Re: [PATCH 08/20] adfs: remove the big kernel lock

Russell King
2011-01-25T22:20:53Z

On Tue, Jan 25, 2011 at 11:17:22PM +0100, Arnd Bergmann wrote:
> According to Russell King, adfs was written to not require the big
> kernel lock, and all inode updates are done under adfs_dir_lock.
>
> All other metadata in adfs is read-only and does not require locking.
> The use of the BKL is the result of various pushdowns from the VFS
> operations.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Cc: Russell King <rmk@arm.linux.org.uk>

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

> Cc: Stuart Swales <stuart.swales.croftnuisk@gmail.com>
> ---
> fs/adfs/Kconfig | 1 -
> fs/adfs/dir.c | 6 ------
> fs/adfs/inode.c | 6 ------
> fs/adfs/super.c | 13 +------------
> 4 files changed, 1 insertions(+), 25 deletions(-)
>
> diff --git a/fs/adfs/Kconfig b/fs/adfs/Kconfig
> index 1dd5f34..e55182a 100644
> --- a/fs/adfs/Kconfig
> +++ b/fs/adfs/Kconfig
> @@ -1,7 +1,6 @@
> config ADFS_FS
> tristate "ADFS file system support (EXPERIMENTAL)"
> depends on BLOCK && EXPERIMENTAL
> - depends on BKL # need to fix
> help
> The Acorn Disc Filing System is the standard file system of the
> RiscOS operating system which runs on Acorn's ARM-based Risc PC
> diff --git a/fs/adfs/dir.c b/fs/adfs/dir.c
> index 3b4a764..3d83075 100644
> --- a/fs/adfs/dir.c
> +++ b/fs/adfs/dir.c
> @@ -9,7 +9,6 @@
> *
> * Common directory handling for ADFS
> */
> -#include <linux/smp_lock.h>
> #include "adfs.h"
>
> /*
> @@ -27,8 +26,6 @@ adfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
> struct adfs_dir dir;
> int ret = 0;
>
> - lock_kernel();
> -
> if (filp->f_pos >> 32)
> goto out;
>
> @@ -70,7 +67,6 @@ free_out:
> ops->free(&dir);
>
> out:
> - unlock_kernel();
> return ret;
> }
>
> @@ -276,7 +272,6 @@ adfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
> struct object_info obj;
> int error;
>
> - lock_kernel();
> error = adfs_dir_lookup_byname(dir, &dentry->d_name, &obj);
> if (error == 0) {
> error = -EACCES;
> @@ -288,7 +283,6 @@ adfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
> if (inode)
> error = 0;
> }
> - unlock_kernel();
> d_add(dentry, inode);
> return ERR_PTR(error);
> }
> diff --git a/fs/adfs/inode.c b/fs/adfs/inode.c
> index 65794b8..09fe401 100644
> --- a/fs/adfs/inode.c
> +++ b/fs/adfs/inode.c
> @@ -7,7 +7,6 @@
> * it under the terms of the GNU General Public License version 2 as
> * published by the Free Software Foundation.
> */
> -#include <linux/smp_lock.h>
> #include <linux/buffer_head.h>
> #include <linux/writeback.h>
> #include "adfs.h"
> @@ -316,8 +315,6 @@ adfs_notify_change(struct dentry *dentry, struct iattr *attr)
> unsigned int ia_valid = attr->ia_valid;
> int error;
>
> - lock_kernel();
> -
> error = inode_change_ok(inode, attr);
>
> /*
> @@ -359,7 +356,6 @@ adfs_notify_change(struct dentry *dentry, struct iattr *attr)
> if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
> mark_inode_dirty(inode);
> out:
> - unlock_kernel();
> return error;
> }
>
> @@ -374,7 +370,6 @@ int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
> struct object_info obj;
> int ret;
>
> - lock_kernel();
> obj.file_id = inode->i_ino;
> obj.name_len = 0;
> obj.parent_id = ADFS_I(inode)->parent_id;
> @@ -384,6 +379,5 @@ int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
> obj.size = inode->i_size;
>
> ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
> - unlock_kernel();
> return ret;
> }
> diff --git a/fs/adfs/super.c b/fs/adfs/super.c
> index 2d79540..06d7388 100644
> --- a/fs/adfs/super.c
> +++ b/fs/adfs/super.c
> @@ -14,7 +14,6 @@
> #include <linux/mount.h>
> #include <linux/seq_file.h>
> #include <linux/slab.h>
> -#include <linux/smp_lock.h>
> #include <linux/statfs.h>
> #include "adfs.h"
> #include "dir_f.h"
> @@ -120,15 +119,11 @@ static void adfs_put_super(struct super_block *sb)
> int i;
> struct adfs_sb_info *asb = ADFS_SB(sb);
>
> - lock_kernel();
> -
> for (i = 0; i < asb->s_map_size; i++)
> brelse(asb->s_map[i].dm_bh);
> kfree(asb->s_map);
> kfree(asb);
> sb->s_fs_info = NULL;
> -
> - unlock_kernel();
> }
>
> static int adfs_show_options(struct seq_file *seq, struct vfsmount *mnt)
> @@ -359,15 +354,11 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
> struct adfs_sb_info *asb;
> struct inode *root;
>
> - lock_kernel();
> -
> sb->s_flags |= MS_NODIRATIME;
>
> asb = kzalloc(sizeof(*asb), GFP_KERNEL);
> - if (!asb) {
> - unlock_kernel();
> + if (!asb)
> return -ENOMEM;
> - }
> sb->s_fs_info = asb;
>
> /* set default options */
> @@ -485,7 +476,6 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
> adfs_error(sb, "get root inode failed\n");
> goto error;
> }
> - unlock_kernel();
> return 0;
>
> error_free_bh:
> @@ -493,7 +483,6 @@ error_free_bh:
> error:
> sb->s_fs_info = NULL;
> kfree(asb);
> - unlock_kernel();
> return -EINVAL;
> }
>
> --
> 1.7.1
>

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/