/* * linux/fs/block_dev.c * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE */ #include <linux/config.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/fcntl.h> #include <linux/slab.h> #include <linux/kmod.h> #include <linux/major.h> #include <linux/devfs_fs_kernel.h> #include <linux/smp_lock.h> #include <linux/highmem.h> #include <linux/blkdev.h> #include <linux/module.h> #include <linux/blkpg.h> #include <linux/buffer_head.h> #include <linux/mpage.h> #include <linux/mount.h> #include <linux/uio.h> #include <linux/namei.h> #include <asm/uaccess.h> static sector_t max_block(struct block_device *bdev) { sector_t retval = ~((sector_t)0); loff_t sz = bdev->bd_inode->i_size; if (sz) { unsigned int size = block_size(bdev); unsigned int sizebits = blksize_bits(size); retval = (sz >> sizebits); } return retval; } /* Kill _all_ buffers, dirty or not.. */ static void kill_bdev(struct block_device *bdev) { invalidate_bdev(bdev, 1); truncate_inode_pages(bdev->bd_inode->i_mapping, 0); } int set_blocksize(struct block_device *bdev, int size) { int oldsize; /* Size must be a power of two, and between 512 and PAGE_SIZE */ if (size > PAGE_SIZE || size < 512 || (size & (size-1))) return -EINVAL; /* Size cannot be smaller than the size supported by the device */ if (size < bdev_hardsect_size(bdev)) return -EINVAL; oldsize = bdev->bd_block_size; if (oldsize == size) return 0; /* Ok, we're actually changing the blocksize.. */ sync_blockdev(bdev); bdev->bd_block_size = size; bdev->bd_inode->i_blkbits = blksize_bits(size); kill_bdev(bdev); return 0; } int sb_set_blocksize(struct super_block *sb, int size) { int bits; if (set_blocksize(sb->s_bdev, size) < 0) return 0; sb->s_blocksize = size; for (bits = 9, size >>= 9; size >>= 1; bits++) ; sb->s_blocksize_bits = bits; return sb->s_blocksize; } int sb_min_blocksize(struct super_block *sb, int size) { int minsize = bdev_hardsect_size(sb->s_bdev); if (size < minsize) size = minsize; return sb_set_blocksize(sb, size); } static int blkdev_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh, int create) { if (iblock >= max_block(inode->i_bdev)) return -EIO; bh->b_bdev = inode->i_bdev; bh->b_blocknr = iblock; set_buffer_mapped(bh); return 0; } static int blkdev_get_blocks(struct inode *inode, sector_t iblock, unsigned long max_blocks, struct buffer_head *bh, int create) { if ((iblock + max_blocks) > max_block(inode->i_bdev)) return -EIO; bh->b_bdev = inode->i_bdev; bh->b_blocknr = iblock; bh->b_size = max_blocks << inode->i_blkbits; set_buffer_mapped(bh); return 0; } static int blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t offset, unsigned long nr_segs) { struct file *file = iocb->ki_filp; struct inode *inode = file->f_dentry->d_inode->i_mapping->host; return blockdev_direct_IO(rw, iocb, inode, inode->i_bdev, iov, offset, nr_segs, blkdev_get_blocks); } static int blkdev_writepage(struct page *page, struct writeback_control *wbc) { return block_write_full_page(page, blkdev_get_block, wbc); } static int blkdev_readpage(struct file * file, struct page * page) { return block_read_full_page(page, blkdev_get_block); } static int blkdev_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) { return block_prepare_write(page, from, to, blkdev_get_block); } static int blkdev_commit_write(struct file *file, struct page *page, unsigned from, unsigned to) { return block_commit_write(page, from, to); } /* * private llseek: * for a block special file file->f_dentry->d_inode->i_size is zero * so we compute the size by hand (just as in block_read/write above) */ static loff_t block_llseek(struct file *file, loff_t offset, int origin) { /* ewww */ loff_t size = file->f_dentry->d_inode->i_bdev->bd_inode->i_size; loff_t retval; lock_kernel(); switch (origin) { case 2: offset += size; break; case 1: offset += file->f_pos; } retval = -EINVAL; if (offset >= 0 && offset <= size) { if (offset != file->f_pos) { file->f_pos = offset; } retval = offset; } unlock_kernel(); return retval; } /* * Filp may be NULL when we are called by an msync of a vma * since the vma has no handle. */ static int block_fsync(struct file *filp, struct dentry *dentry, int datasync) { struct inode * inode = dentry->d_inode; return sync_blockdev(inode->i_bdev); } /* * pseudo-fs */ static struct super_block *bd_get_sb(struct file_system_type *fs_type, int flags, char *dev_name, void *data) { return get_sb_pseudo(fs_type, "bdev:", NULL, 0x62646576); } static struct file_system_type bd_type = { .name = "bdev", .get_sb = bd_get_sb, .kill_sb = kill_anon_super, }; static struct vfsmount *bd_mnt; struct super_block *blockdev_superblock; /* * bdev cache handling - shamelessly stolen from inode.c * We use smaller hashtable, though. */ #define HASH_BITS 6 #define HASH_SIZE (1UL << HASH_BITS) #define HASH_MASK (HASH_SIZE-1) static struct list_head bdev_hashtable[HASH_SIZE]; static spinlock_t bdev_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED; static kmem_cache_t * bdev_cachep; #define alloc_bdev() \ ((struct block_device *) kmem_cache_alloc(bdev_cachep, SLAB_KERNEL)) #define destroy_bdev(bdev) kmem_cache_free(bdev_cachep, (bdev)) static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags) { struct block_device * bdev = (struct block_device *) foo; if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) { memset(bdev, 0, sizeof(*bdev)); sema_init(&bdev->bd_sem, 1); INIT_LIST_HEAD(&bdev->bd_inodes); } } void __init bdev_cache_init(void) { int i, err; struct list_head *head = bdev_hashtable; i = HASH_SIZE; do { INIT_LIST_HEAD(head); head++; i--; } while (i); bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct block_device), 0, SLAB_HWCACHE_ALIGN, init_once, NULL); if (!bdev_cachep) panic("Cannot create bdev_cache SLAB cache"); err = register_filesystem(&bd_type); if (err) panic("Cannot register bdev pseudo-fs"); bd_mnt = kern_mount(&bd_type); err = PTR_ERR(bd_mnt); if (IS_ERR(bd_mnt)) panic("Cannot create bdev pseudo-fs"); blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ } /* * Most likely _very_ bad one - but then it's hardly critical for small * /dev and can be fixed when somebody will need really large one. */ static inline unsigned long hash(dev_t dev) { unsigned long tmp = dev; tmp = tmp + (tmp >> HASH_BITS) + (tmp >> HASH_BITS*2); return tmp & HASH_MASK; } static struct block_device *bdfind(dev_t dev, struct list_head *head) { struct list_head *p; struct block_device *bdev; list_for_each(p, head) { bdev = list_entry(p, struct block_device, bd_hash); if (bdev->bd_dev != dev) continue; atomic_inc(&bdev->bd_count); return bdev; } return NULL; } struct block_device *bdget(dev_t dev) { struct list_head * head = bdev_hashtable + hash(dev); struct block_device *bdev, *new_bdev; spin_lock(&bdev_lock); bdev = bdfind(dev, head); spin_unlock(&bdev_lock); if (bdev) return bdev; new_bdev = alloc_bdev(); if (new_bdev) { struct inode *inode = new_inode(bd_mnt->mnt_sb); if (inode) { kdev_t kdev = to_kdev_t(dev); atomic_set(&new_bdev->bd_count,1); new_bdev->bd_dev = dev; new_bdev->bd_contains = NULL; new_bdev->bd_inode = inode; new_bdev->bd_block_size = (1 << inode->i_blkbits); new_bdev->bd_part_count = 0; new_bdev->bd_invalidated = 0; inode->i_mode = S_IFBLK; inode->i_rdev = kdev; inode->i_bdev = new_bdev; inode->i_data.a_ops = &def_blk_aops; inode->i_data.gfp_mask = GFP_USER; inode->i_data.backing_dev_info = &default_backing_dev_info; spin_lock(&bdev_lock); bdev = bdfind(dev, head); if (!bdev) { list_add(&new_bdev->bd_hash, head); spin_unlock(&bdev_lock); return new_bdev; } spin_unlock(&bdev_lock); iput(new_bdev->bd_inode); } destroy_bdev(new_bdev); } return bdev; } long nr_blockdev_pages(void) { long ret = 0; int i; spin_lock(&bdev_lock); for (i = 0; i < ARRAY_SIZE(bdev_hashtable); i++) { struct list_head *head = &bdev_hashtable[i]; struct list_head *lh; if (head == NULL) continue; list_for_each(lh, head) { struct block_device *bdev; bdev = list_entry(lh, struct block_device, bd_hash); ret += bdev->bd_inode->i_mapping->nrpages; } } spin_unlock(&bdev_lock); return ret; } static inline void __bd_forget(struct inode *inode) { list_del_init(&inode->i_devices); inode->i_bdev = NULL; inode->i_mapping = &inode->i_data; } void bdput(struct block_device *bdev) { if (atomic_dec_and_lock(&bdev->bd_count, &bdev_lock)) { struct list_head *p; if (bdev->bd_openers) BUG(); list_del(&bdev->bd_hash); while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) { __bd_forget(list_entry(p, struct inode, i_devices)); } spin_unlock(&bdev_lock); iput(bdev->bd_inode); destroy_bdev(bdev); } } int bd_acquire(struct inode *inode) { struct block_device *bdev; spin_lock(&bdev_lock); if (inode->i_bdev) { atomic_inc(&inode->i_bdev->bd_count); spin_unlock(&bdev_lock); return 0; } spin_unlock(&bdev_lock); bdev = bdget(kdev_t_to_nr(inode->i_rdev)); if (!bdev) return -ENOMEM; spin_lock(&bdev_lock); if (!inode->i_bdev) { inode->i_bdev = bdev; inode->i_mapping = bdev->bd_inode->i_mapping; list_add(&inode->i_devices, &bdev->bd_inodes); } else if (inode->i_bdev != bdev) BUG(); spin_unlock(&bdev_lock); return 0; } /* Call when you free inode */ void bd_forget(struct inode *inode) { spin_lock(&bdev_lock); if (inode->i_bdev) __bd_forget(inode); spin_unlock(&bdev_lock); } int bd_claim(struct block_device *bdev, void *holder) { int res = -EBUSY; spin_lock(&bdev_lock); if (!bdev->bd_holder || bdev->bd_holder == holder) { bdev->bd_holder = holder; bdev->bd_holders++; res = 0; } spin_unlock(&bdev_lock); return res; } void bd_release(struct block_device *bdev) { spin_lock(&bdev_lock); if (!--bdev->bd_holders) bdev->bd_holder = NULL; spin_unlock(&bdev_lock); } /* * This routine checks whether a removable media has been changed, * and invalidates all buffer-cache-entries in that case. This * is a relatively slow routine, so we have to try to minimize using * it. Thus it is called only upon a 'mount' or 'open'. This * is the best way of combining speed and utility, I think. * People changing diskettes in the middle of an operation deserve * to lose :-) */ int check_disk_change(struct block_device *bdev) { struct gendisk *disk = bdev->bd_disk; struct block_device_operations * bdops = disk->fops; kdev_t dev = to_kdev_t(bdev->bd_dev); if (!bdops->media_changed) return 0; if (!bdops->media_changed(bdev->bd_disk)) return 0; if (invalidate_device(dev, 0)) printk("VFS: busy inodes on changed media.\n"); if (bdops->revalidate_disk) bdops->revalidate_disk(bdev->bd_disk); if (bdev->bd_disk->minors > 1) bdev->bd_invalidated = 1; return 1; } int full_check_disk_change(struct block_device *bdev) { int res = 0; if (bdev->bd_contains != bdev) BUG(); down(&bdev->bd_sem); if (check_disk_change(bdev) && bdev->bd_invalidated) { rescan_partitions(bdev->bd_disk, bdev); res = 1; } up(&bdev->bd_sem); return res; } /* * Will die as soon as two remaining callers get converted. */ int __check_disk_change(dev_t dev) { struct block_device *bdev = bdget(dev); int res; if (!bdev) return 0; if (blkdev_get(bdev, FMODE_READ, 0, BDEV_RAW) < 0) return 0; res = full_check_disk_change(bdev); blkdev_put(bdev, BDEV_RAW); return res; } static void bd_set_size(struct block_device *bdev, loff_t size) { unsigned bsize = bdev_hardsect_size(bdev); bdev->bd_inode->i_size = size; while (bsize < PAGE_CACHE_SIZE) { if (size & bsize) break; bsize <<= 1; } bdev->bd_block_size = bsize; bdev->bd_inode->i_blkbits = blksize_bits(bsize); } static int do_open(struct block_device *bdev, struct inode *inode, struct file *file) { struct module *owner = NULL; struct gendisk *disk; int ret = -ENXIO; int part; lock_kernel(); disk = get_gendisk(bdev->bd_dev, &part); if (!disk) { unlock_kernel(); bdput(bdev); return ret; } owner = disk->fops->owner; down(&bdev->bd_sem); if (!bdev->bd_openers) { bdev->bd_disk = disk; bdev->bd_contains = bdev; if (!part) { struct backing_dev_info *bdi; if (disk->fops->open) { ret = disk->fops->open(inode, file); if (ret) goto out_first; } bdev->bd_offset = 0; if (!bdev->bd_openers) { bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); bdi = blk_get_backing_dev_info(bdev); if (bdi == NULL) bdi = &default_backing_dev_info; bdev->bd_inode->i_data.backing_dev_info = bdi; } if (bdev->bd_invalidated) rescan_partitions(disk, bdev); } else { struct hd_struct *p; struct block_device *whole; whole = bdget(MKDEV(disk->major, disk->first_minor)); ret = -ENOMEM; if (!whole) goto out_first; ret = blkdev_get(whole, file->f_mode, file->f_flags, BDEV_RAW); if (ret) goto out_first; bdev->bd_contains = whole; down(&whole->bd_sem); whole->bd_part_count++; p = disk->part[part - 1]; bdev->bd_inode->i_data.backing_dev_info = whole->bd_inode->i_data.backing_dev_info; if (!(disk->flags & GENHD_FL_UP) || !p || !p->nr_sects) { whole->bd_part_count--; up(&whole->bd_sem); ret = -ENXIO; goto out_first; } bdev->bd_offset = p->start_sect; bd_set_size(bdev, (loff_t) p->nr_sects << 9); up(&whole->bd_sem); } } else { put_disk(disk); module_put(owner); if (bdev->bd_contains == bdev) { if (bdev->bd_disk->fops->open) { ret = bdev->bd_disk->fops->open(inode, file); if (ret) goto out; } if (bdev->bd_invalidated) rescan_partitions(bdev->bd_disk, bdev); } else { down(&bdev->bd_contains->bd_sem); bdev->bd_contains->bd_part_count++; up(&bdev->bd_contains->bd_sem); } } bdev->bd_openers++; up(&bdev->bd_sem); unlock_kernel(); return 0; out_first: bdev->bd_disk = NULL; bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info; if (bdev != bdev->bd_contains) blkdev_put(bdev->bd_contains, BDEV_RAW); bdev->bd_contains = NULL; put_disk(disk); module_put(owner); out: up(&bdev->bd_sem); unlock_kernel(); if (ret) bdput(bdev); return ret; } int blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags, int kind) { /* * This crockload is due to bad choice of ->open() type. * It will go away. * For now, block device ->open() routine must _not_ * examine anything in 'inode' argument except ->i_rdev. */ struct file fake_file = {}; struct dentry fake_dentry = {}; fake_file.f_mode = mode; fake_file.f_flags = flags; fake_file.f_dentry = &fake_dentry; fake_dentry.d_inode = bdev->bd_inode; return do_open(bdev, bdev->bd_inode, &fake_file); } 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; bd_acquire(inode); bdev = inode->i_bdev; return do_open(bdev, inode, filp); } int blkdev_put(struct block_device *bdev, int kind) { int ret = 0; struct inode *bd_inode = bdev->bd_inode; struct gendisk *disk = bdev->bd_disk; down(&bdev->bd_sem); lock_kernel(); if (!--bdev->bd_openers) { switch (kind) { case BDEV_FILE: case BDEV_FS: sync_blockdev(bd_inode->i_bdev); break; } kill_bdev(bdev); } if (bdev->bd_contains == bdev) { if (disk->fops->release) ret = disk->fops->release(bd_inode, NULL); } else { down(&bdev->bd_contains->bd_sem); bdev->bd_contains->bd_part_count--; up(&bdev->bd_contains->bd_sem); } if (!bdev->bd_openers) { struct module *owner = disk->fops->owner; put_disk(disk); module_put(owner); bdev->bd_disk = NULL; bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info; if (bdev != bdev->bd_contains) { blkdev_put(bdev->bd_contains, BDEV_RAW); } bdev->bd_contains = NULL; } unlock_kernel(); up(&bdev->bd_sem); bdput(bdev); return ret; } int blkdev_close(struct inode * inode, struct file * filp) { return blkdev_put(inode->i_bdev, BDEV_FILE); } static ssize_t blkdev_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos) { struct iovec local_iov = { .iov_base = (void *)buf, .iov_len = count }; return generic_file_write_nolock(file, &local_iov, 1, ppos); } struct address_space_operations def_blk_aops = { .readpage = blkdev_readpage, .writepage = blkdev_writepage, .sync_page = block_sync_page, .prepare_write = blkdev_prepare_write, .commit_write = blkdev_commit_write, .writepages = generic_writepages, .direct_IO = blkdev_direct_IO, }; struct file_operations def_blk_fops = { .open = blkdev_open, .release = blkdev_close, .llseek = block_llseek, .read = generic_file_read, .write = blkdev_file_write, .mmap = generic_file_mmap, .fsync = block_fsync, .ioctl = blkdev_ioctl, .readv = generic_file_readv, .writev = generic_file_writev, .sendfile = generic_file_sendfile, }; int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg) { int res; mm_segment_t old_fs = get_fs(); set_fs(KERNEL_DS); res = blkdev_ioctl(bdev->bd_inode, NULL, cmd, arg); set_fs(old_fs); return res; } /** * lookup_bdev - lookup a struct block_device by name * * @path: special file representing the block device * * Get a reference to the blockdevice at @path in the current * namespace if possible and return it. Return ERR_PTR(error) * otherwise. */ struct block_device *lookup_bdev(const char *path) { struct block_device *bdev; struct inode *inode; struct nameidata nd; int error; if (!path || !*path) return ERR_PTR(-EINVAL); error = path_lookup(path, LOOKUP_FOLLOW, &nd); if (error) return ERR_PTR(error); inode = nd.dentry->d_inode; error = -ENOTBLK; if (!S_ISBLK(inode->i_mode)) goto fail; error = -EACCES; if (nd.mnt->mnt_flags & MNT_NODEV) goto fail; error = bd_acquire(inode); if (error) goto fail; bdev = inode->i_bdev; out: path_release(&nd); return bdev; fail: bdev = ERR_PTR(error); goto out; } /** * open_bdev_excl - open a block device by name and set it up for use * * @path: special file representing the block device * @flags: %MS_RDONLY for opening read-only * @kind: usage (same as the 4th paramter to blkdev_get) * @holder: owner for exclusion * * Open the blockdevice described by the special file at @path, claim it * for the @holder and properly set it up for @kind usage. */ struct block_device *open_bdev_excl(const char *path, int flags, int kind, void *holder) { struct block_device *bdev; mode_t mode = FMODE_READ; int error = 0; bdev = lookup_bdev(path); if (IS_ERR(bdev)) return bdev; if (!(flags & MS_RDONLY)) mode |= FMODE_WRITE; error = blkdev_get(bdev, mode, 0, kind); if (error) return ERR_PTR(error); error = -EACCES; if (!(flags & MS_RDONLY) && bdev_read_only(bdev)) goto blkdev_put; error = bd_claim(bdev, holder); if (error) goto blkdev_put; return bdev; blkdev_put: blkdev_put(bdev, BDEV_FS); return ERR_PTR(error); } /** * close_bdev_excl - release a blockdevice openen by open_bdev_excl() * * @bdev: blockdevice to close * @kind: usage (same as the 4th paramter to blkdev_get) * * This is the counterpart to open_bdev_excl(). */ void close_bdev_excl(struct block_device *bdev, int kind) { bd_release(bdev); blkdev_put(bdev, kind); }