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authorJan Blunck <jblunck@infradead.org>2010-08-16 00:51:10 +0400
committerArnd Bergmann <arnd@arndb.de>2010-10-04 23:10:10 +0400
commitdb71922217a214e5c9268448e537b54fc1f301ea (patch)
tree9c9afbf29411547891f6968e5ade29ce59d66c07 /kernel/cgroup.c
parent899611ee7d373e5eeda08e9a8632684e1ebbbf00 (diff)
downloadlinux-db71922217a214e5c9268448e537b54fc1f301ea.tar.xz
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>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c9483d8f6140..a7ba3bccadc5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1430,6 +1430,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
struct super_block *sb;
struct cgroupfs_root *new_root;
+ lock_kernel();
+
/* First find the desired set of subsystems */
mutex_lock(&cgroup_mutex);
ret = parse_cgroupfs_options(data, &opts);
@@ -1559,6 +1561,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
simple_set_mnt(mnt, sb);
kfree(opts.release_agent);
kfree(opts.name);
+ unlock_kernel();
return 0;
drop_new_super:
@@ -1568,6 +1571,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
out_err:
kfree(opts.release_agent);
kfree(opts.name);
+ unlock_kernel();
return ret;
}