lkml.org 
[lkml]   [2010]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[125/139] md: deal with merge_bvec_fn in component devices better.
    2.6.33-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: NeilBrown <neilb@suse.de>

    commit 627a2d3c29427637f4c5d31ccc7fcbd8d312cd71 upstream.

    If a component device has a merge_bvec_fn then as we never call it
    we must ensure we never need to. Currently this is done by setting
    max_sector to 1 PAGE, however this does not stop a bio being created
    with several sub-page iovecs that would violate the merge_bvec_fn.

    So instead set max_phys_segments to 1 and set the segment boundary to the
    same as a page boundary to ensure there is only ever one single-page
    segment of IO requested at a time.

    This can particularly be an issue when 'xen' is used as it is
    known to submit multiple small buffers in a single bio.

    Signed-off-by: NeilBrown <neilb@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    drivers/md/linear.c | 12 +++++++-----
    drivers/md/multipath.c | 20 ++++++++++++--------
    drivers/md/raid0.c | 13 +++++++------
    drivers/md/raid10.c | 28 +++++++++++++++++-----------
    4 files changed, 43 insertions(+), 30 deletions(-)

    --- a/drivers/md/linear.c
    +++ b/drivers/md/linear.c
    @@ -172,12 +172,14 @@ static linear_conf_t *linear_conf(mddev_
    disk_stack_limits(mddev->gendisk, rdev->bdev,
    rdev->data_offset << 9);
    /* as we don't honour merge_bvec_fn, we must never risk
    - * violating it, so limit ->max_sector to one PAGE, as
    - * a one page request is never in violation.
    + * violating it, so limit max_phys_segments to 1 lying within
    + * a single page.
    */
    - if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
    - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
    - blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
    + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
    + blk_queue_max_phys_segments(mddev->queue, 1);
    + blk_queue_segment_boundary(mddev->queue,
    + PAGE_CACHE_SIZE - 1);
    + }

    conf->array_sectors += rdev->sectors;
    cnt++;
    --- a/drivers/md/multipath.c
    +++ b/drivers/md/multipath.c
    @@ -301,14 +301,16 @@ static int multipath_add_disk(mddev_t *m
    rdev->data_offset << 9);

    /* as we don't honour merge_bvec_fn, we must never risk
    - * violating it, so limit ->max_sector to one PAGE, as
    - * a one page request is never in violation.
    + * violating it, so limit ->max_phys_segments to one, lying
    + * within a single page.
    * (Note: it is very unlikely that a device with
    * merge_bvec_fn will be involved in multipath.)
    */
    - if (q->merge_bvec_fn &&
    - queue_max_sectors(q) > (PAGE_SIZE>>9))
    - blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
    + if (q->merge_bvec_fn) {
    + blk_queue_max_phys_segments(mddev->queue, 1);
    + blk_queue_segment_boundary(mddev->queue,
    + PAGE_CACHE_SIZE - 1);
    + }

    conf->working_disks++;
    mddev->degraded--;
    @@ -476,9 +478,11 @@ static int multipath_run (mddev_t *mddev
    /* as we don't honour merge_bvec_fn, we must never risk
    * violating it, not that we ever expect a device with
    * a merge_bvec_fn to be involved in multipath */
    - if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
    - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
    - blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
    + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
    + blk_queue_max_phys_segments(mddev->queue, 1);
    + blk_queue_segment_boundary(mddev->queue,
    + PAGE_CACHE_SIZE - 1);
    + }

    if (!test_bit(Faulty, &rdev->flags))
    conf->working_disks++;
    --- a/drivers/md/raid0.c
    +++ b/drivers/md/raid0.c
    @@ -176,14 +176,15 @@ static int create_strip_zones(mddev_t *m
    disk_stack_limits(mddev->gendisk, rdev1->bdev,
    rdev1->data_offset << 9);
    /* as we don't honour merge_bvec_fn, we must never risk
    - * violating it, so limit ->max_sector to one PAGE, as
    - * a one page request is never in violation.
    + * violating it, so limit ->max_phys_segments to 1, lying within
    + * a single page.
    */

    - if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
    - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
    - blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
    -
    + if (rdev1->bdev->bd_disk->queue->merge_bvec_fn) {
    + blk_queue_max_phys_segments(mddev->queue, 1);
    + blk_queue_segment_boundary(mddev->queue,
    + PAGE_CACHE_SIZE - 1);
    + }
    if (!smallest || (rdev1->sectors < smallest->sectors))
    smallest = rdev1;
    cnt++;
    --- a/drivers/md/raid10.c
    +++ b/drivers/md/raid10.c
    @@ -1155,13 +1155,17 @@ static int raid10_add_disk(mddev_t *mdde

    disk_stack_limits(mddev->gendisk, rdev->bdev,
    rdev->data_offset << 9);
    - /* as we don't honour merge_bvec_fn, we must never risk
    - * violating it, so limit ->max_sector to one PAGE, as
    - * a one page request is never in violation.
    + /* as we don't honour merge_bvec_fn, we must
    + * never risk violating it, so limit
    + * ->max_phys_segments to one lying with a single
    + * page, as a one page request is never in
    + * violation.
    */
    - if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
    - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
    - blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
    + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
    + blk_queue_max_phys_segments(mddev->queue, 1);
    + blk_queue_segment_boundary(mddev->queue,
    + PAGE_CACHE_SIZE - 1);
    + }

    p->head_position = 0;
    rdev->raid_disk = mirror;
    @@ -2255,12 +2259,14 @@ static int run(mddev_t *mddev)
    disk_stack_limits(mddev->gendisk, rdev->bdev,
    rdev->data_offset << 9);
    /* as we don't honour merge_bvec_fn, we must never risk
    - * violating it, so limit ->max_sector to one PAGE, as
    - * a one page request is never in violation.
    + * violating it, so limit max_phys_segments to 1 lying
    + * within a single page.
    */
    - if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
    - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
    - blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
    + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
    + blk_queue_max_phys_segments(mddev->queue, 1);
    + blk_queue_segment_boundary(mddev->queue,
    + PAGE_CACHE_SIZE - 1);
    + }

    disk->head_position = 0;
    }



    \
     
     \ /
      Last update: 2010-04-22 22:09    [W:0.027 / U:2.696 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site