| Message ID | 20210303222547.1056428-1-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/filemap: Drop check for truncated page after I/O | expand |
LGTM. Reviewed-by: William Kucharski <william.kucharski@oracle.com> > On Mar 3, 2021, at 3:25 PM, Matthew Wilcox (Oracle) <willy@infradead.org> wrote: > > 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. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > mm/filemap.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 8d3e0daed7c9..3d1635d3be3e 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2238,8 +2238,6 @@ static int filemap_read_page(struct file *file, struct address_space *mapping, > 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; > } > -- > 2.30.0 > >
diff --git a/mm/filemap.c b/mm/filemap.c index 8d3e0daed7c9..3d1635d3be3e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2238,8 +2238,6 @@ static int filemap_read_page(struct file *file, struct address_space *mapping, 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; }
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. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- mm/filemap.c | 2 -- 1 file changed, 2 deletions(-)