Add support for calls to ext4_writepages() than cannot map blocks. These
will be issued from jbd2 transaction commit code.
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/inode.c | 62 ++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 48 insertions(+), 14 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 43eb175d0c1c..9ba843b7a92c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1557,6 +1557,7 @@ struct mpage_da_data {
struct ext4_map_blocks map;
struct ext4_io_submit io_submit; /* IO submission data */
unsigned int do_map:1;
+ unsigned int can_map:1; /* Can writepages call map blocks? */
unsigned int scanned_until_end:1;
};
@@ -2549,18 +2550,33 @@ static int ext4_da_writepages_trans_blocks(struct inode *inode)
MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
}
+/* Return true if the page needs to be written as part of transaction commit */
+static bool ext4_page_nomap_can_writeout(struct page *page)
+{
+ struct buffer_head *bh, *head;
+
+ bh = head = page_buffers(page);
+ do {
+ if (buffer_dirty(bh) && buffer_mapped(bh) && !buffer_delay(bh))
+ return true;
+ } while ((bh = bh->b_this_page) != head);
+ return false;
+}
+
/*
* mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
- * and underlying extent to map
+ * needing mapping, submit mapped pages
*
* @mpd - where to look for pages
*
* Walk dirty pages in the mapping. If they are fully mapped, submit them for
- * IO immediately. When we find a page which isn't mapped we start accumulating
- * extent of buffers underlying these pages that needs mapping (formed by
- * either delayed or unwritten buffers). We also lock the pages containing
- * these buffers. The extent found is returned in @mpd structure (starting at
- * mpd->lblk with length mpd->len blocks).
+ * IO immediately. If we cannot map blocks, we submit just already mapped
+ * buffers in the page for IO and keep page dirty. When we can map blocks and
+ * we find a page which isn't mapped we start accumulating extent of buffers
+ * underlying these pages that needs mapping (formed by either delayed or
+ * unwritten buffers). We also lock the pages containing these buffers. The
+ * extent found is returned in @mpd structure (starting at mpd->lblk with
+ * length mpd->len blocks).
*
* Note that this function can attach bios to one io_end structure which are
* neither logically nor physically contiguous. Although it may seem as an
@@ -2651,14 +2667,30 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
if (mpd->map.m_len == 0)
mpd->first_page = page->index;
mpd->next_page = page->index + 1;
- /* Add all dirty buffers to mpd */
- lblk = ((ext4_lblk_t)page->index) <<
- (PAGE_SHIFT - blkbits);
- head = page_buffers(page);
- err = mpage_process_page_bufs(mpd, head, head, lblk);
- if (err <= 0)
- goto out;
- err = 0;
+ /*
+ * Writeout for transaction commit where we cannot
+ * modify metadata is simple. Just submit the page.
+ */
+ if (!mpd->can_map) {
+ if (ext4_page_nomap_can_writeout(page)) {
+ err = mpage_submit_page(mpd, page);
+ if (err < 0)
+ goto out;
+ } else {
+ unlock_page(page);
+ mpd->first_page++;
+ }
+ } else {
+ /* Add all dirty buffers to mpd */
+ lblk = ((ext4_lblk_t)page->index) <<
+ (PAGE_SHIFT - blkbits);
+ head = page_buffers(page);
+ err = mpage_process_page_bufs(mpd, head, head,
+ lblk);
+ if (err <= 0)
+ goto out;
+ err = 0;
+ }
left--;
}
pagevec_release(&pvec);
@@ -2778,6 +2810,7 @@ static int ext4_writepages(struct address_space *mapping,
*/
mpd.do_map = 0;
mpd.scanned_until_end = 0;
+ mpd.can_map = 1;
mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
if (!mpd.io_submit.io_end) {
ret = -ENOMEM;
@@ -2801,6 +2834,7 @@ static int ext4_writepages(struct address_space *mapping,
break;
}
+ WARN_ON_ONCE(!mpd->can_map);
/*
* We have two constraints: We find one extent to map and we
* must always write out whole page (makes a difference when
--
2.35.3
