[PATCH 6/8] nilfs2: emit error message when I/O error is detected

[Ryusuke Konishi]

When nilfs returned -EIO as an error code, it's not always clear if it
came from the underlying block device or not.  This will mend the
issue by having low level I/O routines of nilfs output an error
message when they detected an I/O error.

Signed-off-by: Ryusuke Konishi <konishi.ryus...@lab.ntt.co.jp>
---
 fs/nilfs2/btree.c   | 3 +++
 fs/nilfs2/gcinode.c | 9 ++++++++-
 fs/nilfs2/mdt.c     | 6 +++++-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
index 4816c5a..493e699 100644
--- a/fs/nilfs2/btree.c
+++ b/fs/nilfs2/btree.c
@@ -515,6 +515,9 @@ static int __nilfs_btree_get_block(const struct nilfs_bmap 
*btree, __u64 ptr,
 
  out_no_wait:
        if (!buffer_uptodate(bh)) {
+               nilfs_msg(btree->b_inode->i_sb, KERN_ERR,
+                         "I/O error reading b-tree node block (ino=%lu, 
blocknr=%llu)",
+                         btree->b_inode->i_ino, (unsigned long long)ptr);
                brelse(bh);
                return -EIO;
        }
diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
index 693aded..b94db89 100644
--- a/fs/nilfs2/gcinode.c
+++ b/fs/nilfs2/gcinode.c
@@ -147,8 +147,15 @@ int nilfs_gccache_submit_read_node(struct inode *inode, 
sector_t pbn,
 int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
 {
        wait_on_buffer(bh);
-       if (!buffer_uptodate(bh))
+       if (!buffer_uptodate(bh)) {
+               struct inode *inode = bh->b_page->mapping->host;
+
+               nilfs_msg(inode->i_sb, KERN_ERR,
+                         "I/O error reading %s block for GC (ino=%lu, 
vblocknr=%llu)",
+                         buffer_nilfs_node(bh) ? "node" : "data",
+                         inode->i_ino, (unsigned long long)bh->b_blocknr);
                return -EIO;
+       }
        if (buffer_dirty(bh))
                return -EEXIST;
 
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index 3417d85..27ba7c7 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -206,8 +206,12 @@ static int nilfs_mdt_read_block(struct inode *inode, 
unsigned long block,
 
  out_no_wait:
        err = -EIO;
-       if (!buffer_uptodate(first_bh))
+       if (!buffer_uptodate(first_bh)) {
+               nilfs_msg(inode->i_sb, KERN_ERR,
+                         "I/O error reading meta-data file (ino=%lu, 
block-offset=%lu)",
+                         inode->i_ino, block);
                goto failed_bh;
+       }
  out:
        *out_bh = first_bh;
        return 0;
-- 
1.8.3.1