• Jeff Mahoney's avatar
    btrfs: account for non-CoW'd blocks in btrfs_abort_transaction · 64c12921
    Jeff Mahoney authored
    The test for !trans->blocks_used in btrfs_abort_transaction is
    insufficient to determine whether it's safe to drop the transaction
    handle on the floor.  btrfs_cow_block, informed by should_cow_block,
    can return blocks that have already been CoW'd in the current
    transaction.  trans->blocks_used is only incremented for new block
    allocations. If an operation overlaps the blocks in the current
    transaction entirely and must abort the transaction, we'll happily
    let it clean up the trans handle even though it may have modified
    the blocks and will commit an incomplete operation.
    
    In the long-term, I'd like to do closer tracking of when the fs
    is actually modified so we can still recover as gracefully as possible,
    but that approach will need some discussion.  In the short term,
    since this is the only code using trans->blocks_used, let's just
    switch it to a bool indicating whether any blocks were used and set
    it when should_cow_block returns false.
    
    Cc: stable@vger.kernel.org # 3.4+
    Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
    Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
    64c12921
super.c 64.7 KB