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    Subject[PATCH v1 7/9] block: loop: introduce lo_discard() and lo_req_flush()
    Date
    No behaviour change, just move the handling for REQ_DISCARD
    and REQ_FLUSH in these two functions.

    Signed-off-by: Ming Lei <ming.lei@canonical.com>
    ---
    drivers/block/loop.c | 73 +++++++++++++++++++++++++++-----------------------
    1 file changed, 40 insertions(+), 33 deletions(-)

    diff --git a/drivers/block/loop.c b/drivers/block/loop.c
    index ad43d4b..3836dcc 100644
    --- a/drivers/block/loop.c
    +++ b/drivers/block/loop.c
    @@ -417,6 +417,40 @@ lo_receive(struct loop_device *lo, struct request *rq, int bsize, loff_t pos)
    return 0;
    }

    +static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
    +{
    + /*
    + * We use punch hole to reclaim the free space used by the
    + * image a.k.a. discard. However we do not support discard if
    + * encryption is enabled, because it may give an attacker
    + * useful information.
    + */
    + struct file *file = lo->lo_backing_file;
    + int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
    + int ret;
    +
    + if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
    + ret = -EOPNOTSUPP;
    + goto out;
    + }
    +
    + ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
    + if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
    + ret = -EIO;
    + out:
    + return ret;
    +}
    +
    +static int lo_req_flush(struct loop_device *lo, struct request *rq)
    +{
    + struct file *file = lo->lo_backing_file;
    + int ret = vfs_fsync(file, 0);
    + if (unlikely(ret && ret != -EINVAL))
    + ret = -EIO;
    +
    + return ret;
    +}
    +
    static int do_req_filebacked(struct loop_device *lo, struct request *rq)
    {
    loff_t pos;
    @@ -425,46 +459,19 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
    pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;

    if (rq->cmd_flags & REQ_WRITE) {
    - struct file *file = lo->lo_backing_file;
    -
    - if (rq->cmd_flags & REQ_FLUSH) {
    - ret = vfs_fsync(file, 0);
    - if (unlikely(ret && ret != -EINVAL)) {
    - ret = -EIO;
    - goto out;
    - }
    - }

    - /*
    - * We use punch hole to reclaim the free space used by the
    - * image a.k.a. discard. However we do not support discard if
    - * encryption is enabled, because it may give an attacker
    - * useful information.
    - */
    + if (rq->cmd_flags & REQ_FLUSH)
    + ret = lo_req_flush(lo, rq);
    +
    if (rq->cmd_flags & REQ_DISCARD) {
    - struct file *file = lo->lo_backing_file;
    - int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
    -
    - if ((!file->f_op->fallocate) ||
    - lo->lo_encrypt_key_size) {
    - ret = -EOPNOTSUPP;
    - goto out;
    - }
    - ret = file->f_op->fallocate(file, mode, pos,
    - blk_rq_bytes(rq));
    - if (unlikely(ret && ret != -EINVAL &&
    - ret != -EOPNOTSUPP))
    - ret = -EIO;
    + ret = lo_discard(lo, rq, pos);
    goto out;
    }

    ret = lo_send(lo, rq, pos);

    - if ((rq->cmd_flags & REQ_FUA) && !ret) {
    - ret = vfs_fsync(file, 0);
    - if (unlikely(ret && ret != -EINVAL))
    - ret = -EIO;
    - }
    + if ((rq->cmd_flags & REQ_FUA) && !ret)
    + ret = lo_req_flush(lo, rq);
    } else
    ret = lo_receive(lo, rq, lo->lo_blocksize, pos);

    --
    1.7.9.5


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