Hi,
With delalloc we should not do writepage in ext4_page_mkwrite. The idea
with delalloc is to delay the block allocation and make sure we allocate
chunks of blocks together at writepages. So i guess we should update
ext4_page_mkwrite to use write_begin and write_end instead of writepage.
Taking i_alloc_sem should protect against parallel truncate and the page
lock should protect against parallel write_begin/write_end.
How about the patch below ?
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index cac132b..7f162cc 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3543,18 +3543,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
return err;
}
-static int ext4_bh_prepare_fill(handle_t *handle, struct buffer_head *bh)
-{
- if (!buffer_mapped(bh)) {
- /*
- * Mark buffer as dirty so that
- * block_write_full_page() writes it
- */
- set_buffer_dirty(bh);
- }
- return 0;
-}
-
static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
{
return !buffer_mapped(bh);
@@ -3596,24 +3584,22 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
ext4_bh_unmapped))
goto out_unlock;
- /*
- * Now mark all the buffer head dirty so
- * that writepage can write it
- */
- walk_page_buffers(NULL, page_buffers(page), 0, len,
- NULL, ext4_bh_prepare_fill);
}
/*
- * OK, we need to fill the hole... Lock the page and do writepage.
- * We can't do write_begin and write_end here because we don't
- * have inode_mutex and that allow parallel write_begin, write_end call.
+ * OK, we need to fill the hole... Lock the page and do write_begin
+ * write_end. We are not holding inode.i__mutex here. That allow
+ * parallel write_begin, write_end call.
* (lock_page prevent this from happening on the same page though)
*/
- lock_page(page);
- wbc.range_start = page_offset(page);
- wbc.range_end = page_offset(page) + len;
- ret = mapping->a_ops->writepage(page, &wbc);
- /* writepage unlocks the page */
+ ret = mapping->a_ops->write_begin(file, mapping, page_offset(page),
+ len, AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
+ if (ret < 0)
+ goto out_unlock;
+ ret = mapping->a_ops->write_end(file, mapping, page_offset(page),
+ len, len, page, NULL);
+ if (ret < 0)
+ goto out_unlock;
+ ret = 0;
out_unlock:
up_read(&inode->i_alloc_sem);
return ret;
If we agree i will send an updated ext4_page_mkwrite.patch and other
related patches that needed to be updated so that the patch queue apply
cleanly.
-aneesh
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
