linux-ext4 - Re: [PATCH] badblocks: Limit maximum number of bad blocks

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Date:	Tue, 2 Dec 2014 14:45:38 +0100
From:	Jan Kara <jack@...e.cz>
To:	Ted Tso <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH] badblocks: Limit maximum number of bad blocks

On Thu 11-09-14 12:03:24, Jan Kara wrote:
> Currently maximum number of bad blocks is not limited in any way.
> However our code can really handle at most INT_MAX/2 bad blocks (for
> larger numbers binary search indexes start overflowing). So report
> number of bad blocks is just too big instead of plaing segfault.
> 
> It won't be too hard to raise the limit but I don't think there's any
> real use for disks with over 1 billion of bad blocks...
  Ted, what did happen to this patch? I don't see it in e2fsprogs
master branch... Thanks.

								Honza

> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
>  misc/badblocks.c | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/misc/badblocks.c b/misc/badblocks.c
> index e5024f6c67d1..2c28ee00ec15 100644
> --- a/misc/badblocks.c
> +++ b/misc/badblocks.c
> @@ -65,6 +65,9 @@ extern int optind;
>  #define O_LARGEFILE 0
>  #endif
>  
> +/* Maximum number of bad blocks we support */
> +#define MAX_BAD_BLOCKS (INT_MAX/2)
> +
>  static const char * program_name = "badblocks";
>  static const char * done_string = N_("done                                                 \n");
>  
> @@ -78,7 +81,9 @@ static int t_max;			/* allocated test patterns */
>  static unsigned int *t_patts;		/* test patterns */
>  static int use_buffered_io;
>  static int exclusive_ok;
> -static unsigned int max_bb;		/* Abort test if more than this number of bad blocks has been encountered */
> +static unsigned int max_bb = MAX_BAD_BLOCKS;	/* Abort test if more than this
> +						 * number of bad blocks has been
> +						 * encountered */
>  static unsigned int d_flag;		/* delay factor between reads */
>  static struct timeval time_start;
>  
> @@ -526,7 +531,7 @@ static unsigned int test_ro (int dev, blk_t last_block,
>  		alarm_intr(SIGALRM);
>  	while (currently_testing < last_block)
>  	{
> -		if (max_bb && bb_count >= max_bb) {
> +		if (bb_count >= max_bb) {
>  			if (s_flag || v_flag) {
>  				fputs(_("Too many bad blocks, aborting test\n"), stderr);
>  			}
> @@ -633,7 +638,7 @@ static unsigned int test_rw (int dev, blk_t last_block,
>  
>  		try = blocks_at_once;
>  		while (currently_testing < last_block) {
> -			if (max_bb && bb_count >= max_bb) {
> +			if (bb_count >= max_bb) {
>  				if (s_flag || v_flag) {
>  					fputs(_("Too many bad blocks, aborting test\n"), stderr);
>  				}
> @@ -675,7 +680,7 @@ static unsigned int test_rw (int dev, blk_t last_block,
>  
>  		try = blocks_at_once;
>  		while (currently_testing < last_block) {
> -			if (max_bb && bb_count >= max_bb) {
> +			if (bb_count >= max_bb) {
>  				if (s_flag || v_flag) {
>  					fputs(_("Too many bad blocks, aborting test\n"), stderr);
>  				}
> @@ -822,7 +827,7 @@ static unsigned int test_nd (int dev, blk_t last_block,
>  			alarm_intr(SIGALRM);
>  
>  		while (currently_testing < last_block) {
> -			if (max_bb && bb_count >= max_bb) {
> +			if (bb_count >= max_bb) {
>  				if (s_flag || v_flag) {
>  					fputs(_("Too many bad blocks, aborting test\n"), stderr);
>  				}
> @@ -1117,6 +1122,16 @@ int main (int argc, char ** argv)
>  			break;
>  		case 'e':
>  			max_bb = parse_uint(optarg, "max bad block count");
> +			if (max_bb > MAX_BAD_BLOCKS) {
> +				com_err (program_name, 0,
> +					 _("Too big max bad blocks count %u - "
> +					   "maximum is %u"), max_bb,
> +					   MAX_BAD_BLOCKS);
> +				exit (1);
> +			}
> +			/* 0 really means unlimited but we cannot do that much... */
> +			if (max_bb == 0)
> +				max_bb = MAX_BAD_BLOCKS;
>  			break;
>  		case 'd':
>  			d_flag = parse_uint(optarg, "read delay factor");
> -- 
> 1.8.1.4
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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