From a259beb0746ae8b05fb72e735378244038d129e5 Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: Wed, 14 Jul 2021 17:04:22 +0800
Subject: [PATCH] iomap: Mark read blocks uptodate in write_begin
mainline inclusion
from mainline-v5.10
commit 14284fedf59f1647264f4603d64418cf1fcd3eb0
category: bugfix
bugzilla: 43547
CVE: NA
-----------------------------------------------
When bringing (portions of) a page uptodate, we were marking blocks that
were zeroed as being uptodate, but not blocks that were read from storage.
Like the previous commit, this problem was found with generic/127 and
a kernel which failed readahead I/Os. This bug causes writes to be
silently lost when working with flaky storage.
Fixes: 9dc55f1389f9 ("iomap: add support for sub-pagesize buffered I/O without buffer heads")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
conflicts:
fs/iomap.c
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
fs/iomap.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/fs/iomap.c b/fs/iomap.c
index 57164400077d..7078add7bbf9 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -649,7 +649,6 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
loff_t block_start = pos & ~(block_size - 1);
loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
unsigned from = offset_in_page(pos), to = from + len, poff, plen;
- int status = 0;
if (PageUptodate(page))
return 0;
@@ -668,14 +667,14 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
if (iomap->type != IOMAP_MAPPED ||
block_start >= i_size_read(inode)) {
zero_user_segments(page, poff, from, to, poff + plen);
- iomap_set_range_uptodate(page, poff, plen);
- continue;
+ } else {
+ int status = iomap_read_page_sync(block_start, page,
+ poff, plen, iomap);
+ if (status)
+ return status;
}
- status = iomap_read_page_sync(block_start, page, poff, plen,
- iomap);
- if (status)
- return status;
+ iomap_set_range_uptodate(page, poff, plen);
} while ((block_start += plen) < block_end);
return 0;
--
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