Messages in this thread Patch in this message |  | | Date | Mon, 24 Sep 2001 23:18:54 -0400 | From | Chris Mason <> | Subject | [PATCH] invalidate buffers on blkdev_put |
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Hi guys,
I had sent this to Al, but couldn't tell if he hated it, thought it was broken, or just didn't think it was required. So, I opted for wider testing. This only affects 2.4.10pre15+, as it was caused by the blkdev changes there.
Anyway, the bug looks like this:
dd if=ext2-image-1 of=/dev/ram0 mount /dev/ram0 /mnt umount /mnt
dd if=ext2-image-2 of=/dev/ram0 mount /dev/ram0 /mnt ls -la /mnt (FS looks corrupted and wrong).
The problem is that on unmount, the ramdisk's buffer cache isn't cleared because bd_openers is still one. So, even if a new image is copied in, you still see the old image's superblock/inodes etc on mount.
In this case, we want to leave the dirty pages in the page cache, but get rid of the buffer cache copies.
This should not drop any updated data in the ramdisk because rd_blkdev_pagecache_IO dirties pages as the higher layers send down modified buffer heads (and other rd.c funcs do the same). Patch is below. Linus, please consider (pending lack of nays from Al).
An additional patch is probably to remove the second invalidate_buffers call, since only the filesystems should have buffer cache entries.
-chris
--- 3.1/fs/block_dev.c Sun, 23 Sep 2001 20:11:16 -0400 +++ 3.1(w)/fs/block_dev.c Mon, 24 Sep 2001 15:11:49 -0400 @@ -802,8 +802,10 @@ unlock_super(sb); drop_super(sb); } - } else if (kind == BDEV_FS) + } else if (kind == BDEV_FS) { fsync_no_super(rdev); + invalidate_buffers(rdev); + } if (!--bdev->bd_openers) { truncate_inode_pages(bd_inode->i_mapping, 0); invalidate_buffers(rdev); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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