Hi Alan,
I don't see any standard specifying that fsync should be done on
every blockdevice close.
Any chance you could add the below patch to the next -ac release?
Christoph
Date: Thu, 22 Nov 2001 14:34:50 +0100
From: Miquel van Smoorenburg <[email protected]>
To: Andrea Arcangeli <[email protected]>
Cc: [email protected]
Subject: [PATCH] block_dev.c: fsync() on close() considered harmful
Message-ID: <[email protected]>
Reply-To: [email protected]
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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?
--- 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.
Christoph Hellwig [[email protected]] wrote:
> Hi Alan,
>
> I don't see any standard specifying that fsync should be done on
> every blockdevice close.
>
> Any chance you could add the below patch to the next -ac release?
>
> Christoph
I am writing a partitionable block device driver for the 2.4 kernel.
Once the driver is loaded and the device mounted, reading, writing,
and ioctls work properly.
The driver becomes unstable after many mounts/unmounts, and I have
come to suspect that I am not calling fsync_dev() correctly.
I do call fsync_dev() on release as well as on remove.
Is this incorrect? Can it lead to instability? I've counted four
different ways in which the driver dies, including a call to
BUG() in buffer.c...
Thank you,
Christine
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