On Thu, Nov 15, 2001 at 02:02:54PM -0800, Andrew Morton wrote:
> So shall we try to nail this down? Synchronous mounts and chattr +S
> provide synchronous semantics for directory contents, diretory metadata
> and directory inodes only. And fsync() will write out a file's data,
> metadata and inode?
Sounds sane. UFS sync mounts also update the inode bitmaps
synchronously, and in order, so that they can tell exactly when an
inode is valid. I guess that we don't need that, at least on ext2,
since the i_dtime gives us the necessary information automatically.
> If this is correct then there are a few places where ext2 is
> syncing stuff unnecessarily - file indirect blocks, etc. Not
> very important at this stage I guess.
It's important for people running MTAs which expect dir sync
behaviour: admins have to pay the performance cost of all file updates
being sync as well as the directory updates if they enable chattr +S
on the dir.
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