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SubjectRe: [PATCH] block_dev.c: fsync() on close() considered harmful
On Thu, Nov 22, 2001 at 02:34:50PM +0100, Miquel van Smoorenburg wrote:
> I'm running an INN usenet news server that uses raw partitions for
> storage. I.e. it opens /dev/sda7 etc. and mmap()s [which finally
> works in 2.4, hurray]

:)

> Even though the server is keeping those devices open, when a utility
> program (sm) opens that file/device and closes() it the close() causes
> a fsync() on the device, something that is not wanted.
>
> I applied the following patch which fixes it for me, it prevents
> the sync-after-close if it was close() calling blkdev_put()
> and we're not the last one to call blkdev_put().
>
> That means fsync() will still be done on unmounts or when the
> last user of the device closes it, but not otherwise.
>
> Is this correct or am I overlooking something?

it's correct, thanks.

>
> --- linux-2.4.15-pre8/fs/block_dev.c.orig Thu Oct 25 22:58:35 2001
> +++ linux-2.4.15-pre8/fs/block_dev.c Wed Nov 21 13:32:16 2001
> @@ -603,7 +603,7 @@
>
> down(&bdev->bd_sem);
> lock_kernel();
> - if (kind == BDEV_FILE)
> + if (kind == BDEV_FILE && bdev->bd_openers == 1)
> __block_fsync(bd_inode);
> else if (kind == BDEV_FS)
> fsync_no_super(rdev);
>
>
> Mike.
> --
> "Only two things are infinite, the universe and human stupidity,
> and I'm not sure about the former" -- Albert Einstein.


Andrea
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