hfsplus: use raw bio access for partition tables

Switch the hfsplus partition table reding for cdroms to use our bio
helpers.  Again we don't rely on any caching in the buffer_heads, and
this gets rid of the last buffer_head use in hfsplus.
Signed-off-by: Christoph Hellwig <hch@tuxera.com>

fs/hfsplus/hfsplus_fs.h

@@ -401,23 +401,6 @@ static inline struct hfsplus_inode_info *HFSPLUS_I(struct inode *inode)
 	return list_entry(inode, struct hfsplus_inode_info, vfs_inode);
 }
 
-#define sb_bread512(sb, sec, data) ({			\
-	struct buffer_head *__bh;			\
-	sector_t __block;				\
-	loff_t __start;					\
-	int __offset;					\
-							\
-	__start = (loff_t)(sec) << HFSPLUS_SECTOR_SHIFT;\
-	__block = __start >> (sb)->s_blocksize_bits;	\
-	__offset = __start & ((sb)->s_blocksize - 1);	\
-	__bh = sb_bread((sb), __block);			\
-	if (likely(__bh != NULL))			\
-		data = (void *)(__bh->b_data + __offset);\
-	else						\
-		data = NULL;				\
-	__bh;						\
-})
-
 /* time macros */
 #define __hfsp_mt2ut(t)		(be32_to_cpu(t) - 2082844800U)
 #define __hfsp_ut2mt(t)		(cpu_to_be32(t + 2082844800U))

fs/hfsplus/part_tbl.c

@@ -13,6 +13,7 @@
  *
  */
 
+#include <linux/slab.h>
 #include "hfsplus_fs.h"
 
 /* offsets to various blocks */
@@ -65,70 +66,87 @@ struct old_pmap {
 	}	pdEntry[42];
 } __packed;
 
-/*
- * hfs_part_find()
- *
- * Parse the partition map looking for the
- * start and length of the 'part'th HFS partition.
- */
-int hfs_part_find(struct super_block *sb,
+static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm,
 		sector_t *part_start, sector_t *part_size)
 {
 	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
-	struct buffer_head *bh;
-	__be16 *data;
-	int i, size, res;
+	int i;
 
-	res = -ENOENT;
-	bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data);
-	if (!bh)
-		return -EIO;
+	for (i = 0; i < 42; i++) {
+		struct old_pmap_entry *p = &pm->pdEntry[i];
 
-	switch (be16_to_cpu(*data)) {
-	case HFS_OLD_PMAP_MAGIC:
-	  {
-		struct old_pmap *pm;
-		struct old_pmap_entry *p;
-
-		pm = (struct old_pmap *)bh->b_data;
-		p = pm->pdEntry;
-		size = 42;
-		for (i = 0; i < size; p++, i++) {
 		if (p->pdStart && p->pdSize &&
 		    p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
 		    (sbi->part < 0 || sbi->part == i)) {
 			*part_start += be32_to_cpu(p->pdStart);
 			*part_size = be32_to_cpu(p->pdSize);
-				res = 0;
-			}
+			return 0;
 		}
-		break;
 	}
-	case HFS_NEW_PMAP_MAGIC:
-	  {
-		struct new_pmap *pm;
 
-		pm = (struct new_pmap *)bh->b_data;
-		size = be32_to_cpu(pm->pmMapBlkCnt);
-		for (i = 0; i < size;) {
+	return -ENOENT;
+}
+
+static int hfs_parse_new_pmap(struct super_block *sb, struct new_pmap *pm,
+		sector_t *part_start, sector_t *part_size)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	int size = be32_to_cpu(pm->pmMapBlkCnt);
+	int res;
+	int i = 0;
+
+	do {
 		if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
 		    (sbi->part < 0 || sbi->part == i)) {
 			*part_start += be32_to_cpu(pm->pmPyPartStart);
 			*part_size = be32_to_cpu(pm->pmPartBlkCnt);
-				res = 0;
-				break;
+			return 0;
 		}
-			brelse(bh);
-			bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm);
-			if (!bh)
-				return -EIO;
-			if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC))
+
+		if (++i >= size)
+			return -ENOENT;
+
+		res = hfsplus_submit_bio(sb->s_bdev,
+					 *part_start + HFS_PMAP_BLK + i,
+					 pm, READ);
+		if (res)
+			return res;
+	} while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
+
+	return -ENOENT;
+}
+
+/*
+ * Parse the partition map looking for the start and length of a
+ * HFS/HFS+ partition.
+ */
+int hfs_part_find(struct super_block *sb,
+		sector_t *part_start, sector_t *part_size)
+{
+	void *data;
+	int res;
+
+	data = kmalloc(HFSPLUS_SECTOR_SIZE, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = hfsplus_submit_bio(sb->s_bdev, *part_start + HFS_PMAP_BLK,
+				 data, READ);
+	if (res)
+		return res;
+
+	switch (be16_to_cpu(*((__be16 *)data))) {
+	case HFS_OLD_PMAP_MAGIC:
+		res = hfs_parse_old_pmap(sb, data, part_start, part_size);
 		break;
-		}
+	case HFS_NEW_PMAP_MAGIC:
+		res = hfs_parse_new_pmap(sb, data, part_start, part_size);
+		break;
+	default:
+		res = -ENOENT;
 		break;
 	}
-	}
-	brelse(bh);
 
+	kfree(data);
 	return res;
 }