The following commit has been merged in the linux branch: commit da17bf4306fd3a52e938b121df82a7baa10eb282 Author: Dan Williams dan.j.williams@intel.com Date: Mon Oct 19 14:05:12 2009 -0700

async_tx: fix asynchronous raid6 recovery for ddf layouts

The raid6 recovery code currently requires special handling of the 4-disk and 5-disk recovery scenarios for the native layout. Quoting from commit 0a82a623:

In these situations the default N-disk algorithm will present 0-source or 1-source operations to dma devices. To cover for dma devices where the minimum source count is 2 we implement 4-disk and 5-disk handling in the recovery code.

The ddf layout presents disks=6 and disks=7 to the recovery code in these situations. Instead of looking at the number of disks count the number of non-zero sources in the list and call the special case code when the number of non-failed sources is 0 or 1.

[neilb@suse.de: replace 'ddf' flag with counting good sources] Signed-off-by: Dan Williams dan.j.williams@intel.com

diff --git a/crypto/async_tx/async_raid6_recov.c b/crypto/async_tx/async_raid6_recov.c index 8e30b6e..943f2ab 100644 --- a/crypto/async_tx/async_raid6_recov.c +++ b/crypto/async_tx/async_raid6_recov.c @@ -131,8 +131,8 @@ async_mult(struct page *dest, struct page *src, u8 coef, size_t len, }

static struct dma_async_tx_descriptor * -__2data_recov_4(size_t bytes, int faila, int failb, struct page **blocks, - struct async_submit_ctl *submit) +__2data_recov_4(int disks, size_t bytes, int faila, int failb, + struct page **blocks, struct async_submit_ctl *submit) { struct dma_async_tx_descriptor *tx = NULL; struct page *p, *q, *a, *b; @@ -143,8 +143,8 @@ __2data_recov_4(size_t bytes, int faila, int failb, struct page **blocks, void *cb_param = submit->cb_param; void *scribble = submit->scribble;

- p = blocks[4-2]; - q = blocks[4-1]; + p = blocks[disks-2]; + q = blocks[disks-1];

a = blocks[faila]; b = blocks[failb]; @@ -170,8 +170,8 @@ __2data_recov_4(size_t bytes, int faila, int failb, struct page **blocks, }

static struct dma_async_tx_descriptor * -__2data_recov_5(size_t bytes, int faila, int failb, struct page **blocks, - struct async_submit_ctl *submit) +__2data_recov_5(int disks, size_t bytes, int faila, int failb, + struct page **blocks, struct async_submit_ctl *submit) { struct dma_async_tx_descriptor *tx = NULL; struct page *p, *q, *g, *dp, *dq; @@ -181,21 +181,22 @@ __2data_recov_5(size_t bytes, int faila, int failb, struct page **blocks, dma_async_tx_callback cb_fn = submit->cb_fn; void *cb_param = submit->cb_param; void *scribble = submit->scribble; - int uninitialized_var(good); - int i; + int good_srcs, good, i;

- for (i = 0; i < 3; i++) { + good_srcs = 0; + good = -1; + for (i = 0; i < disks-2; i++) { + if (blocks[i] == NULL) + continue; if (i == faila || i == failb) continue; - else { - good = i; - break; - } + good = i; + good_srcs++; } - BUG_ON(i >= 3); + BUG_ON(good_srcs > 1);

- p = blocks[5-2]; - q = blocks[5-1]; + p = blocks[disks-2]; + q = blocks[disks-1]; g = blocks[good];

/* Compute syndrome with zero for the missing data pages @@ -323,6 +324,8 @@ struct dma_async_tx_descriptor * async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb, struct page **blocks, struct async_submit_ctl *submit) { + int non_zero_srcs, i; + BUG_ON(faila == failb); if (failb < faila) swap(faila, failb); @@ -334,12 +337,11 @@ async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb, */ if (!submit->scribble) { void **ptrs = (void **) blocks; - int i;

async_tx_quiesce(&submit->depend_tx); for (i = 0; i < disks; i++) if (blocks[i] == NULL) - ptrs[i] = (void*)raid6_empty_zero_page; + ptrs[i] = (void *) raid6_empty_zero_page; else ptrs[i] = page_address(blocks[i]);

@@ -350,19 +352,30 @@ async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb, return NULL; }

- switch (disks) { - case 4: + non_zero_srcs = 0; + for (i = 0; i < disks-2 && non_zero_srcs < 4; i++) + if (blocks[i]) + non_zero_srcs++; + switch (non_zero_srcs) { + case 0: + case 1: + /* There must be at least 2 sources - the failed devices. */ + BUG(); + + case 2: /* dma devices do not uniformly understand a zero source pq * operation (in contrast to the synchronous case), so - * explicitly handle the 4 disk special case + * explicitly handle the special case of a 4 disk array with + * both data disks missing. */ - return __2data_recov_4(bytes, faila, failb, blocks, submit); - case 5: + return __2data_recov_4(disks, bytes, faila, failb, blocks, submit); + case 3: /* dma devices do not uniformly understand a single * source pq operation (in contrast to the synchronous - * case), so explicitly handle the 5 disk special case + * case), so explicitly handle the special case of a 5 disk + * array with 2 of 3 data disks missing. */ - return __2data_recov_5(bytes, faila, failb, blocks, submit); + return __2data_recov_5(disks, bytes, faila, failb, blocks, submit); default: return __2data_recov_n(disks, bytes, faila, failb, blocks, submit); } @@ -388,6 +401,7 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila, dma_async_tx_callback cb_fn = submit->cb_fn; void *cb_param = submit->cb_param; void *scribble = submit->scribble; + int good_srcs, good, i; struct page *srcs[2];

pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); @@ -397,7 +411,6 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila, */ if (!scribble) { void **ptrs = (void **) blocks; - int i;

async_tx_quiesce(&submit->depend_tx); for (i = 0; i < disks; i++) @@ -413,6 +426,20 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila, return NULL; }

+ good_srcs = 0; + good = -1; + for (i = 0; i < disks-2; i++) { + if (i == faila) + continue; + if (blocks[i]) { + good = i; + good_srcs++; + if (good_srcs > 1) + break; + } + } + BUG_ON(good_srcs == 0); + p = blocks[disks-2]; q = blocks[disks-1];

@@ -423,11 +450,10 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila, blocks[faila] = NULL; blocks[disks-1] = dq;

- /* in the 4 disk case we only need to perform a single source - * multiplication + /* in the 4-disk case we only need to perform a single source + * multiplication with the one good data block. */ - if (disks == 4) { - int good = faila == 0 ? 1 : 0; + if (good_srcs == 1) { struct page *g = blocks[good];

init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,