NFSv4.1: Add a helper pnfs_commit_and_return_layout

In order to be able to safely return the layout in nfs4_proc_setattr,
we need to block new uses of the layout, wait for all outstanding
users of the layout to complete, commit the layout and then return it.

This patch adds a helper in order to do all this safely.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Boaz Harrosh <bharrosh@panasas.com>

3 files changed, 34 insertions, 1 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 6ccdd4fd9b59..26431cf62ddb 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2632,7 +2632,7 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
         int status;
 
         if (pnfs_ld_layoutret_on_setattr(inode))
-                pnfs_return_layout(inode);
+                pnfs_commit_and_return_layout(inode);
 
         nfs_fattr_init(fattr);
         
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 5044142c1216..4bdffe0ba025 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -866,6 +866,33 @@ out:
 }
 EXPORT_SYMBOL_GPL(_pnfs_return_layout);
 
+int
+pnfs_commit_and_return_layout(struct inode *inode)
+{
+        struct pnfs_layout_hdr *lo;
+        int ret;
+
+        spin_lock(&inode->i_lock);
+        lo = NFS_I(inode)->layout;
+        if (lo == NULL) {
+                spin_unlock(&inode->i_lock);
+                return 0;
+        }
+        pnfs_get_layout_hdr(lo);
+        /* Block new layoutgets and read/write to ds */
+        lo->plh_block_lgets++;
+        spin_unlock(&inode->i_lock);
+        filemap_fdatawait(inode->i_mapping);
+        ret = pnfs_layoutcommit_inode(inode, true);
+        if (ret == 0)
+                ret = _pnfs_return_layout(inode);
+        spin_lock(&inode->i_lock);
+        lo->plh_block_lgets--;
+        spin_unlock(&inode->i_lock);
+        pnfs_put_layout_hdr(lo);
+        return ret;
+}
+
 bool pnfs_roc(struct inode *ino)
 {
         struct pnfs_layout_hdr *lo;
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 94ba80417748..f5f8a470a647 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -219,6 +219,7 @@ void pnfs_set_layoutcommit(struct nfs_write_data *wdata);
 void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data);
 int pnfs_layoutcommit_inode(struct inode *inode, bool sync);
 int _pnfs_return_layout(struct inode *);
+int pnfs_commit_and_return_layout(struct inode *);
 void pnfs_ld_write_done(struct nfs_write_data *);
 void pnfs_ld_read_done(struct nfs_read_data *);
 struct pnfs_layout_segment *pnfs_update_layout(struct inode *ino,
@@ -407,6 +408,11 @@ static inline int pnfs_return_layout(struct inode *ino)
         return 0;
 }
 
+static inline int pnfs_commit_and_return_layout(struct inode *inode)
+{
+        return 0;
+}
+
 static inline bool
 pnfs_ld_layoutret_on_setattr(struct inode *inode)
 {