fs/buffer.c: add device information for error output in __find_get_block_slow()

On the ext4 mailing list[1], we got some report about errors in
__find_get_block_slow(), but the information is very limited.

If the device information is given, we can know the name of the sick
volume.  Futhermore, we can get the corresponding status of that
block(group, inode block etc) by analyzing the disk layout.

[1] http://marc.info/?l=linux-ext4&m=131379831421147&w=2

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <>

diff --git a/fs/buffer.c b/fs/buffer.c
index 58ca57b82a8a56093710643e8f0bfc29f962bbe4..8f84ffac96c602ac7865bbff8980b9edf309196f 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -213,13 +213,16 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
         * elsewhere, don't buffer_error if we had some unmapped buffers
         */
        if (all_mapped) {
+               char b[BDEVNAME_SIZE];
+
                printk("__find_get_block_slow() failed. "
                        "block=%llu, b_blocknr=%llu\n",
                        (unsigned long long)block,
                        (unsigned long long)bh->b_blocknr);
                printk("b_state=0x%08lx, b_size=%zu\n",
                        bh->b_state, bh->b_size);
-               printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
+               printk("device %s blocksize: %d\n", bdevname(bdev, b),
+                       1 << bd_inode->i_blkbits);
        }
 out_unlock:
        spin_unlock(&bd_mapping->private_lock);