lkml.org 
[lkml]   [2012]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v10 3/8] dm: Use bioset's front_pad for dm_rq_clone_bio_info
    Date
    Previously, dm_rq_clone_bio_info needed to be freed by the bio's
    destructor to avoid a memory leak in the blk_rq_prep_clone() error path.
    This gets rid of a memory allocation and means we can kill
    dm_rq_bio_destructor.

    The _rq_bio_info_cache kmem cache is unused now and needs to be deleted,
    but due to the way io_pool is used and overloaded this looks not quite
    trivial so I'm leaving it for a later patch.

    v6: Fix comment on struct dm_rq_clone_bio_info, per Tejun

    Signed-off-by: Kent Overstreet <koverstreet@google.com>
    CC: Alasdair Kergon <agk@redhat.com>
    Acked-by: Tejun Heo <tj@kernel.org>
    ---
    drivers/md/dm.c | 46 ++++++++++++++++++----------------------------
    1 file changed, 18 insertions(+), 28 deletions(-)

    diff --git a/drivers/md/dm.c b/drivers/md/dm.c
    index f43aaf6..33470f0 100644
    --- a/drivers/md/dm.c
    +++ b/drivers/md/dm.c
    @@ -86,12 +86,17 @@ struct dm_rq_target_io {
    };

    /*
    - * For request-based dm.
    - * One of these is allocated per bio.
    + * For request-based dm - the bio clones we allocate are embedded in these
    + * structs.
    + *
    + * We allocate these with bio_alloc_bioset, using the front_pad parameter when
    + * the bioset is created - this means the bio has to come at the end of the
    + * struct.
    */
    struct dm_rq_clone_bio_info {
    struct bio *orig;
    struct dm_rq_target_io *tio;
    + struct bio clone;
    };

    union map_info *dm_get_mapinfo(struct bio *bio)
    @@ -211,6 +216,11 @@ struct dm_md_mempools {
    static struct kmem_cache *_io_cache;
    static struct kmem_cache *_tio_cache;
    static struct kmem_cache *_rq_tio_cache;
    +
    +/*
    + * Unused now, and needs to be deleted. But since io_pool is overloaded and it's
    + * still used for _io_cache, I'm leaving this for a later cleanup
    + */
    static struct kmem_cache *_rq_bio_info_cache;

    static int __init local_init(void)
    @@ -467,16 +477,6 @@ static void free_rq_tio(struct dm_rq_target_io *tio)
    mempool_free(tio, tio->md->tio_pool);
    }

    -static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md)
    -{
    - return mempool_alloc(md->io_pool, GFP_ATOMIC);
    -}
    -
    -static void free_bio_info(struct dm_rq_clone_bio_info *info)
    -{
    - mempool_free(info, info->tio->md->io_pool);
    -}
    -
    static int md_in_flight(struct mapped_device *md)
    {
    return atomic_read(&md->pending[READ]) +
    @@ -1460,30 +1460,17 @@ void dm_dispatch_request(struct request *rq)
    }
    EXPORT_SYMBOL_GPL(dm_dispatch_request);

    -static void dm_rq_bio_destructor(struct bio *bio)
    -{
    - struct dm_rq_clone_bio_info *info = bio->bi_private;
    - struct mapped_device *md = info->tio->md;
    -
    - free_bio_info(info);
    - bio_free(bio, md->bs);
    -}
    -
    static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
    void *data)
    {
    struct dm_rq_target_io *tio = data;
    - struct mapped_device *md = tio->md;
    - struct dm_rq_clone_bio_info *info = alloc_bio_info(md);
    -
    - if (!info)
    - return -ENOMEM;
    + struct dm_rq_clone_bio_info *info =
    + container_of(bio, struct dm_rq_clone_bio_info, clone);

    info->orig = bio_orig;
    info->tio = tio;
    bio->bi_end_io = end_clone_bio;
    bio->bi_private = info;
    - bio->bi_destructor = dm_rq_bio_destructor;

    return 0;
    }
    @@ -2718,7 +2705,10 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity)
    if (!pools->tio_pool)
    goto free_io_pool_and_out;

    - pools->bs = bioset_create(pool_size, 0);
    + pools->bs = (type == DM_TYPE_BIO_BASED) ?
    + bioset_create(pool_size, 0) :
    + bioset_create(pool_size,
    + offsetof(struct dm_rq_clone_bio_info, clone));
    if (!pools->bs)
    goto free_tio_pool_and_out;

    --
    1.7.12


    \
     
     \ /
      Last update: 2012-09-07 01:21    [W:3.026 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site