diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/block_dev.c | 2209 |
1 files changed, 2209 insertions, 0 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c new file mode 100644 index 000000000..b34f76af5 --- /dev/null +++ b/fs/block_dev.c @@ -0,0 +1,2209 @@ +/* + * 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/backing-dev.h> +#include <linux/module.h> +#include <linux/blkpg.h> +#include <linux/magic.h> +#include <linux/dax.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 <linux/dax.h> +#include <linux/badblocks.h> +#include <linux/task_io_accounting_ops.h> +#include <linux/falloc.h> +#include <linux/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); +} + +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.. */ +void kill_bdev(struct block_device *bdev) +{ + struct address_space *mapping = bdev->bd_inode->i_mapping; + + if (mapping->nrpages == 0 && mapping->nrexceptional == 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) { + 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); + +static void set_init_blocksize(struct block_device *bdev) +{ + unsigned 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_block_size = bsize; + 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_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 struct inode *bdev_file_inode(struct file *file) +{ + return file->f_mapping->host; +} + +static unsigned int dio_bio_write_op(struct kiocb *iocb) +{ + unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; + + /* avoid the need for a I/O completion work item */ + if (iocb->ki_flags & IOCB_DSYNC) + op |= REQ_FUA; + return op; +} + +#define DIO_INLINE_BIO_VECS 4 + +static void blkdev_bio_end_io_simple(struct bio *bio) +{ + struct task_struct *waiter = bio->bi_private; + + WRITE_ONCE(bio->bi_private, NULL); + wake_up_process(waiter); +} + +static ssize_t +__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, + int nr_pages) +{ + struct file *file = iocb->ki_filp; + struct block_device *bdev = I_BDEV(bdev_file_inode(file)); + struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs, *bvec; + loff_t pos = iocb->ki_pos; + bool should_dirty = false; + struct bio bio; + ssize_t ret; + blk_qc_t qc; + int i; + + if ((pos | iov_iter_alignment(iter)) & + (bdev_logical_block_size(bdev) - 1)) + return -EINVAL; + + if (nr_pages <= DIO_INLINE_BIO_VECS) + vecs = inline_vecs; + else { + vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec), + GFP_KERNEL); + if (!vecs) + return -ENOMEM; + } + + bio_init(&bio, vecs, nr_pages); + bio_set_dev(&bio, bdev); + bio.bi_iter.bi_sector = pos >> 9; + bio.bi_write_hint = iocb->ki_hint; + bio.bi_private = current; + bio.bi_end_io = blkdev_bio_end_io_simple; + bio.bi_ioprio = iocb->ki_ioprio; + + ret = bio_iov_iter_get_pages(&bio, iter); + if (unlikely(ret)) + goto out; + ret = bio.bi_iter.bi_size; + + if (iov_iter_rw(iter) == READ) { + bio.bi_opf = REQ_OP_READ; + if (iter_is_iovec(iter)) + should_dirty = true; + } else { + bio.bi_opf = dio_bio_write_op(iocb); + task_io_account_write(ret); + } + + qc = submit_bio(&bio); + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(bio.bi_private)) + break; + if (!(iocb->ki_flags & IOCB_HIPRI) || + !blk_poll(bdev_get_queue(bdev), qc)) + io_schedule(); + } + __set_current_state(TASK_RUNNING); + + bio_for_each_segment_all(bvec, &bio, i) { + if (should_dirty && !PageCompound(bvec->bv_page)) + set_page_dirty_lock(bvec->bv_page); + put_page(bvec->bv_page); + } + + if (unlikely(bio.bi_status)) + ret = blk_status_to_errno(bio.bi_status); + +out: + if (vecs != inline_vecs) + kfree(vecs); + + bio_uninit(&bio); + + return ret; +} + +struct blkdev_dio { + union { + struct kiocb *iocb; + struct task_struct *waiter; + }; + size_t size; + atomic_t ref; + bool multi_bio : 1; + bool should_dirty : 1; + bool is_sync : 1; + struct bio bio; +}; + +static struct bio_set blkdev_dio_pool; + +static void blkdev_bio_end_io(struct bio *bio) +{ + struct blkdev_dio *dio = bio->bi_private; + bool should_dirty = dio->should_dirty; + + if (bio->bi_status && !dio->bio.bi_status) + dio->bio.bi_status = bio->bi_status; + + if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) { + if (!dio->is_sync) { + struct kiocb *iocb = dio->iocb; + ssize_t ret; + + if (likely(!dio->bio.bi_status)) { + ret = dio->size; + iocb->ki_pos += ret; + } else { + ret = blk_status_to_errno(dio->bio.bi_status); + } + + dio->iocb->ki_complete(iocb, ret, 0); + bio_put(&dio->bio); + } else { + struct task_struct *waiter = dio->waiter; + + WRITE_ONCE(dio->waiter, NULL); + wake_up_process(waiter); + } + } + + if (should_dirty) { + bio_check_pages_dirty(bio); + } else { + struct bio_vec *bvec; + int i; + + bio_for_each_segment_all(bvec, bio, i) + put_page(bvec->bv_page); + bio_put(bio); + } +} + +static ssize_t +__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) +{ + struct file *file = iocb->ki_filp; + struct inode *inode = bdev_file_inode(file); + struct block_device *bdev = I_BDEV(inode); + struct blk_plug plug; + struct blkdev_dio *dio; + struct bio *bio; + bool is_read = (iov_iter_rw(iter) == READ), is_sync; + loff_t pos = iocb->ki_pos; + blk_qc_t qc = BLK_QC_T_NONE; + int ret = 0; + + if ((pos | iov_iter_alignment(iter)) & + (bdev_logical_block_size(bdev) - 1)) + return -EINVAL; + + bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool); + bio_get(bio); /* extra ref for the completion handler */ + + dio = container_of(bio, struct blkdev_dio, bio); + dio->is_sync = is_sync = is_sync_kiocb(iocb); + if (dio->is_sync) + dio->waiter = current; + else + dio->iocb = iocb; + + dio->size = 0; + dio->multi_bio = false; + dio->should_dirty = is_read && (iter->type == ITER_IOVEC); + + blk_start_plug(&plug); + for (;;) { + bio_set_dev(bio, bdev); + bio->bi_iter.bi_sector = pos >> 9; + bio->bi_write_hint = iocb->ki_hint; + bio->bi_private = dio; + bio->bi_end_io = blkdev_bio_end_io; + bio->bi_ioprio = iocb->ki_ioprio; + + ret = bio_iov_iter_get_pages(bio, iter); + if (unlikely(ret)) { + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + break; + } + + if (is_read) { + bio->bi_opf = REQ_OP_READ; + if (dio->should_dirty) + bio_set_pages_dirty(bio); + } else { + bio->bi_opf = dio_bio_write_op(iocb); + task_io_account_write(bio->bi_iter.bi_size); + } + + dio->size += bio->bi_iter.bi_size; + pos += bio->bi_iter.bi_size; + + nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES); + if (!nr_pages) { + qc = submit_bio(bio); + break; + } + + if (!dio->multi_bio) { + dio->multi_bio = true; + atomic_set(&dio->ref, 2); + } else { + atomic_inc(&dio->ref); + } + + submit_bio(bio); + bio = bio_alloc(GFP_KERNEL, nr_pages); + } + blk_finish_plug(&plug); + + if (!is_sync) + return -EIOCBQUEUED; + + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(dio->waiter)) + break; + + if (!(iocb->ki_flags & IOCB_HIPRI) || + !blk_poll(bdev_get_queue(bdev), qc)) + io_schedule(); + } + __set_current_state(TASK_RUNNING); + + if (!ret) + ret = blk_status_to_errno(dio->bio.bi_status); + if (likely(!ret)) + ret = dio->size; + + bio_put(&dio->bio); + return ret; +} + +static ssize_t +blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) +{ + int nr_pages; + + nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1); + if (!nr_pages) + return 0; + if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES) + return __blkdev_direct_IO_simple(iocb, iter, nr_pages); + + return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES)); +} + +static __init int blkdev_init(void) +{ + return bioset_init(&blkdev_dio_pool, 4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS); +} +module_init(blkdev_init); + +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); + if (sb) + 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++; +out: + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return error; +} +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); + put_page(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 = bdev_file_inode(file); + loff_t retval; + + inode_lock(bd_inode); + retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode)); + inode_unlock(bd_inode); + return retval; +} + +int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) +{ + struct inode *bd_inode = bdev_file_inode(filp); + struct block_device *bdev = I_BDEV(bd_inode); + int error; + + error = file_write_and_wait_range(filp, 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; + int result = -EOPNOTSUPP; + + if (!ops->rw_page || bdev_get_integrity(bdev)) + return result; + + result = blk_queue_enter(bdev->bd_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_queue); + return result; +} +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; + 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_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_queue); + return result; +} +EXPORT_SYMBOL_GPL(bdev_write_page); + +/* + * 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_list); +#ifdef CONFIG_SYSFS + INIT_LIST_HEAD(&bdev->bd_holder_disks); +#endif + bdev->bd_bdi = &noop_backing_dev_info; + inode_init_once(&ei->vfs_inode); + /* Initialize mutex for freeze. */ + mutex_init(&bdev->bd_fsfreeze_mutex); +} + +static void bdev_evict_inode(struct inode *inode) +{ + struct block_device *bdev = &BDEV_I(inode)->bdev; + truncate_inode_pages_final(&inode->i_data); + invalidate_inode_buffers(inode); /* is it needed here? */ + clear_inode(inode); + spin_lock(&bdev_lock); + list_del_init(&bdev->bd_list); + spin_unlock(&bdev_lock); + /* Detach inode from wb early as bdi_put() may free bdi->wb */ + inode_detach_wb(inode); + if (bdev->bd_bdi != &noop_backing_dev_info) { + bdi_put(bdev->bd_bdi); + bdev->bd_bdi = &noop_backing_dev_info; + } +} + +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) +{ + struct dentry *dent; + dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC); + if (!IS_ERR(dent)) + dent->d_sb->s_iflags |= SB_I_CGROUPWB; + return dent; +} + +static struct file_system_type bd_type = { + .name = "bdev", + .mount = bd_mount, + .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 */ +} + +/* + * 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); + +/* + * If there is a bdev inode for this device, unhash it so that it gets evicted + * as soon as last inode reference is dropped. + */ +void bdev_unhash_inode(dev_t dev) +{ + struct inode *inode; + + inode = ilookup5(blockdev_superblock, hash(dev), bdev_test, &dev); + if (inode) { + remove_inode_hash(inode); + iput(inode); + } +} + +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 = i_blocksize(inode); + 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 && !inode_unhashed(bdev->bd_inode)) { + bdgrab(bdev); + spin_unlock(&bdev_lock); + return bdev; + } + spin_unlock(&bdev_lock); + + /* + * i_bdev references block device inode that was already shut down + * (corresponding device got removed). Remove the reference and look + * up block device inode again just in case new device got + * reestablished under the same device number. + */ + if (bdev) + bd_forget(inode); + + 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(). + */ + bdgrab(bdev); + inode->i_bdev = bdev; + inode->i_mapping = bdev->bd_inode->i_mapping; + } + spin_unlock(&bdev_lock); + } + return bdev; +} + +/* Call when you free inode */ + +void bd_forget(struct inode *inode) +{ + struct block_device *bdev = NULL; + + spin_lock(&bdev_lock); + if (!sb_is_blkdev_sb(inode->i_sb)) + bdev = inode->i_bdev; + inode->i_bdev = NULL; + inode->i_mapping = &inode->i_data; + spin_unlock(&bdev_lock); + + if (bdev) + bdput(bdev); +} + +/** + * 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 - 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; +} + +static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno) +{ + struct gendisk *disk = get_gendisk(bdev->bd_dev, partno); + + if (!disk) + return NULL; + /* + * Now that we hold gendisk reference we make sure bdev we looked up is + * not stale. If it is, it means device got removed and created before + * we looked up gendisk and we fail open in such case. Associating + * unhashed bdev with newly created gendisk could lead to two bdevs + * (and thus two independent caches) being associated with one device + * which is bad. + */ + if (inode_unhashed(bdev->bd_inode)) { + put_disk_and_module(disk); + return NULL; + } + return disk; +} + +/** + * 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 = bdev_get_gendisk(bdev, &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); + + put_disk_and_module(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)) { + printk(KERN_WARNING "VFS: busy inodes on changed media or " + "resized disk %s\n", + bdev->bd_disk ? bdev->bd_disk->disk_name : ""); + } + 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. + * @verbose: if %true log a message about a size change if there is any + * + * This routine checks to see if the bdev size does not match the disk size + * and adjusts it if it differs. When shrinking the bdev size, its all caches + * are freed. + */ +void check_disk_size_change(struct gendisk *disk, struct block_device *bdev, + bool verbose) +{ + 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) { + if (verbose) { + printk(KERN_INFO + "%s: detected capacity change from %lld to %lld\n", + disk->disk_name, bdev_size, disk_size); + } + i_size_write(bdev->bd_inode, disk_size); + if (bdev_size > disk_size) + flush_disk(bdev, false); + } +} + +/** + * 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, ret == 0); + 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) +{ + inode_lock(bdev->bd_inode); + i_size_write(bdev->bd_inode, size); + inode_unlock(bdev->bd_inode); +} +EXPORT_SYMBOL(bd_set_size); + +static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); + +static void bdev_disk_changed(struct block_device *bdev, bool invalidate) +{ + if (disk_part_scan_enabled(bdev->bd_disk)) { + if (invalidate) + invalidate_partitions(bdev->bd_disk, bdev); + else + rescan_partitions(bdev->bd_disk, bdev); + } else { + check_disk_size_change(bdev->bd_disk, bdev, !invalidate); + bdev->bd_invalidated = 0; + } +} + +/* + * bd_mutex locking: + * + * mutex_lock(part->bd_mutex) + * mutex_lock_nested(whole->bd_mutex, 1) + */ + +static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) +{ + struct gendisk *disk; + int ret; + int partno; + int perm = 0; + bool first_open = false; + + 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) + return ret; + } + + restart: + + ret = -ENXIO; + disk = bdev_get_gendisk(bdev, &partno); + if (!disk) + goto out; + + disk_block_events(disk); + mutex_lock_nested(&bdev->bd_mutex, for_part); + if (!bdev->bd_openers) { + first_open = true; + bdev->bd_disk = disk; + bdev->bd_queue = disk->queue; + bdev->bd_contains = bdev; + bdev->bd_partno = partno; + + 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_and_module(disk); + goto restart; + } + } + + if (!ret) { + bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); + set_init_blocksize(bdev); + } + + /* + * 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 && + (!ret || ret == -ENOMEDIUM)) + bdev_disk_changed(bdev, ret == -ENOMEDIUM); + + 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) { + bdput(whole); + 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); + set_init_blocksize(bdev); + } + + if (bdev->bd_bdi == &noop_backing_dev_info) + bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info); + } 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 && + (!ret || ret == -ENOMEDIUM)) + bdev_disk_changed(bdev, ret == -ENOMEDIUM); + if (ret) + goto out_unlock_bdev; + } + } + bdev->bd_openers++; + if (for_part) + bdev->bd_part_count++; + mutex_unlock(&bdev->bd_mutex); + disk_unblock_events(disk); + /* only one opener holds refs to the module and disk */ + if (!first_open) + put_disk_and_module(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_and_module(disk); + out: + + 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); + } + + if (res) + bdput(bdev); + + 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; + + filp->f_mode |= FMODE_NOWAIT; + + 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; + filp->f_wb_err = filemap_sample_wb_err(filp->f_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; + + /* + * 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_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); + + bdev_write_inode(bdev); + } + if (bdev->bd_contains == bdev) { + if (disk->fops->release) + disk->fops->release(disk, mode); + } + if (!bdev->bd_openers) { + 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_and_module(disk); + } + 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(bdev_file_inode(filp)); + 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(bdev_file_inode(file)); + 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 = bdev_file_inode(file); + loff_t size = i_size_read(bd_inode); + struct blk_plug plug; + size_t shorted = 0; + 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; + + if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT) + return -EOPNOTSUPP; + + size -= iocb->ki_pos; + if (iov_iter_count(from) > size) { + shorted = iov_iter_count(from) - size; + iov_iter_truncate(from, size); + } + + blk_start_plug(&plug); + ret = __generic_file_write_iter(iocb, from); + if (ret > 0) + ret = generic_write_sync(iocb, ret); + iov_iter_reexpand(from, iov_iter_count(from) + shorted); + 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 = bdev_file_inode(file); + loff_t size = i_size_read(bd_inode); + loff_t pos = iocb->ki_pos; + size_t shorted = 0; + ssize_t ret; + + if (pos >= size) + return 0; + + size -= pos; + if (iov_iter_count(to) > size) { + shorted = iov_iter_count(to) - size; + iov_iter_truncate(to, size); + } + + ret = generic_file_read_iter(iocb, to); + iov_iter_reexpand(to, iov_iter_count(to) + shorted); + return ret; +} +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 int blkdev_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + return generic_writepages(mapping, wbc); +} + +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 = blkdev_writepages, + .releasepage = blkdev_releasepage, + .direct_IO = blkdev_direct_IO, + .is_dirty_writeback = buffer_check_dirty_writeback, +}; + +#define BLKDEV_FALLOC_FL_SUPPORTED \ + (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \ + FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE) + +static long blkdev_fallocate(struct file *file, int mode, loff_t start, + loff_t len) +{ + struct block_device *bdev = I_BDEV(bdev_file_inode(file)); + struct address_space *mapping; + loff_t end = start + len - 1; + loff_t isize; + int error; + + /* Fail if we don't recognize the flags. */ + if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED) + return -EOPNOTSUPP; + + /* Don't go off the end of the device. */ + isize = i_size_read(bdev->bd_inode); + if (start >= isize) + return -EINVAL; + if (end >= isize) { + if (mode & FALLOC_FL_KEEP_SIZE) { + len = isize - start; + end = start + len - 1; + } else + return -EINVAL; + } + + /* + * Don't allow IO that isn't aligned to logical block size. + */ + if ((start | len) & (bdev_logical_block_size(bdev) - 1)) + return -EINVAL; + + /* Invalidate the page cache, including dirty pages. */ + mapping = bdev->bd_inode->i_mapping; + truncate_inode_pages_range(mapping, start, end); + + switch (mode) { + case FALLOC_FL_ZERO_RANGE: + case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE: + error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, + GFP_KERNEL, BLKDEV_ZERO_NOUNMAP); + break; + case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE: + error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, + GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK); + break; + case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE: + error = blkdev_issue_discard(bdev, start >> 9, len >> 9, + GFP_KERNEL, 0); + break; + default: + return -EOPNOTSUPP; + } + if (error) + return error; + + /* + * Invalidate again; if someone wandered in and dirtied a page, + * the caller will be given -EBUSY. The third argument is + * inclusive, so the rounding here is safe. + */ + return invalidate_inode_pages2_range(mapping, + start >> PAGE_SHIFT, + end >> PAGE_SHIFT); +} + +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, + .fallocate = blkdev_fallocate, +}; + +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 (!may_open_dev(&path)) + 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(&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_mutex); + if (bdev->bd_openers) + func(bdev, arg); + mutex_unlock(&bdev->bd_mutex); + + spin_lock(&blockdev_superblock->s_inode_list_lock); + } + spin_unlock(&blockdev_superblock->s_inode_list_lock); + iput(old_inode); +} |