Re: [PATCH] Avoid disk sector_t overflow for >2TB ext3 filesystem

On Mon, 2006-05-22 at 14:10 -0600, Andreas Dilger wrote:
> On May 22, 2006  11:24 -0700, Mingming Cao wrote:
> > If ext3 filesystem is larger than 2TB, and sector_t is a u32 (i.e.
> > CONFIG_LBD not defined in the kernel), the calculation of the disk
> > sector will overflow. Add check at ext3_fill_super() and
> > ext3_group_extend() to prevent mount/remount/resize >2TB ext3 filesystem
> > if sector_t size is 4 bytes.
> > 
> > Verified this patch on a 32 bit platform without CONFIG_LBD defined
> > (sector_t is 32 bits long), mount refuse to mount a 10TB ext3. Patch
> > against 2.6.17-rc4.
> > 
> > Signed-Off-By: Mingming Cao<[email protected]>
> > 
> > 
> > ---
> > 
> >  linux-2.6.16-ming/fs/ext3/resize.c |    9 +++++++++
> >  linux-2.6.16-ming/fs/ext3/super.c  |   10 ++++++++++
> >  2 files changed, 19 insertions(+)
> > 
> > diff -puN fs/ext3/super.c~ext3_check_sector_t_overflow fs/ext3/super.c
> > --- linux-2.6.16/fs/ext3/super.c~ext3_check_sector_t_overflow	2006-05-19 17:19:43.000000000 -0700
> > +++ linux-2.6.16-ming/fs/ext3/super.c	2006-05-22 10:54:27.000000000 -0700
> > @@ -1579,6 +1579,16 @@ static int ext3_fill_super (struct super
> >  		goto failed_mount;
> >  	}
> >  
> > +	if (le32_to_cpu(es->s_blocks_count) >
> > +		(sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
> > +		printk(KERN_ERR "EXT3-fs: filesystem on %s"
> > +			" too large to mount safely\n", sb->s_id);
> 
> Minor - it's a bit easier to read the code if the "continuation" line is
> left-justified with the parenthesis instead of the tab on the next line.
> It would also be nice to print out the actual values involved:
> 
> 	if (le32_to_cpu(es->s_blocks_count) >
> 	    (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
> 		printk(KERN_ERR "EXT3-fs: filesystem on %s (%lu blocks) "
> 		       "too large to mount safely\n", sb->s_id,
> 		       le32_to_cpu(es->s_blocks_count));
> 
> > @@ -926,6 +926,15 @@ int ext3_group_extend(struct super_block
> >  	if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
> >  		return 0;
> >  
> > +	if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
> > +		printk(KERN_ERR "EXT3-fs: filesystem on %s"
> > +			" too large to mount safely\n", sb->s_id);
> 
> Minor - "too large to resize to %lu blocks safely\n", sb->s_id, n_blocks_count
> 
> You can add an:
> Signed-Off-By: Andreas Dilger <[email protected]>
> 


Thanks, I will fix these messages when we dealing the sector_t overflow
check for >32 bit ext3:)

Mingming



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