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authorDan Williams <dan.j.williams@intel.com>2007-01-02 15:52:30 -0500
committerDan Williams <dan.j.williams@intel.com>2007-07-13 11:06:17 -0400
commitf38e12199a94ca458e4f03c5a2c984fb80adadc5 (patch)
tree706f54c46d4a4c839dd43c1403854dde860c6be5 /include/linux
parente33129d84130459dbb764a1a52a4bfceab3da978 (diff)
md: handle_stripe5 - add request/completion logic for async compute ops
handle_stripe will compute a block when a backing disk has failed, or when it determines it can save a disk read by computing the block from all the other up-to-date blocks. Previously a block would be computed under the lock and subsequent logic in handle_stripe could use the newly up-to-date block. With the raid5_run_ops implementation the compute operation is carried out a later time outside the lock. To preserve the old functionality we take advantage of the dependency chain feature of async_tx to flag the block as R5_Wantcompute and then let other parts of handle_stripe operate on the block as if it were up-to-date. raid5_run_ops guarantees that the block will be ready before it is used in another operation. However, this only works in cases where the compute and the dependent operation are scheduled at the same time. If a previous call to handle_stripe sets the R5_Wantcompute flag there is no facility to pass the async_tx dependency chain across successive calls to raid5_run_ops. The req_compute variable protects against this case. Changelog: * remove the req_compute BUG_ON Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-By: NeilBrown <neilb@suse.de>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/raid/raid5.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h
index 6fb9d94e6f2e..2293015de1d5 100644
--- a/include/linux/raid/raid5.h
+++ b/include/linux/raid/raid5.h
@@ -200,7 +200,7 @@ struct stripe_head {
200struct stripe_head_state { 200struct stripe_head_state {
201 int syncing, expanding, expanded; 201 int syncing, expanding, expanded;
202 int locked, uptodate, to_read, to_write, failed, written; 202 int locked, uptodate, to_read, to_write, failed, written;
203 int non_overwrite; 203 int compute, req_compute, non_overwrite;
204 int failed_num; 204 int failed_num;
205}; 205};
206 206