nfsd: fix double-locks of directory mutex

A number of nfsd operations depend on the i_mutex to cover more code
than just the fsync, so the approach of 4c728ef583b3d8 "add a vfs_fsync
helper" doesn't work for nfsd.  Revert the parts of those patches that
touch nfsd.

Note: we can't, however, remove the logic from vfs_fsync that was needed
only for the special case of nfsd, because a vfs_fsync(NULL,...) call
can still result indirectly from a stackable filesystem that was called
by nfsd.  (Thanks to Christoph Hellwig for pointing this out.)

Reported-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 31 insertions, 3 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 44aa92aba891..6e50aaa56ca2 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -744,16 +744,44 @@ nfsd_close(struct file *filp)
         fput(filp);
 }
 
+/*
+ * Sync a file
+ * As this calls fsync (not fdatasync) there is no need for a write_inode
+ * after it.
+ */
+static inline int nfsd_dosync(struct file *filp, struct dentry *dp,
+                              const struct file_operations *fop)
+{
+        struct inode *inode = dp->d_inode;
+        int (*fsync) (struct file *, struct dentry *, int);
+        int err;
+
+        err = filemap_fdatawrite(inode->i_mapping);
+        if (err == 0 && fop && (fsync = fop->fsync))
+                err = fsync(filp, dp, 0);
+        if (err == 0)
+                err = filemap_fdatawait(inode->i_mapping);
+
+        return err;
+}
+
 static int
 nfsd_sync(struct file *filp)
 {
-        return vfs_fsync(filp, filp->f_path.dentry, 0);
+        int err;
+        struct inode *inode = filp->f_path.dentry->d_inode;
+        dprintk("nfsd: sync file %s\n", filp->f_path.dentry->d_name.name);
+        mutex_lock(&inode->i_mutex);
+        err=nfsd_dosync(filp, filp->f_path.dentry, filp->f_op);
+        mutex_unlock(&inode->i_mutex);
+
+        return err;
 }
 
 int
-nfsd_sync_dir(struct dentry *dentry)
+nfsd_sync_dir(struct dentry *dp)
 {
-        return vfs_fsync(NULL, dentry, 0);
+        return nfsd_dosync(NULL, dp, dp->d_inode->i_fop);
 }
 
 /*