iomap: Mark read blocks uptodate in write_begin (14284fed) · Commits · 戴 / test

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: ("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>

fs/iomap/buffered-io.c

+6 −8

Original line number	Diff line number	Diff line
		@@ -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;
		}

		status = iomap_read_page_sync(block_start, page, poff, plen,
		srcmap);
		} else {
		int 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;

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