Btrfs: Send/receive and ioctl()

I saw "transactions" and thought "yay! finally filesystem level transactions", until I read on and found that "abort" is not available, which kind of defeats the whole purpose.

True filesystem transactions would solve lots of race conditions:

Want a temporary file no-one else can see? Start a transaction, use your temporary file, then when you're done abort the transaction. Completely secure.

Replace a file atomically? Wrap the delete and rename in a transaction. No longer does the kernel need to guess what you want the filesystem to look like if there's a crash.

Package installations can become atomic.

I hope someday this world can come to pass.