commit 0f672f6c0b52b7b0700b0915c72b540721af4465
author David Brazdil <dbrazdil@google.com> Tue Dec 10 10:32:29 2019 +0000
committer David Brazdil <dbrazdil@google.com> Tue Dec 10 19:03:18 2019 +0000
tree 85c8cba019caa205e4f8920d72d93f6d6deaf29c
parent 3a0ad55d848b50499b68d7141d4eca997fce28ef

Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd

fs/fat/fatent.c

diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index f58c0ca..3647c65 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2004, OGAWA Hirofumi
- * Released under GPL v2.
  */
 
 #include <linux/blkdev.h>
@@ -290,19 +290,17 @@
 
 	mutex_init(&sbi->fat_lock);
 
-	switch (sbi->fat_bits) {
-	case 32:
+	if (is_fat32(sbi)) {
 		sbi->fatent_shift = 2;
 		sbi->fatent_ops = &fat32_ops;
-		break;
-	case 16:
+	} else if (is_fat16(sbi)) {
 		sbi->fatent_shift = 1;
 		sbi->fatent_ops = &fat16_ops;
-		break;
-	case 12:
+	} else if (is_fat12(sbi)) {
 		sbi->fatent_shift = -1;
 		sbi->fatent_ops = &fat12_ops;
-		break;
+	} else {
+		fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
 	}
 }
 
@@ -310,7 +308,7 @@
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
-	if (sb_rdonly(sb) || sbi->fat_bits != 32)
+	if (sb_rdonly(sb) || !is_fat32(sbi))
 		return;
 
 	__mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
@@ -327,7 +325,7 @@
 	/* Is this fatent's blocks including this entry? */
 	if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
 		return 0;
-	if (sbi->fat_bits == 12) {
+	if (is_fat12(sbi)) {
 		if ((offset + 1) < sb->s_blocksize) {
 			/* This entry is on bhs[0]. */
 			if (fatent->nr_bhs == 2) {
@@ -390,8 +388,11 @@
 				err = -ENOMEM;
 				goto error;
 			}
+			/* Avoid race with userspace read via bdev */
+			lock_buffer(c_bh);
 			memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
 			set_buffer_uptodate(c_bh);
+			unlock_buffer(c_bh);
 			mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
 			if (sb->s_flags & SB_SYNCHRONOUS)
 				err = sync_dirty_buffer(c_bh);