linux-ext4 - Re: there is a BUG in disk full case in inlinedata feature.

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Message-ID: <20131021174842.GA10656@birch.djwong.org>
Date:	Mon, 21 Oct 2013 10:48:42 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	Boxi Liu <boxi10liu@...il.com>
Cc:	Tao Ma <tm@....ma>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Robin Dong <sanbai@...bao.com>, Theodore Tso <tytso@....edu>,
	"lewis.liulei" <lewis.liulei@...wei.com>
Subject: Re: there is a BUG in disk full case in inlinedata feature.

On Tue, Oct 22, 2013 at 12:22:34AM +0800, Boxi Liu wrote:
> hi,
> I make the format patch about the inline_data patch .
> Is there anything incomplete？

Please run scripts/checkpatch.pl on that patch and fix the errors it finds (no
signed-off-by, indentation problems, no changelog, probably more...)

--D
> 
> Thanks
> boxi
> 
> 2013/8/28 Tao Ma <tm@....ma>:
> > Hi Boxi,
> >         Thanks for the detailed explanation and the bug fix. It looks good to me.
> >         So would you mind send out a formal patch?
> >
> > Thanks,
> > Tao
> > On 08/28/2013 01:09 AM, Boxi Liu wrote:
> >> there is a BUG in EXT4 inlinedata feature when the disk is full(0B).
> >> tast case:
> >>     step1: use the dd to make the disk full,has 0B remained.
> >>     step2: touch a inlinedata file
> >>            echo -n "123456" >> test.txt
> >>     step3: make the inlinedata file test.txt convert to extent block.
> >>            echo -n
> >> "123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890">>test.txt
> >> the step3 will write failed.and print the BUG Backtrace:
> >> page:c1963bc0 count:-1 mapcount:0 mapping: (null) index:0x0
> >> page flags:0x40000000()
> >> Backtrace:
> >> [<c004e180>] (dump_backtrace + 0x0/0x12c) from [<c07724ac>]
> >> (dump_stack +0x18/0x1c)
> >> r6:c0043a84  r5:c0bb688  r4:c1963bc0 r3:00000000
> >> [<c0772494>] (dump_stack + 0x0/0x1c) from [<c00f6dd4>] (bad_page + 0xbc/0x13c)
> >> [<c00fbd18>] (bad_page + 0x0/0x13c) from [<c00f74b80>]
> >> (get_page_from_freelist + 0x4cc/0xb6c)
> >> r7:c1963bd8 r6:c0043194 r5:c1963bc0 r4:00000001
> >> [<c00f6fec>] (get_page_from_freelist +0x0/0xb6c) from [<c00f8148>]
> >> (__alloc_pages_nodemask + 0x144/0x820)
> >> [<c00f8004>] (__alloc_pages_nodemask +0x0/0x820) from [<c0115250>]
> >> (handle_pte_fault + 0x574/0x758)
> >> [<c0114cdc>] (handle_pte_fault + 0x0/0x758) from [<c0115500>]
> >> (handle_mm_fault + 0xcc/0x110)
> >> [<c0115434>] (handel_mm_fault + 0x0/0x110) from [<c00521a8>]
> >> (do_page_fault + 0x16c/0x1f4)
> >> [<c005203c>] (do_page_fault + 0x0/0x1f4) from [<c00440d0>]
> >> (do_DataAbort + 0x40/0xac)
> >> [<c0044090>] (do_DataAbort + 0x0/0xac) from [<c004a064>]
> >> (ret_from_exception + 0x0/0x10)
> >>
> >> And when the system reboot , the step2 data "123456" will alse lost.
> >> You can cat the test.txt,but there is no data in the file.
> >> the reason is when the inlinedata convert to extent in the limit case,
> >> the inlinedata read to the page,then destory the inlinedata,next step
> >> is to __block_write_begin,but it can't get block,return -ENOSPC. so
> >> the data lost.
> >>
> >> there is a patch may fix the bug:
> >> in inline.c ext4_convert_inline_data_to_extent
> >>
> >>          needed_blocks = ext4_writepage_trans_blocks(inode);
> >>
> >> +        if(EXT4_C2B(sbi,percpu_counter_read_positive(&sbi->s_freeclusters_counter))
> >> < needed_blocks)
> >> +               return -ENOSPC;
> >> +
> >>          ret = ext4_get_inode_loc(inode, &iloc);
> >>          if (ret)
> >>                  return ret;
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> >> the body of a message to majordomo@...r.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >>
> >


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