Btrfs: clear uptodate flags of pages in sys_array eb

Liu Bo · kdave · commit d865177a5e74 · 2016-06-06T10:14:40.000+02:00
We set uptodate flag to pages in the temporary sys_array eb,
but do not clear the flag after free eb.  As the special
btree inode may still hold a reference on those pages, the
uptodate flag can remain alive in them.

If btrfs_super_chunk_root has been intentionally changed to the
offset of this sys_array eb, reading chunk_root will read content
of sys_array and it will skip our beautiful checks in
btree_readpage_end_io_hook() because of
"pages of eb are uptodate =&gt; eb is uptodate"

This adds the 'clear uptodate' part to force it to read from disk.

Reviewed-by: Josef Bacik &lt;jbacik@fb.com&gt;
Signed-off-by: Liu Bo &lt;bo.li.liu@oracle.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
@@ -6631,12 +6631,14 @@ int btrfs_read_sys_array(struct btrfs_root *root)
 		sb_array_offset += len;
 		cur_offset += len;
 	}
+	clear_extent_buffer_uptodate(sb);
 	free_extent_buffer_stale(sb);
 	return ret;
 
 out_short_read:
 	printk(KERN_ERR "BTRFS: sys_array too short to read %u bytes at offset %u\n",
 			len, cur_offset);
+	clear_extent_buffer_uptodate(sb);
 	free_extent_buffer_stale(sb);
 	return -EIO;
 }

Original file line number	Diff line number	Diff line change
`@@ -6631,12 +6631,14 @@ int btrfs_read_sys_array(struct btrfs_root *root)`
`6631`	`6631`	`sb_array_offset += len;`
`6632`	`6632`	`cur_offset += len;`
`6633`	`6633`	`}`
	`6634`	`+ clear_extent_buffer_uptodate(sb);`
`6634`	`6635`	`free_extent_buffer_stale(sb);`
`6635`	`6636`	`return ret;`
`6636`	`6637`
`6637`	`6638`	`out_short_read:`
`6638`	`6639`	`printk(KERN_ERR "BTRFS: sys_array too short to read %u bytes at offset %u\n",`
`6639`	`6640`	`len, cur_offset);`
	`6641`	`+ clear_extent_buffer_uptodate(sb);`
`6640`	`6642`	`free_extent_buffer_stale(sb);`
`6641`	`6643`	`return -EIO;`
`6642`	`6644`	`}`