ext4: Move page unlocking out of mpage_submit_page()

Move page unlocking during page writeback out of mpage_submit_page()
into the callers. This will allow writeback in data=journal mode to keep
the page locked for a bit longer. Since page unlocking it tightly
connected to increment of mpd->first_page (as that determines cleanup of
locked but unwritten pages), move page unlocking as well as
mpd->first_page handling into a helper function.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230228051319.4085470-6-tytso@mit.edu

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index fcaa2a7a27a5fe41ec9af4358b60f0005ba5f1dc..85951da08d6021df0131999d548f99233998b9bf 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2083,6 +2083,12 @@ static int ext4_writepage(struct page *page,
        return ret;
 }
 
+static void mpage_page_done(struct mpage_da_data *mpd, struct page *page)
+{
+       mpd->first_page++;
+       unlock_page(page);
+}
+
 static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
 {
        int len;
@@ -2111,10 +2117,8 @@ static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
        else
                len = PAGE_SIZE;
        err = ext4_bio_write_page(&mpd->io_submit, page, len);
-       unlock_page(page);
        if (!err)
                mpd->wbc->nr_to_write--;
-       mpd->first_page++;
 
        return err;
 }
@@ -2226,6 +2230,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
        /* So far everything mapped? Submit the page for IO. */
        if (mpd->map.m_len == 0) {
                err = mpage_submit_page(mpd, head->b_page);
+               mpage_page_done(mpd, head->b_page);
                if (err < 0)
                        return err;
        }
@@ -2357,6 +2362,7 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
                                goto out;
                        /* Page fully mapped - let IO run! */
                        err = mpage_submit_page(mpd, page);
+                       mpage_page_done(mpd, page);
                        if (err < 0)
                                goto out;
                }
@@ -2666,14 +2672,11 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
                         * modify metadata is simple. Just submit the page.
                         */
                        if (!mpd->can_map) {
-                               if (ext4_page_nomap_can_writeout(&folio->page)) {
+                               if (ext4_page_nomap_can_writeout(&folio->page))
                                        err = mpage_submit_page(mpd, &folio->page);
-                                       if (err < 0)
-                                               goto out;
-                               } else {
-                                       folio_unlock(folio);
-                                       mpd->first_page += folio_nr_pages(folio);
-                               }
+                               mpage_page_done(mpd, &folio->page);
+                               if (err < 0)
+                                       goto out;
                        } else {
                                /* Add all dirty buffers to mpd */
                                lblk = ((ext4_lblk_t)folio->index) <<