From b808b1d632f6915e4d6b1badb927b2c970ad11bb Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 5 Dec 2015 21:39:06 -0500
Subject: don't open-code generic_file_llseek_size()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/powerpc/kernel/nvram_64.c | 19 +++----------------
 drivers/char/generic_nvram.c   | 21 +++------------------
 drivers/char/mbcs.c            | 28 +++-------------------------
 drivers/char/nvram.c           | 18 +++---------------
 4 files changed, 12 insertions(+), 74 deletions(-)

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index 32e2652..0cab9e8 100644
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -27,6 +27,7 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/kmsg_dump.h>
+#include <linux/pagemap.h>
 #include <linux/pstore.h>
 #include <linux/zlib.h>
 #include <asm/uaccess.h>
@@ -733,24 +734,10 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
 
 static loff_t dev_nvram_llseek(struct file *file, loff_t offset, int origin)
 {
-	int size;
-
 	if (ppc_md.nvram_size == NULL)
 		return -ENODEV;
-	size = ppc_md.nvram_size();
-
-	switch (origin) {
-	case 1:
-		offset += file->f_pos;
-		break;
-	case 2:
-		offset += size;
-		break;
-	}
-	if (offset < 0)
-		return -EINVAL;
-	file->f_pos = offset;
-	return file->f_pos;
+	return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE,
+					ppc_md.nvram_size());
 }
 
 
diff --git a/drivers/char/generic_nvram.c b/drivers/char/generic_nvram.c
index 6c4f4b5..073db95 100644
--- a/drivers/char/generic_nvram.c
+++ b/drivers/char/generic_nvram.c
@@ -20,6 +20,7 @@
 #include <linux/fcntl.h>
 #include <linux/init.h>
 #include <linux/mutex.h>
+#include <linux/pagemap.h>
 #include <asm/uaccess.h>
 #include <asm/nvram.h>
 #ifdef CONFIG_PPC_PMAC
@@ -33,24 +34,8 @@ static ssize_t nvram_len;
 
 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
 {
-	switch (origin) {
-	case 0:
-		break;
-	case 1:
-		offset += file->f_pos;
-		break;
-	case 2:
-		offset += nvram_len;
-		break;
-	default:
-		offset = -1;
-	}
-	if (offset < 0)
-		return -EINVAL;
-
-	file->f_pos = offset;
-
-	return file->f_pos;
+	return generic_file_llseek_size(file, offset, origin,
+					MAX_LFS_FILESIZE, nvram_len);
 }
 
 static ssize_t read_nvram(struct file *file, char __user *buf,
diff --git a/drivers/char/mbcs.c b/drivers/char/mbcs.c
index e5d3e3f..67d4264 100644
--- a/drivers/char/mbcs.c
+++ b/drivers/char/mbcs.c
@@ -26,6 +26,7 @@
 #include <linux/uio.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/pagemap.h>
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -451,31 +452,8 @@ mbcs_sram_write(struct file * fp, const char __user *buf, size_t len, loff_t * o
 
 static loff_t mbcs_sram_llseek(struct file * filp, loff_t off, int whence)
 {
-	loff_t newpos;
-
-	switch (whence) {
-	case SEEK_SET:
-		newpos = off;
-		break;
-
-	case SEEK_CUR:
-		newpos = filp->f_pos + off;
-		break;
-
-	case SEEK_END:
-		newpos = MBCS_SRAM_SIZE + off;
-		break;
-
-	default:		/* can't happen */
-		return -EINVAL;
-	}
-
-	if (newpos < 0)
-		return -EINVAL;
-
-	filp->f_pos = newpos;
-
-	return newpos;
+	return generic_file_llseek_size(filp, off, whence, MAX_LFS_FILESIZE,
+					MBCS_SRAM_SIZE);
 }
 
 static uint64_t mbcs_pioaddr(struct mbcs_soft *soft, uint64_t offset)
diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c
index 97c2d8d..0129232 100644
--- a/drivers/char/nvram.c
+++ b/drivers/char/nvram.c
@@ -110,6 +110,7 @@
 #include <linux/io.h>
 #include <linux/uaccess.h>
 #include <linux/mutex.h>
+#include <linux/pagemap.h>
 
 
 static DEFINE_MUTEX(nvram_mutex);
@@ -213,21 +214,8 @@ void nvram_set_checksum(void)
 
 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
 {
-	switch (origin) {
-	case 0:
-		/* nothing to do */
-		break;
-	case 1:
-		offset += file->f_pos;
-		break;
-	case 2:
-		offset += NVRAM_BYTES;
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	return (offset >= 0) ? (file->f_pos = offset) : -EINVAL;
+	return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE,
+					NVRAM_BYTES);
 }
 
 static ssize_t nvram_read(struct file *file, char __user *buf,
-- 
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