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.

Signed-off-by: KangNing Liao <lkangn.kernel@gmail.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 16dd87aa06f20c5e5bc724ecb967ddf46fb314e4..5f75cf0e14b9510346b9ae6444a41ba61e76f5b5 100644 (file)
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -131,8 +131,10 @@ static int sb_write_pointer(struct block_device *bdev, struct blk_zone *zones,
                        u64 bytenr = ALIGN_DOWN(zone_end, BTRFS_SUPER_INFO_SIZE) -
                                                BTRFS_SUPER_INFO_SIZE;
 
+                       filemap_invalidate_lock(mapping);
                        page[i] = read_cache_page_gfp(mapping,
                                        bytenr >> PAGE_SHIFT, GFP_NOFS);
+                       filemap_invalidate_unlock(mapping);
                        if (IS_ERR(page[i])) {
                                if (i == 1)
                                        btrfs_release_disk_super(super[0]);