[lustre-devel] [PATCH 13/33] lustre: cksum: fix generating T10PI guard tags for partial brw page

From: Li Dongyang <[email protected]>

To get better performance, we allocate a page as the buffer for
T10PI guard tags, we fill the buffer going over every page for brw,
when the buffer is considered full, we use
cfs_crypto_hash_update_page() to update the hash and reuse the buffer.

It doesn't work when there's a page in the brw gets clipped, and the
checksum sector size is 512. For a page with PAGE_SIZE of 4096,
and offset at 1024, we will end up with 6 guard tags, and won't have
enough space in the very end of the buffer for a full brw page, which
needs 8.

Work out the number of guard tags for each page, update the
checksum hash and reuse the buffer when needed.

Fixes: 7c06498be70 ("lustre: osc: add T10PI support for RPC checksum")
WC-bug-id: https://jira.whamcloud.com/browse/LU-16712
Lustre-commit: 3999627447c01eebd ("LU-16712 cksum: fix generating T10PI guard tags for partial brw page")
Signed-off-by: Li Dongyang <[email protected]>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50540
Reviewed-by: Andreas Dilger <[email protected]>
Reviewed-by: Li Xi <[email protected]>
Reviewed-by: Oleg Drokin <[email protected]>
Signed-off-by: James Simmons <[email protected]>
---
 fs/lustre/osc/osc_request.c | 44 +++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/fs/lustre/osc/osc_request.c b/fs/lustre/osc/osc_request.c
index 061767503401..582cd96c304b 100644
--- a/fs/lustre/osc/osc_request.c
+++ b/fs/lustre/osc/osc_request.c
@@ -1197,12 +1197,12 @@ static int osc_checksum_bulk_t10pi(const char *obd_name, int nob,
 	struct page *__page;
 	unsigned char *buffer;
 	__be16 *guard_start;
-	unsigned int bufsize;
 	int guard_number;
 	int used_number = 0;
 	int used;
 	u32 cksum;
-	int rc = 0;
+	unsigned int bufsize = sizeof(cksum);
+	int rc = 0, rc2;
 	int i = 0;
 
 	LASSERT(pg_count > 0);
@@ -1228,6 +1228,15 @@ static int osc_checksum_bulk_t10pi(const char *obd_name, int nob,
 
 	while (nob > 0 && pg_count > 0) {
 		unsigned int count = pga[i]->count > nob ? nob : pga[i]->count;
+		int off = pga[i]->off & ~PAGE_MASK;
+		int guards_needed = DIV_ROUND_UP(off + count, sector_size) -
+				    (off / sector_size);
+
+		if (guards_needed > guard_number - used_number) {
+			cfs_crypto_hash_update_page(hdesc, __page, 0,
+						    used_number * sizeof(*guard_start));
+			used_number = 0;
+		}
 
 		/* corrupt the data before we compute the checksum, to
 		 * simulate an OST->client data error
@@ -1235,7 +1244,6 @@ static int osc_checksum_bulk_t10pi(const char *obd_name, int nob,
 		if (unlikely(i == 0 && opc == OST_READ &&
 			     OBD_FAIL_CHECK(OBD_FAIL_OSC_CHECKSUM_RECEIVE))) {
 			unsigned char *ptr = kmap(pga[i]->pg);
-			int off = pga[i]->off & ~PAGE_MASK;
 
 			memcpy(ptr + off, "bad1", min_t(typeof(nob), 4, nob));
 			kunmap(pga[i]->pg);
@@ -1262,34 +1270,32 @@ static int osc_checksum_bulk_t10pi(const char *obd_name, int nob,
 			break;
 
 		used_number += used;
-		if (used_number == guard_number) {
-			cfs_crypto_hash_update_page(hdesc, __page, 0,
-				used_number * sizeof(*guard_start));
-			used_number = 0;
-		}
-
 		nob -= pga[i]->count;
 		pg_count--;
 		i++;
 	}
 	kunmap(__page);
 	if (rc)
-		goto out;
+		goto out_hash;
 
 	if (used_number != 0)
 		cfs_crypto_hash_update_page(hdesc, __page, 0,
 			used_number * sizeof(*guard_start));
 
-	bufsize = sizeof(cksum);
-	cfs_crypto_hash_final(hdesc, (unsigned char *)&cksum, &bufsize);
-
-	/* For sending we only compute the wrong checksum instead
-	 * of corrupting the data so it is still correct on a redo
-	 */
-	if (opc == OST_WRITE && OBD_FAIL_CHECK(OBD_FAIL_OSC_CHECKSUM_SEND))
-		cksum++;
+out_hash:
+	rc2 = cfs_crypto_hash_final(hdesc, (unsigned char *)&cksum, &bufsize);
+	if (!rc)
+		rc = rc2;
+	if (rc == 0) {
+		/* For sending we only compute the wrong checksum instead
+		 * of corrupting the data so it is still correct on a redo
+		 */
+		if (opc == OST_WRITE &&
+		    OBD_FAIL_CHECK(OBD_FAIL_OSC_CHECKSUM_SEND))
+			cksum++;
 
-	*check_sum = cksum;
+		*check_sum = cksum;
+	}
 out:
 	__free_page(__page);
 	return rc;
-- 
2.39.3

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