From: Jeff Layton <jlayton@redhat.com>
To: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
tytso@mit.edu, jack@suse.cz, willy@infradead.org, neilb@suse.com,
viro@zeniv.linux.org.uk
Subject: [PATCH v2 13/17] mm: don't TestClearPageError in __filemap_fdatawait_range
Date: Wed, 12 Apr 2017 08:06:10 -0400 [thread overview]
Message-ID: <20170412120614.6111-14-jlayton@redhat.com> (raw)
In-Reply-To: <20170412120614.6111-1-jlayton@redhat.com>
The -EIO returned here can end up overriding whatever error is marked in
the address space, and be returned at fsync time, even when there is a
more appropriate error stored in the mapping.
Read errors are also sometimes tracked on a per-page level using
PG_error. Suppose we have a read error on a page, and then that page is
subsequently dirtied by overwriting the whole page. Writeback doesn't
clear PG_error, so we can then end up successfully writing back that
page and still return -EIO on fsync.
Worse yet, PG_error is cleared during a sync() syscall, but the -EIO
return from that is silently discarded. Any subsystem that is relying on
PG_error to report errors during fsync can easily lose writeback errors
due to this. All you need is a stray sync() call on the box at the wrong
time and you've lost the error.
Since the handling of the PG_error flag is somewhat inconsistent across
subsystems, let's just rely on marking the address space when there are
writeback errors. Change the TestClearPageError call to ClearPageError,
and make __filemap_fdatawait_range a void return function.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
mm/filemap.c | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 525dddc15abb..b43975ca7a2e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -362,17 +362,16 @@ int filemap_flush(struct address_space *mapping)
}
EXPORT_SYMBOL(filemap_flush);
-static int __filemap_fdatawait_range(struct address_space *mapping,
+static void __filemap_fdatawait_range(struct address_space *mapping,
loff_t start_byte, loff_t end_byte)
{
pgoff_t index = start_byte >> PAGE_SHIFT;
pgoff_t end = end_byte >> PAGE_SHIFT;
struct pagevec pvec;
int nr_pages;
- int ret = 0;
if (end_byte < start_byte)
- goto out;
+ return;
pagevec_init(&pvec, 0);
while ((index <= end) &&
@@ -389,14 +388,11 @@ static int __filemap_fdatawait_range(struct address_space *mapping,
continue;
wait_on_page_writeback(page);
- if (TestClearPageError(page))
- ret = -EIO;
+ ClearPageError(page);
}
pagevec_release(&pvec);
cond_resched();
}
-out:
- return ret;
}
/**
@@ -416,15 +412,10 @@ static int __filemap_fdatawait_range(struct address_space *mapping,
int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
loff_t end_byte)
{
- int ret, ret2;
wb_err_t since = READ_ONCE(mapping->wb_err);
- ret = __filemap_fdatawait_range(mapping, start_byte, end_byte);
- ret2 = filemap_check_wb_error(mapping, since);
- if (!ret)
- ret = ret2;
-
- return ret;
+ __filemap_fdatawait_range(mapping, start_byte, end_byte);
+ return filemap_check_wb_error(mapping, since);
}
EXPORT_SYMBOL(filemap_fdatawait_range);
--
2.9.3
next prev parent reply other threads:[~2017-04-12 12:06 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-12 12:05 [PATCH v2 00/17] fs: introduce new writeback error reporting and convert existing API as a wrapper around it Jeff Layton
2017-04-12 12:05 ` [PATCH v2 01/17] mm: drop "wait" parameter from write_one_page Jeff Layton
2017-04-12 12:15 ` Jan Kara
2017-04-12 14:27 ` Matthew Wilcox
2017-04-12 14:34 ` Jeff Layton
2017-04-12 15:12 ` Dave Kleikamp
2017-04-12 12:05 ` [PATCH v2 02/17] mm: fix mapping_set_error call in me_pagecache_dirty Jeff Layton
2017-04-12 12:16 ` Jan Kara
2017-04-12 14:28 ` Matthew Wilcox
2017-04-12 12:06 ` [PATCH v2 03/17] buffer: use mapping_set_error instead of setting the flag Jeff Layton
2017-04-12 12:17 ` Jan Kara
2017-04-12 14:29 ` Matthew Wilcox
2017-04-12 12:06 ` [PATCH v2 04/17] ext2: don't test/clear AS_EIO flag Jeff Layton
2017-04-12 12:29 ` Jan Kara
2017-04-12 12:30 ` Jeff Layton
2017-04-12 12:06 ` [PATCH v2 05/17] orangefs: don't call filemap_write_and_wait from fsync Jeff Layton
2017-04-12 12:06 ` [PATCH v2 06/17] mm: doc comment for scary spot in write_one_page Jeff Layton
2017-04-12 13:01 ` Jeff Layton
2017-04-12 14:38 ` Matthew Wilcox
2017-04-12 15:52 ` Jeff Layton
2017-04-12 21:36 ` NeilBrown
2017-04-12 22:55 ` Jeff Layton
2017-04-12 12:06 ` [PATCH v2 07/17] fs: new infrastructure for writeback error handling and reporting Jeff Layton
2017-04-12 18:42 ` Jeff Layton
2017-04-12 21:55 ` NeilBrown
2017-04-12 23:01 ` Jeff Layton
2017-04-17 22:53 ` NeilBrown
2017-04-12 12:06 ` [PATCH v2 08/17] fs: retrofit old error reporting API onto new infrastructure Jeff Layton
2017-04-12 22:14 ` NeilBrown
2017-04-12 22:41 ` Jeff Layton
2017-04-17 22:56 ` NeilBrown
2017-04-21 12:46 ` Jeff Layton
2017-04-23 22:38 ` NeilBrown
2017-04-24 11:50 ` Jeff Layton
2017-04-17 15:17 ` Jeff Layton
2017-04-12 12:06 ` [PATCH v2 09/17] mm: remove AS_EIO and AS_ENOSPC flags Jeff Layton
2017-04-12 12:06 ` [PATCH v2 10/17] dax: set errors in mapping when writeback fails Jeff Layton
2017-04-12 12:06 ` [PATCH v2 11/17] nilfs2: set the mapping error when calling SetPageError on writeback Jeff Layton
2017-04-12 12:06 ` [PATCH v2 12/17] mm: ensure that we set mapping error if writeout() fails Jeff Layton
2017-04-12 12:06 ` Jeff Layton [this message]
2017-04-12 12:06 ` [PATCH v2 14/17] 9p: set mapping error when writeback fails in launder_page Jeff Layton
2017-04-12 12:06 ` [PATCH v2 15/17] fuse: set mapping error in writepage_locked when it fails Jeff Layton
2017-04-12 12:06 ` [PATCH v2 16/17] cifs: set mapping error when page writeback fails in writepage or launder_pages Jeff Layton
2017-04-12 12:06 ` [PATCH v2 17/17] cifs: remove some unneeded mapping_set_error calls Jeff Layton
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