Messages in this thread Patch in this message | | | Subject | [PATCH] Can't unmount bad inode | From | Miklos Szeredi <> | Date | Wed, 19 Jan 2005 22:20:51 +0100 |
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Andrew,
This patch fixes a problem when a inode which is the root of a mount becomes bad (make_bad_inode()). In this case follow_link will return -EIO, so the name resolution fails, and umount won't work. The solution is just to remove the follow_link method from bad_inode_ops. Any filesystem operation (other than unmount) will still fail, since every other method returns -EIO.
A test case for this is:
1) export an smbfs on A and mount the share on B
2) create directory X on A
3) bind mount X to Y on B
4) remove directory X, and create regular file X (same name) on A
5) stat X on B, this will make X a bad inode (file type changed)
6) umount Y
Without the patch applied, umount won't succeed, and a reboot is necessary to get rid of the mount.
With the patch applied, umount will succeed.
The same is true for any filesystem which uses make_bad_inode() to mark an existing inode bad (NFS, SMBFS, FUSE, etc...).
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
--- linux-2.6.10/fs/bad_inode.c.orig 2005-01-19 21:48:24.000000000 +0100 +++ linux-2.6.10/fs/bad_inode.c 2005-01-19 22:07:56.000000000 +0100 @@ -15,17 +15,6 @@ #include <linux/smp_lock.h> #include <linux/namei.h> -/* - * The follow_link operation is special: it must behave as a no-op - * so that a bad root inode can at least be unmounted. To do this - * we must dput() the base and return the dentry with a dget(). - */ -static int bad_follow_link(struct dentry *dent, struct nameidata *nd) -{ - nd_set_link(nd, ERR_PTR(-EIO)); - return 0; -} - static int return_EIO(void) { return -EIO; @@ -70,7 +59,8 @@ struct inode_operations bad_inode_ops = .mknod = EIO_ERROR, .rename = EIO_ERROR, .readlink = EIO_ERROR, - .follow_link = bad_follow_link, + /* follow_link must be no-op, otherwise unmounting this inode + won't work */ .truncate = EIO_ERROR, .permission = EIO_ERROR, .getattr = EIO_ERROR, - 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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