Linux 3.1 compat, fops->fsync()

The Linux 3.1 kernel updated the fops->fsync() callback yet again.
They now pass the requested range and delegate the responsibility
for calling filemap_write_and_wait_range() to the callback.  In
addition imutex is no longer held by the caller and the callback
is responsible for taking the lock if required.

This commit updates the code to provide a zpl_fsync() function
for the updated API.  Implementations for the previous two APIs
are also maintained for compatibility.

Signed-off-by: Brian Behlendorf <[email protected]>
Closes #445

1 files changed, 54 insertions, 13 deletions

diff --git a/module/zfs/zpl_file.c b/module/zfs/zpl_file.c
index 298c0b62d..0ef2c1558 100644
--- a/module/zfs/zpl_file.c
+++ b/module/zfs/zpl_file.c
@@ -76,37 +76,78 @@ zpl_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	return (error);
 }
 
+#if defined(HAVE_FSYNC_WITH_DENTRY)
 /*
- * 2.6.35 API change,
- * As of 2.6.35 the dentry argument to the .fsync() vfs hook was deemed
+ * Linux 2.6.x - 2.6.34 API,
+ * Through 2.6.34 the nfsd kernel server would pass a NULL 'file struct *'
+ * to the fops->fsync() hook.  For this reason, we must be careful not to
+ * use filp unconditionally.
+ */
+static int
+zpl_fsync(struct file *filp, struct dentry *dentry, int datasync)
+{
+	cred_t *cr = CRED();
+	int error;
+
+	crhold(cr);
+	error = -zfs_fsync(dentry->d_inode, datasync, cr);
+	crfree(cr);
+	ASSERT3S(error, <=, 0);
+
+	return (error);
+}
+
+#elif defined(HAVE_FSYNC_WITHOUT_DENTRY)
+/*
+ * Linux 2.6.35 - 3.0 API,
+ * As of 2.6.35 the dentry argument to the fops->fsync() hook was deemed
  * redundant.  The dentry is still accessible via filp->f_path.dentry,
  * and we are guaranteed that filp will never be NULL.
- *
- * 2.6.34 API change,
- * Prior to 2.6.34 the nfsd kernel server would pass a NULL file struct *
- * to the .fsync() hook.  For this reason, we must be careful not to use
- * filp unconditionally in the 3 argument case.
  */
-#ifdef HAVE_2ARGS_FSYNC
 static int
 zpl_fsync(struct file *filp, int datasync)
 {
-	struct dentry *dentry = filp->f_path.dentry;
-#else
+	struct inode *inode = filp->f_mapping->host;
+	cred_t *cr = CRED();
+	int error;
+
+	crhold(cr);
+	error = -zfs_fsync(inode, datasync, cr);
+	crfree(cr);
+	ASSERT3S(error, <=, 0);
+
+	return (error);
+}
+
+#elif defined(HAVE_FSYNC_RANGE)
+/*
+ * Linux 3.1 - 3.x API,
+ * As of 3.1 the responsibility to call filemap_write_and_wait_range() has
+ * been pushed down in to the .fsync() vfs hook.  Additionally, the i_mutex
+ * lock is no longer held by the caller, for zfs we don't require the lock
+ * to be held so we don't acquire it.
+ */
 static int
-zpl_fsync(struct file *filp, struct dentry *dentry, int datasync)
+zpl_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 {
-#endif /* HAVE_2ARGS_FSYNC */
+	struct inode *inode = filp->f_mapping->host;
 	cred_t *cr = CRED();
 	int error;
 
+	error = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (error)
+		return (error);
+
 	crhold(cr);
-	error = -zfs_fsync(dentry->d_inode, datasync, cr);
+	error = -zfs_fsync(inode, datasync, cr);
 	crfree(cr);
 	ASSERT3S(error, <=, 0);
 
 	return (error);
 }
+#else
+#error "Unsupported fops->fsync() implementation"
+#endif
 
 ssize_t
 zpl_read_common(struct inode *ip, const char *buf, size_t len, loff_t pos,