Btrfs: free space cache: make sure there is always room for generation number

io_ctl_set_generation() assumes that the generation number shares
the same page with inline CRCs. Let's make sure this is always true.

Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index d5f80cb..d2c0bdb 100644 (file)
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -300,9 +300,9 @@ static int io_ctl_init(struct btrfs_io_ctl *io_ctl, struct inode *inode,
        if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FREE_INO_OBJECTID)
                check_crcs = 1;
 
-       /* Make sure we can fit our crcs into the first page */
+       /* Make sure we can fit our crcs and generation into the first page */
        if (write && check_crcs &&
-           (num_pages * sizeof(u32)) >= PAGE_SIZE)
+           (num_pages * sizeof(u32) + sizeof(u64)) > PAGE_SIZE)
                return -ENOSPC;
 
        memset(io_ctl, 0, sizeof(struct btrfs_io_ctl));