linux-ext4 - Re: [PATCH] e2fsck: Check for cases where EOFBLOCKS

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Message-ID: <4BE9D4F3.9080003@redhat.com>
Date:	Tue, 11 May 2010 17:06:43 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>
CC:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] e2fsck: Check for cases where EOFBLOCKS_FL is unnecessarily
 set

Theodore Ts'o wrote:
> Some kernels will crash if EOFBLOCKS_FL is set when it is it not

Is there a kernel fix to go with this, then?

Thanks,
-Eric

> needed, and this if it is left set when it isn't needed, it is a sign
> of a kernel bug.
> 
> Addresses-Google-Bug: #2604224
> 
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
>  e2fsck/pass1.c                          |   13 +++++++++++++
>  e2fsck/problem.c                        |    5 +++++
>  e2fsck/problem.h                        |    3 +++
>  tests/f_bad_disconnected_inode/expect.1 |    9 +++++++++
>  4 files changed, 30 insertions(+), 0 deletions(-)
> 
> diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
> index bb5604b..a0249ff 100644
> --- a/e2fsck/pass1.c
> +++ b/e2fsck/pass1.c
> @@ -2000,6 +2000,19 @@ static void check_blocks(e2fsck_t ctx, struct problem_context *pctx,
>  			 ((1ULL << (32 + EXT2_BLOCK_SIZE_BITS(fs->super))) - 1))
>  			/* too big for an extent-based file - 32bit ee_block */
>  			bad_size = 6;
> +
> +		/*
> +		 * Check to see if the EOFBLOCKS flag is set where it
> +		 * doesn't need to be.
> +		 */
> +		if ((inode->i_flags & EXT4_EOFBLOCKS_FL) &&
> +		    (size <= (((__u64)pb.last_block + 1) * fs->blocksize))) {
> +			pctx->blkcount = pb.last_block;
> +			if (fix_problem(ctx, PR_1_EOFBLOCKS_FL_SET, pctx)) {
> +				inode->i_flags &= ~EXT4_EOFBLOCKS_FL;
> +				dirty_inode++;
> +			}
> +		}
>  	}
>  	/* i_size for symlinks is checked elsewhere */
>  	if (bad_size && !LINUX_S_ISLNK(inode->i_mode)) {
> diff --git a/e2fsck/problem.c b/e2fsck/problem.c
> index 9043281..ceb2ae9 100644
> --- a/e2fsck/problem.c
> +++ b/e2fsck/problem.c
> @@ -885,6 +885,11 @@ static struct e2fsck_problem problem_table[] = {
>  	  N_("@i %i has an invalid extent node (blk %b, lblk %c)\n"),
>  	  PROMPT_CLEAR, 0 },
>  
> +	{ PR_1_EOFBLOCKS_FL_SET,
> +	  N_("@i %i should not have EOFBLOCKS_FL set "
> +	     "(size %Is, lblk %r)\n"),
> +	  PROMPT_CLEAR, PR_PREEN_OK },
> +
>  	/* Pass 1b errors */
>  
>  	/* Pass 1B: Rescan for duplicate/bad blocks */
> diff --git a/e2fsck/problem.h b/e2fsck/problem.h
> index f3969e0..b1bc97f 100644
> --- a/e2fsck/problem.h
> +++ b/e2fsck/problem.h
> @@ -517,6 +517,9 @@ struct problem_context {
>  /* Extent node header invalid */
>  #define PR_1_EXTENT_HEADER_INVALID	0x01005F
>  
> +/* EOFBLOCKS flag set when not necessary */
> +#define PR_1_EOFBLOCKS_FL_SET		0x010060
> +
>  /*
>   * Pass 1b errors
>   */
> diff --git a/tests/f_bad_disconnected_inode/expect.1 b/tests/f_bad_disconnected_inode/expect.1
> index 11862f6..d3920e3 100644
> --- a/tests/f_bad_disconnected_inode/expect.1
> +++ b/tests/f_bad_disconnected_inode/expect.1
> @@ -2,12 +2,21 @@ Pass 1: Checking inodes, blocks, and sizes
>  Inode 1 has EXTENTS_FL flag set on filesystem without extents support.
>  Clear? yes
>  
> +Inode 9 should not have EOFBLOCKS_FL set (size 0, lblk -1)
> +Clear? yes
> +
> +Inode 10 should not have EOFBLOCKS_FL set (size 0, lblk -1)
> +Clear? yes
> +
>  Inode 15 has EXTENTS_FL flag set on filesystem without extents support.
>  Clear? yes
>  
>  Inode 16 has EXTENTS_FL flag set on filesystem without extents support.
>  Clear? yes
>  
> +Inode 13 should not have EOFBLOCKS_FL set (size 0, lblk -1)
> +Clear? yes
> +
>  Pass 2: Checking directory structure
>  Pass 3: Checking directory connectivity
>  /lost+found not found.  Create? yes

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