[PATCH 2/2] md: modify dm_io() so it could return bios instead of submitting it

From: Robin Dong
Date: Sun Sep 02 2012 - 22:12:31 EST

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From: Robin Dong <sanbai@xxxxxxxxxx>

When trying to modify flashcache to request based (current it's bio based), we need
to make request from bios by ourselves, but dm_io() will submit these bios directly,
so we propose to modify the dm_io() to return bios instead of submiting it.

This could also improve the flexibility of dm_io().

Signed-off-by: Robin Dong <sanbai@xxxxxxxxxx>
---
drivers/md/dm-bufio.c | 2 +
drivers/md/dm-io.c | 58 +++++++++++++++++++++++----------------
drivers/md/dm-kcopyd.c | 1 +
drivers/md/dm-log.c | 1 +
drivers/md/dm-raid1.c | 3 ++
drivers/md/dm-snap-persistent.c | 1 +
include/linux/dm-io.h | 3 ++
7 files changed, 45 insertions(+), 24 deletions(-)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index cc06a1e..f5867b9 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -487,6 +487,7 @@ static void use_dmio(struct dm_buffer *b, int rw, sector_t block,
.notify.fn = dmio_complete,
.notify.context = b,
.client = b->c->dm_io,
+ .submit_bio = 1,
};
struct dm_io_region region = {
.bdev = b->c->bdev,
@@ -1200,6 +1201,7 @@ int dm_bufio_issue_flush(struct dm_bufio_client *c)
.mem.type = DM_IO_KMEM,
.mem.ptr.addr = NULL,
.client = c->dm_io,
+ .submit_bio = 1,
};
struct dm_io_region io_reg = {
.bdev = c->bdev,
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ea5dd28..f235182 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -287,8 +287,8 @@ static void km_dp_init(struct dpages *dp, void *data)
/*-----------------------------------------------------------------
* IO routines that accept a list of pages.
*---------------------------------------------------------------*/
-static void do_region(int rw, unsigned region, struct dm_io_region *where,
- struct dpages *dp, struct io *io)
+static void do_region(struct dm_io_request *io_req, unsigned region,
+ struct dm_io_region *where, struct dpages *dp, struct io *io)
{
struct bio *bio;
struct page *page;
@@ -298,6 +298,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
sector_t remaining = where->count;
struct request_queue *q = bdev_get_queue(where->bdev);
sector_t discard_sectors;
+ int rw = io_req->bi_rw;

/*
* where->count may be zero if rw holds a flush and we need to
@@ -339,15 +340,26 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
}

atomic_inc(&io->count);
- submit_bio(rw, bio);
+ if (io_req->submit_bio)
+ submit_bio(rw, bio);
+ else {
+ bio->bi_rw |= rw;
+ if (io_req->start) {
+ io_req->end->bi_next = bio;
+ io_req->end = bio;
+ } else
+ io_req->start = io_req->end = bio;
+ bio->bi_next = NULL;
+ }
} while (remaining);
}

-static void dispatch_io(int rw, unsigned int num_regions,
+static void dispatch_io(struct dm_io_request *io_req, unsigned int num_regions,
struct dm_io_region *where, struct dpages *dp,
struct io *io, int sync)
{
int i;
+ int rw = io_req->bi_rw;
struct dpages old_pages = *dp;

BUG_ON(num_regions > DM_IO_MAX_REGIONS);
@@ -362,7 +374,7 @@ static void dispatch_io(int rw, unsigned int num_regions,
for (i = 0; i < num_regions; i++) {
*dp = old_pages;
if (where[i].count || (rw & REQ_FLUSH))
- do_region(rw, i, where + i, dp, io);
+ do_region(io_req, i, where + i, dp, io);
}

/*
@@ -372,8 +384,8 @@ static void dispatch_io(int rw, unsigned int num_regions,
dec_count(io, 0, 0);
}

-static int sync_io(struct dm_io_client *client, unsigned int num_regions,
- struct dm_io_region *where, int rw, struct dpages *dp,
+static int sync_io(struct dm_io_request *io_req, unsigned int num_regions,
+ struct dm_io_region *where, struct dpages *dp,
unsigned long *error_bits)
{
/*
@@ -385,7 +397,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));

- if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
+ if (num_regions > 1 && (io_req->bi_rw & RW_MASK) != WRITE) {
WARN_ON(1);
return -EIO;
}
@@ -393,12 +405,12 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
io->error_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
io->sleeper = current;
- io->client = client;
+ io->client = io_req->client;

io->vma_invalidate_address = dp->vma_invalidate_address;
io->vma_invalidate_size = dp->vma_invalidate_size;

- dispatch_io(rw, num_regions, where, dp, io, 1);
+ dispatch_io(io_req, num_regions, where, dp, io, 1);

while (1) {
set_current_state(TASK_UNINTERRUPTIBLE);
@@ -416,30 +428,29 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
return io->error_bits ? -EIO : 0;
}

-static int async_io(struct dm_io_client *client, unsigned int num_regions,
- struct dm_io_region *where, int rw, struct dpages *dp,
- io_notify_fn fn, void *context)
+static int async_io(struct dm_io_request *io_req, unsigned int num_regions,
+ struct dm_io_region *where, struct dpages *dp)
{
struct io *io;

- if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
+ if (num_regions > 1 && (io_req->bi_rw & RW_MASK) != WRITE) {
WARN_ON(1);
- fn(1, context);
+ io_req->notify.fn(1, io_req->notify.context);
return -EIO;
}

- io = mempool_alloc(client->pool, GFP_NOIO);
+ io = mempool_alloc(io_req->client->pool, GFP_NOIO);
io->error_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
io->sleeper = NULL;
- io->client = client;
- io->callback = fn;
- io->context = context;
+ io->client = io_req->client;
+ io->callback = io_req->notify.fn;
+ io->context = io_req->notify.context;

io->vma_invalidate_address = dp->vma_invalidate_address;
io->vma_invalidate_size = dp->vma_invalidate_size;

- dispatch_io(rw, num_regions, where, dp, io, 0);
+ dispatch_io(io_req, num_regions, where, dp, io, 0);
return 0;
}

@@ -499,11 +510,10 @@ int dm_io(struct dm_io_request *io_req, unsigned num_regions,
return r;

if (!io_req->notify.fn)
- return sync_io(io_req->client, num_regions, where,
- io_req->bi_rw, &dp, sync_error_bits);
+ return sync_io(io_req, num_regions, where,
+ &dp, sync_error_bits);

- return async_io(io_req->client, num_regions, where, io_req->bi_rw,
- &dp, io_req->notify.fn, io_req->notify.context);
+ return async_io(io_req, num_regions, where, &dp);
}
EXPORT_SYMBOL(dm_io);

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index bed444c..6a8ecc9 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -387,6 +387,7 @@ static int run_io_job(struct kcopyd_job *job)
.notify.fn = complete_io,
.notify.context = job,
.client = job->kc->io_client,
+ .submit_bio = 1,
};

if (job->rw == READ)
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 627d191..8425e84 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -463,6 +463,7 @@ static int create_log_context(struct dm_dirty_log *log, struct dm_target *ti,
kfree(lc);
return r;
}
+ lc->io_req.submit_bio = 1;

lc->disk_header = vmalloc(buf_size);
if (!lc->disk_header) {
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index bc5ddba..338d726 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -261,6 +261,7 @@ static int mirror_flush(struct dm_target *ti)
.mem.type = DM_IO_KMEM,
.mem.ptr.addr = NULL,
.client = ms->io_client,
+ .submit_bio = 1,
};

for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
@@ -530,6 +531,7 @@ static void read_async_bio(struct mirror *m, struct bio *bio)
.notify.fn = read_callback,
.notify.context = bio,
.client = m->ms->io_client,
+ .submit_bio = 1,
};

map_region(&io, m, bio);
@@ -633,6 +635,7 @@ static void do_write(struct mirror_set *ms, struct bio *bio)
.notify.fn = write_callback,
.notify.context = bio,
.client = ms->io_client,
+ .submit_bio = 1,
};

if (bio->bi_rw & REQ_DISCARD) {
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 3ac4156..0600e1d 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -241,6 +241,7 @@ static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw,
.mem.ptr.vma = area,
.client = ps->io_client,
.notify.fn = NULL,
+ .submit_bio = 1,
};
struct mdata_req req;

diff --git a/include/linux/dm-io.h b/include/linux/dm-io.h
index f4b0aa3..45f576b 100644
--- a/include/linux/dm-io.h
+++ b/include/linux/dm-io.h
@@ -61,6 +61,9 @@ struct dm_io_request {
struct dm_io_memory mem; /* Memory to use for io */
struct dm_io_notify notify; /* Synchronous if notify.fn is NULL */
struct dm_io_client *client; /* Client memory handler */
+ int submit_bio;
+ struct bio *start;
+ struct bio *end;
};

/*
--
1.7.1

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Next message: Michael Wang: "Re: [PATCH] sched: unify the check on atomic sleeping in __might_sleep()and schedule_bug()"
Previous message: Robin Dong: "[PATCH 1/2] md: add new interface 'mk_rq' in target_type"
In reply to: Robin Dong: "[PATCH 1/2] md: add new interface 'mk_rq' in target_type"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]