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authorMikulas Patocka <mpatocka@redhat.com>2012-10-15 17:20:17 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-28 10:59:37 -0700
commit1a25b1c4ce189e3926f2981f3302352a930086db (patch)
tree8db002bfdbaec616392f563d96621bfd5fbcfcd5
parent1bf11c53535ab87e3bf14ecdf6747bf46f601c5d (diff)
Lock splice_read and splice_write functions
Functions generic_file_splice_read and generic_file_splice_write access the pagecache directly. For block devices these functions must be locked so that block size is not changed while they are in progress. This patch is an additional fix for commit b87570f5d349 ("Fix a crash when block device is read and block size is changed at the same time") that locked aio_read, aio_write and mmap against block size change. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/block_dev.c37
1 files changed, 35 insertions, 2 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index b3c1d3dae77d..1a1e5e3b1eaf 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1661,6 +1661,39 @@ static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
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.
@@ -1699,8 +1732,8 @@ const struct file_operations def_blk_fops = {
#ifdef CONFIG_COMPAT
.compat_ioctl = compat_blkdev_ioctl,
#endif
- .splice_read = generic_file_splice_read,
- .splice_write = generic_file_splice_write,
+ .splice_read = blkdev_splice_read,
+ .splice_write = blkdev_splice_write,
};
int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)