From db71922217a214e5c9268448e537b54fc1f301ea Mon Sep 17 00:00:00 2001 From: Jan Blunck Date: Sun, 15 Aug 2010 22:51:10 +0200 Subject: 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 Signed-off-by: Arnd Bergmann Cc: Matthew Wilcox Cc: Christoph Hellwig --- kernel/cgroup.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c9483d8f614..a7ba3bccadc 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; } -- cgit v1.2.3 From 38d018dba3f725b969f196550d92a6ec1c092428 Mon Sep 17 00:00:00 2001 From: Jan Blunck Date: Wed, 24 Feb 2010 13:25:34 +0100 Subject: BKL: Remove BKL from cgroup The BKL is only used in remount_fs and get_sb that are both protected by the superblocks s_umount rw_semaphore. Therefore it is safe to remove the BKL entirely. Signed-off-by: Jan Blunck Signed-off-by: Arnd Bergmann --- kernel/cgroup.c | 8 -------- 1 file changed, 8 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a7ba3bccadc..304d2775994 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -52,7 +52,6 @@ #include #include #include -#include #include #include #include /* TODO: replace with more sophisticated array */ @@ -1222,7 +1221,6 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) struct cgroup *cgrp = &root->top_cgroup; struct cgroup_sb_opts opts; - lock_kernel(); mutex_lock(&cgrp->dentry->d_inode->i_mutex); mutex_lock(&cgroup_mutex); @@ -1255,7 +1253,6 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) kfree(opts.name); mutex_unlock(&cgroup_mutex); mutex_unlock(&cgrp->dentry->d_inode->i_mutex); - unlock_kernel(); return ret; } @@ -1430,8 +1427,6 @@ 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); @@ -1561,7 +1556,6 @@ 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: @@ -1571,8 +1565,6 @@ static int cgroup_get_sb(struct file_system_type *fs_type, out_err: kfree(opts.release_agent); kfree(opts.name); - unlock_kernel(); - return ret; } -- cgit v1.2.3