blockdev: turn a rw semaphore into a percpu rw semaphore

[deliverable/linux.git] / fs / block_dev.c

diff --git a/fs/block_dev.c b/fs/block_dev.c
index cdfb625824e2404d0dce02888a4da2c8a2050fd9..7eeb0635338bdff8c07e2d5c4f09a3423b458f57 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -127,7 +127,7 @@ int set_blocksize(struct block_device *bdev, int size)
                return -EINVAL;
 
        /* Prevent starting I/O or mapping the device */
-       down_write(&bdev->bd_block_size_semaphore);
+       percpu_down_write(&bdev->bd_block_size_semaphore);
 
        /* Check that the block device is not memory mapped */
        mapping = bdev->bd_inode->i_mapping;
@@ -135,7 +135,7 @@ int set_blocksize(struct block_device *bdev, int size)
        if (!prio_tree_empty(&mapping->i_mmap) ||
            !list_empty(&mapping->i_mmap_nonlinear)) {
                mutex_unlock(&mapping->i_mmap_mutex);
-               up_write(&bdev->bd_block_size_semaphore);
+               percpu_up_write(&bdev->bd_block_size_semaphore);
                return -EBUSY;
        }
        mutex_unlock(&mapping->i_mmap_mutex);
@@ -148,7 +148,7 @@ int set_blocksize(struct block_device *bdev, int size)
                kill_bdev(bdev);
        }
 
-       up_write(&bdev->bd_block_size_semaphore);
+       percpu_up_write(&bdev->bd_block_size_semaphore);
 
        return 0;
 }
@@ -460,6 +460,12 @@ 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;
 }
 
@@ -468,6 +474,8 @@ 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);
 }
 
@@ -491,7 +499,6 @@ static void init_once(void *foo)
        inode_init_once(&ei->vfs_inode);
        /* Initialize mutex for freeze. */
        mutex_init(&bdev->bd_fsfreeze_mutex);
-       init_rwsem(&bdev->bd_block_size_semaphore);
 }
 
 static inline void __bd_forget(struct inode *inode)
@@ -1593,11 +1600,11 @@ ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
        ssize_t ret;
        struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
 
-       down_read(&bdev->bd_block_size_semaphore);
+       percpu_down_read(&bdev->bd_block_size_semaphore);
 
        ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
 
-       up_read(&bdev->bd_block_size_semaphore);
+       percpu_up_read(&bdev->bd_block_size_semaphore);
 
        return ret;
 }
@@ -1622,7 +1629,7 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
 
        blk_start_plug(&plug);
 
-       down_read(&bdev->bd_block_size_semaphore);
+       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) {
@@ -1633,7 +1640,7 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
                        ret = err;
        }
 
-       up_read(&bdev->bd_block_size_semaphore);
+       percpu_up_read(&bdev->bd_block_size_semaphore);
 
        blk_finish_plug(&plug);
 
@@ -1646,11 +1653,11 @@ int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
        int ret;
        struct block_device *bdev = I_BDEV(file->f_mapping->host);
 
-       down_read(&bdev->bd_block_size_semaphore);
+       percpu_down_read(&bdev->bd_block_size_semaphore);
 
        ret = generic_file_mmap(file, vma);
 
-       up_read(&bdev->bd_block_size_semaphore);
+       percpu_up_read(&bdev->bd_block_size_semaphore);
 
        return ret;
 }