[PATCH 05/23] vfs: Teach lseek to use file_hotplug_lock

[Eric W. Biederman]

From: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxxx>

Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxx>
---
 fs/read_write.c |   24 +++++++++++++++++-------
 1 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 9d1e76b..c9511ce 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -136,14 +136,24 @@ EXPORT_SYMBOL(default_llseek);
 loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
 {
 	loff_t (*fn)(struct file *, loff_t, int);
+	loff_t retval = -ESPIPE;
 
-	fn = no_llseek;
-	if (file->f_mode & FMODE_LSEEK) {
-		fn = default_llseek;
-		if (file->f_op && file->f_op->llseek)
-			fn = file->f_op->llseek;
-	}
-	return fn(file, offset, origin);
+	if (!(file->f_mode & FMODE_LSEEK))
+		goto out;
+
+	retval = -EIO;
+	if (!file_hotplug_read_trylock(file))
+		goto out;
+
+	fn = default_llseek;
+	if (file->f_op && file->f_op->llseek)
+		fn = file->f_op->llseek;
+
+	retval = fn(file, offset, origin);
+
+	file_hotplug_read_unlock(file);
+out:
+	return retval;
 }
 EXPORT_SYMBOL(vfs_llseek);
 
-- 
1.6.3.1.54.g99dd.dirty

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