X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=drivers%2Fblock%2Floop.c;h=3efc2ea7ad64395b71a41da99ca0ab7f3edfea4a;hb=6a77f38946aaee1cd85eeec6cf4229b204c15071;hp=f1250943c167f52700fcb5086380d7a117ecab2c;hpb=9213980e6a70d8473e0ffd4b39ab5b6caaba9ff5;p=linux-2.6.git

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f1250943c..3efc2ea7a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -47,7 +47,7 @@
 
 #include <linux/config.h>
 #include <linux/module.h>
-
+#include <linux/moduleparam.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
 #include <linux/file.h>
@@ -293,7 +293,7 @@ lo_read_actor(read_descriptor_t *desc, struct page *page,
 	      unsigned long offset, unsigned long size)
 {
 	unsigned long count = desc->count;
-	struct lo_read_data *p = (struct lo_read_data*)desc->buf;
+	struct lo_read_data *p = desc->arg.data;
 	struct loop_device *lo = p->lo;
 	sector_t IV;
 
@@ -622,10 +622,17 @@ static int loop_change_fd(struct loop_device *lo, struct file *lo_file,
 	return error;
 }
 
+static inline int is_loop_device(struct file *file)
+{
+	struct inode *i = file->f_mapping->host;
+
+	return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
+}
+
 static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
 		       struct block_device *bdev, unsigned int arg)
 {
-	struct file	*file;
+	struct file	*file, *f;
 	struct inode	*inode;
 	struct address_space *mapping;
 	unsigned lo_blocksize;
@@ -636,15 +643,31 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
 	/* This is safe, since we have a reference from open(). */
 	__module_get(THIS_MODULE);
 
-	error = -EBUSY;
-	if (lo->lo_state != Lo_unbound)
-		goto out;
-
 	error = -EBADF;
 	file = fget(arg);
 	if (!file)
 		goto out;
 
+	error = -EBUSY;
+	if (lo->lo_state != Lo_unbound)
+		goto out_putf;
+
+	/* Avoid recursion */
+	f = file;
+	while (is_loop_device(f)) {
+		struct loop_device *l;
+
+		if (f->f_mapping->host->i_rdev == lo_file->f_mapping->host->i_rdev)
+			goto out_putf;
+
+		l = f->f_mapping->host->i_bdev->bd_disk->private_data;
+		if (l->lo_state == Lo_unbound) {
+			error = -EINVAL;
+			goto out_putf;
+		}
+		f = l->lo_backing_file;
+	}
+
 	mapping = file->f_mapping;
 	inode = mapping->host;
 
@@ -1073,7 +1096,7 @@ static struct block_device_operations lo_fops = {
 /*
  * And now the modules code and kernel interface.
  */
-MODULE_PARM(max_loop, "i");
+module_param(max_loop, int, 0);
 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-256)");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);