Revert "sysfs: fix race between readdir and lseek"

This reverts commit 991f76f837bf22c5bb07261cfd86525a0a96650c in Linus'
tree which is f366c8f271888f48e15cc7c0ab70f184c220c8a4 in
linux-stable.git

It depends on ef3d0fd27e90f ("vfs: do (nearly) lockless generic_file_llseek")
which is available only in 3.2+.

When applied on 3.0 codebase, it causes A-A deadlock, whenever anyone does
seek() on sysfs, as both generic_file_llseek() and sysfs_dir_llseek() obtain
i_mutex.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 7cbc5856feea704d4924a5a28d759cbfbf3f3476..3ab78b873376ae15fc54c6f07e4c0486e074b233 100644 (file)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -959,21 +959,9 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
        return 0;
 }
 
-static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
-{
-       struct inode *inode = file->f_path.dentry->d_inode;
-       loff_t ret;
-
-       mutex_lock(&inode->i_mutex);
-       ret = generic_file_llseek(file, offset, whence);
-       mutex_unlock(&inode->i_mutex);
-
-       return ret;
-}
-
 const struct file_operations sysfs_dir_operations = {
        .read           = generic_read_dir,
        .readdir        = sysfs_readdir,
        .release        = sysfs_dir_release,
-       .llseek         = sysfs_dir_llseek,
+       .llseek         = generic_file_llseek,
 };