Jamie Lokier wrote:
Arjan van de Ven wrote:
- removing a million files and queuing all of the
deletes in the async queues....
the async code throttles at 32k outstanding.
Yes 32K is arbitrary, but if you delete a million files fast, all but the
first few thousand are
synchronous.
Hmm.
If I call unlink() a thousand times and then call fsync() on the
parent directories covering files I've unlinked... I expect the
deletes to be committed to disk when the last fsync() has returned. I
require that a crash and restart will not see the files. Several
kinds of transactional software and even some shell scripts expect this.
Will these asynchronous deletes break the guaranteed
commit-of-the-delete provided by fsync() on the parent directory?
3 things:
1) removing the name from the directory and removing the data from disk are independent things.
The former happens from unlink(), the later happens when the refcount hits 0 (eg no more openers nor
any directory on disk referencing it). fsync() on a parent dir obviously only covers the first part,
while only the 2nd part was made asynchronous.
2) with the right synchronization point in fsync, it will still work out
3) this code will be redone for 2.6.30; for 2.6.29 it is removed.
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