btrfs: zlib: use folio_iter to handle zlib_decompress_bio()

Currently zlib_decompress_bio() is using
compressed_bio->compressed_folios[] array to grab each compressed folio.

However cb->compressed_folios[] is just a pointer to each folio of the
compressed bio, meaning we can just replace the compressed_folios[]
array by just grabbing the folio inside the compressed bio.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 10ed48d4a846651e6825632a877e1304d62bb9a7..a004aa4ee9e26b91cbfcbd285173585c9a1c7c42 100644 (file)
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -338,18 +338,23 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 {
        struct btrfs_fs_info *fs_info = cb_to_fs_info(cb);
        struct workspace *workspace = list_entry(ws, struct workspace, list);
+       struct folio_iter fi;
        const u32 min_folio_size = btrfs_min_folio_size(fs_info);
        int ret = 0, ret2;
        int wbits = MAX_WBITS;
        char *data_in;
        size_t total_out = 0;
-       unsigned long folio_in_index = 0;
        size_t srclen = cb->compressed_len;
-       unsigned long total_folios_in = DIV_ROUND_UP(srclen, min_folio_size);
        unsigned long buf_start;
-       struct folio **folios_in = cb->compressed_folios;
 
-       data_in = kmap_local_folio(folios_in[folio_in_index], 0);
+       bio_first_folio(&fi, &cb->bbio.bio, 0);
+
+       /* We must have at least one folio here, that has the correct size. */
+       if (unlikely(!fi.folio))
+               return -EINVAL;
+       ASSERT(folio_size(fi.folio) == min_folio_size);
+
+       data_in = kmap_local_folio(fi.folio, 0);
        workspace->strm.next_in = data_in;
        workspace->strm.avail_in = min_t(size_t, srclen, min_folio_size);
        workspace->strm.total_in = 0;
@@ -404,12 +409,13 @@ int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
                if (workspace->strm.avail_in == 0) {
                        unsigned long tmp;
                        kunmap_local(data_in);
-                       folio_in_index++;
-                       if (folio_in_index >= total_folios_in) {
+                       bio_next_folio(&fi, &cb->bbio.bio);
+                       if (!fi.folio) {
                                data_in = NULL;
                                break;
                        }
-                       data_in = kmap_local_folio(folios_in[folio_in_index], 0);
+                       ASSERT(folio_size(fi.folio) == min_folio_size);
+                       data_in = kmap_local_folio(fi.folio, 0);
                        workspace->strm.next_in = data_in;
                        tmp = srclen - workspace->strm.total_in;
                        workspace->strm.avail_in = min(tmp, min_folio_size);