for-linus-20190620

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Merge tag 'for-linus-20190620' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Three fixes that should go into this series.

  One is a set of two patches from Christoph, fixing a page leak on same
  page merges. Boiled down version of a bigger fix, but this one is more
  appropriate for this late in the cycle (and easier to backport to
  stable).

  The last patch is for a divide error in MD, from Mariusz (via Song)"

* tag 'for-linus-20190620' of git://git.kernel.dk/linux-block:
  md: fix for divide error in status_resync
  block: fix page leak when merging to same page
  block: return from __bio_try_merge_page if merging occured in the same page

block/bio.c

@@ -636,7 +636,7 @@ EXPORT_SYMBOL(bio_clone_fast);
 
 static inline bool page_is_mergeable(const struct bio_vec *bv,
 		struct page *page, unsigned int len, unsigned int off,
-		bool same_page)
+		bool *same_page)
 {
 	phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) +
 		bv->bv_offset + bv->bv_len - 1;
@@ -647,15 +647,9 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
 	if (xen_domain() && !xen_biovec_phys_mergeable(bv, page))
 		return false;
 
-	if ((vec_end_addr & PAGE_MASK) != page_addr) {
-		if (same_page)
-			return false;
-		if (pfn_to_page(PFN_DOWN(vec_end_addr)) + 1 != page)
-			return false;
-	}
-
-	WARN_ON_ONCE(same_page && (len + off) > PAGE_SIZE);
-
+	*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
+	if (!*same_page && pfn_to_page(PFN_DOWN(vec_end_addr)) + 1 != page)
+		return false;
 	return true;
 }
 
@@ -701,6 +695,7 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
 		bool put_same_page)
 {
 	struct bio_vec *bvec;
+	bool same_page = false;
 
 	/*
 	 * cloned bio must not modify vec list
@@ -729,7 +724,7 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
 		if (bvec_gap_to_prev(q, bvec, offset))
 			return 0;
 
-		if (page_is_mergeable(bvec, page, len, offset, false) &&
+		if (page_is_mergeable(bvec, page, len, offset, &same_page) &&
 		    can_add_page_to_seg(q, bvec, page, len, offset)) {
 			bvec->bv_len += len;
 			goto done;
@@ -767,8 +762,7 @@ EXPORT_SYMBOL(bio_add_pc_page);
  * @page: start page to add
  * @len: length of the data to add
  * @off: offset of the data relative to @page
- * @same_page: if %true only merge if the new data is in the same physical
- *		page as the last segment of the bio.
+ * @same_page: return if the segment has been merged inside the same page
  *
  * Try to add the data at @page + @off to the last bvec of @bio.  This is a
  * a useful optimisation for file systems with a block size smaller than the
@@ -779,7 +773,7 @@ EXPORT_SYMBOL(bio_add_pc_page);
  * Return %true on success or %false on failure.
  */
 bool __bio_try_merge_page(struct bio *bio, struct page *page,
-		unsigned int len, unsigned int off, bool same_page)
+		unsigned int len, unsigned int off, bool *same_page)
 {
 	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
 		return false;
@@ -837,7 +831,9 @@ EXPORT_SYMBOL_GPL(__bio_add_page);
 int bio_add_page(struct bio *bio, struct page *page,
 		 unsigned int len, unsigned int offset)
 {
-	if (!__bio_try_merge_page(bio, page, len, offset, false)) {
+	bool same_page = false;
+
+	if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
 		if (bio_full(bio))
 			return 0;
 		__bio_add_page(bio, page, len, offset);
@@ -900,6 +896,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
 	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
 	struct page **pages = (struct page **)bv;
+	bool same_page = false;
 	ssize_t size, left;
 	unsigned len, i;
 	size_t offset;
@@ -920,8 +917,15 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 		struct page *page = pages[i];
 
 		len = min_t(size_t, PAGE_SIZE - offset, left);
-		if (WARN_ON_ONCE(bio_add_page(bio, page, len, offset) != len))
-			return -EINVAL;
+
+		if (__bio_try_merge_page(bio, page, len, offset, &same_page)) {
+			if (same_page)
+				put_page(page);
+		} else {
+			if (WARN_ON_ONCE(bio_full(bio)))
+                                return -EINVAL;
+			__bio_add_page(bio, page, len, offset);
+		}
 		offset = 0;
 	}
 

drivers/md/md.c

@@ -7607,9 +7607,9 @@ static void status_unused(struct seq_file *seq)
 static int status_resync(struct seq_file *seq, struct mddev *mddev)
 {
 	sector_t max_sectors, resync, res;
-	unsigned long dt, db;
-	sector_t rt;
-	int scale;
+	unsigned long dt, db = 0;
+	sector_t rt, curr_mark_cnt, resync_mark_cnt;
+	int scale, recovery_active;
 	unsigned int per_milli;
 
 	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
@@ -7698,22 +7698,30 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
 	 * db: blocks written from mark until now
 	 * rt: remaining time
 	 *
-	 * rt is a sector_t, so could be 32bit or 64bit.
-	 * So we divide before multiply in case it is 32bit and close
-	 * to the limit.
-	 * We scale the divisor (db) by 32 to avoid losing precision
-	 * near the end of resync when the number of remaining sectors
-	 * is close to 'db'.
-	 * We then divide rt by 32 after multiplying by db to compensate.
-	 * The '+1' avoids division by zero if db is very small.
+	 * rt is a sector_t, which is always 64bit now. We are keeping
+	 * the original algorithm, but it is not really necessary.
+	 *
+	 * Original algorithm:
+	 *   So we divide before multiply in case it is 32bit and close
+	 *   to the limit.
+	 *   We scale the divisor (db) by 32 to avoid losing precision
+	 *   near the end of resync when the number of remaining sectors
+	 *   is close to 'db'.
+	 *   We then divide rt by 32 after multiplying by db to compensate.
+	 *   The '+1' avoids division by zero if db is very small.
 	 */
 	dt = ((jiffies - mddev->resync_mark) / HZ);
 	if (!dt) dt++;
-	db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
-		- mddev->resync_mark_cnt;
+
+	curr_mark_cnt = mddev->curr_mark_cnt;
+	recovery_active = atomic_read(&mddev->recovery_active);
+	resync_mark_cnt = mddev->resync_mark_cnt;
+
+	if (curr_mark_cnt >= (recovery_active + resync_mark_cnt))
+		db = curr_mark_cnt - (recovery_active + resync_mark_cnt);
 
 	rt = max_sectors - resync;    /* number of remaining sectors */
-	sector_div(rt, db/32+1);
+	rt = div64_u64(rt, db/32+1);
 	rt *= dt;
 	rt >>= 5;
 

fs/iomap.c

@@ -287,7 +287,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	struct iomap_readpage_ctx *ctx = data;
 	struct page *page = ctx->cur_page;
 	struct iomap_page *iop = iomap_page_create(inode, page);
-	bool is_contig = false;
+	bool same_page = false, is_contig = false;
 	loff_t orig_pos = pos;
 	unsigned poff, plen;
 	sector_t sector;
@@ -315,10 +315,14 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	 * Try to merge into a previous segment if we can.
 	 */
 	sector = iomap_sector(iomap, pos);
-	if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
-		if (__bio_try_merge_page(ctx->bio, page, plen, poff, true))
-			goto done;
+	if (ctx->bio && bio_end_sector(ctx->bio) == sector)
 		is_contig = true;
+
+	if (is_contig &&
+	    __bio_try_merge_page(ctx->bio, page, plen, poff, &same_page)) {
+		if (!same_page && iop)
+			atomic_inc(&iop->read_count);
+		goto done;
 	}
 
 	/*

fs/xfs/xfs_aops.c

@@ -758,6 +758,7 @@ xfs_add_to_ioend(
 	struct block_device	*bdev = xfs_find_bdev_for_inode(inode);
 	unsigned		len = i_blocksize(inode);
 	unsigned		poff = offset & (PAGE_SIZE - 1);
+	bool			merged, same_page = false;
 	sector_t		sector;
 
 	sector = xfs_fsb_to_db(ip, wpc->imap.br_startblock) +
@@ -774,9 +775,13 @@ xfs_add_to_ioend(
 				wpc->imap.br_state, offset, bdev, sector);
 	}
 
-	if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) {
-		if (iop)
-			atomic_inc(&iop->write_count);
+	merged = __bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
+			&same_page);
+
+	if (iop && !same_page)
+		atomic_inc(&iop->write_count);
+
+	if (!merged) {
 		if (bio_full(wpc->ioend->io_bio))
 			xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
 		bio_add_page(wpc->ioend->io_bio, page, len, poff);

include/linux/bio.h

@@ -423,7 +423,7 @@ extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 			   unsigned int, unsigned int);
 bool __bio_try_merge_page(struct bio *bio, struct page *page,
-		unsigned int len, unsigned int off, bool same_page);
+		unsigned int len, unsigned int off, bool *same_page);
 void __bio_add_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off);
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);