BKL: Explicitly add BKL around get_sb/fill_super
This patch is a preparation necessary to remove the BKL from do_new_mount().
It explicitly adds calls to lock_kernel()/unlock_kernel() around
get_sb/fill_super operations for filesystems that still uses the BKL.
I've read through all the code formerly covered by the BKL inside
do_kern_mount() and have satisfied myself that it doesn't need the BKL
any more.
do_kern_mount() is already called without the BKL when mounting the rootfs
and in nfsctl. do_kern_mount() calls vfs_kern_mount(), which is called
from various places without BKL: simple_pin_fs(), nfs_do_clone_mount()
through nfs_follow_mountpoint(), afs_mntpt_do_automount() through
afs_mntpt_follow_link(). Both later functions are actually the filesystems
follow_link inode operation. vfs_kern_mount() is calling the specified
get_sb function and lets the filesystem do its job by calling the given
fill_super function.
Therefore I think it is safe to push down the BKL from the VFS to the
low-level filesystems get_sb/fill_super operation.
[arnd: do not add the BKL to those file systems that already
don't use it elsewhere]
Signed-off-by: Jan Blunck <jblunck@infradead.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Christoph Hellwig <hch@infradead.org>
diff --git a/fs/freevxfs/vxfs_super.c b/fs/freevxfs/vxfs_super.c
index dc0c041..eb2b9e0 100644
--- a/fs/freevxfs/vxfs_super.c
+++ b/fs/freevxfs/vxfs_super.c
@@ -148,7 +148,7 @@
* The superblock on success, else %NULL.
*
* Locking:
- * We are under the bkl and @sbp->s_lock.
+ * We are under @sbp->s_lock.
*/
static int vxfs_fill_super(struct super_block *sbp, void *dp, int silent)
{
@@ -159,11 +159,14 @@
struct inode *root;
int ret = -EINVAL;
+ lock_kernel();
+
sbp->s_flags |= MS_RDONLY;
infp = kzalloc(sizeof(*infp), GFP_KERNEL);
if (!infp) {
printk(KERN_WARNING "vxfs: unable to allocate incore superblock\n");
+ unlock_kernel();
return -ENOMEM;
}
@@ -236,6 +239,7 @@
goto out_free_ilist;
}
+ unlock_kernel();
return 0;
out_free_ilist:
@@ -245,6 +249,7 @@
out:
brelse(bp);
kfree(infp);
+ unlock_kernel();
return ret;
}