nilfs2: use mnt_want_write in ioctls where write access is needed
A few nilfs2 ioctls need to ask for and then later release write
access to the mount in order to avoid potential write to read-only
mounts.
This adds the missing mnt_want_write and mnt_drop_write in
nilfs_ioctl_change_cpmode, nilfs_ioctl_delete_checkpoint, and
nilfs_ioctl_clean_segments.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index d6b2b83..8e5cad0 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -26,6 +26,7 @@
#include <linux/capability.h> /* capable() */
#include <linux/uaccess.h> /* copy_from_user(), copy_to_user() */
#include <linux/vmalloc.h>
+#include <linux/mount.h> /* mnt_want_write(), mnt_drop_write() */
#include <linux/nilfs2_fs.h>
#include "nilfs.h"
#include "segment.h"
@@ -107,20 +108,28 @@
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+
+ ret = mnt_want_write(filp->f_path.mnt);
+ if (ret)
+ return ret;
+
+ ret = -EFAULT;
if (copy_from_user(&cpmode, argp, sizeof(cpmode)))
- return -EFAULT;
+ goto out;
mutex_lock(&nilfs->ns_mount_mutex);
+
nilfs_transaction_begin(inode->i_sb, &ti, 0);
ret = nilfs_cpfile_change_cpmode(
cpfile, cpmode.cm_cno, cpmode.cm_mode);
- if (unlikely(ret < 0)) {
+ if (unlikely(ret < 0))
nilfs_transaction_abort(inode->i_sb);
- mutex_unlock(&nilfs->ns_mount_mutex);
- return ret;
- }
- nilfs_transaction_commit(inode->i_sb); /* never fails */
+ else
+ nilfs_transaction_commit(inode->i_sb); /* never fails */
+
mutex_unlock(&nilfs->ns_mount_mutex);
+out:
+ mnt_drop_write(filp->f_path.mnt);
return ret;
}
@@ -135,16 +144,23 @@
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+
+ ret = mnt_want_write(filp->f_path.mnt);
+ if (ret)
+ return ret;
+
+ ret = -EFAULT;
if (copy_from_user(&cno, argp, sizeof(cno)))
- return -EFAULT;
+ goto out;
nilfs_transaction_begin(inode->i_sb, &ti, 0);
ret = nilfs_cpfile_delete_checkpoint(cpfile, cno);
- if (unlikely(ret < 0)) {
+ if (unlikely(ret < 0))
nilfs_transaction_abort(inode->i_sb);
- return ret;
- }
- nilfs_transaction_commit(inode->i_sb); /* never fails */
+ else
+ nilfs_transaction_commit(inode->i_sb); /* never fails */
+out:
+ mnt_drop_write(filp->f_path.mnt);
return ret;
}
@@ -496,12 +512,19 @@
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (copy_from_user(argv, argp, sizeof(argv)))
- return -EFAULT;
+ ret = mnt_want_write(filp->f_path.mnt);
+ if (ret)
+ return ret;
+ ret = -EFAULT;
+ if (copy_from_user(argv, argp, sizeof(argv)))
+ goto out;
+
+ ret = -EINVAL;
nsegs = argv[4].v_nmembs;
if (argv[4].v_size != argsz[4])
- return -EINVAL;
+ goto out;
+
/*
* argv[4] points to segment numbers this ioctl cleans. We
* use kmalloc() for its buffer because memory used for the
@@ -509,9 +532,10 @@
*/
kbufs[4] = memdup_user((void __user *)(unsigned long)argv[4].v_base,
nsegs * sizeof(__u64));
- if (IS_ERR(kbufs[4]))
- return PTR_ERR(kbufs[4]);
-
+ if (IS_ERR(kbufs[4])) {
+ ret = PTR_ERR(kbufs[4]);
+ goto out;
+ }
nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
for (n = 0; n < 4; n++) {
@@ -563,10 +587,12 @@
nilfs_remove_all_gcinode(nilfs);
clear_nilfs_gc_running(nilfs);
- out_free:
+out_free:
while (--n >= 0)
vfree(kbufs[n]);
kfree(kbufs[4]);
+out:
+ mnt_drop_write(filp->f_path.mnt);
return ret;
}