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authorChristoph Hellwig <hch@lst.de>2021-09-07 16:13:03 +0200
committerJens Axboe <axboe@kernel.dk>2021-09-07 08:39:40 -0600
commit0dca4462ed0681649fdcd5700a6ddfbaa65fa178 (patch)
tree51ea63fa87380ccea8e7d4eb8d5c6b2a1474411f /block/bdev.c
parentcd82cca7ebfe9c6c74a8e5b28382ba88177ba5f1 (diff)
block: move fs/block_dev.c to block/bdev.c
Move it together with the rest of the block layer. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210907141303.1371844-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bdev.c')
-rw-r--r--block/bdev.c1058
1 files changed, 1058 insertions, 0 deletions
diff --git a/block/bdev.c b/block/bdev.c
new file mode 100644
index 000000000000..cf2780cb44a7
--- /dev/null
+++ b/block/bdev.c
@@ -0,0 +1,1058 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
+ * Copyright (C) 2016 - 2020 Christoph Hellwig
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/major.h>
+#include <linux/device_cgroup.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/magic.h>
+#include <linux/buffer_head.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <linux/cleancache.h>
+#include <linux/part_stat.h>
+#include <linux/uaccess.h>
+#include "../fs/internal.h"
+#include "blk.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);
+}
+
+struct block_device *I_BDEV(struct inode *inode)
+{
+ return &BDEV_I(inode)->bdev;
+}
+EXPORT_SYMBOL(I_BDEV);
+
+static void bdev_write_inode(struct block_device *bdev)
+{
+ struct inode *inode = bdev->bd_inode;
+ int ret;
+
+ spin_lock(&inode->i_lock);
+ while (inode->i_state & I_DIRTY) {
+ spin_unlock(&inode->i_lock);
+ ret = write_inode_now(inode, true);
+ if (ret) {
+ char name[BDEVNAME_SIZE];
+ pr_warn_ratelimited("VFS: Dirty inode writeback failed "
+ "for block device %s (err=%d).\n",
+ bdevname(bdev, name), ret);
+ }
+ spin_lock(&inode->i_lock);
+ }
+ spin_unlock(&inode->i_lock);
+}
+
+/* Kill _all_ buffers and pagecache , dirty or not.. */
+static void kill_bdev(struct block_device *bdev)
+{
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+ if (mapping_empty(mapping))
+ return;
+
+ invalidate_bh_lrus();
+ truncate_inode_pages(mapping, 0);
+}
+
+/* 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) {
+ 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);
+
+/*
+ * Drop all buffers & page cache for given bdev range. This function bails
+ * with error if bdev has other exclusive owner (such as filesystem).
+ */
+int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
+ loff_t lstart, loff_t lend)
+{
+ /*
+ * If we don't hold exclusive handle for the device, upgrade to it
+ * while we discard the buffer cache to avoid discarding buffers
+ * under live filesystem.
+ */
+ if (!(mode & FMODE_EXCL)) {
+ int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
+ if (err)
+ goto invalidate;
+ }
+
+ truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
+ if (!(mode & FMODE_EXCL))
+ bd_abort_claiming(bdev, truncate_bdev_range);
+ return 0;
+
+invalidate:
+ /*
+ * Someone else has handle exclusively open. Try invalidating instead.
+ * The 'end' argument is inclusive so the rounding is safe.
+ */
+ return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
+ lstart >> PAGE_SHIFT,
+ lend >> PAGE_SHIFT);
+}
+
+static void set_init_blocksize(struct block_device *bdev)
+{
+ unsigned int bsize = bdev_logical_block_size(bdev);
+ loff_t size = i_size_read(bdev->bd_inode);
+
+ while (bsize < PAGE_SIZE) {
+ if (size & bsize)
+ break;
+ bsize <<= 1;
+ }
+ bdev->bd_inode->i_blkbits = blksize_bits(bsize);
+}
+
+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_inode->i_blkbits != blksize_bits(size)) {
+ sync_blockdev(bdev);
+ 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);
+
+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.
+ */
+int 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)
+ goto done;
+
+ sb = get_active_super(bdev);
+ if (!sb)
+ goto sync;
+ if (sb->s_op->freeze_super)
+ error = sb->s_op->freeze_super(sb);
+ else
+ error = freeze_super(sb);
+ deactivate_super(sb);
+
+ if (error) {
+ bdev->bd_fsfreeze_count--;
+ goto done;
+ }
+ bdev->bd_fsfreeze_sb = sb;
+
+sync:
+ sync_blockdev(bdev);
+done:
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return error;
+}
+EXPORT_SYMBOL(freeze_bdev);
+
+/**
+ * thaw_bdev -- unlock filesystem
+ * @bdev: blockdevice to unlock
+ *
+ * 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;
+
+ sb = bdev->bd_fsfreeze_sb;
+ 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++;
+ else
+ bdev->bd_fsfreeze_sb = NULL;
+out:
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ return error;
+}
+EXPORT_SYMBOL(thaw_bdev);
+
+/**
+ * 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;
+ int result = -EOPNOTSUPP;
+
+ if (!ops->rw_page || bdev_get_integrity(bdev))
+ return result;
+
+ result = blk_queue_enter(bdev->bd_disk->queue, 0);
+ if (result)
+ return result;
+ result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
+ REQ_OP_READ);
+ blk_queue_exit(bdev->bd_disk->queue);
+ return result;
+}
+
+/**
+ * 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;
+ const struct block_device_operations *ops = bdev->bd_disk->fops;
+
+ if (!ops->rw_page || bdev_get_integrity(bdev))
+ return -EOPNOTSUPP;
+ result = blk_queue_enter(bdev->bd_disk->queue, 0);
+ if (result)
+ return result;
+
+ set_page_writeback(page);
+ result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
+ REQ_OP_WRITE);
+ if (result) {
+ end_page_writeback(page);
+ } else {
+ clean_page_buffers(page);
+ unlock_page(page);
+ }
+ blk_queue_exit(bdev->bd_disk->queue);
+ return result;
+}
+
+/*
+ * 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;
+ memset(&ei->bdev, 0, sizeof(ei->bdev));
+ return &ei->vfs_inode;
+}
+
+static void bdev_free_inode(struct inode *inode)
+{
+ struct block_device *bdev = I_BDEV(inode);
+
+ free_percpu(bdev->bd_stats);
+ kfree(bdev->bd_meta_info);
+
+ if (!bdev_is_partition(bdev)) {
+ if (bdev->bd_disk && bdev->bd_disk->bdi)
+ bdi_put(bdev->bd_disk->bdi);
+ kfree(bdev->bd_disk);
+ }
+
+ if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
+ blk_free_ext_minor(MINOR(bdev->bd_dev));
+
+ kmem_cache_free(bdev_cachep, BDEV_I(inode));
+}
+
+static void init_once(void *data)
+{
+ struct bdev_inode *ei = data;
+
+ inode_init_once(&ei->vfs_inode);
+}
+
+static void bdev_evict_inode(struct inode *inode)
+{
+ truncate_inode_pages_final(&inode->i_data);
+ invalidate_inode_buffers(inode); /* is it needed here? */
+ clear_inode(inode);
+}
+
+static const struct super_operations bdev_sops = {
+ .statfs = simple_statfs,
+ .alloc_inode = bdev_alloc_inode,
+ .free_inode = bdev_free_inode,
+ .drop_inode = generic_delete_inode,
+ .evict_inode = bdev_evict_inode,
+};
+
+static int bd_init_fs_context(struct fs_context *fc)
+{
+ struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
+ if (!ctx)
+ return -ENOMEM;
+ fc->s_iflags |= SB_I_CGROUPWB;
+ ctx->ops = &bdev_sops;
+ return 0;
+}
+
+static struct file_system_type bd_type = {
+ .name = "bdev",
+ .init_fs_context = bd_init_fs_context,
+ .kill_sb = kill_anon_super,
+};
+
+struct super_block *blockdev_superblock __read_mostly;
+EXPORT_SYMBOL_GPL(blockdev_superblock);
+
+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_ACCOUNT|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 */
+}
+
+struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
+{
+ struct block_device *bdev;
+ struct inode *inode;
+
+ inode = new_inode(blockdev_superblock);
+ if (!inode)
+ return NULL;
+ inode->i_mode = S_IFBLK;
+ inode->i_rdev = 0;
+ inode->i_data.a_ops = &def_blk_aops;
+ mapping_set_gfp_mask(&inode->i_data, GFP_USER);
+
+ bdev = I_BDEV(inode);
+ mutex_init(&bdev->bd_fsfreeze_mutex);
+ spin_lock_init(&bdev->bd_size_lock);
+ bdev->bd_disk = disk;
+ bdev->bd_partno = partno;
+ bdev->bd_inode = inode;
+ bdev->bd_stats = alloc_percpu(struct disk_stats);
+ if (!bdev->bd_stats) {
+ iput(inode);
+ return NULL;
+ }
+ return bdev;
+}
+
+void bdev_add(struct block_device *bdev, dev_t dev)
+{
+ bdev->bd_dev = dev;
+ bdev->bd_inode->i_rdev = dev;
+ bdev->bd_inode->i_ino = dev;
+ insert_inode_hash(bdev->bd_inode);
+}
+
+long nr_blockdev_pages(void)
+{
+ struct inode *inode;
+ long ret = 0;
+
+ spin_lock(&blockdev_superblock->s_inode_list_lock);
+ list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
+ ret += inode->i_mapping->nrpages;
+ spin_unlock(&blockdev_superblock->s_inode_list_lock);
+
+ return ret;
+}
+
+/**
+ * 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 (whole == 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 - claim a block device
+ * @bdev: block device of interest
+ * @holder: holder trying to claim @bdev
+ *
+ * Claim @bdev. This function fails if @bdev is already claimed by another
+ * holder and waits if another claiming is in progress. return, the caller
+ * has ownership of bd_claiming and bd_holder[s].
+ *
+ * RETURNS:
+ * 0 if @bdev can be claimed, -EBUSY otherwise.
+ */
+int bd_prepare_to_claim(struct block_device *bdev, void *holder)
+{
+ struct block_device *whole = bdev_whole(bdev);
+
+ if (WARN_ON_ONCE(!holder))
+ return -EINVAL;
+retry:
+ spin_lock(&bdev_lock);
+ /* if someone else claimed, fail */
+ if (!bd_may_claim(bdev, whole, holder)) {
+ spin_unlock(&bdev_lock);
+ 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);
+ goto retry;
+ }
+
+ /* yay, all mine */
+ whole->bd_claiming = holder;
+ spin_unlock(&bdev_lock);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
+
+static void bd_clear_claiming(struct block_device *whole, void *holder)
+{
+ lockdep_assert_held(&bdev_lock);
+ /* tell others that we're done */
+ BUG_ON(whole->bd_claiming != holder);
+ whole->bd_claiming = NULL;
+ wake_up_bit(&whole->bd_claiming, 0);
+}
+
+/**
+ * bd_finish_claiming - finish claiming of a block device
+ * @bdev: block device of interest
+ * @holder: holder that has claimed @bdev
+ *
+ * Finish exclusive open of a block device. Mark the device as exlusively
+ * open by the holder and wake up all waiters for exclusive open to finish.
+ */
+static void bd_finish_claiming(struct block_device *bdev, void *holder)
+{
+ struct block_device *whole = bdev_whole(bdev);
+
+ spin_lock(&bdev_lock);
+ 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;
+ bd_clear_claiming(whole, holder);
+ spin_unlock(&bdev_lock);
+}
+
+/**
+ * bd_abort_claiming - abort claiming of a block device
+ * @bdev: block device of interest
+ * @holder: holder that has claimed @bdev
+ *
+ * Abort claiming of a block device when the exclusive open failed. This can be
+ * also used when exclusive open is not actually desired and we just needed
+ * to block other exclusive openers for a while.
+ */
+void bd_abort_claiming(struct block_device *bdev, void *holder)
+{
+ spin_lock(&bdev_lock);
+ bd_clear_claiming(bdev_whole(bdev), holder);
+ spin_unlock(&bdev_lock);
+}
+EXPORT_SYMBOL(bd_abort_claiming);
+
+static void blkdev_flush_mapping(struct block_device *bdev)
+{
+ WARN_ON_ONCE(bdev->bd_holders);
+ sync_blockdev(bdev);
+ kill_bdev(bdev);
+ bdev_write_inode(bdev);
+}
+
+static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
+{
+ struct gendisk *disk = bdev->bd_disk;
+ int ret = 0;
+
+ if (disk->fops->open) {
+ ret = disk->fops->open(bdev, mode);
+ if (ret) {
+ /* avoid ghost partitions on a removed medium */
+ if (ret == -ENOMEDIUM &&
+ test_bit(GD_NEED_PART_SCAN, &disk->state))
+ bdev_disk_changed(disk, true);
+ return ret;
+ }
+ }
+
+ if (!bdev->bd_openers)
+ set_init_blocksize(bdev);
+ if (test_bit(GD_NEED_PART_SCAN, &disk->state))
+ bdev_disk_changed(disk, false);
+ bdev->bd_openers++;
+ return 0;;
+}
+
+static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
+{
+ if (!--bdev->bd_openers)
+ blkdev_flush_mapping(bdev);
+ if (bdev->bd_disk->fops->release)
+ bdev->bd_disk->fops->release(bdev->bd_disk, mode);
+}
+
+static int blkdev_get_part(struct block_device *part, fmode_t mode)
+{
+ struct gendisk *disk = part->bd_disk;
+ int ret;
+
+ if (part->bd_openers)
+ goto done;
+
+ ret = blkdev_get_whole(bdev_whole(part), mode);
+ if (ret)
+ return ret;
+
+ ret = -ENXIO;
+ if (!bdev_nr_sectors(part))
+ goto out_blkdev_put;
+
+ disk->open_partitions++;
+ set_init_blocksize(part);
+done:
+ part->bd_openers++;
+ return 0;
+
+out_blkdev_put:
+ blkdev_put_whole(bdev_whole(part), mode);
+ return ret;
+}
+
+static void blkdev_put_part(struct block_device *part, fmode_t mode)
+{
+ struct block_device *whole = bdev_whole(part);
+
+ if (--part->bd_openers)
+ return;
+ blkdev_flush_mapping(part);
+ whole->bd_disk->open_partitions--;
+ blkdev_put_whole(whole, mode);
+}
+
+struct block_device *blkdev_get_no_open(dev_t dev)
+{
+ struct block_device *bdev;
+ struct inode *inode;
+
+ inode = ilookup(blockdev_superblock, dev);
+ if (!inode) {
+ blk_request_module(dev);
+ inode = ilookup(blockdev_superblock, dev);
+ if (!inode)
+ return NULL;
+ }
+
+ /* switch from the inode reference to a device mode one: */
+ bdev = &BDEV_I(inode)->bdev;
+ if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
+ bdev = NULL;
+ iput(inode);
+
+ if (!bdev)
+ return NULL;
+ if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN) ||
+ !try_module_get(bdev->bd_disk->fops->owner)) {
+ put_device(&bdev->bd_device);
+ return NULL;
+ }
+
+ return bdev;
+}
+
+void blkdev_put_no_open(struct block_device *bdev)
+{
+ module_put(bdev->bd_disk->fops->owner);
+ put_device(&bdev->bd_device);
+}
+
+/**
+ * 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 block device described by device number @dev. If @mode includes
+ * %FMODE_EXCL, the block device is opened with exclusive access. Specifying
+ * %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may nest for
+ * the same @holder.
+ *
+ * Use this interface 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. Everything else should use blkdev_get_by_path().
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Reference to the block_device on success, ERR_PTR(-errno) on failure.
+ */
+struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
+{
+ bool unblock_events = true;
+ struct block_device *bdev;
+ struct gendisk *disk;
+ int ret;
+
+ ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
+ MAJOR(dev), MINOR(dev),
+ ((mode & FMODE_READ) ? DEVCG_ACC_READ : 0) |
+ ((mode & FMODE_WRITE) ? DEVCG_ACC_WRITE : 0));
+ if (ret)
+ return ERR_PTR(ret);
+
+ bdev = blkdev_get_no_open(dev);
+ if (!bdev)
+ return ERR_PTR(-ENXIO);
+ disk = bdev->bd_disk;
+
+ if (mode & FMODE_EXCL) {
+ ret = bd_prepare_to_claim(bdev, holder);
+ if (ret)
+ goto put_blkdev;
+ }
+
+ disk_block_events(disk);
+
+ mutex_lock(&disk->open_mutex);
+ ret = -ENXIO;
+ if (!disk_live(disk))
+ goto abort_claiming;
+ if (bdev_is_partition(bdev))
+ ret = blkdev_get_part(bdev, mode);
+ else
+ ret = blkdev_get_whole(bdev, mode);
+ if (ret)
+ goto abort_claiming;
+ if (mode & FMODE_EXCL) {
+ bd_finish_claiming(bdev, holder);
+
+ /*
+ * 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 ((mode & FMODE_WRITE) && !bdev->bd_write_holder &&
+ (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
+ bdev->bd_write_holder = true;
+ unblock_events = false;
+ }
+ }
+ mutex_unlock(&disk->open_mutex);
+
+ if (unblock_events)
+ disk_unblock_events(disk);
+ return bdev;
+
+abort_claiming:
+ if (mode & FMODE_EXCL)
+ bd_abort_claiming(bdev, holder);
+ mutex_unlock(&disk->open_mutex);
+ disk_unblock_events(disk);
+put_blkdev:
+ blkdev_put_no_open(bdev);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(blkdev_get_by_dev);
+
+/**
+ * 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 block device described by the device file at @path. If @mode
+ * includes %FMODE_EXCL, the block device is opened with exclusive access.
+ * Specifying %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may
+ * nest for the same @holder.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Reference to the 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;
+ dev_t dev;
+ int error;
+
+ error = lookup_bdev(path, &dev);
+ if (error)
+ return ERR_PTR(error);
+
+ bdev = blkdev_get_by_dev(dev, mode, holder);
+ if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
+ blkdev_put(bdev, mode);
+ return ERR_PTR(-EACCES);
+ }
+
+ return bdev;
+}
+EXPORT_SYMBOL(blkdev_get_by_path);
+
+void blkdev_put(struct block_device *bdev, fmode_t mode)
+{
+ struct gendisk *disk = bdev->bd_disk;
+
+ /*
+ * Sync early if it looks like we're the last one. If someone else
+ * opens the block device between now and the decrement of bd_openers
+ * then we did a sync that we didn't need to, but that's not the end
+ * of the world and we want to avoid long (could be several minute)
+ * syncs while holding the mutex.
+ */
+ if (bdev->bd_openers == 1)
+ sync_blockdev(bdev);
+
+ mutex_lock(&disk->open_mutex);
+ if (mode & FMODE_EXCL) {
+ struct block_device *whole = bdev_whole(bdev);
+ bool bdev_free;
+
+ /*
+ * Release a claim on the device. The holder fields
+ * are protected with bdev_lock. open_mutex is to
+ * synchronize disk_holder unlinking.
+ */
+ spin_lock(&bdev_lock);
+
+ WARN_ON_ONCE(--bdev->bd_holders < 0);
+ WARN_ON_ONCE(--whole->bd_holders < 0);
+
+ if ((bdev_free = !bdev->bd_holders))
+ bdev->bd_holder = NULL;
+ if (!whole->bd_holders)
+ whole->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(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(disk, DISK_EVENT_MEDIA_CHANGE);
+
+ if (bdev_is_partition(bdev))
+ blkdev_put_part(bdev, mode);
+ else
+ blkdev_put_whole(bdev, mode);
+ mutex_unlock(&disk->open_mutex);
+
+ blkdev_put_no_open(bdev);
+}
+EXPORT_SYMBOL(blkdev_put);
+
+/**
+ * lookup_bdev - lookup a struct block_device by name
+ * @pathname: special file representing the block device
+ * @dev: return value of the block device's dev_t
+ *
+ * Get a reference to the blockdevice at @pathname in the current
+ * namespace if possible and return it. Return ERR_PTR(error)
+ * otherwise.
+ */
+int lookup_bdev(const char *pathname, dev_t *dev)
+{
+ struct inode *inode;
+ struct path path;
+ int error;
+
+ if (!pathname || !*pathname)
+ return -EINVAL;
+
+ error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+ if (error)
+ return error;
+
+ inode = d_backing_inode(path.dentry);
+ error = -ENOTBLK;
+ if (!S_ISBLK(inode->i_mode))
+ goto out_path_put;
+ error = -EACCES;
+ if (!may_open_dev(&path))
+ goto out_path_put;
+
+ *dev = inode->i_rdev;
+ error = 0;
+out_path_put:
+ path_put(&path);
+ return error;
+}
+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(&blockdev_superblock->s_inode_list_lock);
+ list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
+ struct address_space *mapping = inode->i_mapping;
+ struct block_device *bdev;
+
+ 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(&blockdev_superblock->s_inode_list_lock);
+ /*
+ * We hold a reference to 'inode' so it couldn't have been
+ * removed from s_inodes list while we dropped the
+ * s_inode_list_lock We cannot iput the inode now as we can
+ * be holding the last reference and we cannot iput it under
+ * s_inode_list_lock. So we keep the reference and iput it
+ * later.
+ */
+ iput(old_inode);
+ old_inode = inode;
+ bdev = I_BDEV(inode);
+
+ mutex_lock(&bdev->bd_disk->open_mutex);
+ if (bdev->bd_openers)
+ func(bdev, arg);
+ mutex_unlock(&bdev->bd_disk->open_mutex);
+
+ spin_lock(&blockdev_superblock->s_inode_list_lock);
+ }
+ spin_unlock(&blockdev_superblock->s_inode_list_lock);
+ iput(old_inode);
+}