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blockdev: remove bd_block_size_semaphore again
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This reverts the block-device direct access code to the previous
unlocked code, now that fs/buffer.c no longer needs external locking.

With this, fs/block_dev.c is back to the original version, apart from a
whitespace cleanup that I didn't want to revert.

Signed-off-by: Linus Torvalds <[email protected]>
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@torvalds
torvalds committed Nov 29, 2012
1 parent 45bce8f commit 1e8b333
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Showing 3 changed files with 5 additions and 106 deletions.
2 changes: 1 addition & 1 deletion drivers/char/raw.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -285,7 +285,7 @@ static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,

static const struct file_operations raw_fops = {
.read = do_sync_read,
.aio_read = blkdev_aio_read,
.aio_read = generic_file_aio_read,
.write = do_sync_write,
.aio_write = blkdev_aio_write,
.fsync = blkdev_fsync,
Expand Down
105 changes: 4 additions & 101 deletions fs/block_dev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -116,8 +116,6 @@ EXPORT_SYMBOL(invalidate_bdev);

int set_blocksize(struct block_device *bdev, int size)
{
struct address_space *mapping;

/* 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;
Expand All @@ -126,29 +124,13 @@ int set_blocksize(struct block_device *bdev, int size)
if (size < bdev_logical_block_size(bdev))
return -EINVAL;

/* Prevent starting I/O or mapping the device */
percpu_down_write(&bdev->bd_block_size_semaphore);

/* Check that the block device is not memory mapped */
mapping = bdev->bd_inode->i_mapping;
mutex_lock(&mapping->i_mmap_mutex);
if (mapping_mapped(mapping)) {
mutex_unlock(&mapping->i_mmap_mutex);
percpu_up_write(&bdev->bd_block_size_semaphore);
return -EBUSY;
}
mutex_unlock(&mapping->i_mmap_mutex);

/* 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);
}

percpu_up_write(&bdev->bd_block_size_semaphore);

return 0;
}

Expand Down Expand Up @@ -459,12 +441,6 @@ 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;

if (unlikely(percpu_init_rwsem(&ei->bdev.bd_block_size_semaphore))) {
kmem_cache_free(bdev_cachep, ei);
return NULL;
}

return &ei->vfs_inode;
}

Expand All @@ -473,8 +449,6 @@ 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);

percpu_free_rwsem(&bdi->bdev.bd_block_size_semaphore);

kmem_cache_free(bdev_cachep, bdi);
}

Expand Down Expand Up @@ -1593,22 +1567,6 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
return blkdev_ioctl(bdev, mode, cmd, arg);
}

ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
ssize_t ret;
struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);

percpu_down_read(&bdev->bd_block_size_semaphore);

ret = generic_file_aio_read(iocb, iov, nr_segs, pos);

percpu_up_read(&bdev->bd_block_size_semaphore);

return ret;
}
EXPORT_SYMBOL_GPL(blkdev_aio_read);

/*
* Write data to the block device. Only intended for the block device itself
* and the raw driver which basically is a fake block device.
Expand All @@ -1620,16 +1578,12 @@ 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;
struct block_device *bdev = I_BDEV(file->f_mapping->host);
struct blk_plug plug;
ssize_t ret;

BUG_ON(iocb->ki_pos != pos);

blk_start_plug(&plug);

percpu_down_read(&bdev->bd_block_size_semaphore);

ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
if (ret > 0 || ret == -EIOCBQUEUED) {
ssize_t err;
Expand All @@ -1638,62 +1592,11 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
if (err < 0 && ret > 0)
ret = err;
}

percpu_up_read(&bdev->bd_block_size_semaphore);

blk_finish_plug(&plug);

return ret;
}
EXPORT_SYMBOL_GPL(blkdev_aio_write);

static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret;
struct block_device *bdev = I_BDEV(file->f_mapping->host);

percpu_down_read(&bdev->bd_block_size_semaphore);

ret = generic_file_mmap(file, vma);

percpu_up_read(&bdev->bd_block_size_semaphore);

return ret;
}

static ssize_t blkdev_splice_read(struct file *file, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
ssize_t ret;
struct block_device *bdev = I_BDEV(file->f_mapping->host);

percpu_down_read(&bdev->bd_block_size_semaphore);

ret = generic_file_splice_read(file, ppos, pipe, len, flags);

percpu_up_read(&bdev->bd_block_size_semaphore);

return ret;
}

static ssize_t blkdev_splice_write(struct pipe_inode_info *pipe,
struct file *file, loff_t *ppos, size_t len,
unsigned int flags)
{
ssize_t ret;
struct block_device *bdev = I_BDEV(file->f_mapping->host);

percpu_down_read(&bdev->bd_block_size_semaphore);

ret = generic_file_splice_write(pipe, file, ppos, len, flags);

percpu_up_read(&bdev->bd_block_size_semaphore);

return ret;
}


/*
* Try to release a page associated with block device when the system
* is under memory pressure.
Expand Down Expand Up @@ -1724,16 +1627,16 @@ const struct file_operations def_blk_fops = {
.llseek = block_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = blkdev_aio_read,
.aio_read = generic_file_aio_read,
.aio_write = blkdev_aio_write,
.mmap = blkdev_mmap,
.mmap = generic_file_mmap,
.fsync = blkdev_fsync,
.unlocked_ioctl = block_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = compat_blkdev_ioctl,
#endif
.splice_read = blkdev_splice_read,
.splice_write = blkdev_splice_write,
.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)
Expand Down
4 changes: 0 additions & 4 deletions include/linux/fs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -462,8 +462,6 @@ struct block_device {
int bd_fsfreeze_count;
/* Mutex for freeze */
struct mutex bd_fsfreeze_mutex;
/* A semaphore that prevents I/O while block size is being changed */
struct percpu_rw_semaphore bd_block_size_semaphore;
};

/*
Expand Down Expand Up @@ -2379,8 +2377,6 @@ extern int generic_segment_checks(const struct iovec *iov,
unsigned long *nr_segs, size_t *count, int access_flags);

/* fs/block_dev.c */
extern ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos);
extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos);
extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
Expand Down

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