[PATCH 21/23] vfs: Teach fsync to use file_hotplug_lock

[Eric W. Biederman]

From: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxxxxxxxxxx>

Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxx>
---
 fs/sync.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/fs/sync.c b/fs/sync.c
index e9d56f6..ac6da60 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -197,6 +197,9 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 	 * don't have a struct file available.  Damn nfsd..
 	 */
 	if (file) {
+		ret = -EIO;
+		if (!file_hotplug_read_trylock(file))
+			goto out;
 		mapping = file->f_mapping;
 		fop = file->f_op;
 	} else {
@@ -206,7 +209,7 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 
 	if (!fop || !fop->fsync) {
 		ret = -EINVAL;
-		goto out;
+		goto out_unlock;
 	}
 
 	ret = filemap_fdatawrite(mapping);
@@ -223,6 +226,10 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 	err = filemap_fdatawait(mapping);
 	if (!ret)
 		ret = err;
+
+out_unlock:
+	if (file)
+		file_hotplug_read_unlock(file);
 out:
 	return ret;
 }
-- 
1.6.3.1.54.g99dd.dirty

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