Commit 842a42d1 authored Mar 25, 2020 by Brian Foster Committed by Darrick J. Wong Mar 26, 2020

xfs: shutdown on failure to add page to log bio



If the bio_add_page() call fails, we proceed to write out a
partially constructed log buffer. This corrupts the physical log
such that log recovery is not possible. Worse, persistent
occurrences of this error eventually lead to a BUG_ON() failure in
bio_split() as iclogs wrap the end of the physical log, which
triggers log recovery on subsequent mount.

Rather than warn about writing out a corrupted log buffer, shutdown
the fs as is done for any log I/O related error. This preserves the
consistency of the physical log such that log recovery succeeds on a
subsequent mount. Note that this was observed on a 64k page debug
kernel without upstream commit 59bb4798 ("mm, sl[aou]b:
guarantee natural alignment for kmalloc(power-of-two)"), which
demonstrated frequent iclog bio overflows due to unaligned (slab
allocated) iclog data buffers.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

parent d59f44d3

fs/xfs/xfs_log.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -1703,7 +1703,7 @@ xlog_bio_end_io(
		&iclog->ic_end_io_work);
		}

		static void
		static int
		xlog_map_iclog_data(
		struct bio *bio,
		void *data,
		@@ -1714,11 +1714,14 @@ xlog_map_iclog_data(
		unsigned int off = offset_in_page(data);
		size_t len = min_t(size_t, count, PAGE_SIZE - off);

		WARN_ON_ONCE(bio_add_page(bio, page, len, off) != len);
		if (bio_add_page(bio, page, len, off) != len)
		return -EIO;

		data += len;
		count -= len;
		} while (count);

		return 0;
		}

		STATIC void
		@@ -1762,7 +1765,10 @@ xlog_write_iclog(
		if (need_flush)
		iclog->ic_bio.bi_opf \|= REQ_PREFLUSH;

		xlog_map_iclog_data(&iclog->ic_bio, iclog->ic_data, count);
		if (xlog_map_iclog_data(&iclog->ic_bio, iclog->ic_data, count)) {
		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
		return;
		}
		if (is_vmalloc_addr(iclog->ic_data))
		flush_kernel_vmap_range(iclog->ic_data, count);

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