linux-kernel - Re: XFS assertion from truncate. (3.10-rc2)

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Message-ID: <20130523223038.GB24543@dastard>
Date:	Fri, 24 May 2013 08:30:38 +1000
From:	Dave Chinner <david@...morbit.com>
To:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>, xfs@....sgi.com
Subject: Re: XFS assertion from truncate. (3.10-rc2)

On Thu, May 23, 2013 at 02:49:48PM -0400, Dave Jones wrote:
> On Thu, May 23, 2013 at 07:54:54AM +1000, Dave Chinner wrote:
> 
>  > Gah, I've got not idea what the hell I was smoking yesterday
>  > afternoon. 0x2000 is actually ATTR_FILE, and 0x8000 is ATTR_OPEN.
>  > 
>  > So a mask of 0xa068 is correct and valid from the open path, and
>  > 0x2068 is just file from the truncate path.
>  > 
>  > But, neither of those should trigger that assert. indeed, on a test
>  > kernel (3.10-rc2 based):
>  > 
>  > # echo I need a new drug > /mnt/scr/bah/blah/black/sheep/foo
>  > [  296.742990] XFS (vdb): xfs_setattr_size: mask 0xa068, masked # 0x0 ii 0xffff88003e6297c0, d 0xffff88003e5b9cb0 path /bah/blah/black/sheep/foo
>  > #
>  > 
>  > And there's not assert failure. Indeed, the "masked # 0x0" is what
>  > the assert is checking.
>  > 
>  > And yeah, path output works. Trick for anyone who doesn't read the
>  > code closely - the buffer is filled from the end backwards, and the
>  > start of the path is the return variable. So, the above code is:
>  > 
>  > 	{
>  > 		struct dentry *d = d_find_alias(VFS_I(ip));
>  > 		char buf[MAXPATHLEN];
>  > 		char *ptr;
>  > 
>  > 		memset(buf, 0, MAXPATHLEN);
>  > 		ptr = dentry_path(d, buf, MAXPATHLEN);
>  > 		xfs_warn(mp, "%s: mask 0x%x, masked 0x%x ii 0x%p, d 0x%p path %s",
>  > 			__func__, mask,
>  > 	(mask & (ATTR_MODE|ATTR_UID|ATTR_GID|ATTR_ATIME|ATTR_ATIME_SET|
>  > 			ATTR_MTIME_SET|ATTR_KILL_SUID|ATTR_KILL_SGID|
>  > 			ATTR_KILL_PRIV|ATTR_TIMES_SET)),
>  > 			ip, d, ptr);
>  > 		dput(d);
>  > 	}
>  > 
>  > Which I put just before the assert that is firing on your machine.
>  > 
>  > And, obviously, it isn't firing on mine and obviously shouldn't be firing on a
>  > mask of 0xa068.
> 
> With this, I get a spew of these when I start a kernel build..
> 
> [  964.378690] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a95dac0, d 0xffff880221b5d970 path /davej/tmp/ccN2RrM5.s
> [  964.651927] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a95dac0, d 0xffff88020ff80b90 path /davej/tmp/ccB1Cdmo.s
> [  964.867444] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a95dac0, d 0xffff8802218a5bc0 path /davej/tmp/ccCUaXbG.s
> [  965.102661] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a95dac0, d 0xffff88020ffacde0 path /davej/tmp/cckMLf2X.s
> [  967.743312] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a93c200, d 0xffff88022212c250 path /davej/tmp/ccFMkBbA.s
> [  967.947154] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a93c200, d 0xffff8802226cc6f0 path /davej/tmp/cc5iX4SR.s
> [  968.009414] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a988000, d 0xffff8802219f1970 path /davej/tmp/ccvWCHTZ.o
> [  968.091504] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a9898c0, d 0xffff88022208de10 path /davej/tmp/cc9n6fnm.ld
> [  968.107997] XFS (sda2): xfs_setattr_size: mask 0xa068, masked 0x0 ii 0xffff88020a98dac0, d 0xffff880221160de0 path /davej/tmp/cc5rlvHu.le

Right, It's printing them out for every truncate that is done.
Just print on the conditional that is was triggering the assert...

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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