add new system file

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2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/md/dm-flakey.c
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@@ -124,9 +124,9 @@
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 			 * Direction r or w?
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 			 */
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 			arg_name = dm_shift_arg(as);
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-			if (!strcasecmp(arg_name, "w"))
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+			if (arg_name && !strcasecmp(arg_name, "w"))
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 				fc->corrupt_bio_rw = WRITE;
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-			else if (!strcasecmp(arg_name, "r"))
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+			else if (arg_name && !strcasecmp(arg_name, "r"))
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 				fc->corrupt_bio_rw = READ;
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 			else {
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 				ti->error = "Invalid corrupt bio direction (r or w)";
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@@ -301,8 +301,11 @@
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 	 */
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 	bio_for_each_segment(bvec, bio, iter) {
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 		if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
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-			char *segment = (page_address(bio_iter_page(bio, iter))
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-					 + bio_iter_offset(bio, iter));
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+			char *segment;
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+			struct page *page = bio_iter_page(bio, iter);
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+			if (unlikely(page == ZERO_PAGE(0)))
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+				break;
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+			segment = (page_address(page) + bio_iter_offset(bio, iter));
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 			segment[corrupt_bio_byte] = fc->corrupt_bio_value;
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 			DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
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 				"(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
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@@ -359,9 +362,11 @@
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 		/*
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 		 * Corrupt matching writes.
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 		 */
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-		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
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-			if (all_corrupt_bio_flags_match(bio, fc))
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-				corrupt_bio_data(bio, fc);
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+		if (fc->corrupt_bio_byte) {
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+			if (fc->corrupt_bio_rw == WRITE) {
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+				if (all_corrupt_bio_flags_match(bio, fc))
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+					corrupt_bio_data(bio, fc);
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+			}
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 			goto map_bio;
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 		}
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..
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@@ -387,13 +392,14 @@
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 		return DM_ENDIO_DONE;
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 	if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
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-		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
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-		    all_corrupt_bio_flags_match(bio, fc)) {
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-			/*
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-			 * Corrupt successful matching READs while in down state.
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-			 */
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-			corrupt_bio_data(bio, fc);
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-
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+		if (fc->corrupt_bio_byte) {
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+			if ((fc->corrupt_bio_rw == READ) &&
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+			    all_corrupt_bio_flags_match(bio, fc)) {
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+				/*
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+				 * Corrupt successful matching READs while in down state.
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+				 */
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+				corrupt_bio_data(bio, fc);
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+			}
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 		} else if (!test_bit(DROP_WRITES, &fc->flags) &&
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 			   !test_bit(ERROR_WRITES, &fc->flags)) {
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 			/*