Re: kernel BUG at fs/direct-io.c:916!

[Nathan Scott <nathans@sgi.com>]

On Tue, Mar 28, 2006 at 09:30:44AM -0800, Badari Pulavarty wrote:
> Thanks for working this out. You may want to add a description
> to the patch. Like:
> 
> "inode->i_blkbits should be used instead of dio->blkbits, as
> it may not indicate the filesystem block size all the time".

Will do, thanks.  Oh, another thing - what is the situation
where a NULL bdev would be passed into __blockdev_direct_IO?
All the filesystems seem to pass i_sb->s_bdev, so I guess it
must be blkdev_direct_IO - can I_BDEV(inode) ever be NULL on
a block device inode (doesn't sound right)?  If it cannot, I
suppose we should remove those NULL bdev checks too...

cheers.

-- 
Nathan


Index: xfs-linux-2.6/fs/direct-io.c
===================================================================
--- xfs-linux-2.6.orig/fs/direct-io.c
+++ xfs-linux-2.6/fs/direct-io.c
@@ -1186,8 +1186,8 @@ __blockdev_direct_IO(int rw, struct kioc
 	size_t size;
 	unsigned long addr;
 	unsigned blkbits = inode->i_blkbits;
-	unsigned bdev_blkbits = 0;
 	unsigned blocksize_mask = (1 << blkbits) - 1;
+	unsigned bdev_blkbits = blksize_bits(bdev_hardsect_size(bdev));
 	ssize_t retval = -EINVAL;
 	loff_t end = offset;
 	struct dio *dio;
@@ -1197,12 +1197,8 @@ __blockdev_direct_IO(int rw, struct kioc
 	if (rw & WRITE)
 		current->flags |= PF_SYNCWRITE;
 
-	if (bdev)
-		bdev_blkbits = blksize_bits(bdev_hardsect_size(bdev));
-
 	if (offset & blocksize_mask) {
-		if (bdev)
-			 blkbits = bdev_blkbits;
+		blkbits = bdev_blkbits;
 		blocksize_mask = (1 << blkbits) - 1;
 		if (offset & blocksize_mask)
 			goto out;
@@ -1214,8 +1210,7 @@ __blockdev_direct_IO(int rw, struct kioc
 		size = iov[seg].iov_len;
 		end += size;
 		if ((addr & blocksize_mask) || (size & blocksize_mask))  {
-			if (bdev)
-				 blkbits = bdev_blkbits;
+			blkbits = bdev_blkbits;
 			blocksize_mask = (1 << blkbits) - 1;
 			if ((addr & blocksize_mask) || (size & blocksize_mask))  
 				goto out;