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iomap: Mark read blocks uptodate in write_begin

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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: 9dc55f1389 ("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>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-09-10 08:26:18 -07:00 committed by Darrick J. Wong
parent e6e7ca9262
commit 14284fedf5
1 changed files with 6 additions and 8 deletions
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14
fs/iomap/buffered-io.c
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@ -574,7 +574,6 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
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;
if (PageUptodate(page))
return 0;
@ -595,14 +594,13 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE))
return -EIO;
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, srcmap);
if (status)
return status;
}
status = iomap_read_page_sync(block_start, page, poff, plen,
srcmap);
if (status)
return status;
iomap_set_range_uptodate(page, poff, plen);
} while ((block_start += plen) < block_end);
return 0;