In the Linux kernel, the following vulnerability has been resolved:
btrfs: protect sb_write_pointer() with invalidate lock
sb_write_pointer() reads the super block from the block device page cache
using read_cache_page_gfp(). This has the same race with BLKBSZSET as the
one fixed by commit 3f29d661e568 ("btrfs: sync read disk super and set
block size").
Take the mapping invalidate lock around read_cache_page_gfp() to
serialize the read against block size changes.
