[dm-devel] [patch 8/8] dm-bufio: dont embed bio in dm_buffer
mpatocka at redhat.com
mpatocka at redhat.com
Mon Mar 26 18:29:47 UTC 2018
The bio structure consumes a substantial part of dm_buffer. This structure
is needed only when doing I/O on the buffer, thus we don't have to embed
it in the buffer, we can allocate the structure only when doing I/O.
We don't need to create bio set because in case of allocation failure we
fall back to dmio (which keeps its own bio set).
Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
---
drivers/md/dm-bufio.c | 105 +++++++++++++++++++++-----------------------------
1 file changed, 45 insertions(+), 60 deletions(-)
Index: linux-2.6/drivers/md/dm-bufio.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-bufio.c 2018-03-26 16:44:19.369999000 +0200
+++ linux-2.6/drivers/md/dm-bufio.c 2018-03-26 17:05:13.000000000 +0200
@@ -51,12 +51,6 @@
#define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
/*
- * The number of bvec entries that are embedded directly in the buffer.
- * If the chunk size is larger, dm-io is used to do the io.
- */
-#define DM_BUFIO_INLINE_VECS 16
-
-/*
* Align buffer writes to this boundary.
* Tests show that SSDs have the highest IOPS when using 4k writes.
*/
@@ -153,8 +147,7 @@ struct dm_buffer {
unsigned write_end;
struct dm_bufio_client *c;
struct list_head write_list;
- struct bio bio;
- struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
+ void (*end_io)(struct dm_buffer *, blk_status_t);
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
#define MAX_STACK 10
struct stack_trace stack_trace;
@@ -534,12 +527,11 @@ static void dmio_complete(unsigned long
{
struct dm_buffer *b = context;
- b->bio.bi_status = error ? BLK_STS_IOERR : 0;
- b->bio.bi_end_io(&b->bio);
+ b->end_io(b, unlikely(error != 0) ? BLK_STS_IOERR : 0);
}
static void use_dmio(struct dm_buffer *b, int rw, sector_t sector,
- unsigned n_sectors, unsigned offset, bio_end_io_t *end_io)
+ unsigned n_sectors, unsigned offset)
{
int r;
struct dm_io_request io_req = {
@@ -563,71 +555,69 @@ static void use_dmio(struct dm_buffer *b
io_req.mem.ptr.vma = (char *)b->data + offset;
}
- b->bio.bi_end_io = end_io;
-
r = dm_io(&io_req, 1, ®ion, NULL);
- if (r) {
- b->bio.bi_status = errno_to_blk_status(r);
- end_io(&b->bio);
- }
+ if (unlikely(r))
+ b->end_io(b, errno_to_blk_status(r));
}
-static void inline_endio(struct bio *bio)
+static void bio_complete(struct bio *bio)
{
- bio_end_io_t *end_fn = bio->bi_private;
+ struct dm_buffer *b = bio->bi_private;
blk_status_t status = bio->bi_status;
-
- /*
- * Reset the bio to free any attached resources
- * (e.g. bio integrity profiles).
- */
- bio_reset(bio);
-
- bio->bi_status = status;
- end_fn(bio);
+ bio_put(bio);
+ b->end_io(b, status);
}
-static void use_inline_bio(struct dm_buffer *b, int rw, sector_t sector,
- unsigned n_sectors, unsigned offset, bio_end_io_t *end_io)
+static void use_bio(struct dm_buffer *b, int rw, sector_t sector,
+ unsigned n_sectors, unsigned offset)
{
+ struct bio *bio;
char *ptr;
- unsigned len;
+ unsigned vec_size, len;
- bio_init(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS);
- b->bio.bi_iter.bi_sector = sector;
- bio_set_dev(&b->bio, b->c->bdev);
- b->bio.bi_end_io = inline_endio;
- /*
- * Use of .bi_private isn't a problem here because
- * the dm_buffer's inline bio is local to bufio.
- */
- b->bio.bi_private = end_io;
- bio_set_op_attrs(&b->bio, rw, 0);
+ vec_size = b->c->block_size >> PAGE_SHIFT;
+ if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT))
+ vec_size += 2;
+
+ bio = bio_kmalloc(GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN, vec_size);
+ if (!bio) {
+dmio:
+ use_dmio(b, rw, sector, n_sectors, offset);
+ return;
+ }
+
+ bio->bi_iter.bi_sector = sector;
+ bio_set_dev(bio, b->c->bdev);
+ bio_set_op_attrs(bio, rw, 0);
+ bio->bi_end_io = bio_complete;
+ bio->bi_private = b;
ptr = (char *)b->data + offset;
len = n_sectors << SECTOR_SHIFT;
do {
unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len);
- if (!bio_add_page(&b->bio, virt_to_page(ptr), this_step,
+ if (!bio_add_page(bio, virt_to_page(ptr), this_step,
offset_in_page(ptr))) {
- use_dmio(b, rw, sector, n_sectors, offset, end_io);
- return;
+ bio_put(bio);
+ goto dmio;
}
len -= this_step;
ptr += this_step;
} while (len > 0);
- submit_bio(&b->bio);
+ submit_bio(bio);
}
-static void submit_io(struct dm_buffer *b, int rw, bio_end_io_t *end_io)
+static void submit_io(struct dm_buffer *b, int rw, void (*end_io)(struct dm_buffer *, blk_status_t))
{
unsigned n_sectors;
sector_t sector;
unsigned offset, end;
+ b->end_io = end_io;
+
if (likely(b->c->sectors_per_block_bits >= 0))
sector = b->block << b->c->sectors_per_block_bits;
else
@@ -652,11 +642,10 @@ static void submit_io(struct dm_buffer *
n_sectors = (end - offset) >> SECTOR_SHIFT;
}
- if (n_sectors <= ((DM_BUFIO_INLINE_VECS * PAGE_SIZE) >> SECTOR_SHIFT) &&
- b->data_mode != DATA_MODE_VMALLOC)
- use_inline_bio(b, rw, sector, n_sectors, offset, end_io);
+ if (b->data_mode != DATA_MODE_VMALLOC)
+ use_bio(b, rw, sector, n_sectors, offset);
else
- use_dmio(b, rw, sector, n_sectors, offset, end_io);
+ use_dmio(b, rw, sector, n_sectors, offset);
}
/*----------------------------------------------------------------
@@ -669,16 +658,14 @@ static void submit_io(struct dm_buffer *
* Set the error, clear B_WRITING bit and wake anyone who was waiting on
* it.
*/
-static void write_endio(struct bio *bio)
+static void write_endio(struct dm_buffer *b, blk_status_t status)
{
- struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
-
- b->write_error = bio->bi_status;
- if (unlikely(bio->bi_status)) {
+ b->write_error = status;
+ if (unlikely(status)) {
struct dm_bufio_client *c = b->c;
(void)cmpxchg(&c->async_write_error, 0,
- blk_status_to_errno(bio->bi_status));
+ blk_status_to_errno(status));
}
BUG_ON(!test_bit(B_WRITING, &b->state));
@@ -1055,11 +1042,9 @@ found_buffer:
* The endio routine for reading: set the error, clear the bit and wake up
* anyone waiting on the buffer.
*/
-static void read_endio(struct bio *bio)
+static void read_endio(struct dm_buffer *b, blk_status_t status)
{
- struct dm_buffer *b = container_of(bio, struct dm_buffer, bio);
-
- b->read_error = bio->bi_status;
+ b->read_error = status;
BUG_ON(!test_bit(B_READING, &b->state));
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