scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 455 insertions, 0 deletions

diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
new file mode 100644
index 000000000..dd3627c71
--- /dev/null
+++ b/fs/ext4/readpage.c
@@ -0,0 +1,455 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext4/readpage.c
+ *
+ * Copyright (C) 2002, Linus Torvalds.
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This was originally taken from fs/mpage.c
+ *
+ * The ext4_mpage_readpages() function here is intended to
+ * replace mpage_readahead() in the general case, not just for
+ * encrypted files.  It has some limitations (see below), where it
+ * will fall back to read_block_full_page(), but these limitations
+ * should only be hit when page_size != block_size.
+ *
+ * This will allow us to attach a callback function to support ext4
+ * encryption.
+ *
+ * If anything unusual happens, such as:
+ *
+ * - encountering a page which has buffers
+ * - encountering a page which has a non-hole after a hole
+ * - encountering a page with non-contiguous blocks
+ *
+ * then this code just gives up and calls the buffer_head-based read function.
+ * It does handle a page which has holes at the end - that is a common case:
+ * the end-of-file on blocksize < PAGE_SIZE setups.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/kdev_t.h>
+#include <linux/gfp.h>
+#include <linux/bio.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/blk-crypto.h>
+#include <linux/blkdev.h>
+#include <linux/highmem.h>
+#include <linux/prefetch.h>
+#include <linux/mpage.h>
+#include <linux/writeback.h>
+#include <linux/backing-dev.h>
+
+#include "ext4.h"
+#include <trace/events/ext4.h>
+
+#define NUM_PREALLOC_POST_READ_CTXS	128
+
+static struct kmem_cache *bio_post_read_ctx_cache;
+static mempool_t *bio_post_read_ctx_pool;
+
+/* postprocessing steps for read bios */
+enum bio_post_read_step {
+	STEP_INITIAL = 0,
+	STEP_DECRYPT,
+	STEP_VERITY,
+	STEP_MAX,
+};
+
+struct bio_post_read_ctx {
+	struct bio *bio;
+	struct fsverity_info *vi;
+	struct work_struct work;
+	unsigned int cur_step;
+	unsigned int enabled_steps;
+};
+
+static void __read_end_io(struct bio *bio)
+{
+	struct folio_iter fi;
+
+	bio_for_each_folio_all(fi, bio)
+		folio_end_read(fi.folio, bio->bi_status == 0);
+	if (bio->bi_private)
+		mempool_free(bio->bi_private, bio_post_read_ctx_pool);
+	bio_put(bio);
+}
+
+static void bio_post_read_processing(struct bio_post_read_ctx *ctx);
+
+static void decrypt_work(struct work_struct *work)
+{
+	struct bio_post_read_ctx *ctx =
+		container_of(work, struct bio_post_read_ctx, work);
+	struct bio *bio = ctx->bio;
+
+	if (fscrypt_decrypt_bio(bio))
+		bio_post_read_processing(ctx);
+	else
+		__read_end_io(bio);
+}
+
+static void verity_work(struct work_struct *work)
+{
+	struct bio_post_read_ctx *ctx =
+		container_of(work, struct bio_post_read_ctx, work);
+	struct bio *bio = ctx->bio;
+	struct fsverity_info *vi = ctx->vi;
+
+	/*
+	 * fsverity_verify_bio() may call readahead() again, and although verity
+	 * will be disabled for that, decryption may still be needed, causing
+	 * another bio_post_read_ctx to be allocated.  So to guarantee that
+	 * mempool_alloc() never deadlocks we must free the current ctx first.
+	 * This is safe because verity is the last post-read step.
+	 */
+	BUILD_BUG_ON(STEP_VERITY + 1 != STEP_MAX);
+	mempool_free(ctx, bio_post_read_ctx_pool);
+	bio->bi_private = NULL;
+
+	fsverity_verify_bio(vi, bio);
+
+	__read_end_io(bio);
+}
+
+static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
+{
+	/*
+	 * We use different work queues for decryption and for verity because
+	 * verity may require reading metadata pages that need decryption, and
+	 * we shouldn't recurse to the same workqueue.
+	 */
+	switch (++ctx->cur_step) {
+	case STEP_DECRYPT:
+		if (ctx->enabled_steps & (1 << STEP_DECRYPT)) {
+			INIT_WORK(&ctx->work, decrypt_work);
+			fscrypt_enqueue_decrypt_work(&ctx->work);
+			return;
+		}
+		ctx->cur_step++;
+		fallthrough;
+	case STEP_VERITY:
+		if (IS_ENABLED(CONFIG_FS_VERITY) &&
+		    ctx->enabled_steps & (1 << STEP_VERITY)) {
+			INIT_WORK(&ctx->work, verity_work);
+			fsverity_enqueue_verify_work(&ctx->work);
+			return;
+		}
+		ctx->cur_step++;
+		fallthrough;
+	default:
+		__read_end_io(ctx->bio);
+	}
+}
+
+static bool bio_post_read_required(struct bio *bio)
+{
+	return bio->bi_private && !bio->bi_status;
+}
+
+/*
+ * I/O completion handler for multipage BIOs.
+ *
+ * The mpage code never puts partial pages into a BIO (except for end-of-file).
+ * If a page does not map to a contiguous run of blocks then it simply falls
+ * back to block_read_full_folio().
+ *
+ * Why is this?  If a page's completion depends on a number of different BIOs
+ * which can complete in any order (or at the same time) then determining the
+ * status of that page is hard.  See end_buffer_async_read() for the details.
+ * There is no point in duplicating all that complexity.
+ */
+static void mpage_end_io(struct bio *bio)
+{
+	if (bio_post_read_required(bio)) {
+		struct bio_post_read_ctx *ctx = bio->bi_private;
+
+		ctx->cur_step = STEP_INITIAL;
+		bio_post_read_processing(ctx);
+		return;
+	}
+	__read_end_io(bio);
+}
+
+static void ext4_set_bio_post_read_ctx(struct bio *bio,
+				       const struct inode *inode,
+				       struct fsverity_info *vi)
+{
+	unsigned int post_read_steps = 0;
+
+	if (fscrypt_inode_uses_fs_layer_crypto(inode))
+		post_read_steps |= 1 << STEP_DECRYPT;
+
+	if (vi)
+		post_read_steps |= 1 << STEP_VERITY;
+
+	if (post_read_steps) {
+		/* Due to the mempool, this never fails. */
+		struct bio_post_read_ctx *ctx =
+			mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
+
+		ctx->bio = bio;
+		ctx->vi = vi;
+		ctx->enabled_steps = post_read_steps;
+		bio->bi_private = ctx;
+	}
+}
+
+static inline loff_t ext4_readpage_limit(struct inode *inode)
+{
+	if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
+		return inode->i_sb->s_maxbytes;
+
+	return i_size_read(inode);
+}
+
+static int ext4_mpage_readpages(struct inode *inode, struct fsverity_info *vi,
+		struct readahead_control *rac, struct folio *folio)
+{
+	struct bio *bio = NULL;
+	sector_t last_block_in_bio = 0;
+	const unsigned blkbits = inode->i_blkbits;
+	const unsigned blocksize = 1 << blkbits;
+	sector_t block_in_file;
+	sector_t last_block;
+	sector_t last_block_in_file;
+	sector_t first_block;
+	loff_t pos;
+	unsigned page_block;
+	struct block_device *bdev = inode->i_sb->s_bdev;
+	int length;
+	unsigned relative_block = 0;
+	struct ext4_map_blocks map;
+	unsigned int nr_pages, folio_pages;
+
+	map.m_pblk = 0;
+	map.m_lblk = 0;
+	map.m_len = 0;
+	map.m_flags = 0;
+
+	nr_pages = rac ? readahead_count(rac) : folio_nr_pages(folio);
+	for (; nr_pages; nr_pages -= folio_pages) {
+		int fully_mapped = 1;
+		unsigned int first_hole;
+		unsigned int blocks_per_folio;
+
+		if (rac)
+			folio = readahead_folio(rac);
+
+		folio_pages = folio_nr_pages(folio);
+		prefetchw(&folio->flags);
+
+		if (folio_buffers(folio))
+			goto confused;
+
+		blocks_per_folio = folio_size(folio) >> blkbits;
+		first_hole = blocks_per_folio;
+		pos = folio_pos(folio);
+		block_in_file = pos >> blkbits;
+		last_block = EXT4_PG_TO_LBLK(inode, folio->index + nr_pages);
+		last_block_in_file = (ext4_readpage_limit(inode) +
+				      blocksize - 1) >> blkbits;
+		if (last_block > last_block_in_file)
+			last_block = last_block_in_file;
+		page_block = 0;
+
+		/*
+		 * Map blocks using the previous result first.
+		 */
+		if ((map.m_flags & EXT4_MAP_MAPPED) &&
+		    block_in_file > map.m_lblk &&
+		    block_in_file < (map.m_lblk + map.m_len)) {
+			unsigned map_offset = block_in_file - map.m_lblk;
+			unsigned last = map.m_len - map_offset;
+
+			first_block = map.m_pblk + map_offset;
+			for (relative_block = 0; ; relative_block++) {
+				if (relative_block == last) {
+					/* needed? */
+					map.m_flags &= ~EXT4_MAP_MAPPED;
+					break;
+				}
+				if (page_block == blocks_per_folio)
+					break;
+				page_block++;
+				block_in_file++;
+			}
+		}
+
+		/*
+		 * Then do more ext4_map_blocks() calls until we are
+		 * done with this folio.
+		 */
+		while (page_block < blocks_per_folio) {
+			if (block_in_file < last_block) {
+				map.m_lblk = block_in_file;
+				map.m_len = last_block - block_in_file;
+
+				if (ext4_map_blocks(NULL, inode, &map, 0) < 0) {
+				set_error_page:
+					folio_zero_segment(folio, 0,
+							  folio_size(folio));
+					folio_unlock(folio);
+					goto next_page;
+				}
+			}
+			if ((map.m_flags & EXT4_MAP_MAPPED) == 0) {
+				fully_mapped = 0;
+				if (first_hole == blocks_per_folio)
+					first_hole = page_block;
+				page_block++;
+				block_in_file++;
+				continue;
+			}
+			if (first_hole != blocks_per_folio)
+				goto confused;		/* hole -> non-hole */
+
+			/* Contiguous blocks? */
+			if (!page_block)
+				first_block = map.m_pblk;
+			else if (first_block + page_block != map.m_pblk)
+				goto confused;
+			for (relative_block = 0; ; relative_block++) {
+				if (relative_block == map.m_len) {
+					/* needed? */
+					map.m_flags &= ~EXT4_MAP_MAPPED;
+					break;
+				} else if (page_block == blocks_per_folio)
+					break;
+				page_block++;
+				block_in_file++;
+			}
+		}
+		if (first_hole != blocks_per_folio) {
+			folio_zero_segment(folio, first_hole << blkbits,
+					  folio_size(folio));
+			if (first_hole == 0) {
+				if (vi && !fsverity_verify_folio(vi, folio))
+					goto set_error_page;
+				folio_end_read(folio, true);
+				continue;
+			}
+		} else if (fully_mapped) {
+			folio_set_mappedtodisk(folio);
+		}
+
+		/*
+		 * This folio will go to BIO.  Do we need to send this
+		 * BIO off first?
+		 */
+		if (bio && (last_block_in_bio != first_block - 1 ||
+			    !fscrypt_mergeable_bio(bio, inode, pos))) {
+		submit_and_realloc:
+			blk_crypto_submit_bio(bio);
+			bio = NULL;
+		}
+		if (bio == NULL) {
+			/*
+			 * bio_alloc will _always_ be able to allocate a bio if
+			 * __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
+			 */
+			bio = bio_alloc(bdev, bio_max_segs(nr_pages),
+					REQ_OP_READ, GFP_KERNEL);
+			fscrypt_set_bio_crypt_ctx(bio, inode, pos, GFP_KERNEL);
+			ext4_set_bio_post_read_ctx(bio, inode, vi);
+			bio->bi_iter.bi_sector = first_block << (blkbits - 9);
+			bio->bi_end_io = mpage_end_io;
+			if (rac)
+				bio->bi_opf |= REQ_RAHEAD;
+		}
+
+		length = first_hole << blkbits;
+		if (!bio_add_folio(bio, folio, length, 0))
+			goto submit_and_realloc;
+
+		if (((map.m_flags & EXT4_MAP_BOUNDARY) &&
+		     (relative_block == map.m_len)) ||
+		    (first_hole != blocks_per_folio)) {
+			blk_crypto_submit_bio(bio);
+			bio = NULL;
+		} else
+			last_block_in_bio = first_block + blocks_per_folio - 1;
+		continue;
+	confused:
+		if (bio) {
+			blk_crypto_submit_bio(bio);
+			bio = NULL;
+		}
+		if (!folio_test_uptodate(folio))
+			block_read_full_folio(folio, ext4_get_block);
+		else
+			folio_unlock(folio);
+next_page:
+		; /* A label shall be followed by a statement until C23 */
+	}
+	if (bio)
+		blk_crypto_submit_bio(bio);
+	return 0;
+}
+
+int ext4_read_folio(struct file *file, struct folio *folio)
+{
+	struct inode *inode = folio->mapping->host;
+	struct fsverity_info *vi = NULL;
+	int ret;
+
+	trace_ext4_read_folio(inode, folio);
+
+	if (ext4_has_inline_data(inode)) {
+		ret = ext4_readpage_inline(inode, folio);
+		if (ret != -EAGAIN)
+			return ret;
+	}
+
+	if (folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))
+		vi = fsverity_get_info(inode);
+	if (vi)
+		fsverity_readahead(vi, folio->index, folio_nr_pages(folio));
+	return ext4_mpage_readpages(inode, vi, NULL, folio);
+}
+
+void ext4_readahead(struct readahead_control *rac)
+{
+	struct inode *inode = rac->mapping->host;
+	struct fsverity_info *vi = NULL;
+
+	/* If the file has inline data, no need to do readahead. */
+	if (ext4_has_inline_data(inode))
+		return;
+
+	if (readahead_index(rac) < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))
+		vi = fsverity_get_info(inode);
+	if (vi)
+		fsverity_readahead(vi, readahead_index(rac),
+				   readahead_count(rac));
+	ext4_mpage_readpages(inode, vi, rac, NULL);
+}
+
+int __init ext4_init_post_read_processing(void)
+{
+	bio_post_read_ctx_cache = KMEM_CACHE(bio_post_read_ctx, SLAB_RECLAIM_ACCOUNT);
+
+	if (!bio_post_read_ctx_cache)
+		goto fail;
+	bio_post_read_ctx_pool =
+		mempool_create_slab_pool(NUM_PREALLOC_POST_READ_CTXS,
+					 bio_post_read_ctx_cache);
+	if (!bio_post_read_ctx_pool)
+		goto fail_free_cache;
+	return 0;
+
+fail_free_cache:
+	kmem_cache_destroy(bio_post_read_ctx_cache);
+fail:
+	return -ENOMEM;
+}
+
+void ext4_exit_post_read_processing(void)
+{
+	mempool_destroy(bio_post_read_ctx_pool);
+	kmem_cache_destroy(bio_post_read_ctx_cache);
+}