Re: [CHECKER] Does sys_sync (ext2, 2.6.x) flush metadata?

[Andi Kleen]

Junfeng Yang <yjf@xxxxxxxxxxxx> writes:

> We're working on a file system checker and have a question regarding what
> sys_sync actually does.  It appears to us that sys_sync should sync both
> data and metadata, and wait until both data and metadata hit the disk
> before it returns.  Is this true for all the file systems (especially
> ext2) for kernel 2.6.x?  I've gotten many "error" traces for ext2, where
> directory entries are not flushed to disk after sys_sync.  In other words,
> even if users do call sys_sync, a crash after sys_sync call can still
> cause file losses.  Is this intended?

No, it would be a bug. sync() is supposed to flush everything.
In the ext2 case directory changes should be hold in a dirty buffer,
which sync should normally flush.

-Andi
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