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: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index c547036..9adaa79 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -296,7 +296,7 @@
/* 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 @@
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;
}