[PATCH] NFS: Introduce the use of inode->i_lock to protect fields in nfsi

Down the road we want to eliminate the use of the global kernel lock entirely
from the NFS client.  To do this, we need to protect the fields in the
nfs_inode structure adequately.  Start by serializing updates to the
"cache_validity" field.

Note this change addresses an SMP hang found by njw@osdl.org, where processes
deadlock because nfs_end_data_update and nfs_revalidate_mapping update the
"cache_validity" field without proper serialization.

Test plan:
 Millions of fsx ops on SMP clients.  Run Nick Wilson's breaknfs program on
 large SMP clients.

Signed-off-by: Chuck Lever <cel@netapp.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 31 insertions, 3 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index ee27578277f..541b418327c 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -615,6 +615,8 @@ nfs_zap_caches(struct inode *inode)
 	struct nfs_inode *nfsi = NFS_I(inode);
 	int mode = inode->i_mode;
 
+	spin_lock(&inode->i_lock);
+
 	NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
 	NFS_ATTRTIMEO_UPDATE(inode) = jiffies;
 
@@ -623,6 +625,8 @@ nfs_zap_caches(struct inode *inode)
 		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL|NFS_INO_REVAL_PAGECACHE;
 	else
 		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL|NFS_INO_REVAL_PAGECACHE;
+
+	spin_unlock(&inode->i_lock);
 }
 
 static void nfs_zap_acl_cache(struct inode *inode)
@@ -632,7 +636,9 @@ static void nfs_zap_acl_cache(struct inode *inode)
 	clear_acl_cache = NFS_PROTO(inode)->clear_acl_cache;
 	if (clear_acl_cache != NULL)
 		clear_acl_cache(inode);
+	spin_lock(&inode->i_lock);
 	NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_ACL;
+	spin_unlock(&inode->i_lock);
 }
 
 /*
@@ -841,7 +847,9 @@ void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr)
 			inode->i_uid = attr->ia_uid;
 		if ((attr->ia_valid & ATTR_GID) != 0)
 			inode->i_gid = attr->ia_gid;
+		spin_lock(&inode->i_lock);
 		NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
+		spin_unlock(&inode->i_lock);
 	}
 	if ((attr->ia_valid & ATTR_SIZE) != 0) {
 		inode->i_size = attr->ia_size;
@@ -1082,6 +1090,7 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
 			 (long long)NFS_FILEID(inode), status);
 		goto out;
 	}
+	spin_lock(&inode->i_lock);
 	cache_validity = nfsi->cache_validity;
 	nfsi->cache_validity &= ~NFS_INO_REVAL_PAGECACHE;
 
@@ -1091,6 +1100,7 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
 	 */
 	if (verifier == nfsi->cache_change_attribute)
 		nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME);
+	spin_unlock(&inode->i_lock);
 
 	nfs_revalidate_mapping(inode, inode->i_mapping);
 
@@ -1149,12 +1159,16 @@ void nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
 			nfs_wb_all(inode);
 		}
 		invalidate_inode_pages2(mapping);
+
+		spin_lock(&inode->i_lock);
 		nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
 		if (S_ISDIR(inode->i_mode)) {
 			memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
 			/* This ensures we revalidate child dentries */
 			nfsi->cache_change_attribute++;
 		}
+		spin_unlock(&inode->i_lock);
+
 		dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated\n",
 				inode->i_sb->s_id,
 				(long long)NFS_FILEID(inode));
@@ -1184,10 +1198,12 @@ void nfs_end_data_update(struct inode *inode)
 
 	if (!nfs_have_delegation(inode, FMODE_READ)) {
 		/* Mark the attribute cache for revalidation */
+		spin_lock(&inode->i_lock);
 		nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
 		/* Directories and symlinks: invalidate page cache too */
 		if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
 			nfsi->cache_validity |= NFS_INO_INVALID_DATA;
+		spin_unlock(&inode->i_lock);
 	}
 	nfsi->cache_change_attribute ++;
 	atomic_dec(&nfsi->data_updates);
@@ -1212,6 +1228,8 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
 	if (nfs_have_delegation(inode, FMODE_READ))
 		return 0;
 
+	spin_lock(&inode->i_lock);
+
 	/* Are we in the process of updating data on the server? */
 	data_unstable = nfs_caches_unstable(inode);
 
@@ -1226,13 +1244,17 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
 		}
 	}
 
-	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
+	if ((fattr->valid & NFS_ATTR_FATTR) == 0) {
+		spin_unlock(&inode->i_lock);
 		return 0;
+	}
 
 	/* Has the inode gone and changed behind our back? */
 	if (nfsi->fileid != fattr->fileid
-			|| (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
+			|| (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) {
+		spin_unlock(&inode->i_lock);
 		return -EIO;
+	}
 
 	cur_size = i_size_read(inode);
  	new_isize = nfs_size_to_loff_t(fattr->size);
@@ -1271,6 +1293,7 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
 		nfsi->cache_validity |= NFS_INO_INVALID_ATIME;
 
 	nfsi->read_cache_jiffies = fattr->timestamp;
+	spin_unlock(&inode->i_lock);
 	return 0;
 }
 
@@ -1309,11 +1332,15 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
 		goto out_err;
 	}
 
+	spin_lock(&inode->i_lock);
+
 	/*
 	 * Make sure the inode's type hasn't changed.
 	 */
-	if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
+	if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) {
+		spin_unlock(&inode->i_lock);
 		goto out_changed;
+	}
 
 	/*
 	 * Update the read time so we don't revalidate too often.
@@ -1406,6 +1433,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
 	if (!nfs_have_delegation(inode, FMODE_READ))
 		nfsi->cache_validity |= invalid;
 
+	spin_unlock(&inode->i_lock);
 	return 0;
  out_changed:
 	/*