From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm/filemap: drop check for truncated page after I/O
If the I/O completed successfully, the page will remain Uptodate, even if
it is subsequently truncated. If the I/O completed with an error, this
check would cause us to retry the I/O if the page were truncated before we
woke up. There is no need to retry the I/O; the I/O to fill the page
failed, so we can legitimately just return -EIO.
This code was originally added by commit 56f0d5fe6851 ("[PATCH]
readpage-vs-invalidate fix") in 2005 (this commit ID is from the
linux-fullhistory tree; it is also commit ba1f08f14b52 in tglx-history).
At the time, truncate_complete_page() called ClearPageUptodate(), and so
this was fixing a real bug. In 2008, commit 84209e02de48 ("mm: dont clear
PG_uptodate on truncate/invalidate") removed the call to
ClearPageUptodate, and this check has been unnecessary ever since.
It doesn't do any real harm, but there's no need to keep it.
Link: https://lkml.kernel.org/r/20210303222547.1056428-1-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 2 --
1 file changed, 2 deletions(-)
--- a/mm/filemap.c~mm-filemap-drop-check-for-truncated-page-after-i-o
+++ a/mm/filemap.c
@@ -2348,8 +2348,6 @@ static int filemap_read_page(struct file
return error;
if (PageUptodate(page))
return 0;
- if (!page->mapping) /* page truncated */
- return AOP_TRUNCATED_PAGE;
shrink_readahead_size_eio(&file->f_ra);
return -EIO;
}
_
