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vbdev: add get_buf call to passthru example

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Previously a null buffer on read would get passed on which would
be fine for a simple example but for something more complex where
the module in question might need that buffer at some time after
the read callback, it's possible that an underlying module might
free it too soon.  So, to be a good example we now own the buffer
in this module.

Change-Id: I411477e83b1e222c64011688952cfd587c32c16e
Signed-off-by: paul luse <paul.e.luse@intel.com>
Reviewed-on: https://review.gerrithub.io/422603
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
This commit is contained in:
paul luse 2018-08-16 13:10:49 -07:00 committed by Jim Harris
parent 1570c87f81
commit 6fd1d004a8
1 changed files with 20 additions and 5 deletions
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25
lib/bdev/passthru/vbdev_passthru.c Normal file → Executable file
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@ -151,6 +151,23 @@ _pt_complete_io(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
spdk_bdev_free_io(bdev_io);
}
/* Callback for getting a buf from the bdev pool in the event that the caller passed
* in NULL, we need to own the buffer so it doesn't get freed by another vbdev module
* beneath us before we're done with it. That won't happen in this example but it could
* if this example were used as a template for something more complex.
*/
static void
pt_read_get_buf_cb(struct spdk_io_channel *ch, struct spdk_bdev_io *bdev_io)
{
struct vbdev_passthru *pt_node = SPDK_CONTAINEROF(bdev_io->bdev, struct vbdev_passthru,
pt_bdev);
struct pt_io_channel *pt_ch = spdk_io_channel_get_ctx(ch);
spdk_bdev_readv_blocks(pt_node->base_desc, pt_ch->base_ch, bdev_io->u.bdev.iovs,
bdev_io->u.bdev.iovcnt, bdev_io->u.bdev.offset_blocks,
bdev_io->u.bdev.num_blocks, _pt_complete_io,
bdev_io);
}
/* Called when someone above submits IO to this pt vbdev. We're simply passing it on here
* via SPDK IO calls which in turn allocate another bdev IO and call our cpl callback provided
@ -162,7 +179,7 @@ vbdev_passthru_submit_request(struct spdk_io_channel *ch, struct spdk_bdev_io *b
struct vbdev_passthru *pt_node = SPDK_CONTAINEROF(bdev_io->bdev, struct vbdev_passthru, pt_bdev);
struct pt_io_channel *pt_ch = spdk_io_channel_get_ctx(ch);
struct passthru_bdev_io *io_ctx = (struct passthru_bdev_io *)bdev_io->driver_ctx;
int rc = 1;
int rc = 0;
/* Setup a per IO context value; we don't do anything with it in the vbdev other
* than confirm we get the same thing back in the completion callback just to
@ -172,10 +189,8 @@ vbdev_passthru_submit_request(struct spdk_io_channel *ch, struct spdk_bdev_io *b
switch (bdev_io->type) {
case SPDK_BDEV_IO_TYPE_READ:
rc = spdk_bdev_readv_blocks(pt_node->base_desc, pt_ch->base_ch, bdev_io->u.bdev.iovs,
bdev_io->u.bdev.iovcnt, bdev_io->u.bdev.offset_blocks,
bdev_io->u.bdev.num_blocks, _pt_complete_io,
bdev_io);
spdk_bdev_io_get_buf(bdev_io, pt_read_get_buf_cb,
bdev_io->u.bdev.num_blocks * bdev_io->bdev->blocklen);
break;
case SPDK_BDEV_IO_TYPE_WRITE:
rc = spdk_bdev_writev_blocks(pt_node->base_desc, pt_ch->base_ch, bdev_io->u.bdev.iovs,