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authorDan Williams <dan.j.williams@intel.com>2009-09-08 17:42:50 -0700
committerDan Williams <dan.j.williams@intel.com>2009-09-08 17:42:50 -0700
commit0403e3827788d878163f9ef0541b748b0f88ca5d (patch)
tree2dc73744bd92c268a1310f24668167f130877278 /drivers/md
parentf9dd2134374c8de6b911e2b8652c6c9622eaa658 (diff)
dmaengine: add fence support
Some engines optimize operation by reading ahead in the descriptor chain such that descriptor2 may start execution before descriptor1 completes. If descriptor2 depends on the result from descriptor1 then a fence is required (on descriptor2) to disable this optimization. The async_tx api could implicitly identify dependencies via the 'depend_tx' parameter, but that would constrain cases where the dependency chain only specifies a completion order rather than a data dependency. So, provide an ASYNC_TX_FENCE to explicitly identify data dependencies. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/raid5.c37
1 files changed, 23 insertions, 14 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0a5cf217121..54ef8d75541 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -502,13 +502,17 @@ async_copy_data(int frombio, struct bio *bio, struct page *page,
int i;
int page_offset;
struct async_submit_ctl submit;
+ enum async_tx_flags flags = 0;
if (bio->bi_sector >= sector)
page_offset = (signed)(bio->bi_sector - sector) * 512;
else
page_offset = (signed)(sector - bio->bi_sector) * -512;
- init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
+ if (frombio)
+ flags |= ASYNC_TX_FENCE;
+ init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
+
bio_for_each_segment(bvl, bio, i) {
int len = bio_iovec_idx(bio, i)->bv_len;
int clen;
@@ -685,7 +689,7 @@ ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
atomic_inc(&sh->count);
- init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
+ init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
ops_complete_compute, sh, to_addr_conv(sh, percpu));
if (unlikely(count == 1))
tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
@@ -763,7 +767,8 @@ ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
count = set_syndrome_sources(blocks, sh);
blocks[count] = NULL; /* regenerating p is not necessary */
BUG_ON(blocks[count+1] != dest); /* q should already be set */
- init_async_submit(&submit, 0, NULL, ops_complete_compute, sh,
+ init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
+ ops_complete_compute, sh,
to_addr_conv(sh, percpu));
tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
} else {
@@ -775,8 +780,8 @@ ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
blocks[count++] = sh->dev[i].page;
}
- init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
- ops_complete_compute, sh,
+ init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
+ NULL, ops_complete_compute, sh,
to_addr_conv(sh, percpu));
tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
}
@@ -837,8 +842,9 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
/* Q disk is one of the missing disks */
if (faila == syndrome_disks) {
/* Missing P+Q, just recompute */
- init_async_submit(&submit, 0, NULL, ops_complete_compute,
- sh, to_addr_conv(sh, percpu));
+ init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
+ ops_complete_compute, sh,
+ to_addr_conv(sh, percpu));
return async_gen_syndrome(blocks, 0, count+2,
STRIPE_SIZE, &submit);
} else {
@@ -859,21 +865,24 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
blocks[count++] = sh->dev[i].page;
}
dest = sh->dev[data_target].page;
- init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, NULL,
- NULL, NULL, to_addr_conv(sh, percpu));
+ init_async_submit(&submit,
+ ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
+ NULL, NULL, NULL,
+ to_addr_conv(sh, percpu));
tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
&submit);
count = set_syndrome_sources(blocks, sh);
- init_async_submit(&submit, 0, tx, ops_complete_compute,
- sh, to_addr_conv(sh, percpu));
+ init_async_submit(&submit, ASYNC_TX_FENCE, tx,
+ ops_complete_compute, sh,
+ to_addr_conv(sh, percpu));
return async_gen_syndrome(blocks, 0, count+2,
STRIPE_SIZE, &submit);
}
}
- init_async_submit(&submit, 0, NULL, ops_complete_compute, sh,
- to_addr_conv(sh, percpu));
+ init_async_submit(&submit, ASYNC_TX_FENCE, NULL, ops_complete_compute,
+ sh, to_addr_conv(sh, percpu));
if (failb == syndrome_disks) {
/* We're missing D+P. */
return async_raid6_datap_recov(syndrome_disks+2, STRIPE_SIZE,
@@ -916,7 +925,7 @@ ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
xor_srcs[count++] = dev->page;
}
- init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST, tx,
+ init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
ops_complete_prexor, sh, to_addr_conv(sh, percpu));
tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);