1 files changed, 233 insertions, 137 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d8da3edf2ac3..556484cf5d93 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -87,19 +87,9 @@ void btrfs_leak_debug_check(void)
 static inline void __btrfs_debug_check_extent_io_range(const char *caller,
 		struct extent_io_tree *tree, u64 start, u64 end)
 {
-	struct inode *inode;
-	u64 isize;
-
-	if (!tree->mapping)
-		return;
-
-	inode = tree->mapping->host;
-	isize = i_size_read(inode);
-	if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
-		btrfs_debug_rl(BTRFS_I(inode)->root->fs_info,
-		    "%s: ino %llu isize %llu odd range [%llu,%llu]",
-			caller, btrfs_ino(BTRFS_I(inode)), isize, start, end);
-	}
+	if (tree->ops && tree->ops->check_extent_io_range)
+		tree->ops->check_extent_io_range(tree->private_data, caller,
+						 start, end);
 }
 #else
 #define btrfs_leak_debug_add(new, head)	do {} while (0)
@@ -154,9 +144,9 @@ static noinline void flush_write_bio(void *data);
 static inline struct btrfs_fs_info *
 tree_fs_info(struct extent_io_tree *tree)
 {
-	if (!tree->mapping)
-		return NULL;
-	return btrfs_sb(tree->mapping->host->i_sb);
+	if (tree->ops)
+		return tree->ops->tree_fs_info(tree->private_data);
+	return NULL;
 }
 
 int __init extent_io_init(void)
@@ -174,7 +164,8 @@ int __init extent_io_init(void)
 		goto free_state_cache;
 
 	btrfs_bioset = bioset_create(BIO_POOL_SIZE,
-				     offsetof(struct btrfs_io_bio, bio));
+				     offsetof(struct btrfs_io_bio, bio),
+				     BIOSET_NEED_BVECS);
 	if (!btrfs_bioset)
 		goto free_buffer_cache;
 
@@ -213,13 +204,13 @@ void extent_io_exit(void)
 }
 
 void extent_io_tree_init(struct extent_io_tree *tree,
-			 struct address_space *mapping)
+			 void *private_data)
 {
 	tree->state = RB_ROOT;
 	tree->ops = NULL;
 	tree->dirty_bytes = 0;
 	spin_lock_init(&tree->lock);
-	tree->mapping = mapping;
+	tree->private_data = private_data;
 }
 
 static struct extent_state *alloc_extent_state(gfp_t mask)
@@ -369,8 +360,7 @@ static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
 		     struct extent_state *other)
 {
 	if (tree->ops && tree->ops->merge_extent_hook)
-		tree->ops->merge_extent_hook(tree->mapping->host, new,
-					     other);
+		tree->ops->merge_extent_hook(tree->private_data, new, other);
 }
 
 /*
@@ -421,15 +411,14 @@ static void set_state_cb(struct extent_io_tree *tree,
 			 struct extent_state *state, unsigned *bits)
 {
 	if (tree->ops && tree->ops->set_bit_hook)
-		tree->ops->set_bit_hook(tree->mapping->host, state, bits);
+		tree->ops->set_bit_hook(tree->private_data, state, bits);
 }
 
 static void clear_state_cb(struct extent_io_tree *tree,
 			   struct extent_state *state, unsigned *bits)
 {
 	if (tree->ops && tree->ops->clear_bit_hook)
-		tree->ops->clear_bit_hook(BTRFS_I(tree->mapping->host),
-				state, bits);
+		tree->ops->clear_bit_hook(tree->private_data, state, bits);
 }
 
 static void set_state_bits(struct extent_io_tree *tree,
@@ -478,7 +467,7 @@ static void split_cb(struct extent_io_tree *tree, struct extent_state *orig,
 		     u64 split)
 {
 	if (tree->ops && tree->ops->split_extent_hook)
-		tree->ops->split_extent_hook(tree->mapping->host, orig, split);
+		tree->ops->split_extent_hook(tree->private_data, orig, split);
 }
 
 /*
@@ -1402,17 +1391,7 @@ void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
  */
 static void set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
 {
-	unsigned long index = start >> PAGE_SHIFT;
-	unsigned long end_index = end >> PAGE_SHIFT;
-	struct page *page;
-
-	while (index <= end_index) {
-		page = find_get_page(tree->mapping, index);
-		BUG_ON(!page); /* Pages should be in the extent_io_tree */
-		set_page_writeback(page);
-		put_page(page);
-		index++;
-	}
+	tree->ops->set_range_writeback(tree->private_data, start, end);
 }
 
 /* find the first state struct with 'bits' set after 'start', and
@@ -1961,11 +1940,12 @@ static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
 		SetPageUptodate(page);
 }
 
-int free_io_failure(struct btrfs_inode *inode, struct io_failure_record *rec)
+int free_io_failure(struct extent_io_tree *failure_tree,
+		    struct extent_io_tree *io_tree,
+		    struct io_failure_record *rec)
 {
 	int ret;
 	int err = 0;
-	struct extent_io_tree *failure_tree = &inode->io_failure_tree;
 
 	set_state_failrec(failure_tree, rec->start, NULL);
 	ret = clear_extent_bits(failure_tree, rec->start,
@@ -1974,7 +1954,7 @@ int free_io_failure(struct btrfs_inode *inode, struct io_failure_record *rec)
 	if (ret)
 		err = ret;
 
-	ret = clear_extent_bits(&inode->io_tree, rec->start,
+	ret = clear_extent_bits(io_tree, rec->start,
 				rec->start + rec->len - 1,
 				EXTENT_DAMAGED);
 	if (ret && !err)
@@ -1994,11 +1974,10 @@ int free_io_failure(struct btrfs_inode *inode, struct io_failure_record *rec)
  * currently, there can be no more than two copies of every data bit. thus,
  * exactly one rewrite is required.
  */
-int repair_io_failure(struct btrfs_inode *inode, u64 start, u64 length,
-		u64 logical, struct page *page,
-		unsigned int pg_offset, int mirror_num)
+int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
+		      u64 length, u64 logical, struct page *page,
+		      unsigned int pg_offset, int mirror_num)
 {
-	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct bio *bio;
 	struct btrfs_device *dev;
 	u64 map_length = 0;
@@ -2009,9 +1988,7 @@ int repair_io_failure(struct btrfs_inode *inode, u64 start, u64 length,
 	ASSERT(!(fs_info->sb->s_flags & MS_RDONLY));
 	BUG_ON(!mirror_num);
 
-	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
-	if (!bio)
-		return -EIO;
+	bio = btrfs_io_bio_alloc(1);
 	bio->bi_iter.bi_size = 0;
 	map_length = length;
 
@@ -2070,7 +2047,7 @@ int repair_io_failure(struct btrfs_inode *inode, u64 start, u64 length,
 
 	btrfs_info_rl_in_rcu(fs_info,
 		"read error corrected: ino %llu off %llu (dev %s sector %llu)",
-				  btrfs_ino(inode), start,
+				  ino, start,
 				  rcu_str_deref(dev->name), sector);
 	btrfs_bio_counter_dec(fs_info);
 	bio_put(bio);
@@ -2090,8 +2067,7 @@ int repair_eb_io_failure(struct btrfs_fs_info *fs_info,
 	for (i = 0; i < num_pages; i++) {
 		struct page *p = eb->pages[i];
 
-		ret = repair_io_failure(BTRFS_I(fs_info->btree_inode), start,
-					PAGE_SIZE, start, p,
+		ret = repair_io_failure(fs_info, 0, start, PAGE_SIZE, start, p,
 					start - page_offset(p), mirror_num);
 		if (ret)
 			break;
@@ -2105,24 +2081,24 @@ int repair_eb_io_failure(struct btrfs_fs_info *fs_info,
  * each time an IO finishes, we do a fast check in the IO failure tree
  * to see if we need to process or clean up an io_failure_record
  */
-int clean_io_failure(struct btrfs_inode *inode, u64 start, struct page *page,
-		     unsigned int pg_offset)
+int clean_io_failure(struct btrfs_fs_info *fs_info,
+		     struct extent_io_tree *failure_tree,
+		     struct extent_io_tree *io_tree, u64 start,
+		     struct page *page, u64 ino, unsigned int pg_offset)
 {
 	u64 private;
 	struct io_failure_record *failrec;
-	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct extent_state *state;
 	int num_copies;
 	int ret;
 
 	private = 0;
-	ret = count_range_bits(&inode->io_failure_tree, &private,
-				(u64)-1, 1, EXTENT_DIRTY, 0);
+	ret = count_range_bits(failure_tree, &private, (u64)-1, 1,
+			       EXTENT_DIRTY, 0);
 	if (!ret)
 		return 0;
 
-	ret = get_state_failrec(&inode->io_failure_tree, start,
-			&failrec);
+	ret = get_state_failrec(failure_tree, start, &failrec);
 	if (ret)
 		return 0;
 
@@ -2138,25 +2114,25 @@ int clean_io_failure(struct btrfs_inode *inode, u64 start, struct page *page,
 	if (fs_info->sb->s_flags & MS_RDONLY)
 		goto out;
 
-	spin_lock(&inode->io_tree.lock);
-	state = find_first_extent_bit_state(&inode->io_tree,
+	spin_lock(&io_tree->lock);
+	state = find_first_extent_bit_state(io_tree,
 					    failrec->start,
 					    EXTENT_LOCKED);
-	spin_unlock(&inode->io_tree.lock);
+	spin_unlock(&io_tree->lock);
 
 	if (state && state->start <= failrec->start &&
 	    state->end >= failrec->start + failrec->len - 1) {
 		num_copies = btrfs_num_copies(fs_info, failrec->logical,
 					      failrec->len);
 		if (num_copies > 1)  {
-			repair_io_failure(inode, start, failrec->len,
-					  failrec->logical, page,
-					  pg_offset, failrec->failed_mirror);
+			repair_io_failure(fs_info, ino, start, failrec->len,
+					  failrec->logical, page, pg_offset,
+					  failrec->failed_mirror);
 		}
 	}
 
 out:
-	free_io_failure(inode, failrec);
+	free_io_failure(failure_tree, io_tree, failrec);
 
 	return 0;
 }
@@ -2356,10 +2332,7 @@ struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
 	struct btrfs_io_bio *btrfs_failed_bio;
 	struct btrfs_io_bio *btrfs_bio;
 
-	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
-	if (!bio)
-		return NULL;
-
+	bio = btrfs_io_bio_alloc(1);
 	bio->bi_end_io = endio_func;
 	bio->bi_iter.bi_sector = failrec->logical >> 9;
 	bio->bi_bdev = fs_info->fs_devices->latest_bdev;
@@ -2397,8 +2370,10 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
 	struct io_failure_record *failrec;
 	struct inode *inode = page->mapping->host;
 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
+	struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
 	struct bio *bio;
 	int read_mode = 0;
+	blk_status_t status;
 	int ret;
 
 	BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);
@@ -2409,7 +2384,7 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
 
 	ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
 	if (!ret) {
-		free_io_failure(BTRFS_I(inode), failrec);
+		free_io_failure(failure_tree, tree, failrec);
 		return -EIO;
 	}
 
@@ -2422,7 +2397,7 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
 				      (int)phy_offset, failed_bio->bi_end_io,
 				      NULL);
 	if (!bio) {
-		free_io_failure(BTRFS_I(inode), failrec);
+		free_io_failure(failure_tree, tree, failrec);
 		return -EIO;
 	}
 	bio_set_op_attrs(bio, REQ_OP_READ, read_mode);
@@ -2431,11 +2406,12 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
 		"Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d",
 		read_mode, failrec->this_mirror, failrec->in_validation);
 
-	ret = tree->ops->submit_bio_hook(inode, bio, failrec->this_mirror,
+	status = tree->ops->submit_bio_hook(tree->private_data, bio, failrec->this_mirror,
 					 failrec->bio_flags, 0);
-	if (ret) {
-		free_io_failure(BTRFS_I(inode), failrec);
+	if (status) {
+		free_io_failure(failure_tree, tree, failrec);
 		bio_put(bio);
+		ret = blk_status_to_errno(status);
 	}
 
 	return ret;
@@ -2458,7 +2434,7 @@ void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
 	if (!uptodate) {
 		ClearPageUptodate(page);
 		SetPageError(page);
-		ret = ret < 0 ? ret : -EIO;
+		ret = err < 0 ? err : -EIO;
 		mapping_set_error(page->mapping, ret);
 	}
 }
@@ -2474,6 +2450,7 @@ void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
  */
 static void end_bio_extent_writepage(struct bio *bio)
 {
+	int error = blk_status_to_errno(bio->bi_status);
 	struct bio_vec *bvec;
 	u64 start;
 	u64 end;
@@ -2503,7 +2480,7 @@ static void end_bio_extent_writepage(struct bio *bio)
 		start = page_offset(page);
 		end = start + bvec->bv_offset + bvec->bv_len - 1;
 
-		end_extent_writepage(page, bio->bi_error, start, end);
+		end_extent_writepage(page, error, start, end);
 		end_page_writeback(page);
 	}
 
@@ -2536,9 +2513,9 @@ endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
 static void end_bio_extent_readpage(struct bio *bio)
 {
 	struct bio_vec *bvec;
-	int uptodate = !bio->bi_error;
+	int uptodate = !bio->bi_status;
 	struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
-	struct extent_io_tree *tree;
+	struct extent_io_tree *tree, *failure_tree;
 	u64 offset = 0;
 	u64 start;
 	u64 end;
@@ -2556,9 +2533,10 @@ static void end_bio_extent_readpage(struct bio *bio)
 
 		btrfs_debug(fs_info,
 			"end_bio_extent_readpage: bi_sector=%llu, err=%d, mirror=%u",
-			(u64)bio->bi_iter.bi_sector, bio->bi_error,
+			(u64)bio->bi_iter.bi_sector, bio->bi_status,
 			io_bio->mirror_num);
 		tree = &BTRFS_I(inode)->io_tree;
+		failure_tree = &BTRFS_I(inode)->io_failure_tree;
 
 		/* We always issue full-page reads, but if some block
 		 * in a page fails to read, blk_update_request() will
@@ -2588,8 +2566,10 @@ static void end_bio_extent_readpage(struct bio *bio)
 			if (ret)
 				uptodate = 0;
 			else
-				clean_io_failure(BTRFS_I(inode), start,
-						page, 0);
+				clean_io_failure(BTRFS_I(inode)->root->fs_info,
+						 failure_tree, tree, start,
+						 page,
+						 btrfs_ino(BTRFS_I(inode)), 0);
 		}
 
 		if (likely(uptodate))
@@ -2615,7 +2595,7 @@ static void end_bio_extent_readpage(struct bio *bio)
 				ret = bio_readpage_error(bio, offset, page,
 							 start, end, mirror);
 				if (ret == 0) {
-					uptodate = !bio->bi_error;
+					uptodate = !bio->bi_status;
 					offset += len;
 					continue;
 				}
@@ -2673,77 +2653,80 @@ readpage_ok:
 		endio_readpage_release_extent(tree, extent_start, extent_len,
 					      uptodate);
 	if (io_bio->end_io)
-		io_bio->end_io(io_bio, bio->bi_error);
+		io_bio->end_io(io_bio, blk_status_to_errno(bio->bi_status));
 	bio_put(bio);
 }
 
 /*
- * this allocates from the btrfs_bioset.  We're returning a bio right now
- * but you can call btrfs_io_bio for the appropriate container_of magic
+ * Initialize the members up to but not including 'bio'. Use after allocating a
+ * new bio by bio_alloc_bioset as it does not initialize the bytes outside of
+ * 'bio' because use of __GFP_ZERO is not supported.
  */
-struct bio *
-btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
-		gfp_t gfp_flags)
+static inline void btrfs_io_bio_init(struct btrfs_io_bio *btrfs_bio)
 {
-	struct btrfs_io_bio *btrfs_bio;
-	struct bio *bio;
-
-	bio = bio_alloc_bioset(gfp_flags, nr_vecs, btrfs_bioset);
+	memset(btrfs_bio, 0, offsetof(struct btrfs_io_bio, bio));
+}
 
-	if (bio == NULL && (current->flags & PF_MEMALLOC)) {
-		while (!bio && (nr_vecs /= 2)) {
-			bio = bio_alloc_bioset(gfp_flags,
-					       nr_vecs, btrfs_bioset);
-		}
-	}
+/*
+ * The following helpers allocate a bio. As it's backed by a bioset, it'll
+ * never fail.  We're returning a bio right now but you can call btrfs_io_bio
+ * for the appropriate container_of magic
+ */
+struct bio *btrfs_bio_alloc(struct block_device *bdev, u64 first_byte)
+{
+	struct bio *bio;
 
-	if (bio) {
-		bio->bi_bdev = bdev;
-		bio->bi_iter.bi_sector = first_sector;
-		btrfs_bio = btrfs_io_bio(bio);
-		btrfs_bio->csum = NULL;
-		btrfs_bio->csum_allocated = NULL;
-		btrfs_bio->end_io = NULL;
-	}
+	bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, btrfs_bioset);
+	bio->bi_bdev = bdev;
+	bio->bi_iter.bi_sector = first_byte >> 9;
+	btrfs_io_bio_init(btrfs_io_bio(bio));
 	return bio;
 }
 
-struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
+struct bio *btrfs_bio_clone(struct bio *bio)
 {
 	struct btrfs_io_bio *btrfs_bio;
 	struct bio *new;
 
-	new = bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
-	if (new) {
-		btrfs_bio = btrfs_io_bio(new);
-		btrfs_bio->csum = NULL;
-		btrfs_bio->csum_allocated = NULL;
-		btrfs_bio->end_io = NULL;
-	}
+	/* Bio allocation backed by a bioset does not fail */
+	new = bio_clone_fast(bio, GFP_NOFS, btrfs_bioset);
+	btrfs_bio = btrfs_io_bio(new);
+	btrfs_io_bio_init(btrfs_bio);
+	btrfs_bio->iter = bio->bi_iter;
 	return new;
 }
 
-/* this also allocates from the btrfs_bioset */
-struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
+struct bio *btrfs_io_bio_alloc(unsigned int nr_iovecs)
 {
-	struct btrfs_io_bio *btrfs_bio;
 	struct bio *bio;
 
-	bio = bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
-	if (bio) {
-		btrfs_bio = btrfs_io_bio(bio);
-		btrfs_bio->csum = NULL;
-		btrfs_bio->csum_allocated = NULL;
-		btrfs_bio->end_io = NULL;
-	}
+	/* Bio allocation backed by a bioset does not fail */
+	bio = bio_alloc_bioset(GFP_NOFS, nr_iovecs, btrfs_bioset);
+	btrfs_io_bio_init(btrfs_io_bio(bio));
 	return bio;
 }
 
+struct bio *btrfs_bio_clone_partial(struct bio *orig, int offset, int size)
+{
+	struct bio *bio;
+	struct btrfs_io_bio *btrfs_bio;
+
+	/* this will never fail when it's backed by a bioset */
+	bio = bio_clone_fast(orig, GFP_NOFS, btrfs_bioset);
+	ASSERT(bio);
+
+	btrfs_bio = btrfs_io_bio(bio);
+	btrfs_io_bio_init(btrfs_bio);
+
+	bio_trim(bio, offset >> 9, size >> 9);
+	btrfs_bio->iter = bio->bi_iter;
+	return bio;
+}
 
 static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 				       unsigned long bio_flags)
 {
-	int ret = 0;
+	blk_status_t ret = 0;
 	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
 	struct page *page = bvec->bv_page;
 	struct extent_io_tree *tree = bio->bi_private;
@@ -2755,13 +2738,13 @@ static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 	bio_get(bio);
 
 	if (tree->ops)
-		ret = tree->ops->submit_bio_hook(page->mapping->host, bio,
+		ret = tree->ops->submit_bio_hook(tree->private_data, bio,
 					   mirror_num, bio_flags, start);
 	else
 		btrfsic_submit_bio(bio);
 
 	bio_put(bio);
-	return ret;
+	return blk_status_to_errno(ret);
 }
 
 static int merge_bio(struct extent_io_tree *tree, struct page *page,
@@ -2818,14 +2801,11 @@ static int submit_extent_page(int op, int op_flags, struct extent_io_tree *tree,
 		}
 	}
 
-	bio = btrfs_bio_alloc(bdev, sector, BIO_MAX_PAGES,
-			GFP_NOFS | __GFP_HIGH);
-	if (!bio)
-		return -ENOMEM;
-
+	bio = btrfs_bio_alloc(bdev, sector << 9);
 	bio_add_page(bio, page, page_size, offset);
 	bio->bi_end_io = end_io_func;
 	bio->bi_private = tree;
+	bio->bi_write_hint = page->mapping->host->i_write_hint;
 	bio_set_op_attrs(bio, op, op_flags);
 	if (wbc) {
 		wbc_init_bio(wbc, bio);
@@ -3597,9 +3577,9 @@ lock_extent_buffer_for_io(struct extent_buffer *eb,
 		set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
 		spin_unlock(&eb->refs_lock);
 		btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
-		__percpu_counter_add(&fs_info->dirty_metadata_bytes,
-				     -eb->len,
-				     fs_info->dirty_metadata_batch);
+		percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
+					 -eb->len,
+					 fs_info->dirty_metadata_batch);
 		ret = 1;
 	} else {
 		spin_unlock(&eb->refs_lock);
@@ -3707,7 +3687,7 @@ static void end_bio_extent_buffer_writepage(struct bio *bio)
 		BUG_ON(!eb);
 		done = atomic_dec_and_test(&eb->io_pages);
 
-		if (bio->bi_error ||
+		if (bio->bi_status ||
 		    test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {
 			ClearPageUptodate(page);
 			set_btree_ioerr(page);
@@ -3757,7 +3737,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
 		 * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0
 		 */
 		start = btrfs_item_nr_offset(nritems);
-		end = btrfs_leaf_data(eb) + leaf_data_end(fs_info, eb);
+		end = BTRFS_LEAF_DATA_OFFSET + leaf_data_end(fs_info, eb);
 		memzero_extent_buffer(eb, start, end - start);
 	}
 
@@ -4377,6 +4357,119 @@ static struct extent_map *get_extent_skip_holes(struct inode *inode,
 	return NULL;
 }
 
+/*
+ * To cache previous fiemap extent
+ *
+ * Will be used for merging fiemap extent
+ */
+struct fiemap_cache {
+	u64 offset;
+	u64 phys;
+	u64 len;
+	u32 flags;
+	bool cached;
+};
+
+/*
+ * Helper to submit fiemap extent.
+ *
+ * Will try to merge current fiemap extent specified by @offset, @phys,
+ * @len and @flags with cached one.
+ * And only when we fails to merge, cached one will be submitted as
+ * fiemap extent.
+ *
+ * Return value is the same as fiemap_fill_next_extent().
+ */
+static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
+				struct fiemap_cache *cache,
+				u64 offset, u64 phys, u64 len, u32 flags)
+{
+	int ret = 0;
+
+	if (!cache->cached)
+		goto assign;
+
+	/*
+	 * Sanity check, extent_fiemap() should have ensured that new
+	 * fiemap extent won't overlap with cahced one.
+	 * Not recoverable.
+	 *
+	 * NOTE: Physical address can overlap, due to compression
+	 */
+	if (cache->offset + cache->len > offset) {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	/*
+	 * Only merges fiemap extents if
+	 * 1) Their logical addresses are continuous
+	 *
+	 * 2) Their physical addresses are continuous
+	 *    So truly compressed (physical size smaller than logical size)
+	 *    extents won't get merged with each other
+	 *
+	 * 3) Share same flags except FIEMAP_EXTENT_LAST
+	 *    So regular extent won't get merged with prealloc extent
+	 */
+	if (cache->offset + cache->len  == offset &&
+	    cache->phys + cache->len == phys  &&
+	    (cache->flags & ~FIEMAP_EXTENT_LAST) ==
+			(flags & ~FIEMAP_EXTENT_LAST)) {
+		cache->len += len;
+		cache->flags |= flags;
+		goto try_submit_last;
+	}
+
+	/* Not mergeable, need to submit cached one */
+	ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
+				      cache->len, cache->flags);
+	cache->cached = false;
+	if (ret)
+		return ret;
+assign:
+	cache->cached = true;
+	cache->offset = offset;
+	cache->phys = phys;
+	cache->len = len;
+	cache->flags = flags;
+try_submit_last:
+	if (cache->flags & FIEMAP_EXTENT_LAST) {
+		ret = fiemap_fill_next_extent(fieinfo, cache->offset,
+				cache->phys, cache->len, cache->flags);
+		cache->cached = false;
+	}
+	return ret;
+}
+
+/*
+ * Emit last fiemap cache
+ *
+ * The last fiemap cache may still be cached in the following case:
+ * 0		      4k		    8k
+ * |<- Fiemap range ->|
+ * |<------------  First extent ----------->|
+ *
+ * In this case, the first extent range will be cached but not emitted.
+ * So we must emit it before ending extent_fiemap().
+ */
+static int emit_last_fiemap_cache(struct btrfs_fs_info *fs_info,
+				  struct fiemap_extent_info *fieinfo,
+				  struct fiemap_cache *cache)
+{
+	int ret;
+
+	if (!cache->cached)
+		return 0;
+
+	ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
+				      cache->len, cache->flags);
+	cache->cached = false;
+	if (ret > 0)
+		ret = 0;
+	return ret;
+}
+
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		__u64 start, __u64 len, get_extent_t *get_extent)
 {
@@ -4394,6 +4487,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	struct extent_state *cached_state = NULL;
 	struct btrfs_path *path;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct fiemap_cache cache = { 0 };
 	int end = 0;
 	u64 em_start = 0;
 	u64 em_len = 0;
@@ -4573,8 +4667,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			flags |= FIEMAP_EXTENT_LAST;
 			end = 1;
 		}
-		ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
-					      em_len, flags);
+		ret = emit_fiemap_extent(fieinfo, &cache, em_start, disko,
+					   em_len, flags);
 		if (ret) {
 			if (ret == 1)
 				ret = 0;
@@ -4582,6 +4676,8 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		}
 	}
 out_free:
+	if (!ret)
+		ret = emit_last_fiemap_cache(root->fs_info, fieinfo, &cache);
 	free_extent_map(em);
 out:
 	btrfs_free_path(path);