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From: Eric Sandeen <sandeen@sandeen.net>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 07/11] xfs_scrub: request fewer bmaps when we can
Date: Mon, 21 Oct 2019 13:05:06 -0500	[thread overview]
Message-ID: <220f16b6-8604-7f83-924c-3a148e0dd5cb@sandeen.net> (raw)
In-Reply-To: <156944741018.300131.13838435268141846825.stgit@magnolia>

On 9/25/19 4:36 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> In xfs_iterate_filemaps, we query the number of bmaps for a given file
> that we're going to iterate, so feed that information to bmap so that
> the kernel won't waste time allocating in-kernel memory unnecessarily.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  scrub/filemap.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> 
> diff --git a/scrub/filemap.c b/scrub/filemap.c
> index bdc6d8f9..aaaa0521 100644
> --- a/scrub/filemap.c
> +++ b/scrub/filemap.c
> @@ -71,7 +71,6 @@ xfs_iterate_filemaps(
>  		map->bmv_length = ULLONG_MAX;
>  	else
>  		map->bmv_length = BTOBB(key->bm_length);
> -	map->bmv_count = BMAP_NR;
>  	map->bmv_iflags = BMV_IF_NO_DMAPI_READ | BMV_IF_PREALLOC |
>  			  BMV_IF_NO_HOLES;
>  	switch (whichfork) {
> @@ -96,6 +95,7 @@ xfs_iterate_filemaps(
>  		moveon = false;
>  		goto out;
>  	}
> +	map->bmv_count = min(fsx.fsx_nextents + 2, BMAP_NR);

Was going to ask you to document the magical +2 here but IRC discussion suggests
that it is in case fsx_nextents is 0, and we need to send in a count of at least
2 (header + 1 structure?)

But if there are no extents, what are we trying to map in the loop below,
anyway?

>  
>  	while ((error = ioctl(fd, XFS_IOC_GETBMAPX, map)) == 0) {
>  		for (i = 0, p = &map[i + 1]; i < map->bmv_entries; i++, p++) {
> 

  reply	other threads:[~2019-10-21 18:05 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 21:36 [PATCH 00/11] xfs_scrub: fix IO error reporting Darrick J. Wong
2019-09-25 21:36 ` [PATCH 01/11] xfs_scrub: separate media error reporting for attribute forks Darrick J. Wong
2019-10-21 16:18   ` Eric Sandeen
2019-10-21 17:32     ` Darrick J. Wong
2019-09-25 21:36 ` [PATCH 02/11] xfs_scrub: improve reporting of file data media errors Darrick J. Wong
2019-10-21 16:33   ` Eric Sandeen
2019-10-21 17:56     ` Darrick J. Wong
2019-09-25 21:36 ` [PATCH 03/11] xfs_scrub: better reporting of metadata " Darrick J. Wong
2019-10-21 16:46   ` Eric Sandeen
2019-10-21 18:10     ` Darrick J. Wong
2019-09-25 21:36 ` [PATCH 04/11] xfs_scrub: improve reporting of file " Darrick J. Wong
2019-10-21 16:53   ` Eric Sandeen
2019-09-25 21:36 ` [PATCH 05/11] xfs_scrub: don't report media errors on unwritten extents Darrick J. Wong
2019-10-21 16:54   ` Eric Sandeen
2019-09-25 21:36 ` [PATCH 06/11] xfs_scrub: reduce fsmap activity for media errors Darrick J. Wong
2019-10-21 17:17   ` Eric Sandeen
2019-10-21 18:14     ` Darrick J. Wong
2019-09-25 21:36 ` [PATCH 07/11] xfs_scrub: request fewer bmaps when we can Darrick J. Wong
2019-10-21 18:05   ` Eric Sandeen [this message]
2019-10-21 18:15     ` Darrick J. Wong
2019-09-25 21:36 ` [PATCH 08/11] xfs_scrub: fix media verification thread pool size calculations Darrick J. Wong
2019-10-21 19:28   ` Eric Sandeen
2019-09-25 21:37 ` [PATCH 09/11] libfrog: clean up platform_nproc Darrick J. Wong
2019-10-21 19:31   ` Eric Sandeen
2019-10-21 20:13     ` Darrick J. Wong
2019-09-25 21:37 ` [PATCH 10/11] xfs_scrub: clean out the nproc global variable Darrick J. Wong
2019-10-21 19:32   ` Eric Sandeen
2019-09-25 21:37 ` [PATCH 11/11] xfs_scrub: create a new category for unfixable errors Darrick J. Wong
2019-10-21 19:45   ` Eric Sandeen
2019-10-21 20:29     ` Darrick J. Wong
2019-10-21 20:38       ` Eric Sandeen
  -- strict thread matches above, loose matches on Subject: below --
2019-09-06  3:38 [PATCH 00/11] xfs_scrub: fix IO error reporting Darrick J. Wong
2019-09-06  3:39 ` [PATCH 07/11] xfs_scrub: request fewer bmaps when we can Darrick J. Wong
2019-08-26 21:31 [PATCH 00/11] xfs_scrub: fix IO error reporting Darrick J. Wong
2019-08-26 21:31 ` [PATCH 07/11] xfs_scrub: request fewer bmaps when we can Darrick J. Wong

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