1 files changed, 146 insertions, 127 deletions

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 4f9b9fb59362..64f61330564a 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -13,6 +13,7 @@
  * datablocks and metadata blocks.
  */
 
+#include <linux/blkdev.h>
 #include <linux/fs.h>
 #include <linux/vfs.h>
 #include <linux/slab.h>
@@ -27,44 +28,103 @@
 #include "page_actor.h"
 
 /*
- * Read the metadata block length, this is stored in the first two
- * bytes of the metadata block.
+ * Returns the amount of bytes copied to the page actor.
  */
-static struct buffer_head *get_block_length(struct super_block *sb,
-			u64 *cur_index, int *offset, int *length)
+static int copy_bio_to_actor(struct bio *bio,
+			     struct squashfs_page_actor *actor,
+			     int offset, int req_length)
+{
+	void *actor_addr = squashfs_first_page(actor);
+	struct bvec_iter_all iter_all = {};
+	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
+	int copied_bytes = 0;
+	int actor_offset = 0;
+
+	if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all)))
+		return 0;
+
+	while (copied_bytes < req_length) {
+		int bytes_to_copy = min_t(int, bvec->bv_len - offset,
+					  PAGE_SIZE - actor_offset);
+
+		bytes_to_copy = min_t(int, bytes_to_copy,
+				      req_length - copied_bytes);
+		memcpy(actor_addr + actor_offset,
+		       page_address(bvec->bv_page) + bvec->bv_offset + offset,
+		       bytes_to_copy);
+
+		actor_offset += bytes_to_copy;
+		copied_bytes += bytes_to_copy;
+		offset += bytes_to_copy;
+
+		if (actor_offset >= PAGE_SIZE) {
+			actor_addr = squashfs_next_page(actor);
+			if (!actor_addr)
+				break;
+			actor_offset = 0;
+		}
+		if (offset >= bvec->bv_len) {
+			if (!bio_next_segment(bio, &iter_all))
+				break;
+			offset = 0;
+		}
+	}
+	squashfs_finish_page(actor);
+	return copied_bytes;
+}
+
+static int squashfs_bio_read(struct super_block *sb, u64 index, int length,
+			     struct bio **biop, int *block_offset)
 {
 	struct squashfs_sb_info *msblk = sb->s_fs_info;
-	struct buffer_head *bh;
-
-	bh = sb_bread(sb, *cur_index);
-	if (bh == NULL)
-		return NULL;
-
-	if (msblk->devblksize - *offset == 1) {
-		*length = (unsigned char) bh->b_data[*offset];
-		put_bh(bh);
-		bh = sb_bread(sb, ++(*cur_index));
-		if (bh == NULL)
-			return NULL;
-		*length |= (unsigned char) bh->b_data[0] << 8;
-		*offset = 1;
-	} else {
-		*length = (unsigned char) bh->b_data[*offset] |
-			(unsigned char) bh->b_data[*offset + 1] << 8;
-		*offset += 2;
-
-		if (*offset == msblk->devblksize) {
-			put_bh(bh);
-			bh = sb_bread(sb, ++(*cur_index));
-			if (bh == NULL)
-				return NULL;
-			*offset = 0;
+	const u64 read_start = round_down(index, msblk->devblksize);
+	const sector_t block = read_start >> msblk->devblksize_log2;
+	const u64 read_end = round_up(index + length, msblk->devblksize);
+	const sector_t block_end = read_end >> msblk->devblksize_log2;
+	int offset = read_start - round_down(index, PAGE_SIZE);
+	int total_len = (block_end - block) << msblk->devblksize_log2;
+	const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE);
+	int error, i;
+	struct bio *bio;
+
+	bio = bio_alloc(GFP_NOIO, page_count);
+	if (!bio)
+		return -ENOMEM;
+
+	bio_set_dev(bio, sb->s_bdev);
+	bio->bi_opf = READ;
+	bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT);
+
+	for (i = 0; i < page_count; ++i) {
+		unsigned int len =
+			min_t(unsigned int, PAGE_SIZE - offset, total_len);
+		struct page *page = alloc_page(GFP_NOIO);
+
+		if (!page) {
+			error = -ENOMEM;
+			goto out_free_bio;
+		}
+		if (!bio_add_page(bio, page, len, offset)) {
+			error = -EIO;
+			goto out_free_bio;
 		}
+		offset = 0;
+		total_len -= len;
 	}
 
-	return bh;
-}
+	error = submit_bio_wait(bio);
+	if (error)
+		goto out_free_bio;
 
+	*biop = bio;
+	*block_offset = index & ((1 << msblk->devblksize_log2) - 1);
+	return 0;
+
+out_free_bio:
+	bio_free_pages(bio);
+	bio_put(bio);
+	return error;
+}
 
 /*
  * Read and decompress a metadata block or datablock.  Length is non-zero
@@ -76,129 +136,88 @@ static struct buffer_head *get_block_length(struct super_block *sb,
  * algorithms).
  */
 int squashfs_read_data(struct super_block *sb, u64 index, int length,
-		u64 *next_index, struct squashfs_page_actor *output)
+		       u64 *next_index, struct squashfs_page_actor *output)
 {
 	struct squashfs_sb_info *msblk = sb->s_fs_info;
-	struct buffer_head **bh;
-	int offset = index & ((1 << msblk->devblksize_log2) - 1);
-	u64 cur_index = index >> msblk->devblksize_log2;
-	int bytes, compressed, b = 0, k = 0, avail, i;
-
-	bh = kcalloc(((output->length + msblk->devblksize - 1)
-		>> msblk->devblksize_log2) + 1, sizeof(*bh), GFP_KERNEL);
-	if (bh == NULL)
-		return -ENOMEM;
+	struct bio *bio = NULL;
+	int compressed;
+	int res;
+	int offset;
 
 	if (length) {
 		/*
 		 * Datablock.
 		 */
-		bytes = -offset;
 		compressed = SQUASHFS_COMPRESSED_BLOCK(length);
 		length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length);
-		if (next_index)
-			*next_index = index + length;
-
 		TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
 			index, compressed ? "" : "un", length, output->length);
-
-		if (length < 0 || length > output->length ||
-				(index + length) > msblk->bytes_used)
-			goto read_failure;
-
-		for (b = 0; bytes < length; b++, cur_index++) {
-			bh[b] = sb_getblk(sb, cur_index);
-			if (bh[b] == NULL)
-				goto block_release;
-			bytes += msblk->devblksize;
-		}
-		ll_rw_block(REQ_OP_READ, 0, b, bh);
 	} else {
 		/*
 		 * Metadata block.
 		 */
-		if ((index + 2) > msblk->bytes_used)
-			goto read_failure;
+		const u8 *data;
+		struct bvec_iter_all iter_all = {};
+		struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
 
-		bh[0] = get_block_length(sb, &cur_index, &offset, &length);
-		if (bh[0] == NULL)
-			goto read_failure;
-		b = 1;
+		if (index + 2 > msblk->bytes_used) {
+			res = -EIO;
+			goto out;
+		}
+		res = squashfs_bio_read(sb, index, 2, &bio, &offset);
+		if (res)
+			goto out;
+
+		if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
+			res = -EIO;
+			goto out_free_bio;
+		}
+		/* Extract the length of the metadata block */
+		data = page_address(bvec->bv_page) + bvec->bv_offset;
+		length = data[offset];
+		if (offset <= bvec->bv_len - 1) {
+			length |= data[offset + 1] << 8;
+		} else {
+			if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
+				res = -EIO;
+				goto out_free_bio;
+			}
+			data = page_address(bvec->bv_page) + bvec->bv_offset;
+			length |= data[0] << 8;
+		}
+		bio_free_pages(bio);
+		bio_put(bio);
 
-		bytes = msblk->devblksize - offset;
 		compressed = SQUASHFS_COMPRESSED(length);
 		length = SQUASHFS_COMPRESSED_SIZE(length);
-		if (next_index)
-			*next_index = index + length + 2;
+		index += 2;
 
 		TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
-				compressed ? "" : "un", length);
-
-		if (length < 0 || length > output->length ||
-					(index + length) > msblk->bytes_used)
-			goto block_release;
-
-		for (; bytes < length; b++) {
-			bh[b] = sb_getblk(sb, ++cur_index);
-			if (bh[b] == NULL)
-				goto block_release;
-			bytes += msblk->devblksize;
-		}
-		ll_rw_block(REQ_OP_READ, 0, b - 1, bh + 1);
+		      compressed ? "" : "un", length);
 	}
+	if (next_index)
+		*next_index = index + length;
 
-	for (i = 0; i < b; i++) {
-		wait_on_buffer(bh[i]);
-		if (!buffer_uptodate(bh[i]))
-			goto block_release;
-	}
+	res = squashfs_bio_read(sb, index, length, &bio, &offset);
+	if (res)
+		goto out;
 
 	if (compressed) {
-		if (!msblk->stream)
-			goto read_failure;
-		length = squashfs_decompress(msblk, bh, b, offset, length,
-			output);
-		if (length < 0)
-			goto read_failure;
-	} else {
-		/*
-		 * Block is uncompressed.
-		 */
-		int in, pg_offset = 0;
-		void *data = squashfs_first_page(output);
-
-		for (bytes = length; k < b; k++) {
-			in = min(bytes, msblk->devblksize - offset);
-			bytes -= in;
-			while (in) {
-				if (pg_offset == PAGE_SIZE) {
-					data = squashfs_next_page(output);
-					pg_offset = 0;
-				}
-				avail = min_t(int, in, PAGE_SIZE -
-						pg_offset);
-				memcpy(data + pg_offset, bh[k]->b_data + offset,
-						avail);
-				in -= avail;
-				pg_offset += avail;
-				offset += avail;
-			}
-			offset = 0;
-			put_bh(bh[k]);
+		if (!msblk->stream) {
+			res = -EIO;
+			goto out_free_bio;
 		}
-		squashfs_finish_page(output);
+		res = squashfs_decompress(msblk, bio, offset, length, output);
+	} else {
+		res = copy_bio_to_actor(bio, output, offset, length);
 	}
 
-	kfree(bh);
-	return length;
-
-block_release:
-	for (; k < b; k++)
-		put_bh(bh[k]);
+out_free_bio:
+	bio_free_pages(bio);
+	bio_put(bio);
+out:
+	if (res < 0)
+		ERROR("Failed to read block 0x%llx: %d\n", index, res);
 
-read_failure:
-	ERROR("squashfs_read_data failed to read block 0x%llx\n",
-					(unsigned long long) index);
-	kfree(bh);
-	return -EIO;
+	return res;
 }