btrfs: don't use btrfs_bio_ctrl for extent buffer reading

The btrfs_bio_ctrl machinery is overkill for reading extent_buffers
as we always operate on PAGE_SIZE chunks (or one smaller one for the
subpage case) that are contiguous and are guaranteed to fit into a
single bio.  Replace it with open coded btrfs_bio_alloc, __bio_add_page
and btrfs_submit_bio calls in a helper function shared between
the subpage and node size >= PAGE_SIZE cases.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ede7c88..681e677 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -98,7 +98,6 @@ void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info)
  */
 struct btrfs_bio_ctrl {
        struct btrfs_bio *bbio;
-       int mirror_num;
        enum btrfs_compression_type compress_type;
        u32 len_to_oe_boundary;
        blk_opf_t opf;
@@ -106,15 +105,6 @@ struct btrfs_bio_ctrl {
        struct writeback_control *wbc;
 
        /*
-        * This is for metadata read, to provide the extra needed verification
-        * info.  This has to be provided for submit_one_bio(), as
-        * submit_one_bio() can submit a bio if it ends at stripe boundary.  If
-        * no such parent_check is provided, the metadata can hit false alert at
-        * endio time.
-        */
-       struct btrfs_tree_parent_check *parent_check;
-
-       /*
         * Tell writepage not to lock the state bits for this range, it still
         * does the unlocking.
         */
@@ -124,7 +114,6 @@ struct btrfs_bio_ctrl {
 static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
 {
        struct btrfs_bio *bbio = bio_ctrl->bbio;
-       int mirror_num = bio_ctrl->mirror_num;
 
        if (!bbio)
                return;
@@ -132,25 +121,14 @@ static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
        /* Caller should ensure the bio has at least some range added */
        ASSERT(bbio->bio.bi_iter.bi_size);
 
-       if (!is_data_inode(&bbio->inode->vfs_inode)) {
-               if (btrfs_op(&bbio->bio) != BTRFS_MAP_WRITE) {
-                       /*
-                        * For metadata read, we should have the parent_check,
-                        * and copy it to bbio for metadata verification.
-                        */
-                       ASSERT(bio_ctrl->parent_check);
-                       memcpy(&bbio->parent_check,
-                              bio_ctrl->parent_check,
-                              sizeof(struct btrfs_tree_parent_check));
-               }
+       if (!is_data_inode(&bbio->inode->vfs_inode))
                bbio->bio.bi_opf |= REQ_META;
-       }
 
        if (btrfs_op(&bbio->bio) == BTRFS_MAP_READ &&
            bio_ctrl->compress_type != BTRFS_COMPRESS_NONE)
-               btrfs_submit_compressed_read(bbio, mirror_num);
+               btrfs_submit_compressed_read(bbio, 0);
        else
-               btrfs_submit_bio(bbio, mirror_num);
+               btrfs_submit_bio(bbio, 0);
 
        /* The bbio is owned by the end_io handler now */
        bio_ctrl->bbio = NULL;
@@ -4243,6 +4221,36 @@ void set_extent_buffer_uptodate(struct extent_buffer *eb)
        }
 }
 
+static void __read_extent_buffer_pages(struct extent_buffer *eb, int mirror_num,
+                                      struct btrfs_tree_parent_check *check)
+{
+       int num_pages = num_extent_pages(eb), i;
+       struct btrfs_bio *bbio;
+
+       clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
+       eb->read_mirror = 0;
+       atomic_set(&eb->io_pages, num_pages);
+       check_buffer_tree_ref(eb);
+
+       bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
+                              REQ_OP_READ | REQ_META, eb->fs_info,
+                              end_bio_extent_readpage, NULL);
+       bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
+       bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
+       bbio->file_offset = eb->start;
+       memcpy(&bbio->parent_check, check, sizeof(*check));
+       if (eb->fs_info->nodesize < PAGE_SIZE) {
+               __bio_add_page(&bbio->bio, eb->pages[0], eb->len,
+                              eb->start - page_offset(eb->pages[0]));
+       } else {
+               for (i = 0; i < num_pages; i++) {
+                       ClearPageError(eb->pages[i]);
+                       __bio_add_page(&bbio->bio, eb->pages[i], PAGE_SIZE, 0);
+               }
+       }
+       btrfs_submit_bio(bbio, mirror_num);
+}
+
 static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
                                      int mirror_num,
                                      struct btrfs_tree_parent_check *check)
@@ -4251,11 +4259,6 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
        struct extent_io_tree *io_tree;
        struct page *page = eb->pages[0];
        struct extent_state *cached_state = NULL;
-       struct btrfs_bio_ctrl bio_ctrl = {
-               .opf = REQ_OP_READ,
-               .mirror_num = mirror_num,
-               .parent_check = check,
-       };
        int ret;
 
        ASSERT(!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags));
@@ -4283,18 +4286,10 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
                return 0;
        }
 
-       clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
-       eb->read_mirror = 0;
-       atomic_set(&eb->io_pages, 1);
-       check_buffer_tree_ref(eb);
-       bio_ctrl.end_io_func = end_bio_extent_readpage;
-
        btrfs_subpage_clear_error(fs_info, page, eb->start, eb->len);
-
        btrfs_subpage_start_reader(fs_info, page, eb->start, eb->len);
-       submit_extent_page(&bio_ctrl, eb->start, page, eb->len,
-                          eb->start - page_offset(page));
-       submit_one_bio(&bio_ctrl);
+
+       __read_extent_buffer_pages(eb, mirror_num, check);
        if (wait != WAIT_COMPLETE) {
                free_extent_state(cached_state);
                return 0;
@@ -4315,11 +4310,6 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
        int locked_pages = 0;
        int all_uptodate = 1;
        int num_pages;
-       struct btrfs_bio_ctrl bio_ctrl = {
-               .opf = REQ_OP_READ,
-               .mirror_num = mirror_num,
-               .parent_check = check,
-       };
 
        if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
                return 0;
@@ -4369,24 +4359,7 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
                goto unlock_exit;
        }
 
-       clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
-       eb->read_mirror = 0;
-       atomic_set(&eb->io_pages, num_pages);
-       /*
-        * It is possible for release_folio to clear the TREE_REF bit before we
-        * set io_pages. See check_buffer_tree_ref for a more detailed comment.
-        */
-       check_buffer_tree_ref(eb);
-       bio_ctrl.end_io_func = end_bio_extent_readpage;
-       for (i = 0; i < num_pages; i++) {
-               page = eb->pages[i];
-
-               ClearPageError(page);
-               submit_extent_page(&bio_ctrl, page_offset(page), page,
-                                  PAGE_SIZE, 0);
-       }
-
-       submit_one_bio(&bio_ctrl);
+       __read_extent_buffer_pages(eb, mirror_num, check);
 
        if (wait != WAIT_COMPLETE)
                return 0;