[006/128] fs/buffer.c: record blockdev write errors in super_block that it backs

Commit Message

Andrew Morton June 2, 2020, 4:45 a.m. UTC

From: Jeff Layton <[e-mail]>
Subject: fs/buffer.c: record blockdev write errors in super_block that it backs

When syncing out a block device (a'la __sync_blockdev), any error
encountered will only be recorded in the bd_inode's mapping.  When the
blockdev contains a filesystem however, we'd like to also record the error
in the super_block that's stored there.

Make mark_buffer_write_io_error also record the error in the corresponding
super_block when a writeback error occurs and the block device contains a
mounted superblock.

Since superblocks are RCU freed, hold the rcu_read_lock to ensure that the
superblock doesn't go away while we're marking it.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Jeff Layton <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>
Cc: Al Viro <[e-mail]>
Cc: Andres Freund <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: David Howells <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Dave Chinner <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 fs/buffer.c |    7 +++++++
 1 file changed, 7 insertions(+)

Patch

--- a/fs/buffer.c~buffer-record-blockdev-write-errors-in-super_block-that-it-backs
+++ a/fs/buffer.c
@@ -1154,12 +1154,19 @@  EXPORT_SYMBOL(mark_buffer_dirty);
 
 void mark_buffer_write_io_error(struct buffer_head *bh)
 {
+	struct super_block *sb;
+
 	set_buffer_write_io_error(bh);
 	/* FIXME: do we need to set this in both places? */
 	if (bh->b_page && bh->b_page->mapping)
 		mapping_set_error(bh->b_page->mapping, -EIO);
 	if (bh->b_assoc_map)
 		mapping_set_error(bh->b_assoc_map, -EIO);
+	rcu_read_lock();
+	sb = READ_ONCE(bh->b_bdev->bd_super);
+	if (sb)
+		errseq_set(&sb->s_wb_err, -EIO);
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL(mark_buffer_write_io_error);