1 files changed, 69 insertions, 36 deletions

diff --git a/fs/fat/cache.c b/fs/fat/cache.c
index 91ad9e1c9441..2af424e200b3 100644
--- a/fs/fat/cache.c
+++ b/fs/fat/cache.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  *  linux/fs/fat/cache.c
  *
@@ -8,9 +9,7 @@
  *  May 1999. AV. Fixed the bogosity with FAT32 (read "FAT28"). Fscking lusers.
  */
 
-#include <linux/fs.h>
 #include <linux/slab.h>
-#include <linux/buffer_head.h>
 #include "fat.h"
 
 /* this must be > 0. */
@@ -48,7 +47,7 @@ int __init fat_cache_init(void)
 {
 	fat_cache_cachep = kmem_cache_create("fat_cache",
 				sizeof(struct fat_cache),
-				0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
+				0, SLAB_RECLAIM_ACCOUNT,
 				init_once);
 	if (fat_cache_cachep == NULL)
 		return -ENOMEM;
@@ -226,7 +225,8 @@ static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus)
 int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
 {
 	struct super_block *sb = inode->i_sb;
-	const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->cluster_bits;
+	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+	const int limit = sb->s_maxbytes >> sbi->cluster_bits;
 	struct fat_entry fatent;
 	struct fat_cache_id cid;
 	int nr;
@@ -235,6 +235,12 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
 
 	*fclus = 0;
 	*dclus = MSDOS_I(inode)->i_start;
+	if (!fat_valid_entry(sbi, *dclus)) {
+		fat_fs_error_ratelimit(sb,
+			"%s: invalid start cluster (i_pos %lld, start %08x)",
+			__func__, MSDOS_I(inode)->i_pos, *dclus);
+		return -EIO;
+	}
 	if (cluster == 0)
 		return 0;
 
@@ -251,9 +257,8 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
 		/* prevent the infinite loop of cluster chain */
 		if (*fclus > limit) {
 			fat_fs_error_ratelimit(sb,
-					"%s: detected the cluster chain loop"
-					" (i_pos %lld)", __func__,
-					MSDOS_I(inode)->i_pos);
+				"%s: detected the cluster chain loop (i_pos %lld)",
+				__func__, MSDOS_I(inode)->i_pos);
 			nr = -EIO;
 			goto out;
 		}
@@ -263,9 +268,8 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
 			goto out;
 		else if (nr == FAT_ENT_FREE) {
 			fat_fs_error_ratelimit(sb,
-				       "%s: invalid cluster chain (i_pos %lld)",
-				       __func__,
-				       MSDOS_I(inode)->i_pos);
+				"%s: invalid cluster chain (i_pos %lld)",
+				__func__, MSDOS_I(inode)->i_pos);
 			nr = -EIO;
 			goto out;
 		} else if (nr == FAT_ENT_EOF) {
@@ -303,19 +307,63 @@ static int fat_bmap_cluster(struct inode *inode, int cluster)
 	return dclus;
 }
 
-int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
-	     unsigned long *mapped_blocks, int create)
+int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
+			   sector_t last_block,
+			   unsigned long *mapped_blocks, sector_t *bmap)
 {
 	struct super_block *sb = inode->i_sb;
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+	int cluster, offset;
+
+	cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
+	offset  = sector & (sbi->sec_per_clus - 1);
+	cluster = fat_bmap_cluster(inode, cluster);
+	if (cluster < 0)
+		return cluster;
+	else if (cluster) {
+		*bmap = fat_clus_to_blknr(sbi, cluster) + offset;
+		*mapped_blocks = sbi->sec_per_clus - offset;
+		if (*mapped_blocks > last_block - sector)
+			*mapped_blocks = last_block - sector;
+	}
+
+	return 0;
+}
+
+static int is_exceed_eof(struct inode *inode, sector_t sector,
+			 sector_t *last_block, int create)
+{
+	struct super_block *sb = inode->i_sb;
 	const unsigned long blocksize = sb->s_blocksize;
 	const unsigned char blocksize_bits = sb->s_blocksize_bits;
+
+	*last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
+	if (sector >= *last_block) {
+		if (!create)
+			return 1;
+
+		/*
+		 * ->mmu_private can access on only allocation path.
+		 * (caller must hold ->i_mutex)
+		 */
+		*last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
+			>> blocksize_bits;
+		if (sector >= *last_block)
+			return 1;
+	}
+
+	return 0;
+}
+
+int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
+	     unsigned long *mapped_blocks, int create, bool from_bmap)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 	sector_t last_block;
-	int cluster, offset;
 
 	*phys = 0;
 	*mapped_blocks = 0;
-	if ((sbi->fat_bits != 32) && (inode->i_ino == MSDOS_ROOT_INO)) {
+	if (!is_fat32(sbi) && (inode->i_ino == MSDOS_ROOT_INO)) {
 		if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
 			*phys = sector + sbi->dir_start;
 			*mapped_blocks = 1;
@@ -323,31 +371,16 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
 		return 0;
 	}
 
-	last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
-	if (sector >= last_block) {
-		if (!create)
+	if (!from_bmap) {
+		if (is_exceed_eof(inode, sector, &last_block, create))
 			return 0;
-
-		/*
-		 * ->mmu_private can access on only allocation path.
-		 * (caller must hold ->i_mutex)
-		 */
-		last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
-			>> blocksize_bits;
+	} else {
+		last_block = inode->i_blocks >>
+				(inode->i_sb->s_blocksize_bits - 9);
 		if (sector >= last_block)
 			return 0;
 	}
 
-	cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
-	offset  = sector & (sbi->sec_per_clus - 1);
-	cluster = fat_bmap_cluster(inode, cluster);
-	if (cluster < 0)
-		return cluster;
-	else if (cluster) {
-		*phys = fat_clus_to_blknr(sbi, cluster) + offset;
-		*mapped_blocks = sbi->sec_per_clus - offset;
-		if (*mapped_blocks > last_block - sector)
-			*mapped_blocks = last_block - sector;
-	}
-	return 0;
+	return fat_get_mapped_cluster(inode, sector, last_block, mapped_blocks,
+				      phys);
 }