NFSv4.1: Replace dprintk() in pnfs_update_layout with something less buggy

Dereferencing nfsi->layout in order to read plh_flags without holding
a spin lock is bug prone. Furthermore, the dprintk() tells you nothing
about whether or not the call succeeded.
Replace it with something that tells you about whether or not a valid
layout segment was returned for the inode in question.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 498af8779959..df45acaf91f7 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1027,17 +1027,15 @@ pnfs_update_layout(struct inode *ino,
         bool first = false;
 
         if (!pnfs_enabled_sb(NFS_SERVER(ino)))
-                return NULL;
+                goto out;
 
         if (pnfs_within_mdsthreshold(ctx, ino, iomode))
-                return NULL;
+                goto out;
 
         spin_lock(&ino->i_lock);
         lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
-        if (lo == NULL) {
-                dprintk("%s ERROR: can't get pnfs_layout_hdr\n", __func__);
+        if (lo == NULL)
                 goto out_unlock;
-        }
 
         /* Do we even need to bother with this? */
         if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
@@ -1093,8 +1091,14 @@ pnfs_update_layout(struct inode *ino,
         atomic_dec(&lo->plh_outstanding);
         pnfs_put_layout_hdr(lo);
 out:
-        dprintk("%s end, state 0x%lx lseg %p\n", __func__,
-                nfsi->layout ? nfsi->layout->plh_flags : -1, lseg);
+        dprintk("%s: inode %s/%llu pNFS layout segment %s for "
+                        "(%s, offset: %llu, length: %llu)\n",
+                        __func__, ino->i_sb->s_id,
+                        (unsigned long long)NFS_FILEID(ino),
+                        lseg == NULL ? "not found" : "found",
+                        iomode==IOMODE_RW ?  "read/write" : "read-only",
+                        (unsigned long long)pos,
+                        (unsigned long long)count);
         return lseg;
 out_unlock:
         spin_unlock(&ino->i_lock);