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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/fs/block_dev.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/block_dev.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
*/
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/major.h>
#include <linux/device_cgroup.h>
#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/module.h>
#include <linux/blkpg.h>
#include <linux/magic.h>
#include <linux/dax.h>
#include <linux/buffer_head.h>
#include <linux/swap.h>
#include <linux/pagevec.h>
#include <linux/writeback.h>
#include <linux/mpage.h>
#include <linux/mount.h>
#include <linux/pseudo_fs.h>
#include <linux/uio.h>
#include <linux/namei.h>
#include <linux/log2.h>
#include <linux/cleancache.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/falloc.h>
#include <linux/uaccess.h>
#include "internal.h"
struct bdev_inode {
struct block_device bdev;
struct inode vfs_inode;
};
static const struct address_space_operations def_blk_aops;
static inline struct bdev_inode *BDEV_I(struct inode *inode)
{
return container_of(inode, struct bdev_inode, vfs_inode);
}
struct block_device *I_BDEV(struct inode *inode)
{
return &BDEV_I(inode)->bdev;
}
EXPORT_SYMBOL(I_BDEV);
static void bdev_write_inode(struct block_device *bdev)
{
struct inode *inode = bdev->bd_inode;
int ret;
spin_lock(&inode->i_lock);
while (inode->i_state & I_DIRTY) {
spin_unlock(&inode->i_lock);
ret = write_inode_now(inode, true);
if (ret) {
char name[BDEVNAME_SIZE];
pr_warn_ratelimited("VFS: Dirty inode writeback failed "
"for block device %s (err=%d).\n",
bdevname(bdev, name), ret);
}
spin_lock(&inode->i_lock);
}
spin_unlock(&inode->i_lock);
}
/* Kill _all_ buffers and pagecache , dirty or not.. */
void kill_bdev(struct block_device *bdev)
{
struct address_space *mapping = bdev->bd_inode->i_mapping;
if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
return;
invalidate_bh_lrus();
truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(kill_bdev);
/* Invalidate clean unused buffers and pagecache. */
void invalidate_bdev(struct block_device *bdev)
{
struct address_space *mapping = bdev->bd_inode->i_mapping;
if (mapping->nrpages) {
invalidate_bh_lrus();
lru_add_drain_all(); /* make sure all lru add caches are flushed */
invalidate_mapping_pages(mapping, 0, -1);
}
/* 99% of the time, we don't need to flush the cleancache on the bdev.
* But, for the strange corners, lets be cautious
*/
cleancache_invalidate_inode(mapping);
}
EXPORT_SYMBOL(invalidate_bdev);
static void set_init_blocksize(struct block_device *bdev)
{
unsigned bsize = bdev_logical_block_size(bdev);
loff_t size = i_size_read(bdev->bd_inode);
while (bsize < PAGE_SIZE) {
if (size & bsize)
break;
bsize <<= 1;
}
bdev->bd_block_size = bsize;
bdev->bd_inode->i_blkbits = blksize_bits(bsize);
}
int set_blocksize(struct block_device *bdev, int size)
{
/* Size must be a power of two, and between 512 and PAGE_SIZE */
if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
return -EINVAL;
/* Size cannot be smaller than the size supported by the device */
if (size < bdev_logical_block_size(bdev))
return -EINVAL;
/* Don't change the size if it is same as current */
if (bdev->bd_block_size != size) {
sync_blockdev(bdev);
bdev->bd_block_size = size;
bdev->bd_inode->i_blkbits = blksize_bits(size);
kill_bdev(bdev);
}
return 0;
}
EXPORT_SYMBOL(set_blocksize);
int sb_set_blocksize(struct super_block *sb, int size)
{
if (set_blocksize(sb->s_bdev, size))
return 0;
/* If we get here, we know size is power of two
* and it's value is between 512 and PAGE_SIZE */
sb->s_blocksize = size;
sb->s_blocksize_bits = blksize_bits(size);
return sb->s_blocksize;
}
EXPORT_SYMBOL(sb_set_blocksize);
int sb_min_blocksize(struct super_block *sb, int size)
{
int minsize = bdev_logical_block_size(sb->s_bdev);
if (size < minsize)
size = minsize;
return sb_set_blocksize(sb, size);
}
EXPORT_SYMBOL(sb_min_blocksize);
static int
blkdev_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
bh->b_bdev = I_BDEV(inode);
bh->b_blocknr = iblock;
set_buffer_mapped(bh);
return 0;
}
static struct inode *bdev_file_inode(struct file *file)
{
return file->f_mapping->host;
}
static unsigned int dio_bio_write_op(struct kiocb *iocb)
{
unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
/* avoid the need for a I/O completion work item */
if (iocb->ki_flags & IOCB_DSYNC)
op |= REQ_FUA;
return op;
}
#define DIO_INLINE_BIO_VECS 4
static void blkdev_bio_end_io_simple(struct bio *bio)
{
struct task_struct *waiter = bio->bi_private;
WRITE_ONCE(bio->bi_private, NULL);
blk_wake_io_task(waiter);
}
static ssize_t
__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
int nr_pages)
{
struct file *file = iocb->ki_filp;
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
loff_t pos = iocb->ki_pos;
bool should_dirty = false;
struct bio bio;
ssize_t ret;
blk_qc_t qc;
if ((pos | iov_iter_alignment(iter)) &
(bdev_logical_block_size(bdev) - 1))
return -EINVAL;
if (nr_pages <= DIO_INLINE_BIO_VECS)
vecs = inline_vecs;
else {
vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
GFP_KERNEL);
if (!vecs)
return -ENOMEM;
}
bio_init(&bio, vecs, nr_pages);
bio_set_dev(&bio, bdev);
bio.bi_iter.bi_sector = pos >> 9;
bio.bi_write_hint = iocb->ki_hint;
bio.bi_private = current;
bio.bi_end_io = blkdev_bio_end_io_simple;
bio.bi_ioprio = iocb->ki_ioprio;
ret = bio_iov_iter_get_pages(&bio, iter);
if (unlikely(ret))
goto out;
ret = bio.bi_iter.bi_size;
if (iov_iter_rw(iter) == READ) {
bio.bi_opf = REQ_OP_READ;
if (iter_is_iovec(iter))
should_dirty = true;
} else {
bio.bi_opf = dio_bio_write_op(iocb);
task_io_account_write(ret);
}
if (iocb->ki_flags & IOCB_HIPRI)
bio_set_polled(&bio, iocb);
qc = submit_bio(&bio);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!READ_ONCE(bio.bi_private))
break;
if (!(iocb->ki_flags & IOCB_HIPRI) ||
!blk_poll(bdev_get_queue(bdev), qc, true))
io_schedule();
}
__set_current_state(TASK_RUNNING);
bio_release_pages(&bio, should_dirty);
if (unlikely(bio.bi_status))
ret = blk_status_to_errno(bio.bi_status);
out:
if (vecs != inline_vecs)
kfree(vecs);
bio_uninit(&bio);
return ret;
}
struct blkdev_dio {
union {
struct kiocb *iocb;
struct task_struct *waiter;
};
size_t size;
atomic_t ref;
bool multi_bio : 1;
bool should_dirty : 1;
bool is_sync : 1;
struct bio bio;
};
static struct bio_set blkdev_dio_pool;
static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
{
struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
struct request_queue *q = bdev_get_queue(bdev);
return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
}
static void blkdev_bio_end_io(struct bio *bio)
{
struct blkdev_dio *dio = bio->bi_private;
bool should_dirty = dio->should_dirty;
if (bio->bi_status && !dio->bio.bi_status)
dio->bio.bi_status = bio->bi_status;
if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) {
if (!dio->is_sync) {
struct kiocb *iocb = dio->iocb;
ssize_t ret;
if (likely(!dio->bio.bi_status)) {
ret = dio->size;
iocb->ki_pos += ret;
} else {
ret = blk_status_to_errno(dio->bio.bi_status);
}
dio->iocb->ki_complete(iocb, ret, 0);
if (dio->multi_bio)
bio_put(&dio->bio);
} else {
struct task_struct *waiter = dio->waiter;
WRITE_ONCE(dio->waiter, NULL);
blk_wake_io_task(waiter);
}
}
if (should_dirty) {
bio_check_pages_dirty(bio);
} else {
bio_release_pages(bio, false);
bio_put(bio);
}
}
static ssize_t
__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
{
struct file *file = iocb->ki_filp;
struct inode *inode = bdev_file_inode(file);
struct block_device *bdev = I_BDEV(inode);
struct blk_plug plug;
struct blkdev_dio *dio;
struct bio *bio;
bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
bool is_read = (iov_iter_rw(iter) == READ), is_sync;
loff_t pos = iocb->ki_pos;
blk_qc_t qc = BLK_QC_T_NONE;
int ret = 0;
if ((pos | iov_iter_alignment(iter)) &
(bdev_logical_block_size(bdev) - 1))
return -EINVAL;
bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool);
dio = container_of(bio, struct blkdev_dio, bio);
dio->is_sync = is_sync = is_sync_kiocb(iocb);
if (dio->is_sync) {
dio->waiter = current;
bio_get(bio);
} else {
dio->iocb = iocb;
}
dio->size = 0;
dio->multi_bio = false;
dio->should_dirty = is_read && iter_is_iovec(iter);
/*
* Don't plug for HIPRI/polled IO, as those should go straight
* to issue
*/
if (!is_poll)
blk_start_plug(&plug);
for (;;) {
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = pos >> 9;
bio->bi_write_hint = iocb->ki_hint;
bio->bi_private = dio;
bio->bi_end_io = blkdev_bio_end_io;
bio->bi_ioprio = iocb->ki_ioprio;
ret = bio_iov_iter_get_pages(bio, iter);
if (unlikely(ret)) {
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
break;
}
if (is_read) {
bio->bi_opf = REQ_OP_READ;
if (dio->should_dirty)
bio_set_pages_dirty(bio);
} else {
bio->bi_opf = dio_bio_write_op(iocb);
task_io_account_write(bio->bi_iter.bi_size);
}
dio->size += bio->bi_iter.bi_size;
pos += bio->bi_iter.bi_size;
nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
if (!nr_pages) {
bool polled = false;
if (iocb->ki_flags & IOCB_HIPRI) {
bio_set_polled(bio, iocb);
polled = true;
}
qc = submit_bio(bio);
if (polled)
WRITE_ONCE(iocb->ki_cookie, qc);
break;
}
if (!dio->multi_bio) {
/*
* AIO needs an extra reference to ensure the dio
* structure which is embedded into the first bio
* stays around.
*/
if (!is_sync)
bio_get(bio);
dio->multi_bio = true;
atomic_set(&dio->ref, 2);
} else {
atomic_inc(&dio->ref);
}
submit_bio(bio);
bio = bio_alloc(GFP_KERNEL, nr_pages);
}
if (!is_poll)
blk_finish_plug(&plug);
if (!is_sync)
return -EIOCBQUEUED;
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!READ_ONCE(dio->waiter))
break;
if (!(iocb->ki_flags & IOCB_HIPRI) ||
!blk_poll(bdev_get_queue(bdev), qc, true))
io_schedule();
}
__set_current_state(TASK_RUNNING);
if (!ret)
ret = blk_status_to_errno(dio->bio.bi_status);
if (likely(!ret))
ret = dio->size;
bio_put(&dio->bio);
return ret;
}
static ssize_t
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
int nr_pages;
nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1);
if (!nr_pages)
return 0;
if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
}
static __init int blkdev_init(void)
{
return bioset_init(&blkdev_dio_pool, 4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
}
module_init(blkdev_init);
int __sync_blockdev(struct block_device *bdev, int wait)
{
if (!bdev)
return 0;
if (!wait)
return filemap_flush(bdev->bd_inode->i_mapping);
return filemap_write_and_wait(bdev->bd_inode->i_mapping);
}
/*
* Write out and wait upon all the dirty data associated with a block
* device via its mapping. Does not take the superblock lock.
*/
int sync_blockdev(struct block_device *bdev)
{
return __sync_blockdev(bdev, 1);
}
EXPORT_SYMBOL(sync_blockdev);
/*
* Write out and wait upon all dirty data associated with this
* device. Filesystem data as well as the underlying block
* device. Takes the superblock lock.
*/
int fsync_bdev(struct block_device *bdev)
{
struct super_block *sb = get_super(bdev);
if (sb) {
int res = sync_filesystem(sb);
drop_super(sb);
return res;
}
return sync_blockdev(bdev);
}
EXPORT_SYMBOL(fsync_bdev);
/**
* freeze_bdev -- lock a filesystem and force it into a consistent state
* @bdev: blockdevice to lock
*
* If a superblock is found on this device, we take the s_umount semaphore
* on it to make sure nobody unmounts until the snapshot creation is done.
* The reference counter (bd_fsfreeze_count) guarantees that only the last
* unfreeze process can unfreeze the frozen filesystem actually when multiple
* freeze requests arrive simultaneously. It counts up in freeze_bdev() and
* count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
* actually.
*/
struct super_block *freeze_bdev(struct block_device *bdev)
{
struct super_block *sb;
int error = 0;
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (++bdev->bd_fsfreeze_count > 1) {
/*
* We don't even need to grab a reference - the first call
* to freeze_bdev grab an active reference and only the last
* thaw_bdev drops it.
*/
sb = get_super(bdev);
if (sb)
drop_super(sb);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return sb;
}
sb = get_active_super(bdev);
if (!sb)
goto out;
if (sb->s_op->freeze_super)
error = sb->s_op->freeze_super(sb);
else
error = freeze_super(sb);
if (error) {
deactivate_super(sb);
bdev->bd_fsfreeze_count--;
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return ERR_PTR(error);
}
deactivate_super(sb);
out:
sync_blockdev(bdev);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return sb; /* thaw_bdev releases s->s_umount */
}
EXPORT_SYMBOL(freeze_bdev);
/**
* thaw_bdev -- unlock filesystem
* @bdev: blockdevice to unlock
* @sb: associated superblock
*
* Unlocks the filesystem and marks it writeable again after freeze_bdev().
*/
int thaw_bdev(struct block_device *bdev, struct super_block *sb)
{
int error = -EINVAL;
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (!bdev->bd_fsfreeze_count)
goto out;
error = 0;
if (--bdev->bd_fsfreeze_count > 0)
goto out;
if (!sb)
goto out;
if (sb->s_op->thaw_super)
error = sb->s_op->thaw_super(sb);
else
error = thaw_super(sb);
if (error)
bdev->bd_fsfreeze_count++;
out:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return error;
}
EXPORT_SYMBOL(thaw_bdev);
static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, blkdev_get_block, wbc);
}
static int blkdev_readpage(struct file * file, struct page * page)
{
return block_read_full_page(page, blkdev_get_block);
}
static int blkdev_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
}
static int blkdev_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
return block_write_begin(mapping, pos, len, flags, pagep,
blkdev_get_block);
}
static int blkdev_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
int ret;
ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
unlock_page(page);
put_page(page);
return ret;
}
/*
* private llseek:
* for a block special file file_inode(file)->i_size is zero
* so we compute the size by hand (just as in block_read/write above)
*/
static loff_t block_llseek(struct file *file, loff_t offset, int whence)
{
struct inode *bd_inode = bdev_file_inode(file);
loff_t retval;
inode_lock(bd_inode);
retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
inode_unlock(bd_inode);
return retval;
}
int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
struct inode *bd_inode = bdev_file_inode(filp);
struct block_device *bdev = I_BDEV(bd_inode);
int error;
error = file_write_and_wait_range(filp, start, end);
if (error)
return error;
/*
* There is no need to serialise calls to blkdev_issue_flush with
* i_mutex and doing so causes performance issues with concurrent
* O_SYNC writers to a block device.
*/
error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
if (error == -EOPNOTSUPP)
error = 0;
return error;
}
EXPORT_SYMBOL(blkdev_fsync);
/**
* bdev_read_page() - Start reading a page from a block device
* @bdev: The device to read the page from
* @sector: The offset on the device to read the page to (need not be aligned)
* @page: The page to read
*
* On entry, the page should be locked. It will be unlocked when the page
* has been read. If the block driver implements rw_page synchronously,
* that will be true on exit from this function, but it need not be.
*
* Errors returned by this function are usually "soft", eg out of memory, or
* queue full; callers should try a different route to read this page rather
* than propagate an error back up the stack.
*
* Return: negative errno if an error occurs, 0 if submission was successful.
*/
int bdev_read_page(struct block_device *bdev, sector_t sector,
struct page *page)
{
const struct block_device_operations *ops = bdev->bd_disk->fops;
int result = -EOPNOTSUPP;
if (!ops->rw_page || bdev_get_integrity(bdev))
return result;
result = blk_queue_enter(bdev->bd_queue, 0);
if (result)
return result;
result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
REQ_OP_READ);
blk_queue_exit(bdev->bd_queue);
return result;
}
EXPORT_SYMBOL_GPL(bdev_read_page);
/**
* bdev_write_page() - Start writing a page to a block device
* @bdev: The device to write the page to
* @sector: The offset on the device to write the page to (need not be aligned)
* @page: The page to write
* @wbc: The writeback_control for the write
*
* On entry, the page should be locked and not currently under writeback.
* On exit, if the write started successfully, the page will be unlocked and
* under writeback. If the write failed already (eg the driver failed to
* queue the page to the device), the page will still be locked. If the
* caller is a ->writepage implementation, it will need to unlock the page.
*
* Errors returned by this function are usually "soft", eg out of memory, or
* queue full; callers should try a different route to write this page rather
* than propagate an error back up the stack.
*
* Return: negative errno if an error occurs, 0 if submission was successful.
*/
int bdev_write_page(struct block_device *bdev, sector_t sector,
struct page *page, struct writeback_control *wbc)
{
int result;
const struct block_device_operations *ops = bdev->bd_disk->fops;
if (!ops->rw_page || bdev_get_integrity(bdev))
return -EOPNOTSUPP;
result = blk_queue_enter(bdev->bd_queue, 0);
if (result)
return result;
set_page_writeback(page);
result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
REQ_OP_WRITE);
if (result) {
end_page_writeback(page);
} else {
clean_page_buffers(page);
unlock_page(page);
}
blk_queue_exit(bdev->bd_queue);
return result;
}
EXPORT_SYMBOL_GPL(bdev_write_page);
/*
* pseudo-fs
*/
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
static struct kmem_cache * bdev_cachep __read_mostly;
static struct inode *bdev_alloc_inode(struct super_block *sb)
{
struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
if (!ei)
return NULL;
return &ei->vfs_inode;
}
static void bdev_free_inode(struct inode *inode)
{
kmem_cache_free(bdev_cachep, BDEV_I(inode));
}
static void init_once(void *foo)
{
struct bdev_inode *ei = (struct bdev_inode *) foo;
struct block_device *bdev = &ei->bdev;
memset(bdev, 0, sizeof(*bdev));
mutex_init(&bdev->bd_mutex);
INIT_LIST_HEAD(&bdev->bd_list);
#ifdef CONFIG_SYSFS
INIT_LIST_HEAD(&bdev->bd_holder_disks);
#endif
bdev->bd_bdi = &noop_backing_dev_info;
inode_init_once(&ei->vfs_inode);
/* Initialize mutex for freeze. */
mutex_init(&bdev->bd_fsfreeze_mutex);
}
static void bdev_evict_inode(struct inode *inode)
{
struct block_device *bdev = &BDEV_I(inode)->bdev;
truncate_inode_pages_final(&inode->i_data);
invalidate_inode_buffers(inode); /* is it needed here? */
clear_inode(inode);
spin_lock(&bdev_lock);
list_del_init(&bdev->bd_list);
spin_unlock(&bdev_lock);
/* Detach inode from wb early as bdi_put() may free bdi->wb */
inode_detach_wb(inode);
if (bdev->bd_bdi != &noop_backing_dev_info) {
bdi_put(bdev->bd_bdi);
bdev->bd_bdi = &noop_backing_dev_info;
}
}
static const struct super_operations bdev_sops = {
.statfs = simple_statfs,
.alloc_inode = bdev_alloc_inode,
.free_inode = bdev_free_inode,
.drop_inode = generic_delete_inode,
.evict_inode = bdev_evict_inode,
};
static int bd_init_fs_context(struct fs_context *fc)
{
struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
if (!ctx)
return -ENOMEM;
fc->s_iflags |= SB_I_CGROUPWB;
ctx->ops = &bdev_sops;
return 0;
}
static struct file_system_type bd_type = {
.name = "bdev",
.init_fs_context = bd_init_fs_context,
.kill_sb = kill_anon_super,
};
struct super_block *blockdev_superblock __read_mostly;
EXPORT_SYMBOL_GPL(blockdev_superblock);
void __init bdev_cache_init(void)
{
int err;
static struct vfsmount *bd_mnt;
bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
init_once);
err = register_filesystem(&bd_type);
if (err)
panic("Cannot register bdev pseudo-fs");
bd_mnt = kern_mount(&bd_type);
if (IS_ERR(bd_mnt))
panic("Cannot create bdev pseudo-fs");
blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
}
/*
* Most likely _very_ bad one - but then it's hardly critical for small
* /dev and can be fixed when somebody will need really large one.
* Keep in mind that it will be fed through icache hash function too.
*/
static inline unsigned long hash(dev_t dev)
{
return MAJOR(dev)+MINOR(dev);
}
static int bdev_test(struct inode *inode, void *data)
{
return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
}
static int bdev_set(struct inode *inode, void *data)
{
BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
return 0;
}
static LIST_HEAD(all_bdevs);
/*
* If there is a bdev inode for this device, unhash it so that it gets evicted
* as soon as last inode reference is dropped.
*/
void bdev_unhash_inode(dev_t dev)
{
struct inode *inode;
inode = ilookup5(blockdev_superblock, hash(dev), bdev_test, &dev);
if (inode) {
remove_inode_hash(inode);
iput(inode);
}
}
struct block_device *bdget(dev_t dev)
{
struct block_device *bdev;
struct inode *inode;
inode = iget5_locked(blockdev_superblock, hash(dev),
bdev_test, bdev_set, &dev);
if (!inode)
return NULL;
bdev = &BDEV_I(inode)->bdev;
if (inode->i_state & I_NEW) {
bdev->bd_contains = NULL;
bdev->bd_super = NULL;
bdev->bd_inode = inode;
bdev->bd_block_size = i_blocksize(inode);
bdev->bd_part_count = 0;
bdev->bd_invalidated = 0;
inode->i_mode = S_IFBLK;
inode->i_rdev = dev;
inode->i_bdev = bdev;
inode->i_data.a_ops = &def_blk_aops;
mapping_set_gfp_mask(&inode->i_data, GFP_USER);
spin_lock(&bdev_lock);
list_add(&bdev->bd_list, &all_bdevs);
spin_unlock(&bdev_lock);
unlock_new_inode(inode);
}
return bdev;
}
EXPORT_SYMBOL(bdget);
/**
* bdgrab -- Grab a reference to an already referenced block device
* @bdev: Block device to grab a reference to.
*/
struct block_device *bdgrab(struct block_device *bdev)
{
ihold(bdev->bd_inode);
return bdev;
}
EXPORT_SYMBOL(bdgrab);
long nr_blockdev_pages(void)
{
struct block_device *bdev;
long ret = 0;
spin_lock(&bdev_lock);
list_for_each_entry(bdev, &all_bdevs, bd_list) {
ret += bdev->bd_inode->i_mapping->nrpages;
}
spin_unlock(&bdev_lock);
return ret;
}
void bdput(struct block_device *bdev)
{
iput(bdev->bd_inode);
}
EXPORT_SYMBOL(bdput);
static struct block_device *bd_acquire(struct inode *inode)
{
struct block_device *bdev;
spin_lock(&bdev_lock);
bdev = inode->i_bdev;
if (bdev && !inode_unhashed(bdev->bd_inode)) {
bdgrab(bdev);
spin_unlock(&bdev_lock);
return bdev;
}
spin_unlock(&bdev_lock);
/*
* i_bdev references block device inode that was already shut down
* (corresponding device got removed). Remove the reference and look
* up block device inode again just in case new device got
* reestablished under the same device number.
*/
if (bdev)
bd_forget(inode);
bdev = bdget(inode->i_rdev);
if (bdev) {
spin_lock(&bdev_lock);
if (!inode->i_bdev) {
/*
* We take an additional reference to bd_inode,
* and it's released in clear_inode() of inode.
* So, we can access it via ->i_mapping always
* without igrab().
*/
bdgrab(bdev);
inode->i_bdev = bdev;
inode->i_mapping = bdev->bd_inode->i_mapping;
}
spin_unlock(&bdev_lock);
}
return bdev;
}
/* Call when you free inode */
void bd_forget(struct inode *inode)
{
struct block_device *bdev = NULL;
spin_lock(&bdev_lock);
if (!sb_is_blkdev_sb(inode->i_sb))
bdev = inode->i_bdev;
inode->i_bdev = NULL;
inode->i_mapping = &inode->i_data;
spin_unlock(&bdev_lock);
if (bdev)
bdput(bdev);
}
/**
* bd_may_claim - test whether a block device can be claimed
* @bdev: block device of interest
* @whole: whole block device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Test whether @bdev can be claimed by @holder.
*
* CONTEXT:
* spin_lock(&bdev_lock).
*
* RETURNS:
* %true if @bdev can be claimed, %false otherwise.
*/
static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
void *holder)
{
if (bdev->bd_holder == holder)
return true; /* already a holder */
else if (bdev->bd_holder != NULL)
return false; /* held by someone else */
else if (whole == bdev)
return true; /* is a whole device which isn't held */
else if (whole->bd_holder == bd_may_claim)
return true; /* is a partition of a device that is being partitioned */
else if (whole->bd_holder != NULL)
return false; /* is a partition of a held device */
else
return true; /* is a partition of an un-held device */
}
/**
* bd_prepare_to_claim - prepare to claim a block device
* @bdev: block device of interest
* @whole: the whole device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Prepare to claim @bdev. This function fails if @bdev is already
* claimed by another holder and waits if another claiming is in
* progress. This function doesn't actually claim. On successful
* return, the caller has ownership of bd_claiming and bd_holder[s].
*
* CONTEXT:
* spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
* it multiple times.
*
* RETURNS:
* 0 if @bdev can be claimed, -EBUSY otherwise.
*/
static int bd_prepare_to_claim(struct block_device *bdev,
struct block_device *whole, void *holder)
{
retry:
/* if someone else claimed, fail */
if (!bd_may_claim(bdev, whole, holder))
return -EBUSY;
/* if claiming is already in progress, wait for it to finish */
if (whole->bd_claiming) {
wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
DEFINE_WAIT(wait);
prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&bdev_lock);
schedule();
finish_wait(wq, &wait);
spin_lock(&bdev_lock);
goto retry;
}
/* yay, all mine */
return 0;
}
static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
{
struct gendisk *disk = get_gendisk(bdev->bd_dev, partno);
if (!disk)
return NULL;
/*
* Now that we hold gendisk reference we make sure bdev we looked up is
* not stale. If it is, it means device got removed and created before
* we looked up gendisk and we fail open in such case. Associating
* unhashed bdev with newly created gendisk could lead to two bdevs
* (and thus two independent caches) being associated with one device
* which is bad.
*/
if (inode_unhashed(bdev->bd_inode)) {
put_disk_and_module(disk);
return NULL;
}
return disk;
}
/**
* bd_start_claiming - start claiming a block device
* @bdev: block device of interest
* @holder: holder trying to claim @bdev
*
* @bdev is about to be opened exclusively. Check @bdev can be opened
* exclusively and mark that an exclusive open is in progress. Each
* successful call to this function must be matched with a call to
* either bd_finish_claiming() or bd_abort_claiming() (which do not
* fail).
*
* This function is used to gain exclusive access to the block device
* without actually causing other exclusive open attempts to fail. It
* should be used when the open sequence itself requires exclusive
* access but may subsequently fail.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* Pointer to the block device containing @bdev on success, ERR_PTR()
* value on failure.
*/
struct block_device *bd_start_claiming(struct block_device *bdev, void *holder)
{
struct gendisk *disk;
struct block_device *whole;
int partno, err;
might_sleep();
/*
* @bdev might not have been initialized properly yet, look up
* and grab the outer block device the hard way.
*/
disk = bdev_get_gendisk(bdev, &partno);
if (!disk)
return ERR_PTR(-ENXIO);
/*
* Normally, @bdev should equal what's returned from bdget_disk()
* if partno is 0; however, some drivers (floppy) use multiple
* bdev's for the same physical device and @bdev may be one of the
* aliases. Keep @bdev if partno is 0. This means claimer
* tracking is broken for those devices but it has always been that
* way.
*/
if (partno)
whole = bdget_disk(disk, 0);
else
whole = bdgrab(bdev);
put_disk_and_module(disk);
if (!whole)
return ERR_PTR(-ENOMEM);
/* prepare to claim, if successful, mark claiming in progress */
spin_lock(&bdev_lock);
err = bd_prepare_to_claim(bdev, whole, holder);
if (err == 0) {
whole->bd_claiming = holder;
spin_unlock(&bdev_lock);
return whole;
} else {
spin_unlock(&bdev_lock);
bdput(whole);
return ERR_PTR(err);
}
}
EXPORT_SYMBOL(bd_start_claiming);
static void bd_clear_claiming(struct block_device *whole, void *holder)
{
lockdep_assert_held(&bdev_lock);
/* tell others that we're done */
BUG_ON(whole->bd_claiming != holder);
whole->bd_claiming = NULL;
wake_up_bit(&whole->bd_claiming, 0);
}
/**
* bd_finish_claiming - finish claiming of a block device
* @bdev: block device of interest
* @whole: whole block device (returned from bd_start_claiming())
* @holder: holder that has claimed @bdev
*
* Finish exclusive open of a block device. Mark the device as exlusively
* open by the holder and wake up all waiters for exclusive open to finish.
*/
void bd_finish_claiming(struct block_device *bdev, struct block_device *whole,
void *holder)
{
spin_lock(&bdev_lock);
BUG_ON(!bd_may_claim(bdev, whole, holder));
/*
* Note that for a whole device bd_holders will be incremented twice,
* and bd_holder will be set to bd_may_claim before being set to holder
*/
whole->bd_holders++;
whole->bd_holder = bd_may_claim;
bdev->bd_holders++;
bdev->bd_holder = holder;
bd_clear_claiming(whole, holder);
spin_unlock(&bdev_lock);
}
EXPORT_SYMBOL(bd_finish_claiming);
/**
* bd_abort_claiming - abort claiming of a block device
* @bdev: block device of interest
* @whole: whole block device (returned from bd_start_claiming())
* @holder: holder that has claimed @bdev
*
* Abort claiming of a block device when the exclusive open failed. This can be
* also used when exclusive open is not actually desired and we just needed
* to block other exclusive openers for a while.
*/
void bd_abort_claiming(struct block_device *bdev, struct block_device *whole,
void *holder)
{
spin_lock(&bdev_lock);
bd_clear_claiming(whole, holder);
spin_unlock(&bdev_lock);
}
EXPORT_SYMBOL(bd_abort_claiming);
#ifdef CONFIG_SYSFS
struct bd_holder_disk {
struct list_head list;
struct gendisk *disk;
int refcnt;
};
static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
struct gendisk *disk)
{
struct bd_holder_disk *holder;
list_for_each_entry(holder, &bdev->bd_holder_disks, list)
if (holder->disk == disk)
return holder;
return NULL;
}
static int add_symlink(struct kobject *from, struct kobject *to)
{
return sysfs_create_link(from, to, kobject_name(to));
}
static void del_symlink(struct kobject *from, struct kobject *to)
{
sysfs_remove_link(from, kobject_name(to));
}
/**
* bd_link_disk_holder - create symlinks between holding disk and slave bdev
* @bdev: the claimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* This functions creates the following sysfs symlinks.
*
* - from "slaves" directory of the holder @disk to the claimed @bdev
* - from "holders" directory of the @bdev to the holder @disk
*
* For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
* passed to bd_link_disk_holder(), then:
*
* /sys/block/dm-0/slaves/sda --> /sys/block/sda
* /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
*
* The caller must have claimed @bdev before calling this function and
* ensure that both @bdev and @disk are valid during the creation and
* lifetime of these symlinks.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
int ret = 0;
mutex_lock(&bdev->bd_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
/* FIXME: remove the following once add_disk() handles errors */
if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
goto out_unlock;
holder = bd_find_holder_disk(bdev, disk);
if (holder) {
holder->refcnt++;
goto out_unlock;
}
holder = kzalloc(sizeof(*holder), GFP_KERNEL);
if (!holder) {
ret = -ENOMEM;
goto out_unlock;
}
INIT_LIST_HEAD(&holder->list);
holder->disk = disk;
holder->refcnt = 1;
ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
if (ret)
goto out_free;
ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
if (ret)
goto out_del;
/*
* bdev could be deleted beneath us which would implicitly destroy
* the holder directory. Hold on to it.
*/
kobject_get(bdev->bd_part->holder_dir);
list_add(&holder->list, &bdev->bd_holder_disks);
goto out_unlock;
out_del:
del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
out_free:
kfree(holder);
out_unlock:
mutex_unlock(&bdev->bd_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
/**
* bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
* @bdev: the calimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* CONTEXT:
* Might sleep.
*/
void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
mutex_lock(&bdev->bd_mutex);
holder = bd_find_holder_disk(bdev, disk);
if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
del_symlink(bdev->bd_part->holder_dir,
&disk_to_dev(disk)->kobj);
kobject_put(bdev->bd_part->holder_dir);
list_del_init(&holder->list);
kfree(holder);
}
mutex_unlock(&bdev->bd_mutex);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
#endif
/**
* flush_disk - invalidates all buffer-cache entries on a disk
*
* @bdev: struct block device to be flushed
* @kill_dirty: flag to guide handling of dirty inodes
*
* Invalidates all buffer-cache entries on a disk. It should be called
* when a disk has been changed -- either by a media change or online
* resize.
*/
static void flush_disk(struct block_device *bdev, bool kill_dirty)
{
if (__invalidate_device(bdev, kill_dirty)) {
printk(KERN_WARNING "VFS: busy inodes on changed media or "
"resized disk %s\n",
bdev->bd_disk ? bdev->bd_disk->disk_name : "");
}
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.
* @verbose: if %true log a message about a size change if there is any
*
* This routine checks to see if the bdev size does not match the disk size
* and adjusts it if it differs. When shrinking the bdev size, its all caches
* are freed.
*/
void check_disk_size_change(struct gendisk *disk, struct block_device *bdev,
bool verbose)
{
loff_t disk_size, bdev_size;
disk_size = (loff_t)get_capacity(disk) << 9;
bdev_size = i_size_read(bdev->bd_inode);
if (disk_size != bdev_size) {
if (verbose) {
printk(KERN_INFO
"%s: detected capacity change from %lld to %lld\n",
disk->disk_name, bdev_size, disk_size);
}
i_size_write(bdev->bd_inode, disk_size);
if (bdev_size > disk_size)
flush_disk(bdev, false);
}
}
/**
* revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
* @disk: struct gendisk to be revalidated
*
* This routine is a wrapper for lower-level driver's revalidate_disk
* call-backs. It is used to do common pre and post operations needed
* for all revalidate_disk operations.
*/
int revalidate_disk(struct gendisk *disk)
{
int ret = 0;
if (disk->fops->revalidate_disk)
ret = disk->fops->revalidate_disk(disk);
/*
* Hidden disks don't have associated bdev so there's no point in
* revalidating it.
*/
if (!(disk->flags & GENHD_FL_HIDDEN)) {
struct block_device *bdev = bdget_disk(disk, 0);
if (!bdev)
return ret;
mutex_lock(&bdev->bd_mutex);
check_disk_size_change(disk, bdev, ret == 0);
bdev->bd_invalidated = 0;
mutex_unlock(&bdev->bd_mutex);
bdput(bdev);
}
return ret;
}
EXPORT_SYMBOL(revalidate_disk);
/*
* This routine checks whether a removable media has been changed,
* and invalidates all buffer-cache-entries in that case. This
* is a relatively slow routine, so we have to try to minimize using
* it. Thus it is called only upon a 'mount' or 'open'. This
* is the best way of combining speed and utility, I think.
* People changing diskettes in the middle of an operation deserve
* to lose :-)
*/
int check_disk_change(struct block_device *bdev)
{
struct gendisk *disk = bdev->bd_disk;
const struct block_device_operations *bdops = disk->fops;
unsigned int events;
events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
DISK_EVENT_EJECT_REQUEST);
if (!(events & DISK_EVENT_MEDIA_CHANGE))
return 0;
flush_disk(bdev, true);
if (bdops->revalidate_disk)
bdops->revalidate_disk(bdev->bd_disk);
return 1;
}
EXPORT_SYMBOL(check_disk_change);
void bd_set_size(struct block_device *bdev, loff_t size)
{
inode_lock(bdev->bd_inode);
i_size_write(bdev->bd_inode, size);
inode_unlock(bdev->bd_inode);
}
EXPORT_SYMBOL(bd_set_size);
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
/*
* bd_mutex locking:
*
* mutex_lock(part->bd_mutex)
* mutex_lock_nested(whole->bd_mutex, 1)
*/
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
{
struct gendisk *disk;
int ret;
int partno;
int perm = 0;
bool first_open = false;
if (mode & FMODE_READ)
perm |= MAY_READ;
if (mode & FMODE_WRITE)
perm |= MAY_WRITE;
/*
* hooks: /n/, see "layering violations".
*/
if (!for_part) {
ret = devcgroup_inode_permission(bdev->bd_inode, perm);
if (ret != 0) {
bdput(bdev);
return ret;
}
}
restart:
ret = -ENXIO;
disk = bdev_get_gendisk(bdev, &partno);
if (!disk)
goto out;
disk_block_events(disk);
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (!bdev->bd_openers) {
first_open = true;
bdev->bd_disk = disk;
bdev->bd_queue = disk->queue;
bdev->bd_contains = bdev;
bdev->bd_partno = partno;
if (!partno) {
ret = -ENXIO;
bdev->bd_part = disk_get_part(disk, partno);
if (!bdev->bd_part)
goto out_clear;
ret = 0;
if (disk->fops->open) {
ret = disk->fops->open(bdev, mode);
if (ret == -ERESTARTSYS) {
/* Lost a race with 'disk' being
* deleted, try again.
* See md.c
*/
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
bdev->bd_disk = NULL;
bdev->bd_queue = NULL;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
put_disk_and_module(disk);
goto restart;
}
}
if (!ret) {
bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
set_init_blocksize(bdev);
}
/*
* If the device is invalidated, rescan partition
* if open succeeded or failed with -ENOMEDIUM.
* The latter is necessary to prevent ghost
* partitions on a removed medium.
*/
if (bdev->bd_invalidated) {
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);
set_init_blocksize(bdev);
}
if (bdev->bd_bdi == &noop_backing_dev_info)
bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
} else {
if (bdev->bd_contains == bdev) {
ret = 0;
if (bdev->bd_disk->fops->open)
ret = bdev->bd_disk->fops->open(bdev, mode);
/* the same as first opener case, read comment there */
if (bdev->bd_invalidated) {
if (!ret)
rescan_partitions(bdev->bd_disk, bdev);
else if (ret == -ENOMEDIUM)
invalidate_partitions(bdev->bd_disk, bdev);
}
if (ret)
goto out_unlock_bdev;
}
}
bdev->bd_openers++;
if (for_part)
bdev->bd_part_count++;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
/* only one opener holds refs to the module and disk */
if (!first_open)
put_disk_and_module(disk);
return 0;
out_clear:
disk_put_part(bdev->bd_part);
bdev->bd_disk = NULL;
bdev->bd_part = NULL;
bdev->bd_queue = NULL;
if (bdev != bdev->bd_contains)
__blkdev_put(bdev->bd_contains, mode, 1);
bdev->bd_contains = NULL;
out_unlock_bdev:
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
put_disk_and_module(disk);
out:
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);
if (!res)
bd_finish_claiming(bdev, whole, holder);
else
bd_abort_claiming(bdev, whole, holder);
/*
* Block event polling for write claims if requested. Any
* write holder makes the write_holder state stick until
* all are released. This is good enough and tracking
* individual writeable reference is too fragile given the
* way @mode is used in blkdev_get/put().
*/
if (!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;
filp->f_mode |= FMODE_NOWAIT;
if (filp->f_flags & O_NDELAY)
filp->f_mode |= FMODE_NDELAY;
if (filp->f_flags & O_EXCL)
filp->f_mode |= FMODE_EXCL;
if ((filp->f_flags & O_ACCMODE) == 3)
filp->f_mode |= FMODE_WRITE_IOCTL;
bdev = bd_acquire(inode);
if (bdev == NULL)
return -ENOMEM;
filp->f_mapping = bdev->bd_inode->i_mapping;
filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
return blkdev_get(bdev, filp->f_mode, filp);
}
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
{
struct gendisk *disk = bdev->bd_disk;
struct block_device *victim = NULL;
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (for_part)
bdev->bd_part_count--;
if (!--bdev->bd_openers) {
WARN_ON_ONCE(bdev->bd_holders);
sync_blockdev(bdev);
kill_bdev(bdev);
bdev_write_inode(bdev);
}
if (bdev->bd_contains == bdev) {
if (disk->fops->release)
disk->fops->release(disk, mode);
}
if (!bdev->bd_openers) {
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
bdev->bd_disk = NULL;
if (bdev != bdev->bd_contains)
victim = bdev->bd_contains;
bdev->bd_contains = NULL;
put_disk_and_module(disk);
}
mutex_unlock(&bdev->bd_mutex);
bdput(bdev);
if (victim)
__blkdev_put(victim, mode, 1);
}
void blkdev_put(struct block_device *bdev, fmode_t mode)
{
mutex_lock(&bdev->bd_mutex);
if (mode & FMODE_EXCL) {
bool bdev_free;
/*
* Release a claim on the device. The holder fields
* are protected with bdev_lock. bd_mutex is to
* synchronize disk_holder unlinking.
*/
spin_lock(&bdev_lock);
WARN_ON_ONCE(--bdev->bd_holders < 0);
WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
/* bd_contains might point to self, check in a separate step */
if ((bdev_free = !bdev->bd_holders))
bdev->bd_holder = NULL;
if (!bdev->bd_contains->bd_holders)
bdev->bd_contains->bd_holder = NULL;
spin_unlock(&bdev_lock);
/*
* If this was the last claim, remove holder link and
* unblock evpoll if it was a write holder.
*/
if (bdev_free && bdev->bd_write_holder) {
disk_unblock_events(bdev->bd_disk);
bdev->bd_write_holder = false;
}
}
/*
* Trigger event checking and tell drivers to flush MEDIA_CHANGE
* event. This is to ensure detection of media removal commanded
* from userland - e.g. eject(1).
*/
disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
mutex_unlock(&bdev->bd_mutex);
__blkdev_put(bdev, mode, 0);
}
EXPORT_SYMBOL(blkdev_put);
static int blkdev_close(struct inode * inode, struct file * filp)
{
struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
blkdev_put(bdev, filp->f_mode);
return 0;
}
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
{
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
fmode_t mode = file->f_mode;
/*
* O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
* to updated it before every ioctl.
*/
if (file->f_flags & O_NDELAY)
mode |= FMODE_NDELAY;
else
mode &= ~FMODE_NDELAY;
return blkdev_ioctl(bdev, mode, cmd, arg);
}
/*
* Write data to the block device. Only intended for the block device itself
* and the raw driver which basically is a fake block device.
*
* Does not take i_mutex for the write and thus is not for general purpose
* use.
*/
ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
struct blk_plug plug;
ssize_t ret;
if (bdev_read_only(I_BDEV(bd_inode)))
return -EPERM;
if (IS_SWAPFILE(bd_inode))
return -ETXTBSY;
if (!iov_iter_count(from))
return 0;
if (iocb->ki_pos >= size)
return -ENOSPC;
if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
return -EOPNOTSUPP;
iov_iter_truncate(from, size - iocb->ki_pos);
blk_start_plug(&plug);
ret = __generic_file_write_iter(iocb, from);
if (ret > 0)
ret = generic_write_sync(iocb, ret);
blk_finish_plug(&plug);
return ret;
}
EXPORT_SYMBOL_GPL(blkdev_write_iter);
ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
loff_t pos = iocb->ki_pos;
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 int blkdev_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
return generic_writepages(mapping, wbc);
}
static const struct address_space_operations def_blk_aops = {
.readpage = blkdev_readpage,
.readpages = blkdev_readpages,
.writepage = blkdev_writepage,
.write_begin = blkdev_write_begin,
.write_end = blkdev_write_end,
.writepages = blkdev_writepages,
.releasepage = blkdev_releasepage,
.direct_IO = blkdev_direct_IO,
.migratepage = buffer_migrate_page_norefs,
.is_dirty_writeback = buffer_check_dirty_writeback,
};
#define BLKDEV_FALLOC_FL_SUPPORTED \
(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
static long blkdev_fallocate(struct file *file, int mode, loff_t start,
loff_t len)
{
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
struct address_space *mapping;
loff_t end = start + len - 1;
loff_t isize;
int error;
/* Fail if we don't recognize the flags. */
if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
return -EOPNOTSUPP;
/* Don't go off the end of the device. */
isize = i_size_read(bdev->bd_inode);
if (start >= isize)
return -EINVAL;
if (end >= isize) {
if (mode & FALLOC_FL_KEEP_SIZE) {
len = isize - start;
end = start + len - 1;
} else
return -EINVAL;
}
/*
* Don't allow IO that isn't aligned to logical block size.
*/
if ((start | len) & (bdev_logical_block_size(bdev) - 1))
return -EINVAL;
/* Invalidate the page cache, including dirty pages. */
mapping = bdev->bd_inode->i_mapping;
truncate_inode_pages_range(mapping, start, end);
switch (mode) {
case FALLOC_FL_ZERO_RANGE:
case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
break;
case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
break;
case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
GFP_KERNEL, 0);
break;
default:
return -EOPNOTSUPP;
}
if (error)
return error;
/*
* Invalidate again; if someone wandered in and dirtied a page,
* the caller will be given -EBUSY. The third argument is
* inclusive, so the rounding here is safe.
*/
return invalidate_inode_pages2_range(mapping,
start >> PAGE_SHIFT,
end >> PAGE_SHIFT);
}
const struct file_operations def_blk_fops = {
.open = blkdev_open,
.release = blkdev_close,
.llseek = block_llseek,
.read_iter = blkdev_read_iter,
.write_iter = blkdev_write_iter,
.iopoll = blkdev_iopoll,
.mmap = generic_file_mmap,
.fsync = blkdev_fsync,
.unlocked_ioctl = block_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = compat_blkdev_ioctl,
#endif
.splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.fallocate = blkdev_fallocate,
};
int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
{
int res;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
res = blkdev_ioctl(bdev, 0, cmd, arg);
set_fs(old_fs);
return res;
}
EXPORT_SYMBOL(ioctl_by_bdev);
/**
* lookup_bdev - lookup a struct block_device by name
* @pathname: special file representing the block device
*
* Get a reference to the blockdevice at @pathname in the current
* namespace if possible and return it. Return ERR_PTR(error)
* otherwise.
*/
struct block_device *lookup_bdev(const char *pathname)
{
struct block_device *bdev;
struct inode *inode;
struct path path;
int error;
if (!pathname || !*pathname)
return ERR_PTR(-EINVAL);
error = kern_path(pathname, LOOKUP_FOLLOW, &path);
if (error)
return ERR_PTR(error);
inode = d_backing_inode(path.dentry);
error = -ENOTBLK;
if (!S_ISBLK(inode->i_mode))
goto fail;
error = -EACCES;
if (!may_open_dev(&path))
goto fail;
error = -ENOMEM;
bdev = bd_acquire(inode);
if (!bdev)
goto fail;
out:
path_put(&path);
return bdev;
fail:
bdev = ERR_PTR(error);
goto out;
}
EXPORT_SYMBOL(lookup_bdev);
int __invalidate_device(struct block_device *bdev, bool kill_dirty)
{
struct super_block *sb = get_super(bdev);
int res = 0;
if (sb) {
/*
* no need to lock the super, get_super holds the
* read mutex so the filesystem cannot go away
* under us (->put_super runs with the write lock
* hold).
*/
shrink_dcache_sb(sb);
res = invalidate_inodes(sb, kill_dirty);
drop_super(sb);
}
invalidate_bdev(bdev);
return res;
}
EXPORT_SYMBOL(__invalidate_device);
void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
{
struct inode *inode, *old_inode = NULL;
spin_lock(&blockdev_superblock->s_inode_list_lock);
list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
struct address_space *mapping = inode->i_mapping;
struct block_device *bdev;
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
mapping->nrpages == 0) {
spin_unlock(&inode->i_lock);
continue;
}
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&blockdev_superblock->s_inode_list_lock);
/*
* We hold a reference to 'inode' so it couldn't have been
* removed from s_inodes list while we dropped the
* s_inode_list_lock We cannot iput the inode now as we can
* be holding the last reference and we cannot iput it under
* s_inode_list_lock. So we keep the reference and iput it
* later.
*/
iput(old_inode);
old_inode = inode;
bdev = I_BDEV(inode);
mutex_lock(&bdev->bd_mutex);
if (bdev->bd_openers)
func(bdev, arg);
mutex_unlock(&bdev->bd_mutex);
spin_lock(&blockdev_superblock->s_inode_list_lock);
}
spin_unlock(&blockdev_superblock->s_inode_list_lock);
iput(old_inode);
}
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