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filesystem freeze: implement generic freeze feature

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The ioctls for the generic freeze feature are below.
o Freeze the filesystem
  int ioctl(int fd, int FIFREEZE, arg)
    fd: The file descriptor of the mountpoint
    FIFREEZE: request code for the freeze
    arg: Ignored
    Return value: 0 if the operation succeeds. Otherwise, -1

o Unfreeze the filesystem
  int ioctl(int fd, int FITHAW, arg)
    fd: The file descriptor of the mountpoint
    FITHAW: request code for unfreeze
    arg: Ignored
    Return value: 0 if the operation succeeds. Otherwise, -1
    Error number: If the filesystem has already been unfrozen,
                  errno is set to EINVAL.

[akpm@linux-foundation.org: fix CONFIG_BLOCK=n]
Signed-off-by: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Masayuki Hamaguchi <m-hamaguchi@ys.jp.nec.com>
Cc: <xfs-masters@oss.sgi.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Takashi Sato
2009-01-09 16:40:59 -08:00
committed by Linus Torvalds
parent c4be0c1dc4
commit fcccf50254
5 changed files with 130 additions and 10 deletions
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46
fs/ioctl.c
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@@ -439,6 +439,43 @@ static int ioctl_fioasync(unsigned int fd, struct file *filp,
return error;
}
static int ioctl_fsfreeze(struct file *filp)
{
struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/* If filesystem doesn't support freeze feature, return. */
if (sb->s_op->freeze_fs == NULL)
return -EOPNOTSUPP;
/* If a blockdevice-backed filesystem isn't specified, return. */
if (sb->s_bdev == NULL)
return -EINVAL;
/* Freeze */
sb = freeze_bdev(sb->s_bdev);
if (IS_ERR(sb))
return PTR_ERR(sb);
return 0;
}
static int ioctl_fsthaw(struct file *filp)
{
struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/* If a blockdevice-backed filesystem isn't specified, return EINVAL. */
if (sb->s_bdev == NULL)
return -EINVAL;
/* Thaw */
return thaw_bdev(sb->s_bdev, sb);
}
/*
* When you add any new common ioctls to the switches above and below
* please update compat_sys_ioctl() too.
@@ -486,6 +523,15 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
} else
error = -ENOTTY;
break;
case FIFREEZE:
error = ioctl_fsfreeze(filp);
break;
case FITHAW:
error = ioctl_fsthaw(filp);
break;
default:
if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
error = file_ioctl(filp, cmd, arg);