/* * 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/buffer_head.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/kmemleak.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); /* * Move the inode from its current bdi to a new bdi. If the inode is dirty we * need to move it onto the dirty list of @dst so that the inode is always on * the right list. */ static void bdev_inode_switch_bdi(struct inode *inode, struct backing_dev_info *dst) { struct backing_dev_info *old = inode->i_data.backing_dev_info; if (unlikely(dst == old)) /* deadlock avoidance */ return; bdi_lock_two(&old->wb, &dst->wb); spin_lock(&inode->i_lock); inode->i_data.backing_dev_info = dst; if (inode->i_state & I_DIRTY) list_move(&inode->i_wb_list, &dst->wb.b_dirty); spin_unlock(&inode->i_lock); spin_unlock(&old->wb.list_lock); spin_unlock(&dst->wb.list_lock); } static sector_t max_block(struct block_device *bdev) { sector_t retval = ~((sector_t)0); loff_t sz = i_size_read(bdev->bd_inode); if (sz) { unsigned int size = block_size(bdev); unsigned int sizebits = blksize_bits(size); retval = (sz >> sizebits); } return retval; } /* Kill _all_ buffers and pagecache , dirty or not.. */ static void kill_bdev(struct block_device *bdev) { if (bdev->bd_inode->i_mapping->nrpages == 0) return; invalidate_bh_lrus(); truncate_inode_pages(bdev->bd_inode->i_mapping, 0); } 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) { if (iblock >= max_block(I_BDEV(inode))) { if (create) return -EIO; /* * for reads, we're just trying to fill a partial page. * return a hole, they will have to call get_block again * before they can fill it, and they will get -EIO at that * time */ return 0; } bh->b_bdev = I_BDEV(inode); bh->b_blocknr = iblock; set_buffer_mapped(bh); return 0; } static int blkdev_get_blocks(struct inode *inode, sector_t iblock, struct buffer_head *bh, int create) { sector_t end_block = max_block(I_BDEV(inode)); unsigned long max_blocks = bh->b_size >> inode->i_blkbits; if ((iblock + max_blocks) > end_block) { max_blocks = end_block - iblock; if ((long)max_blocks <= 0) { if (create) return -EIO; /* write fully beyond EOF */ /* * It is a read which is fully beyond EOF. We return * a !buffer_mapped buffer */ max_blocks = 0; } } bh->b_bdev = I_BDEV(inode); bh->b_blocknr = iblock; bh->b_size = max_blocks << inode->i_blkbits; if (max_blocks) set_buffer_mapped(bh); return 0; } static ssize_t 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_mapping->host; return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset, nr_segs, blkdev_get_blocks, NULL, NULL, 0); } 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; 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; 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_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->f_path.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) { struct inode *bd_inode = file->f_mapping->host; loff_t size; loff_t retval; mutex_lock(&bd_inode->i_mutex); size = i_size_read(bd_inode); retval = -EINVAL; switch (origin) { case SEEK_END: offset += size; break; case SEEK_CUR: offset += file->f_pos; case SEEK_SET: break; default: goto out; } if (offset >= 0 && offset <= size) { if (offset != file->f_pos) { file->f_pos = offset; } retval = offset; } out: 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); /* * 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); INIT_LIST_HEAD(&inode->i_dentry); 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(&inode->i_data, 0); invalidate_inode_buffers(inode); /* is it needed here? */ end_writeback(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, 0x62646576); } static struct file_system_type bd_type = { .name = "bdev", .mount = bd_mount, .kill_sb = kill_anon_super, }; struct super_block *blockdev_superblock __read_mostly; void __init bdev_cache_init(void) { int err; 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"); /* * This vfsmount structure is only used to obtain the * blockdev_superblock, so tell kmemleak not to report it. */ kmemleak_not_leak(bd_mnt); 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); inode->i_data.backing_dev_info = &default_backing_dev_info; 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; } 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; } /* Call when you free inode */ void bd_forget(struct inode *inode) { struct block_device *bdev = NULL; spin_lock(&bdev_lock); if (inode->i_bdev) { 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); 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); 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); } EXPORT_SYMBOL(bd_set_size); static int __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_contains = bdev; if (!partno) { struct backing_dev_info *bdi; 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; mutex_unlock(&bdev->bd_mutex); disk_unblock_events(disk); put_disk(disk); module_put(owner); goto restart; } } if (!ret && !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_inode_switch_bdi(bdev->bd_inode, bdi); } /* * 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)) rescan_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_inode_switch_bdi(bdev->bd_inode, whole->bd_inode->i_data.backing_dev_info); 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 && (!ret || ret == -ENOMEDIUM)) rescan_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_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info); 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 int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) { int ret = 0; 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 old bdi to disappear, * so must switch it out first */ bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info); } if (bdev->bd_contains == bdev) { if (disk->fops->release) ret = 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); return ret; } int 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); return __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); return blkdev_put(bdev, filp->f_mode); } 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_aio_write(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { struct file *file = iocb->ki_filp; ssize_t ret; BUG_ON(iocb->ki_pos != pos); ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); if (ret > 0 || ret == -EIOCBQUEUED) { ssize_t err; err = generic_write_sync(file, pos, ret); if (err < 0 && ret > 0) ret = err; } return ret; } EXPORT_SYMBOL_GPL(blkdev_aio_write); /* * 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, .writepage = blkdev_writepage, .write_begin = blkdev_write_begin, .write_end = blkdev_write_end, .writepages = generic_writepages, .releasepage = blkdev_releasepage, .direct_IO = blkdev_direct_IO, }; const struct file_operations def_blk_fops = { .open = blkdev_open, .release = blkdev_close, .llseek = block_llseek, .read = do_sync_read, .write = do_sync_write, .aio_read = generic_file_aio_read, .aio_write = blkdev_aio_write, .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 = generic_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 = path.dentry->d_inode; 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);