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* [patch 013/158] mm/filemap.c: warn if stale pagecache is left after direct write
@ 2019-12-01  1:49 akpm
  0 siblings, 0 replies; only message in thread
From: akpm @ 2019-12-01  1:49 UTC (permalink / raw)
  To: akpm, axboe, jack, khlebnikov, linux-mm, mm-commits, torvalds, viro

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Subject: mm/filemap.c: warn if stale pagecache is left after direct write

generic_file_direct_write() tries to invalidate pagecache after O_DIRECT
write.  Unlike to similar code in dio_complete() this silently ignores
error returned from invalidate_inode_pages2_range().

According to comment this code here because not all filesystems call
dio_complete() to do proper invalidation after O_DIRECT write.  Noticeable
example is a blkdev_direct_IO().

This patch calls dio_warn_stale_pagecache() if invalidation fails.

Link: http://lkml.kernel.org/r/157270038294.4812.2238891109785106069.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/filemap.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/mm/filemap.c~fs-warn-if-stale-pagecache-is-left-after-direct-write
+++ a/mm/filemap.c
@@ -3241,11 +3241,13 @@ generic_file_direct_write(struct kiocb *
 	 * do not end up with dio_complete() being called, so let's not break
 	 * them by removing it completely.
 	 *
+	 * Noticeable example is a blkdev_direct_IO().
+	 *
 	 * Skip invalidation for async writes or if mapping has no pages.
 	 */
-	if (written > 0 && mapping->nrpages)
-		invalidate_inode_pages2_range(mapping,
-					pos >> PAGE_SHIFT, end);
+	if (written > 0 && mapping->nrpages &&
+	    invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end))
+		dio_warn_stale_pagecache(file);
 
 	if (written > 0) {
 		pos += written;
_


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2019-12-01  1:49 [patch 013/158] mm/filemap.c: warn if stale pagecache is left after direct write akpm

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