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BKL: Explicitly add BKL around get_sb/fill_super

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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>
This commit is contained in:
Jan Blunck
2010-08-15 22:51:10 +02:00
committed by Arnd Bergmann
parent 899611ee7d
commit db71922217
28 changed files with 187 additions and 25 deletions
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4
kernel/cgroup.c
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@@ -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;
}