[PATCH 11/28] elevate writer count for chown and friends

Dave Hansen
2006-08-02T00:02:40Z

chown/chmod,etc... don't call permission in the same way
that the normal "open for write" calls do. They still
write to the filesystem, so bump the write count during
these operations.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

lxc-dave/fs/open.c | 38 +++++++++++++++++++++++++++++++++-----
1 files changed, 33 insertions(+), 5 deletions(-)

diff -puN fs/open.c~C-elevate-writers-chown-and-friends fs/open.c
--- lxc/fs/open.c~C-elevate-writers-chown-and-friends 2006-08-01 16:35:13.000000000 -0700
+++ lxc-dave/fs/open.c 2006-08-01 16:35:22.000000000 -0700
@@ -644,9 +644,12 @@ asmlinkage long sys_fchmod(unsigned int
err = -EROFS;
if (IS_RDONLY(inode))
goto out_putf;
+ err = mnt_want_write(file->f_vfsmnt);
+ if (err)
+ goto out_putf;
err = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto out_putf;
+ goto out_drop_write;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
mode = inode->i_mode;
@@ -655,6 +658,8 @@ asmlinkage long sys_fchmod(unsigned int
err = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);

+out_drop_write:
+ mnt_drop_write(file->f_vfsmnt);
out_putf:
fput(file);
out:
@@ -674,13 +679,16 @@ asmlinkage long sys_fchmodat(int dfd, co
goto out;
inode = nd.dentry->d_inode;

+ error = mnt_want_write(nd.mnt);
+ if (error)
+ goto dput_and_out;
error = -EROFS;
if (IS_RDONLY(inode))
- goto dput_and_out;
+ goto out_drop_write;

error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto dput_and_out;
+ goto out_drop_write;

mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
@@ -690,6 +698,8 @@ asmlinkage long sys_fchmodat(int dfd, co
error = notify_change(nd.dentry, &newattrs);
mutex_unlock(&inode->i_mutex);

+out_drop_write:
+ mnt_drop_write(nd.mnt);
dput_and_out:
path_release(&nd);
out:
@@ -715,7 +725,7 @@ static int chown_common(struct dentry *
error = -EROFS;
if (IS_RDONLY(inode))
goto out;
- error = -EPERM;
+ error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto out;
newattrs.ia_valid = ATTR_CTIME;
@@ -744,7 +754,12 @@ asmlinkage long sys_chown(const char __u
error = user_path_walk(filename, &nd);
if (error)
goto out;
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ goto out_release;
error = chown_common(nd.dentry, user, group);
+ mnt_drop_write(nd.mnt);
+out_release:
path_release(&nd);
out:
return error;
@@ -764,7 +779,12 @@ asmlinkage long sys_fchownat(int dfd, co
error = __user_walk_fd(dfd, filename, follow, &nd);
if (error)
goto out;
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ goto out_release;
error = chown_common(nd.dentry, user, group);
+ mnt_drop_write(nd.mnt);
+out_release:
path_release(&nd);
out:
return error;
@@ -778,7 +798,11 @@ asmlinkage long sys_lchown(const char __
error = user_path_walk_link(filename, &nd);
if (error)
goto out;
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ goto out_release;
error = chown_common(nd.dentry, user, group);
+out_release:
path_release(&nd);
out:
return error;
@@ -794,10 +818,14 @@ asmlinkage long sys_fchown(unsigned int
file = fget(fd);
if (!file)
goto out;
-
+ error = mnt_want_write(file->f_vfsmnt);
+ if (error)
+ goto out_fput;
dentry = file->f_dentry;
audit_inode(NULL, dentry->d_inode);
error = chown_common(dentry, user, group);
+ mnt_drop_write(file->f_vfsmnt);
+out_fput:
fput(file);
out:
return error;
_