btrfs: cleanup main loop in btrfs_encoded_read_regular_fill_pages

btrfs_encoded_read_regular_fill_pages has a pretty odd control flow.
Unwind it so that there is a single loop over the pages array.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c7bb166..25b675c 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9928,39 +9928,34 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
                .pending = ATOMIC_INIT(1),
        };
        unsigned long i = 0;
-       u64 cur = 0;
+       struct bio *bio;
 
        init_waitqueue_head(&priv.wait);
-       /* Submit bios for the extent, splitting due to bio limits as necessary. */
-       while (cur < disk_io_size) {
-               struct bio *bio = NULL;
-               u64 remaining = disk_io_size - cur;
-
-               while (bio || remaining) {
-                       size_t bytes = min_t(u64, remaining, PAGE_SIZE);
-
-                       if (!bio) {
-                               bio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ,
-                                                     inode,
-                                                     btrfs_encoded_read_endio,
-                                                     &priv);
-                               bio->bi_iter.bi_sector =
-                                       (disk_bytenr + cur) >> SECTOR_SHIFT;
-                       }
 
-                       if (!bytes ||
-                           bio_add_page(bio, pages[i], bytes, 0) < bytes) {
-                               atomic_inc(&priv.pending);
-                               btrfs_submit_bio(bio, 0);
-                               bio = NULL;
-                               continue;
-                       }
+       bio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode,
+                             btrfs_encoded_read_endio, &priv);
+       bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
 
-                       i++;
-                       cur += bytes;
-                       remaining -= bytes;
+       do {
+               size_t bytes = min_t(u64, disk_io_size, PAGE_SIZE);
+
+               if (bio_add_page(bio, pages[i], bytes, 0) < bytes) {
+                       atomic_inc(&priv.pending);
+                       btrfs_submit_bio(bio, 0);
+
+                       bio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode,
+                                             btrfs_encoded_read_endio, &priv);
+                       bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+                       continue;
                }
-       }
+
+               i++;
+               disk_bytenr += bytes;
+               disk_io_size -= bytes;
+       } while (disk_io_size);
+
+       atomic_inc(&priv.pending);
+       btrfs_submit_bio(bio, 0);
 
        if (atomic_dec_return(&priv.pending))
                io_wait_event(priv.wait, !atomic_read(&priv.pending));