Message-ID: <20241017145630.GU21853@frogsfrogsfrogs>
Date: Thu, 17 Oct 2024 07:56:30 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
Cc: linux-xfs@...r.kernel.org, Ritesh Harjani <ritesh.list@...il.com>,
	linux-kernel@...r.kernel.org, dchinner@...hat.com,
	Chandan Babu R <chandan.babu@...cle.com>,
	Christoph Hellwig <hch@....de>, nirjhar@...ux.ibm.com
Subject: Re: [PATCH v3] xfs: Check for delayed allocations before setting
 extsize

On Thu, Oct 17, 2024 at 12:33:32PM +0530, Ojaswin Mujoo wrote:
> On Tue, Oct 15, 2024 at 09:22:37AM -0700, Darrick J. Wong wrote:
> > On Tue, Oct 15, 2024 at 12:23:21PM +0530, Ojaswin Mujoo wrote:
> > > On Mon, Oct 14, 2024 at 08:28:56AM -0700, Darrick J. Wong wrote:
> > > > On Mon, Oct 14, 2024 at 03:02:45PM +0530, Ojaswin Mujoo wrote:
> > > > > On Fri, Oct 11, 2024 at 09:40:57AM -0700, Darrick J. Wong wrote:
> > > > > > On Fri, Oct 11, 2024 at 09:38:30AM -0700, Darrick J. Wong wrote:
> > > > > > > On Fri, Oct 11, 2024 at 08:24:27PM +0530, Ojaswin Mujoo wrote:
> > > > > > > > Extsize is allowed to be set on files with no data in it. For this,
> > > > > > > > we were checking if the files have extents but missed to check if
> > > > > > > > delayed extents were present. This patch adds that check.
> > > > > > > > 
> > > > > > > > While we are at it, also refactor this check into a helper since
> > > > > > > > its used in some other places as well like xfs_inactive() or
> > > > > > > > xfs_ioctl_setattr_xflags()
> > > > > > > > 
> > > > > > > > **Without the patch (SUCCEEDS)**
> > > > > > > > 
> > > > > > > > $ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'
> > > > > > > > 
> > > > > > > > wrote 1024/1024 bytes at offset 0
> > > > > > > > 1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
> > > > > > > > 
> > > > > > > > **With the patch (FAILS as expected)**
> > > > > > > > 
> > > > > > > > $ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'
> > > > > > > > 
> > > > > > > > wrote 1024/1024 bytes at offset 0
> > > > > > > > 1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
> > > > > > > > xfs_io: FS_IOC_FSSETXATTR testfile: Invalid argument
> > > > > > > > 
> > > > > > > > Reviewed-by: Christoph Hellwig <hch@....de>
> > > > > > > > Signed-off-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
> > > > > > > 
> > > > > > > Looks good now,
> > > > > > > Reviewed-by: Darrick J. Wong <djwong@...nel.org>
> > > > > > 
> > > > > > That said, could you add a fixes tag for the xfs_ioctl_setattr_*
> > > > > > changes, please?
> > > > > 
> > > > > Actually a small doubt Darrick regarding the Fixes commit (asked inline
> > > > > below):
> > > > > 
> > > > > > 
> > > > > > --D
> > > > > > 
> > > > > > > --D
> > > > > > > 
> > > > > > > > ---
> > > > > > > >  fs/xfs/xfs_inode.c | 2 +-
> > > > > > > >  fs/xfs/xfs_inode.h | 5 +++++
> > > > > > > >  fs/xfs/xfs_ioctl.c | 4 ++--
> > > > > > > >  3 files changed, 8 insertions(+), 3 deletions(-)
> > > > > > > > 
> > > > > > > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> > > > > > > > index bcc277fc0a83..19dcb569a3e7 100644
> > > > > > > > --- a/fs/xfs/xfs_inode.c
> > > > > > > > +++ b/fs/xfs/xfs_inode.c
> > > > > > > > @@ -1409,7 +1409,7 @@ xfs_inactive(
> > > > > > > >  
> > > > > > > >  	if (S_ISREG(VFS_I(ip)->i_mode) &&
> > > > > > > >  	    (ip->i_disk_size != 0 || XFS_ISIZE(ip) != 0 ||
> > > > > > > > -	     ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0))
> > > > > > > > +	     xfs_inode_has_filedata(ip)))
> > > > > > > >  		truncate = 1;
> > > > > > > >  
> > > > > > > >  	if (xfs_iflags_test(ip, XFS_IQUOTAUNCHECKED)) {
> > > > > > > > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> > > > > > > > index 97ed912306fd..03944b6c5fba 100644
> > > > > > > > --- a/fs/xfs/xfs_inode.h
> > > > > > > > +++ b/fs/xfs/xfs_inode.h
> > > > > > > > @@ -292,6 +292,11 @@ static inline bool xfs_is_cow_inode(struct xfs_inode *ip)
> > > > > > > >  	return xfs_is_reflink_inode(ip) || xfs_is_always_cow_inode(ip);
> > > > > > > >  }
> > > > > > > >  
> > > > > > > > +static inline bool xfs_inode_has_filedata(const struct xfs_inode *ip)
> > > > > > > > +{
> > > > > > > > +	return ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0;
> > > > > > > > +}
> > > > > > > > +
> > > > > > > >  /*
> > > > > > > >   * Check if an inode has any data in the COW fork.  This might be often false
> > > > > > > >   * even for inodes with the reflink flag when there is no pending COW operation.
> > > > > > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> > > > > > > > index a20d426ef021..2567fd2a0994 100644
> > > > > > > > --- a/fs/xfs/xfs_ioctl.c
> > > > > > > > +++ b/fs/xfs/xfs_ioctl.c
> > > > > > > > @@ -481,7 +481,7 @@ xfs_ioctl_setattr_xflags(
> > > > > > > >  
> > > > > > > >  	if (rtflag != XFS_IS_REALTIME_INODE(ip)) {
> > > > > > > >  		/* Can't change realtime flag if any extents are allocated. */
> > > > > > > > -		if (ip->i_df.if_nextents || ip->i_delayed_blks)
> > > > > > > > +		if (xfs_inode_has_filedata(ip))
> > > > > > > >  			return -EINVAL;
> > > > > > > >  
> > > > > > > >  		/*
> > > > > > > > @@ -602,7 +602,7 @@ xfs_ioctl_setattr_check_extsize(
> > > > > > > >  	if (!fa->fsx_valid)
> > > > > > > >  		return 0;
> > > > > > > >  
> > > > > > > > -	if (S_ISREG(VFS_I(ip)->i_mode) && ip->i_df.if_nextents &&
> > > > > > > > +	if (S_ISREG(VFS_I(ip)->i_mode) && xfs_inode_has_filedata(ip) &&
> > > > > 
> > > > > So seems like there have been lots of changes to this particular line
> > > > > mostly as a part of refactoring other areas but seems like the actual
> > > > > commit that introduced it was:
> > > > > 
> > > > >   commit e94af02a9cd7b6590bec81df9d6ab857d6cf322f
> > > > >   Author: Eric Sandeen <sandeen@....com>
> > > > >   Date:   Wed Nov 2 15:10:41 2005 +1100
> > > > >   
> > > > >       [XFS] fix old xfs_setattr mis-merge from irix; mostly harmless esp if not
> > > > >       using xfs rt
> > > > > 
> > > > > Before this we were actually checking ip->i_delayed_blks correctly. So just wanted 
> > > > > to confirm that the fixes would have the above commit right?
> > > > > 
> > > > > If this looks okay I'll send a revision with this above tags:
> > > > > 
> > > > > Fixes: e94af02a9cd7 ("[XFS] fix old xfs_setattr mis-merge from irix; mostly harmless esp if not using xfs rt")
> > > > 
> > > > Yeah, that sounds fine.  Want to write a quick fstest to bang on
> > > > xfs_ioctl_setattr_check_extsize to force everyone to backport it? :)
> > > 
> > > Got it, thanks, I'll send a v4.
> > > 
> > > Regarding the tests, we were thinking of adding more comprehensive
> > > generic tests for extsize now that ext4 is also implementing it. We
> > > have a new team member Nirjhar (cc'd) who is interested in writing the 
> > > xfstest and is working on it as we speak.
> > 
> > Heh, welcome! :)
> > 
> > > Since the area is new to him, it might take a bit of time to get that
> > > out, hope that is okay?
> > 
> > Sounds good to me.  You might see how many of the tests/xfs/ stuff can
> > be pulled up to tests/generic/ as a starting point.
> 
> Sure Darrick, I believe you mean how many of the extsize related tests
> we can pull up right?
> 
> So I was checking this and I could find some relevant tests:
> 
>  * Looking into existing tests around extsize:
>    * xfs/074
>      * Check some extent size hint boundary conditions that can result in
>        MAXEXTLEN overflows.
>      * This looks specific to xfs however
> 
>    * xfs/208
>      * Testing interactinon b/w cowextsize and extsize but again seems xfs specific
> 
>    * xfs/207
>      * basic test on setting and getting (cow)extsize on file with data or empty
>      * This is a subset of the features we are testing with our test, but only
>        for extsize not cowextsize.
>      * So we can probably remove the equivalent tests from here when we add the generic
>        one.
> 
>    * xfs/419
>      * These are related to extsize inherit feature but with rtinherit.
>      * The current patchset in ext4 doesn't implement this extszinherit but it
>        might be something we might want to do in the future
>      * We can look into hoisting the extszinherit related tests at some point
> 
>   * The other ones I looked into around extsize again seemed to be specific to
>     xfx but maybe i missed something.
> 
> Are there any other tests you had in mind Darrick?

Not really.  Most of my testing comes from setting up an entire vm
config with extszinherit=X in the MKFS_OPTIONS.  I wonder if we need a
single generic test to kick the tires on the functionality just to make
sure that everyone runs it even if they only do an all-defaults testrun?

--D

> Regards,
> ojaswin
> 
> > 
> > --D
> > 
> > > Regards,
> > > Ojaswin
> > > 
> > > > 
> > > > --D
> > > > 
> > > > > Thanks,
> > > > > Ojaswin
> > > > > 
> > > > > > > >  	    XFS_FSB_TO_B(mp, ip->i_extsize) != fa->fsx_extsize)
> > > > > > > >  		return -EINVAL;
> > > > > > > >  
> > > > > > > > -- 
> > > > > > > > 2.43.5
> > > > > > > > 
> > > > > > > > 
> > > > > > > 
> > > > > 
> > > 
> 

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