btrfs: merge write_one_subpage_eb into write_one_eb

Most of the code in write_one_subpage_eb and write_one_eb is shared,
so merge the two functions into one.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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 650cb68..b38fbdd 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1808,54 +1808,11 @@ static void prepare_eb_write(struct extent_buffer *eb)
        }
 }
 
-/*
- * Unlike the work in write_one_eb(), we rely completely on extent locking.
- * Page locking is only utilized at minimum to keep the VMM code happy.
- */
-static void write_one_subpage_eb(struct extent_buffer *eb,
-                                struct writeback_control *wbc)
-{
-       struct btrfs_fs_info *fs_info = eb->fs_info;
-       struct page *page = eb->pages[0];
-       bool no_dirty_ebs = false;
-       struct btrfs_bio *bbio;
-
-       prepare_eb_write(eb);
-
-       /* clear_page_dirty_for_io() in subpage helper needs page locked */
-       lock_page(page);
-       btrfs_subpage_set_writeback(fs_info, page, eb->start, eb->len);
-
-       /* Check if this is the last dirty bit to update nr_written */
-       no_dirty_ebs = btrfs_subpage_clear_and_test_dirty(fs_info, page,
-                                                         eb->start, eb->len);
-       if (no_dirty_ebs)
-               clear_page_dirty_for_io(page);
-
-       bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
-                              REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),
-                              eb->fs_info, extent_buffer_write_end_io, eb);
-       bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
-       bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
-       bbio->file_offset = eb->start;
-       __bio_add_page(&bbio->bio, page, eb->len, eb->start - page_offset(page));
-       wbc_account_cgroup_owner(wbc, page, eb->len);
-       unlock_page(page);
-       btrfs_submit_bio(bbio, 0);
-
-       /*
-        * Submission finished without problem, if no range of the page is
-        * dirty anymore, we have submitted a page.  Update nr_written in wbc.
-        */
-       if (no_dirty_ebs)
-               wbc->nr_to_write--;
-}
-
 static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
                                            struct writeback_control *wbc)
 {
+       struct btrfs_fs_info *fs_info = eb->fs_info;
        struct btrfs_bio *bbio;
-       int i, num_pages;
 
        prepare_eb_write(eb);
 
@@ -1863,22 +1820,35 @@ static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
                               REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),
                               eb->fs_info, extent_buffer_write_end_io, eb);
        bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
-       bio_set_dev(&bbio->bio, eb->fs_info->fs_devices->latest_dev->bdev);
+       bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev);
        wbc_init_bio(wbc, &bbio->bio);
        bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
        bbio->file_offset = eb->start;
-
-       num_pages = num_extent_pages(eb);
-       for (i = 0; i < num_pages; i++) {
-               struct page *p = eb->pages[i];
+       if (fs_info->nodesize < PAGE_SIZE) {
+               struct page *p = eb->pages[0];
 
                lock_page(p);
-               clear_page_dirty_for_io(p);
-               set_page_writeback(p);
-               __bio_add_page(&bbio->bio, p, PAGE_SIZE, 0);
-               wbc_account_cgroup_owner(wbc, p, PAGE_SIZE);
-               wbc->nr_to_write--;
+               btrfs_subpage_set_writeback(fs_info, p, eb->start, eb->len);
+               if (btrfs_subpage_clear_and_test_dirty(fs_info, p, eb->start,
+                                                      eb->len)) {
+                       clear_page_dirty_for_io(p);
+                       wbc->nr_to_write--;
+               }
+               __bio_add_page(&bbio->bio, p, eb->len, eb->start - page_offset(p));
+               wbc_account_cgroup_owner(wbc, p, eb->len);
                unlock_page(p);
+       } else {
+               for (int i = 0; i < num_extent_pages(eb); i++) {
+                       struct page *p = eb->pages[i];
+
+                       lock_page(p);
+                       clear_page_dirty_for_io(p);
+                       set_page_writeback(p);
+                       __bio_add_page(&bbio->bio, p, PAGE_SIZE, 0);
+                       wbc_account_cgroup_owner(wbc, p, PAGE_SIZE);
+                       wbc->nr_to_write--;
+                       unlock_page(p);
+               }
        }
        btrfs_submit_bio(bbio, 0);
 }
@@ -1950,7 +1920,7 @@ static int submit_eb_subpage(struct page *page, struct writeback_control *wbc)
                        continue;
 
                if (lock_extent_buffer_for_io(eb, wbc)) {
-                       write_one_subpage_eb(eb, wbc);
+                       write_one_eb(eb, wbc);
                        submitted++;
                }
                free_extent_buffer(eb);