[PATCH] fuse: add blksize option

Add 'blksize' option for block device based filesystems.  During
initialization this is used to set the block size on the device and the super
block.  The default block size is 512bytes.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/filesystems/fuse.txt

@@ -110,6 +110,11 @@ Mount options
   The default is infinite.  Note that the size of read requests is
   limited anyway to 32 pages (which is 128kbyte on i386).
 
+'blksize=N'
+
+  Set the block size for the filesystem.  The default is 512.  This
+  option is only valid for 'fuseblk' type mounts.
+
 Control filesystem
 ~~~~~~~~~~~~~~~~~~
 

fs/fuse/inode.c

@@ -39,6 +39,7 @@ struct fuse_mount_data {
 	unsigned group_id_present : 1;
 	unsigned flags;
 	unsigned max_read;
+	unsigned blksize;
 };
 
 static struct inode *fuse_alloc_inode(struct super_block *sb)
@@ -274,6 +275,7 @@ enum {
 	OPT_DEFAULT_PERMISSIONS,
 	OPT_ALLOW_OTHER,
 	OPT_MAX_READ,
+	OPT_BLKSIZE,
 	OPT_ERR
 };
 
@@ -285,14 +287,16 @@ static match_table_t tokens = {
 	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
 	{OPT_ALLOW_OTHER,		"allow_other"},
 	{OPT_MAX_READ,			"max_read=%u"},
+	{OPT_BLKSIZE,			"blksize=%u"},
 	{OPT_ERR,			NULL}
 };
 
-static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
+static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
 {
 	char *p;
 	memset(d, 0, sizeof(struct fuse_mount_data));
 	d->max_read = ~0;
+	d->blksize = 512;
 
 	while ((p = strsep(&opt, ",")) != NULL) {
 		int token;
@@ -345,6 +349,12 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
 			d->max_read = value;
 			break;
 
+		case OPT_BLKSIZE:
+			if (!is_bdev || match_int(&args[0], &value))
+				return 0;
+			d->blksize = value;
+			break;
+
 		default:
 			return 0;
 		}
@@ -500,15 +510,21 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 	struct dentry *root_dentry;
 	struct fuse_req *init_req;
 	int err;
+	int is_bdev = sb->s_bdev != NULL;
 
 	if (sb->s_flags & MS_MANDLOCK)
 		return -EINVAL;
 
-	if (!parse_fuse_opt((char *) data, &d))
+	if (!parse_fuse_opt((char *) data, &d, is_bdev))
 		return -EINVAL;
 
+	if (is_bdev) {
+		if (!sb_set_blocksize(sb, d.blksize))
+			return -EINVAL;
+	} else {
 		sb->s_blocksize = PAGE_CACHE_SIZE;
 		sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	}
 	sb->s_magic = FUSE_SUPER_MAGIC;
 	sb->s_op = &fuse_super_operations;
 	sb->s_maxbytes = MAX_LFS_FILESIZE;