btrfs: factor out allocating an array of pages

Several functions currently populate an array of page pointers one
allocated page at a time. Factor out the common code so as to allow
improvements to all of the sites at once.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 15 insertions, 21 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 19bf36d8ffea..d6b6b6cfaa6a 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -809,8 +809,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	struct extent_map_tree *em_tree;
 	struct compressed_bio *cb;
 	unsigned int compressed_len;
-	unsigned int nr_pages;
-	unsigned int pg_index;
 	struct bio *comp_bio = NULL;
 	const u64 disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
 	u64 cur_disk_byte = disk_bytenr;
@@ -820,7 +818,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	u64 em_start;
 	struct extent_map *em;
 	blk_status_t ret;
-	int faili = 0;
+	int ret2;
+	int i;
 	u8 *sums;
 
 	em_tree = &BTRFS_I(inode)->extent_tree;
@@ -863,24 +862,18 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	cb->compress_type = extent_compress_type(bio_flags);
 	cb->orig_bio = bio;
 
-	nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
-	cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
-				       GFP_NOFS);
+	cb->nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
+	cb->compressed_pages = kcalloc(cb->nr_pages, sizeof(struct page *), GFP_NOFS);
 	if (!cb->compressed_pages) {
 		ret = BLK_STS_RESOURCE;
-		goto fail1;
+		goto fail;
 	}
 
-	for (pg_index = 0; pg_index < nr_pages; pg_index++) {
-		cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS);
-		if (!cb->compressed_pages[pg_index]) {
-			faili = pg_index - 1;
-			ret = BLK_STS_RESOURCE;
-			goto fail2;
-		}
+	ret2 = btrfs_alloc_page_array(cb->nr_pages, cb->compressed_pages);
+	if (ret2) {
+		ret = BLK_STS_RESOURCE;
+		goto fail;
 	}
-	faili = nr_pages - 1;
-	cb->nr_pages = nr_pages;
 
 	add_ra_bio_pages(inode, em_start + em_len, cb);
 
@@ -957,14 +950,15 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	}
 	return BLK_STS_OK;
 
-fail2:
-	while (faili >= 0) {
-		__free_page(cb->compressed_pages[faili]);
-		faili--;
+fail:
+	if (cb->compressed_pages) {
+		for (i = 0; i < cb->nr_pages; i++) {
+			if (cb->compressed_pages[i])
+				__free_page(cb->compressed_pages[i]);
+		}
 	}
 
 	kfree(cb->compressed_pages);
-fail1:
 	kfree(cb);
 out:
 	free_extent_map(em);