lkml.org 
[lkml]   [2010]   [Jun]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    SubjectRe: [PATCH 1/2] block: fix leaks associated with discard request payload
    From
    On Sat, 26 Jun 2010 15:56:50 -0400
    Mike Snitzer <snitzer@redhat.com> wrote:

    > Fix leaks introduced via "block: don't allocate a payload for discard
    > request" commit a1d949f5f44.
    >
    > sd_done() is not called for REQ_TYPE_BLOCK_PC commands so cleanup
    > discard request's payload directly in scsi_finish_command().

    Instead of adding another discard hack to scsi_finish_command(), how
    about converting discard to REQ_TYPE_FS request? discard is FS request
    from the perspective of the block layer. It also fixes a problem that
    discard isn't retried in the case of UNIT ATTENTION.

    I think that we can get more cleaner code if we handle discard as
    normal (fs) request in the block layer (and scsi-ml). We need more
    changes but this patch is the first step.

    This patch depends on the patchset to convert flush request to
    REQ_TYPE_FS:

    http://marc.info/?l=linux-kernel&m=127730591527424&w=2

    The git tree is also available:

    git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git flush


    > Also cleanup page allocated for discard payload in
    > scsi_setup_discard_cmnd's scsi_setup_blk_pc_cmnd error path.

    This patch doesn't address on this (since it's a different problem). I
    think that scsi_setup_discard_cmnd() sees if it already allocates a
    page before allocating a page. That's similar to how other prep
    functions work, I think.

    =
    From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
    Subject: [PATCH] convert discard request to REQ_TYPE_FS instead of BLOCK_PC

    Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
    ---
    block/blk-lib.c | 4 ++++
    drivers/scsi/sd.c | 11 +----------
    2 files changed, 5 insertions(+), 10 deletions(-)

    diff --git a/block/blk-lib.c b/block/blk-lib.c
    index e16185b..9e15c46 100644
    --- a/block/blk-lib.c
    +++ b/block/blk-lib.c
    @@ -20,6 +20,10 @@ static void blkdev_discard_end_io(struct bio *bio, int err)
    if (bio->bi_private)
    complete(bio->bi_private);

    + /* free the page that the lower layer allocated */
    + if (bio_page(bio))
    + __free_page(bio_page(bio));
    +
    bio_put(bio);
    }

    diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
    index d447726..1b182de 100644
    --- a/drivers/scsi/sd.c
    +++ b/drivers/scsi/sd.c
    @@ -432,7 +432,7 @@ static int scsi_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
    nr_sectors >>= 3;
    }

    - rq->cmd_type = REQ_TYPE_BLOCK_PC;
    + rq->cmd_type = REQ_TYPE_FS;
    rq->timeout = SD_TIMEOUT;

    memset(rq->cmd, 0, rq->cmd_len);
    @@ -1177,15 +1177,6 @@ static int sd_done(struct scsi_cmnd *SCpnt)
    int sense_valid = 0;
    int sense_deferred = 0;

    - /*
    - * If this is a discard request that originated from the kernel
    - * we need to free our payload here. Note that we need to check
    - * the request flag as the normal payload rules apply for
    - * pass-through UNMAP / WRITE SAME requests.
    - */
    - if (SCpnt->request->cmd_flags & REQ_DISCARD)
    - __free_page(bio_page(SCpnt->request->bio));
    -
    if (result) {
    sense_valid = scsi_command_normalize_sense(SCpnt, &sshdr);
    if (sense_valid)
    --
    1.6.5


    \
     
     \ /
      Last update: 2010-06-27 10:53    [W:0.024 / U:29.756 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site