diff options
Diffstat (limited to 'kernel/fs/block_dev.c')
| -rw-r--r-- | kernel/fs/block_dev.c | 1795 |
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); +} |