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Commit cfbc246e authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: walk compressed pages based on the nr_pages count instead of bytes 



The byte walk counting was awkward and error prone.  This uses the
number of pages sent the higher layer to build bios.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 87ef2bb4

fs/btrfs/compression.c

+5 −2
Original line number Diff line number Diff line
@@ -296,7 +296,7 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, 


	/* create and submit bios for the compressed pages */

	bytes_left = compressed_len;

	while(bytes_left > 0) {

	for (page_index = 0; page_index < cb->nr_pages; page_index++) {

		page = compressed_pages[page_index];

		page->mapping = inode->i_mapping;

		if (bio->bi_size)
@@ -324,7 +324,10 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, 
			bio->bi_end_io = end_compressed_bio_write;

			bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);

		}

		page_index++;

		if (bytes_left < PAGE_CACHE_SIZE) {

			printk("bytes left %lu compress len %lu nr %lu\n",

			       bytes_left, cb->compressed_len, cb->nr_pages);

		}

		bytes_left -= PAGE_CACHE_SIZE;

		first_byte += PAGE_CACHE_SIZE;

	}

fs/btrfs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -338,7 +338,7 @@ static int cow_file_range(struct inode *inode, struct page *locked_page, 
	if (!btrfs_test_flag(inode, NOCOMPRESS) &&

	    btrfs_test_opt(root, COMPRESS)) {

		WARN_ON(pages);

		pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);

		pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);



		/* we want to make sure the amount of IO required to satisfy

		 * a random read is reasonably small, so we limit the size