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authorJoe Thornber <ejt@redhat.com>2014-06-30 13:26:30 -0400
committerMike Snitzer <snitzer@redhat.com>2014-08-01 12:30:30 -0400
commit97e7cdf12ba324b599d404172c5899185ef2bbde (patch)
tree044e4e2465d6716ae3cbb7e549b49a022da1e299
parent44fa816bb778edbab6b6ddaaf24908dd6295937e (diff)
dm io: simplify dec_count and sync_io
Remove the io struct off the stack in sync_io() and allocate it from the mempool like is done in async_io(). dec_count() now always calls a callback function and always frees the io struct back to the mempool (so sync_io and async_io share this pattern). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
-rw-r--r--drivers/md/dm-io.c77
1 files changed, 42 insertions, 35 deletions
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index db404a0f7e2c..c09359db3a90 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -33,7 +33,6 @@ struct dm_io_client {
struct io {
unsigned long error_bits;
atomic_t count;
- struct completion *wait;
struct dm_io_client *client;
io_notify_fn callback;
void *context;
@@ -112,28 +111,27 @@ static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
* We need an io object to keep track of the number of bios that
* have been dispatched for a particular io.
*---------------------------------------------------------------*/
-static void dec_count(struct io *io, unsigned int region, int error)
+static void complete_io(struct io *io)
{
- if (error)
- set_bit(region, &io->error_bits);
+ unsigned long error_bits = io->error_bits;
+ io_notify_fn fn = io->callback;
+ void *context = io->context;
- if (atomic_dec_and_test(&io->count)) {
- if (io->vma_invalidate_size)
- invalidate_kernel_vmap_range(io->vma_invalidate_address,
- io->vma_invalidate_size);
+ if (io->vma_invalidate_size)
+ invalidate_kernel_vmap_range(io->vma_invalidate_address,
+ io->vma_invalidate_size);
- if (io->wait)
- complete(io->wait);
+ mempool_free(io, io->client->pool);
+ fn(error_bits, context);
+}
- else {
- unsigned long r = io->error_bits;
- io_notify_fn fn = io->callback;
- void *context = io->context;
+static void dec_count(struct io *io, unsigned int region, int error)
+{
+ if (error)
+ set_bit(region, &io->error_bits);
- mempool_free(io, io->client->pool);
- fn(r, context);
- }
- }
+ if (atomic_dec_and_test(&io->count))
+ complete_io(io);
}
static void endio(struct bio *bio, int error)
@@ -376,41 +374,51 @@ static void dispatch_io(int rw, unsigned int num_regions,
dec_count(io, 0, 0);
}
+struct sync_io {
+ unsigned long error_bits;
+ struct completion wait;
+};
+
+static void sync_io_complete(unsigned long error, void *context)
+{
+ struct sync_io *sio = context;
+
+ sio->error_bits = error;
+ complete(&sio->wait);
+}
+
static int sync_io(struct dm_io_client *client, unsigned int num_regions,
struct dm_io_region *where, int rw, struct dpages *dp,
unsigned long *error_bits)
{
- /*
- * gcc <= 4.3 can't do the alignment for stack variables, so we must
- * align it on our own.
- * volatile prevents the optimizer from removing or reusing
- * "io_" field from the stack frame (allowed in ANSI C).
- */
- volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
- struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));
- DECLARE_COMPLETION_ONSTACK(wait);
+ struct io *io;
+ struct sync_io sio;
if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
WARN_ON(1);
return -EIO;
}
+ init_completion(&sio.wait);
+
+ io = mempool_alloc(client->pool, GFP_NOIO);
io->error_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
- io->wait = &wait;
io->client = client;
+ io->callback = sync_io_complete;
+ io->context = &sio;
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);
- wait_for_completion_io(&wait);
+ wait_for_completion_io(&sio.wait);
if (error_bits)
- *error_bits = io->error_bits;
+ *error_bits = sio.error_bits;
- return io->error_bits ? -EIO : 0;
+ return sio.error_bits ? -EIO : 0;
}
static int async_io(struct dm_io_client *client, unsigned int num_regions,
@@ -428,7 +436,6 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions,
io = mempool_alloc(client->pool, GFP_NOIO);
io->error_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
- io->wait = NULL;
io->client = client;
io->callback = fn;
io->context = context;
@@ -481,9 +488,9 @@ static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
* New collapsed (a)synchronous interface.
*
* If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
- * the queue with blk_unplug() some time later or set REQ_SYNC in
-io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
- * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
+ * the queue with blk_unplug() some time later or set REQ_SYNC in io_req->bi_rw.
+ * If you fail to do one of these, the IO will be submitted to the disk after
+ * q->unplug_delay, which defaults to 3ms in blk-settings.c.
*/
int dm_io(struct dm_io_request *io_req, unsigned num_regions,
struct dm_io_region *where, unsigned long *sync_error_bits)