev().
+ */
+int thaw_bdev(struct block_device *bdev, struct super_block *sb)
+{
+ int error = -EINVAL;
+
+ mutex_lock(&bdev->bd_fsfreeze_mutex);
+ if (!bdev->bd_fsfreeze_count)
+ goto out;
+
+ error = 0;
+ if (--bdev->bd_fsfreeze_count > 0)
+ goto out;
+
+ if (!sb)
+ goto out;
+
+ if (sb->s_op->thaw_super)
+ error = sb->s_op->thaw_super(sb);
+ else
+ error = thaw_super(sb);
+ if (error) {
+ bdev->bd_fsfreeze_count++;
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return error;
+ }
+out:
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return 0;
+}
+EXPORT_SYMBOL(thaw_bdev);
+
+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_readpages(struct file *file, struct address_space *mapping,
+ struct list_head *pages, unsigned nr_pages)
+{
+ return mpage_readpages(mapping, pages, nr_pages, 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)
+{
+ return block_write_begin(mapping, pos, len, flags, pagep,
+ 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_inode(file)->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 whence)
+{
+ struct inode *bd_inode = file->f_mapping->host;
+ loff_t retval;
+
+ mutex_lock(&bd_inode->i_mutex);
+ retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
+ mutex_unlock(&bd_inode->i_mutex);
+ return retval;
+}
+
+int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
+{
+ struct inode *bd_inode = filp->f_mapping->host;
+ struct block_device *bdev = I_BDEV(bd_inode);
+ int error;
+
+ error = filemap_write_and_wait_range(filp->f_mapping, start, end);
+ if (error)
+ return error;
+
+ /*
+ * There is no need to serialise calls to blkdev_issue_flush with
+ * i_mutex and doing so causes performance issues with concurrent
+ * O_SYNC writers to a block device.
+ */
+ error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
+ if (error == -EOPNOTSUPP)
+ error = 0;
+
+ return error;
+}
+EXPORT_SYMBOL(blkdev_fsync);
+
+/**
+ * bdev_read_page() - Start reading a page from a block device
+ * @bdev: The device to read the page from
+ * @sector: The offset on the device to read the page to (need not be aligned)
+ * @page: The page to read
+ *
+ * On entry, the page should be locked. It will be unlocked when the page
+ * has been read. If the block driver implements rw_page synchronously,
+ * that will be true on exit from this function, but it need not be.
+ *
+ * Errors returned by this function are usually "soft", eg out of memory, or
+ * queue full; callers should try a different route to read this page rather
+ * than propagate an error back up the stack.
+ *
+ * Return: negative errno if an error occurs, 0 if submission was successful.
+ */
+int bdev_read_page(struct block_device *bdev, sector_t sector,
+ struct page *page)
+{
+ const struct block_device_operations *ops = bdev->bd_disk->fops;
+ if (!ops->rw_page)
+ return -EOPNOTSUPP;
+ return ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ);
+}
+EXPORT_SYMBOL_GPL(bdev_read_page);
+
+/**
+ * bdev_write_page() - Start writing a page to a block device
+ * @bdev: The device to write the page to
+ * @sector: The offset on the device to write the page to (need not be aligned)
+ * @page: The page to write
+ * @wbc: The writeback_control for the write
+ *
+ * On entry, the page should be locked and not currently under writeback.
+ * On exit, if the write started successfully, the page will be unlocked and
+ * under writeback. If the write failed already (eg the driver failed to
+ * queue the page to the device), the page will still be locked. If the
+ * caller is a ->writepage implementation, it will need to unlock the page.
+ *
+ * Errors returned by this function are usually "soft", eg out of memory, or
+ * queue full; callers should try a different route to write this page rather
+ * than propagate an error back up the stack.
+ *
+ * Return: negative errno if an error occurs, 0 if submission was successful.
+ */
+int bdev_write_page(struct block_device *bdev, sector_t sector,
+ struct page *page, struct writeback_control *wbc)
+{
+ int result;
+ int rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE;
+ const struct block_device_operations *ops = bdev->bd_disk->fops;
+ if (!ops->rw_page)
+ return -EOPNOTSUPP;
+ set_page_writeback(page);
+ result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, rw);
+ if (result)
+ end_page_writeback(page);
+ else
+ unlock_page(page);
+ return result;
+}
+EXPORT_SYMBOL_GPL(bdev_write_page);
+
+/**
+ * bdev_direct_access() - Get the address for directly-accessibly memory
+ * @bdev: The device containing the memory
+ * @sector: The offset within the device
+ * @addr: Where to put the address of the memory
+ * @pfn: The Page Frame Number for the memory
+ * @size: The number of bytes requested
+ *
+ * If a block device is made up of directly addressable memory, this function
+ * will tell the caller the PFN and the address of the memory. The address
+ * may be directly dereferenced within the kernel without the need to call
+ * ioremap(), kmap() or similar. The PFN is suitable for inserting into
+ * page tables.
+ *
+ * Return: negative errno if an error occurs, otherwise the number of bytes
+ * accessible at this address.
+ */
+long bdev_direct_access(struct block_device *bdev, sector_t sector,
+ void **addr, unsigned long *pfn, long size)
+{
+ long avail;
+ const struct block_device_operations *ops = bdev->bd_disk->fops;
+
+ if (size < 0)
+ return size;
+ if (!ops->direct_access)
+ return -EOPNOTSUPP;
+ if ((sector + DIV_ROUND_UP(size, 512)) >
+ part_nr_sects_read(bdev->bd_part))
+ return -ERANGE;
+ sector += get_start_sect(bdev);
+ if (sector % (PAGE_SIZE / 512))
+ return -EINVAL;
+ avail = ops->direct_access(bdev, sector, addr, pfn, size);
+ if (!avail)
+ return -ERANGE;
+ return min(avail, size);
+}
+EXPORT_SYMBOL_GPL(bdev_direct_access);
+
+/*
+ * 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_i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+ struct bdev_inode *bdi = BDEV_I(inode);
+
+ kmem_cache_free(bdev_cachep, bdi);
+}
+
+static void bdev_destroy_inode(struct inode *inode)
+{
+ call_rcu(&inode->i_rcu, bdev_i_callback);
+}
+
+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);
+ INIT_LIST_HEAD(&bdev->bd_inodes);
+ INIT_LIST_HEAD(&bdev->bd_list);
+#ifdef CONFIG_SYSFS
+ INIT_LIST_HEAD(&bdev->bd_holder_disks);
+#endif
+ inode_init_once(&ei->vfs_inode);
+ /* Initialize mutex for freeze. */
+ mutex_init(&bdev->bd_fsfreeze_mutex);
+}
+
+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_evict_inode(struct inode *inode)
+{
+ struct block_device *bdev = &BDEV_I(inode)->bdev;
+ struct list_head *p;
+ truncate_inode_pages_final(&inode->i_data);
+ invalidate_inode_buffers(inode); /* is it needed here? */
+ clear_inode(inode);
+ 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,
+ .evict_inode = bdev_evict_inode,
+};
+
+static struct dentry *bd_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
+}
+
+static struct file_system_type bd_type = {
+ .name = "bdev",
+ .mount = bd_mount,
+ .kill_sb = kill_anon_super,
+};
+
+static struct super_block *blockdev_superblock __read_mostly;
+
+void __init bdev_cache_init(void)
+{
+ int err;
+ static struct vfsmount *bd_mnt;
+
+ 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(blockdev_superblock, 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_super = 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);
+ spin_lock(&bdev_lock);
+ list_add(&bdev->bd_list, &all_bdevs);
+ spin_unlock(&bdev_lock);
+ unlock_new_inode(inode);
+ }
+ return bdev;
+}
+
+EXPORT_SYMBOL(bdget);
+
+/**
+ * bdgrab -- Grab a reference to an already referenced block device
+ * @bdev: Block device to grab a reference to.
+ */
+struct block_device *bdgrab(struct block_device *bdev)
+{
+ ihold(bdev->bd_inode);
+ return bdev;
+}
+EXPORT_SYMBOL(bdgrab);
+
+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) {
+ ihold(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) {
+ /*
+ * We take an additional reference to bd_inode,
+ * and it's released in clear_inode() of inode.
+ * So, we can access it via ->i_mapping always
+ * without igrab().
+ */
+ ihold(bdev->bd_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;
+}
+
+int sb_is_blkdev_sb(struct super_block *sb)
+{
+ return sb == blockdev_superblock;
+}
+
+/* Call when you free inode */
+
+void bd_forget(struct inode *inode)
+{
+ struct block_device *bdev = NULL;
+
+ spin_lock(&bdev_lock);
+ if (!sb_is_blkdev_sb(inode->i_sb))
+ bdev = inode->i_bdev;
+ __bd_forget(inode);
+ spin_unlock(&bdev_lock);
+
+ if (bdev)
+ iput(bdev->bd_inode);
+}
+
+/**
+ * bd_may_claim - test whether a block device can be claimed
+ * @bdev: block device of interest
+ * @whole: whole block device containing @bdev, may equal @bdev
+ * @holder: holder trying to claim @bdev
+ *
+ * Test whether @bdev can be claimed by @holder.
+ *
+ * CONTEXT:
+ * spin_lock(&bdev_lock).
+ *
+ * RETURNS:
+ * %true if @bdev can be claimed, %false otherwise.
+ */
+static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
+ void *holder)
+{
+ if (bdev->bd_holder == holder)
+ return true; /* already a holder */
+ else if (bdev->bd_holder != NULL)
+ return false; /* held by someone else */
+ else if (bdev->bd_contains == bdev)
+ return true; /* is a whole device which isn't held */
+
+ else if (whole->bd_holder == bd_may_claim)
+ return true; /* is a partition of a device that is being partitioned */
+ else if (whole->bd_holder != NULL)
+ return false; /* is a partition of a held device */
+ else
+ return true; /* is a partition of an un-held device */
+}
+
+/**
+ * bd_prepare_to_claim - prepare to claim a block device
+ * @bdev: block device of interest
+ * @whole: the whole device containing @bdev, may equal @bdev
+ * @holder: holder trying to claim @bdev
+ *
+ * Prepare to claim @bdev. This function fails if @bdev is already
+ * claimed by another holder and waits if another claiming is in
+ * progress. This function doesn't actually claim. On successful
+ * return, the caller has ownership of bd_claiming and bd_holder[s].
+ *
+ * CONTEXT:
+ * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
+ * it multiple times.
+ *
+ * RETURNS:
+ * 0 if @bdev can be claimed, -EBUSY otherwise.
+ */
+static int bd_prepare_to_claim(struct block_device *bdev,
+ struct block_device *whole, void *holder)
+{
+retry:
+ /* if someone else claimed, fail */
+ if (!bd_may_claim(bdev, whole, holder))
+ return -EBUSY;
+
+ /* if claiming is already in progress, wait for it to finish */
+ if (whole->bd_claiming) {
+ wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
+ DEFINE_WAIT(wait);
+
+ prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
+ spin_unlock(&bdev_lock);
+ schedule();
+ finish_wait(wq, &wait);
+ spin_lock(&bdev_lock);
+ goto retry;
+ }
+
+ /* yay, all mine */
+ return 0;
+}
+
+/**
+ * bd_start_claiming - start claiming a block device
+ * @bdev: block device of interest
+ * @holder: holder trying to claim @bdev
+ *
+ * @bdev is about to be opened exclusively. Check @bdev can be opened
+ * exclusively and mark that an exclusive open is in progress. Each
+ * successful call to this function must be matched with a call to
+ * either bd_finish_claiming() or bd_abort_claiming() (which do not
+ * fail).
+ *
+ * This function is used to gain exclusive access to the block device
+ * without actually causing other exclusive open attempts to fail. It
+ * should be used when the open sequence itself requires exclusive
+ * access but may subsequently fail.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Pointer to the block device containing @bdev on success, ERR_PTR()
+ * value on failure.
+ */
+static struct block_device *bd_start_claiming(struct block_device *bdev,
+ void *holder)
+{
+ struct gendisk *disk;
+ struct block_device *whole;
+ int partno, err;
+
+ might_sleep();
+
+ /*
+ * @bdev might not have been initialized properly yet, look up
+ * and grab the outer block device the hard way.
+ */
+ disk = get_gendisk(bdev->bd_dev, &partno);
+ if (!disk)
+ return ERR_PTR(-ENXIO);
+
+ /*
+ * Normally, @bdev should equal what's returned from bdget_disk()
+ * if partno is 0; however, some drivers (floppy) use multiple
+ * bdev's for the same physical device and @bdev may be one of the
+ * aliases. Keep @bdev if partno is 0. This means claimer
+ * tracking is broken for those devices but it has always been that
+ * way.
+ */
+ if (partno)
+ whole = bdget_disk(disk, 0);
+ else
+ whole = bdgrab(bdev);
+
+ module_put(disk->fops->owner);
+ put_disk(disk);
+ if (!whole)
+ return ERR_PTR(-ENOMEM);
+
+ /* prepare to claim, if successful, mark claiming in progress */
+ spin_lock(&bdev_lock);
+
+ err = bd_prepare_to_claim(bdev, whole, holder);
+ if (err == 0) {
+ whole->bd_claiming = holder;
+ spin_unlock(&bdev_lock);
+ return whole;
+ } else {
+ spin_unlock(&bdev_lock);
+ bdput(whole);
+ return ERR_PTR(err);
+ }
+}
+
+#ifdef CONFIG_SYSFS
+struct bd_holder_disk {
+ struct list_head list;
+ struct gendisk *disk;
+ int refcnt;
+};
+
+static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
+ struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+
+ list_for_each_entry(holder, &bdev->bd_holder_disks, list)
+ if (holder->disk == disk)
+ return holder;
+ return NULL;
+}
+
+static int add_symlink(struct kobject *from, struct kobject *to)
+{
+ return sysfs_create_link(from, to, kobject_name(to));
+}
+
+static void del_symlink(struct kobject *from, struct kobject *to)
+{
+ sysfs_remove_link(from, kobject_name(to));
+}
+
+/**
+ * bd_link_disk_holder - create symlinks between holding disk and slave bdev
+ * @bdev: the claimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * This functions creates the following sysfs symlinks.
+ *
+ * - from "slaves" directory of the holder @disk to the claimed @bdev
+ * - from "holders" directory of the @bdev to the holder @disk
+ *
+ * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
+ * passed to bd_link_disk_holder(), then:
+ *
+ * /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ *
+ * The caller must have claimed @bdev before calling this function and
+ * ensure that both @bdev and @disk are valid during the creation and
+ * lifetime of these symlinks.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+ int ret = 0;
+
+ mutex_lock(&bdev->bd_mutex);
+
+ WARN_ON_ONCE(!bdev->bd_holder);
+
+ /* FIXME: remove the following once add_disk() handles errors */
+ if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
+ goto out_unlock;
+
+ holder = bd_find_holder_disk(bdev, disk);
+ if (holder) {
+ holder->refcnt++;
+ goto out_unlock;
+ }
+
+ holder = kzalloc(sizeof(*holder), GFP_KERNEL);
+ if (!holder) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ INIT_LIST_HEAD(&holder->list);
+ holder->disk = disk;
+ holder->refcnt = 1;
+
+ ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+ if (ret)
+ goto out_free;
+
+ ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
+ if (ret)
+ goto out_del;
+ /*
+ * bdev could be deleted beneath us which would implicitly destroy
+ * the holder directory. Hold on to it.
+ */
+ kobject_get(bdev->bd_part->holder_dir);
+
+ list_add(&holder->list, &bdev->bd_holder_disks);
+ goto out_unlock;
+
+out_del:
+ del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+out_free:
+ kfree(holder);
+out_unlock:
+ mutex_unlock(&bdev->bd_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(bd_link_disk_holder);
+
+/**
+ * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
+ * @bdev: the calimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+ struct bd_holder_disk *holder;
+
+ mutex_lock(&bdev->bd_mutex);
+
+ holder = bd_find_holder_disk(bdev, disk);
+
+ if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
+ del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+ del_symlink(bdev->bd_part->holder_dir,
+ &disk_to_dev(disk)->kobj);
+ kobject_put(bdev->bd_part->holder_dir);
+ list_del_init(&holder->list);
+ kfree(holder);
+ }
+
+ mutex_unlock(&bdev->bd_mutex);
+}
+EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
+#endif
+
+/**
+ * flush_disk - invalidates all buffer-cache entries on a disk
+ *
+ * @bdev: struct block device to be flushed
+ * @kill_dirty: flag to guide handling of dirty inodes
+ *
+ * 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, bool kill_dirty)
+{
+ if (__invalidate_device(bdev, kill_dirty)) {
+ 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_part_scan_enabled(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, false);
+ }
+}
+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);
+ bdev->bd_invalidated = 0;
+ 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;
+ const struct block_device_operations *bdops = disk->fops;
+ unsigned int events;
+
+ events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
+ DISK_EVENT_EJECT_REQUEST);
+ if (!(events & DISK_EVENT_MEDIA_CHANGE))
+ return 0;
+
+ flush_disk(bdev, true);
+ 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_logical_block_size(bdev);
+
+ mutex_lock(&bdev->bd_inode->i_mutex);
+ i_size_write(bdev->bd_inode, size);
+ mutex_unlock(&bdev->bd_inode->i_mutex);
+ 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 void __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;
+ struct module *owner;
+ 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".
+ */
+ if (!for_part) {
+ ret = devcgroup_inode_permission(bdev->bd_inode, perm);
+ if (ret != 0) {
+ bdput(bdev);
+ return ret;
+ }
+ }
+
+ restart:
+
+ ret = -ENXIO;
+ disk = get_gendisk(bdev->bd_dev, &partno);
+ if (!disk)
+ goto out;
+ owner = disk->fops->owner;
+
+ disk_block_events(disk);
+ mutex_lock_nested(&bdev->bd_mutex, for_part);
+ if (!bdev->bd_openers) {
+ bdev->bd_disk = disk;
+ bdev->bd_queue = disk->queue;
+ bdev->bd_contains = bdev;
+ if (!partno) {
+ ret = -ENXIO;
+ bdev->bd_part = disk_get_part(disk, partno);
+ if (!bdev->bd_part)
+ goto out_clear;
+
+ ret = 0;
+ if (disk->fops->open) {
+ ret = disk->fops->open(bdev, mode);
+ if (ret == -ERESTARTSYS) {
+ /* Lost a race with 'disk' being
+ * deleted, try again.
+ * See md.c
+ */
+ disk_put_part(bdev->bd_part);
+ bdev->bd_part = NULL;
+ bdev->bd_disk = NULL;
+ bdev->bd_queue = NULL;
+ mutex_unlock(&bdev->bd_mutex);
+ disk_unblock_events(disk);
+ put_disk(disk);
+ module_put(owner);
+ goto restart;
+ }
+ }
+
+ if (!ret)
+ bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
+
+ /*
+ * If the device is invalidated, rescan partition
+ * if open succeeded or failed with -ENOMEDIUM.
+ * The latter is necessary to prevent ghost
+ * partitions on a removed medium.
+ */
+ if (bdev->bd_invalidated) {
+ if (!ret)
+ rescan_partitions(disk, bdev);
+ else if (ret == -ENOMEDIUM)
+ invalidate_partitions(disk, bdev);
+ }
+ if (ret)
+ goto out_clear;
+ } 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_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 {
+ if (bdev->bd_contains == bdev) {
+ ret = 0;
+ if (bdev->bd_disk->fops->open)
+ ret = bdev->bd_disk->fops->open(bdev, mode);
+ /* the same as first opener case, read comment there */
+ if (bdev->bd_invalidated) {
+ if (!ret)
+ rescan_partitions(bdev->bd_disk, bdev);
+ else if (ret == -ENOMEDIUM)
+ invalidate_partitions(bdev->bd_disk, bdev);
+ }
+ if (ret)
+ goto out_unlock_bdev;
+ }
+ /* only one opener holds refs to the module and disk */
+ put_disk(disk);
+ module_put(owner);
+ }
+ bdev->bd_openers++;
+ if (for_part)
+ bdev->bd_part_count++;
+ mutex_unlock(&bdev->bd_mutex);
+ disk_unblock_events(disk);
+ return 0;
+
+ out_clear:
+ disk_put_part(bdev->bd_part);
+ bdev->bd_disk = NULL;
+ bdev->bd_part = NULL;
+ bdev->bd_queue = NULL;
+ if (bdev != bdev->bd_contains)
+ __blkdev_put(bdev->bd_contains, mode, 1);
+ bdev->bd_contains = NULL;
+ out_unlock_bdev:
+ mutex_unlock(&bdev->bd_mutex);
+ disk_unblock_events(disk);
+ put_disk(disk);
+ module_put(owner);
+ out:
+ bdput(bdev);
+
+ return ret;
+}
+
+/**
+ * blkdev_get - open a block device
+ * @bdev: block_device to open
+ * @mode: FMODE_* mask
+ * @holder: exclusive holder identifier
+ *
+ * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
+ * open with exclusive access. Specifying %FMODE_EXCL with %NULL
+ * @holder is invalid. Exclusive opens may nest for the same @holder.
+ *
+ * On success, the reference count of @bdev is unchanged. On failure,
+ * @bdev is put.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
+{
+ struct block_device *whole = NULL;
+ int res;
+
+ WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
+
+ if ((mode & FMODE_EXCL) && holder) {
+ whole = bd_start_claiming(bdev, holder);
+ if (IS_ERR(whole)) {
+ bdput(bdev);
+ return PTR_ERR(whole);
+ }
+ }
+
+ res = __blkdev_get(bdev, mode, 0);
+
+ if (whole) {
+ struct gendisk *disk = whole->bd_disk;
+
+ /* finish claiming */
+ mutex_lock(&bdev->bd_mutex);
+ spin_lock(&bdev_lock);
+
+ if (!res) {
+ BUG_ON(!bd_may_claim(bdev, whole, holder));
+ /*
+ * Note that for a whole device bd_holders
+ * will be incremented twice, and bd_holder
+ * will be set to bd_may_claim before being
+ * set to holder
+ */
+ whole->bd_holders++;
+ whole->bd_holder = bd_may_claim;
+ bdev->bd_holders++;
+ bdev->bd_holder = holder;
+ }
+
+ /* tell others that we're done */
+ BUG_ON(whole->bd_claiming != holder);
+ whole->bd_claiming = NULL;
+ wake_up_bit(&whole->bd_claiming, 0);
+
+ spin_unlock(&bdev_lock);
+
+ /*
+ * Block event polling for write claims if requested. Any
+ * write holder makes the write_holder state stick until
+ * all are released. This is good enough and tracking
+ * individual writeable reference is too fragile given the
+ * way @mode is used in blkdev_get/put().
+ */
+ if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
+ (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
+ bdev->bd_write_holder = true;
+ disk_block_events(disk);
+ }
+
+ mutex_unlock(&bdev->bd_mutex);
+ bdput(whole);
+ }
+
+ return res;
+}
+EXPORT_SYMBOL(blkdev_get);
+
+/**
+ * blkdev_get_by_path - open a block device by name
+ * @path: path to the block device to open
+ * @mode: FMODE_* mask
+ * @holder: exclusive holder identifier
+ *
+ * Open the blockdevice described by the device file at @path. @mode
+ * and @holder are identical to blkdev_get().
+ *
+ * On success, the returned block_device has reference count of one.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Pointer to block_device on success, ERR_PTR(-errno) on failure.
+ */
+struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
+ void *holder)
+{
+ struct block_device *bdev;
+ int err;
+
+ bdev = lookup_bdev(path);
+ if (IS_ERR(bdev))
+ return bdev;
+
+ err = blkdev_get(bdev, mode, holder);
+ if (err)
+ return ERR_PTR(err);
+
+ if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
+ blkdev_put(bdev, mode);
+ return ERR_PTR(-EACCES);
+ }
+
+ return bdev;
+}
+EXPORT_SYMBOL(blkdev_get_by_path);
+
+/**
+ * blkdev_get_by_dev - open a block device by device number
+ * @dev: device number of block device to open
+ * @mode: FMODE_* mask
+ * @holder: exclusive holder identifier
+ *
+ * Open the blockdevice described by device number @dev. @mode and
+ * @holder are identical to blkdev_get().
+ *
+ * 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.
+ *
+ * On success, the returned block_device has reference count of one.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Pointer to block_device on success, ERR_PTR(-errno) on failure.
+ */
+struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
+{
+ struct block_device *bdev;
+ int err;
+
+ bdev = bdget(dev);
+ if (!bdev)
+ return ERR_PTR(-ENOMEM);
+
+ err = blkdev_get(bdev, mode, holder);
+ if (err)
+ return ERR_PTR(err);
+
+ return bdev;
+}
+EXPORT_SYMBOL(blkdev_get_by_dev);
+
+static int blkdev_open(struct inode * inode, struct file * filp)
+{
+ struct block_device *bdev;
+
+ /*
+ * 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;
+
+ return blkdev_get(bdev, filp->f_mode, filp);
+}
+
+static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
+{
+ struct gendisk *disk = bdev->bd_disk;
+ struct block_device *victim = NULL;
+
+ mutex_lock_nested(&bdev->bd_mutex, for_part);
+ if (for_part)
+ bdev->bd_part_count--;
+
+ if (!--bdev->bd_openers) {
+ WARN_ON_ONCE(bdev->bd_holders);
+ sync_blockdev(bdev);
+ kill_bdev(bdev);
+ /*
+ * ->release can cause the queue to disappear, so flush all
+ * dirty data before.
+ */
+ bdev_write_inode(bdev->bd_inode);
+ }
+ if (bdev->bd_contains == bdev) {
+ if (disk->fops->release)
+ disk->fops->release(disk, mode);
+ }
+ if (!bdev->bd_openers) {
+ struct module *owner = disk->fops->owner;
+
+ disk_put_part(bdev->bd_part);
+ bdev->bd_part = NULL;
+ bdev->bd_disk = NULL;
+ if (bdev != bdev->bd_contains)
+ victim = bdev->bd_contains;
+ bdev->bd_contains = NULL;
+
+ put_disk(disk);
+ module_put(owner);
+ }
+ mutex_unlock(&bdev->bd_mutex);
+ bdput(bdev);
+ if (victim)
+ __blkdev_put(victim, mode, 1);
+}
+
+void blkdev_put(struct block_device *bdev, fmode_t mode)
+{
+ mutex_lock(&bdev->bd_mutex);
+
+ if (mode & FMODE_EXCL) {
+ bool bdev_free;
+
+ /*
+ * Release a claim on the device. The holder fields
+ * are protected with bdev_lock. bd_mutex is to
+ * synchronize disk_holder unlinking.
+ */
+ spin_lock(&bdev_lock);
+
+ WARN_ON_ONCE(--bdev->bd_holders < 0);
+ WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
+
+ /* bd_contains might point to self, check in a separate step */
+ if ((bdev_free = !bdev->bd_holders))
+ bdev->bd_holder = NULL;
+ if (!bdev->bd_contains->bd_holders)
+ bdev->bd_contains->bd_holder = NULL;
+
+ spin_unlock(&bdev_lock);
+
+ /*
+ * If this was the last claim, remove holder link and
+ * unblock evpoll if it was a write holder.
+ */
+ if (bdev_free && bdev->bd_write_holder) {
+ disk_unblock_events(bdev->bd_disk);
+ bdev->bd_write_holder = false;
+ }
+ }
+
+ /*
+ * Trigger event checking and tell drivers to flush MEDIA_CHANGE
+ * event. This is to ensure detection of media removal commanded
+ * from userland - e.g. eject(1).
+ */
+ disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
+
+ mutex_unlock(&bdev->bd_mutex);
+
+ __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);
+ blkdev_put(bdev, filp->f_mode);
+ return 0;
+}
+
+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);
+}
+
+/*
+ * Write data to the block device. Only intended for the block device itself
+ * and the raw driver which basically is a fake block device.
+ *
+ * Does not take i_mutex for the write and thus is not for general purpose
+ * use.
+ */
+ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *bd_inode = file->f_mapping->host;
+ loff_t size = i_size_read(bd_inode);
+ struct blk_plug plug;
+ ssize_t ret;
+
+ if (bdev_read_only(I_BDEV(bd_inode)))
+ return -EPERM;
+
+ if (!iov_iter_count(from))
+ return 0;
+
+ if (iocb->ki_pos >= size)
+ return -ENOSPC;
+
+ iov_iter_truncate(from, size - iocb->ki_pos);
+
+ blk_start_plug(&plug);
+ ret = __generic_file_write_iter(iocb, from);
+ if (ret > 0) {
+ ssize_t err;
+ err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+ if (err < 0)
+ ret = err;
+ }
+ blk_finish_plug(&plug);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(blkdev_write_iter);
+
+ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *bd_inode = file->f_mapping->host;
+ loff_t size = i_size_read(bd_inode);
+ loff_t pos = iocb->ki_pos;
+
+ if (pos >= size)
+ return 0;
+
+ size -= pos;
+ iov_iter_truncate(to, size);
+ return generic_file_read_iter(iocb, to);
+}
+EXPORT_SYMBOL_GPL(blkdev_read_iter);
+
+/*
+ * Try to release a page associated with block device when the system
+ * is under memory pressure.
+ */
+static int blkdev_releasepage(struct page *page, gfp_t wait)
+{
+ struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
+
+ if (super && super->s_op->bdev_try_to_free_page)
+ return super->s_op->bdev_try_to_free_page(super, page, wait);
+
+ return try_to_free_buffers(page);
+}
+
+static const struct address_space_operations def_blk_aops = {
+ .readpage = blkdev_readpage,
+ .readpages = blkdev_readpages,
+ .writepage = blkdev_writepage,
+ .write_begin = blkdev_write_begin,
+ .write_end = blkdev_write_end,
+ .writepages = generic_writepages,
+ .releasepage = blkdev_releasepage,
+ .direct_IO = blkdev_direct_IO,
+ .is_dirty_writeback = buffer_check_dirty_writeback,
+};
+
+const struct file_operations def_blk_fops = {
+ .open = blkdev_open,
+ .release = blkdev_close,
+ .llseek = block_llseek,
+ .read_iter = blkdev_read_iter,
+ .write_iter = blkdev_write_iter,
+ .mmap = generic_file_mmap,
+ .fsync = blkdev_fsync,
+ .unlocked_ioctl = block_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = compat_blkdev_ioctl,
+#endif
+ .splice_read = generic_file_splice_read,
+ .splice_write = iter_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
+ * @pathname: 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 = d_backing_inode(path.dentry);
+ 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);
+
+int __invalidate_device(struct block_device *bdev, bool kill_dirty)
+{
+ 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, kill_dirty);
+ drop_super(sb);
+ }
+ invalidate_bdev(bdev);
+ return res;
+}
+EXPORT_SYMBOL(__invalidate_device);
+
+void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
+{
+ struct inode *inode, *old_inode = NULL;
+
+ spin_lock(&inode_sb_list_lock);
+ list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
+ struct address_space *mapping = inode->i_mapping;
+
+ spin_lock(&inode->i_lock);
+ if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
+ mapping->nrpages == 0) {
+ spin_unlock(&inode->i_lock);
+ continue;
+ }
+ __iget(inode);
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&inode_sb_list_lock);
+ /*
+ * We hold a reference to 'inode' so it couldn't have been
+ * removed from s_inodes list while we dropped the
+ * inode_sb_list_lock. We cannot iput the inode now as we can
+ * be holding the last reference and we cannot iput it under
+ * inode_sb_list_lock. So we keep the reference and iput it
+ * later.
+ */
+ iput(old_inode);
+ old_inode = inode;
+
+ func(I_BDEV(inode), arg);
+
+ spin_lock(&inode_sb_list_lock);
+ }
+ spin_unlock(&inode_sb_list_lock);
+ iput(old_inode);
+}