[PATCH] restoring block size upon umount

get_sb_bdev() stores original block size in ->s_old_blocksize and
kill_block_super() restores it.

This kills 99% of crap with "oh, I've mounted/umounted that device and
its behaviour had changed" (remaining 1% can be dealt in pretty similar
ways; ideally I'd like to see ioctls that get/set block size dead and
gone).

fs/fat/inode.c

@@ -177,7 +177,6 @@ void fat_put_super(struct super_block *sb)
 		fat_clusters_flush(sb);
 	}
 	fat_cache_inval_dev(sb);
-	set_blocksize (sb->s_dev,BLOCK_SIZE);
 	if (sbi->nls_disk) {
 		unload_nls(sbi->nls_disk);
 		sbi->nls_disk = NULL;

fs/hfs/super.c

@@ -176,9 +176,6 @@ static void hfs_put_super(struct super_block *sb)
 	/* release the MDB's resources */
 	hfs_mdb_put(mdb, sb->s_flags & MS_RDONLY);
 
-	/* restore default blocksize for the device */
-	set_blocksize(sb->s_dev, BLOCK_SIZE);
-
 	kfree(sb->u.generic_sbp);
 	sb->u.generic_sbp = NULL;
 }
@@ -449,7 +446,6 @@ int hfs_fill_super(struct super_block *s, void *data, int silent)
 	struct hfs_sb_info *sbi;
 	struct hfs_mdb *mdb;
 	struct hfs_cat_key key;
-	kdev_t dev = s->s_dev;
 	hfs_s32 part_size, part_start;
 	struct inode *root_inode;
 	int part;
@@ -462,7 +458,7 @@ int hfs_fill_super(struct super_block *s, void *data, int silent)
 
 	if (!parse_options((char *)data, sbi, &part)) {
 		hfs_warn("hfs_fs: unable to parse mount options.\n");
-		goto bail3;
+		goto bail2;
 	}
 
 	/* set the device driver to 512-byte blocks */
@@ -530,8 +526,6 @@ int hfs_fill_super(struct super_block *s, void *data, int silent)
 bail1:
 	hfs_mdb_put(mdb, s->s_flags & MS_RDONLY);
 bail2:
-	set_blocksize(dev, BLOCK_SIZE);
-bail3:
 	kfree(sbi);
 	s->u.generic_sbp = NULL;
 	return -EINVAL;	

fs/reiserfs/super.c

@@ -991,7 +991,6 @@ int function2code (hashf_t func)
 //
 static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
 {
-    int size;
     struct inode *root_inode;
     int j;
     struct reiserfs_transaction_handle th ;
@@ -1013,9 +1012,6 @@ static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
 	return -EINVAL;
     }	
 
-    size = block_size(s->s_dev);
-    sb_set_blocksize(s, size);
-    
     /* try old format (undistributed bitmap, super block in 8-th 1k block of a device) */
     if (!read_super_block (s, REISERFS_OLD_DISK_OFFSET_IN_BYTES)) 
       old_format = 1;

fs/super.c

@@ -26,6 +26,7 @@
 #include <linux/smp_lock.h>
 #include <linux/devfs_fs_kernel.h>
 #include <linux/acct.h>
+#include <linux/blkdev.h>
 #include <asm/uaccess.h>
 
 void get_filesystem(struct file_system_type *fs);
@@ -513,6 +514,8 @@ struct super_block *get_sb_bdev(struct file_system_type *fs_type,
 	} else {
 		s->s_flags = flags;
 		strncpy(s->s_id, bdevname(dev), sizeof(s->s_id));
+		s->s_old_blocksize = block_size(dev);
+		sb_set_blocksize(s, s->s_old_blocksize);
 		error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
 		if (error) {
 			up_write(&s->s_umount);
@@ -535,6 +538,7 @@ void kill_block_super(struct super_block *sb)
 {
 	struct block_device *bdev = sb->s_bdev;
 	generic_shutdown_super(sb);
+	set_blocksize(to_kdev_t(bdev->bd_dev), sb->s_old_blocksize);
 	bd_release(bdev);
 	blkdev_put(bdev, BDEV_FS);
 }

include/linux/fs.h

@@ -664,6 +664,7 @@ struct super_block {
 	kdev_t			s_dev;
 	unsigned long		s_blocksize;
 	unsigned char		s_blocksize_bits;
+	unsigned long		s_old_blocksize;
 	unsigned char		s_dirt;
 	unsigned long long	s_maxbytes;	/* Max file size */
 	struct file_system_type	*s_type;