linux-kernel - [PATCH 2/6] fs: Return error from block_read_full

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Message-Id: <20201022212228.15703-3-willy@infradead.org>
Date:   Thu, 22 Oct 2020 22:22:24 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, linux-fscrypt@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Subject: [PATCH 2/6] fs: Return error from block_read_full_page

If the filesystem returns an error from get_block, report it
instead of ineffectually setting PageError.  Don't bother starting
any I/Os in this case since they won't bring the page Uptodate.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 fs/buffer.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 1d5337517dcd..1b0ba1d59966 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2262,7 +2262,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
 	sector_t iblock, lblock;
 	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 	unsigned int blocksize, bbits;
-	int nr, i;
+	int nr, i, err = 0;
 	int fully_mapped = 1;
 
 	head = create_page_buffers(page, inode, 0);
@@ -2280,19 +2280,16 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
 			continue;
 
 		if (!buffer_mapped(bh)) {
-			int err = 0;
-
 			fully_mapped = 0;
 			if (iblock < lblock) {
 				WARN_ON(bh->b_size != blocksize);
 				err = get_block(inode, iblock, bh, 0);
 				if (err)
-					SetPageError(page);
+					break;
 			}
 			if (!buffer_mapped(bh)) {
 				zero_user(page, i * blocksize, blocksize);
-				if (!err)
-					set_buffer_uptodate(bh);
+				set_buffer_uptodate(bh);
 				continue;
 			}
 			/*
@@ -2305,18 +2302,17 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
 		arr[nr++] = bh;
 	} while (i++, iblock++, (bh = bh->b_this_page) != head);
 
+	if (err) {
+		unlock_page(page);
+		return err;
+	}
 	if (fully_mapped)
 		SetPageMappedToDisk(page);
 
 	if (!nr) {
-		/*
-		 * All buffers are uptodate - we can set the page uptodate
-		 * as well. But not if get_block() returned an error.
-		 */
-		if (!PageError(page))
-			SetPageUptodate(page);
-		unlock_page(page);
-		return 0;
+		/* All buffers are uptodate - we can set the page uptodate */
+		SetPageUptodate(page);
+		return AOP_UPDATED_PAGE;
 	}
 
 	/* Stage two: lock the buffers */
-- 
2.28.0