[PATCH 04/22] elevate writer count for chown and friends

Dave Hansen
2007-02-09T23:01:01Z

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 | 37 +++++++++++++++++++++++++++++++++----
1 file changed, 33 insertions(+), 4 deletions(-)

diff -puN fs/open.c~06-24-elevate-writer-count-for-chown-and-friends fs/open.c
--- lxc/fs/open.c~06-24-elevate-writer-count-for-chown-and-friends 2007-02-09 14:26:48.000000000 -0800
+++ lxc-dave/fs/open.c 2007-02-09 14:26:48.000000000 -0800
@@ -511,9 +511,12 @@ 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;
@@ -522,6 +525,8 @@ 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:
@@ -541,13 +546,16 @@ 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)
@@ -557,6 +565,8 @@ 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:
@@ -582,7 +592,7 @@ 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;
@@ -611,7 +621,12 @@ 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;
@@ -631,7 +646,12 @@ 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;
@@ -645,7 +665,11 @@ 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;
@@ -662,9 +686,14 @@ asmlinkage long sys_fchown(unsigned int
if (!file)
goto out;

+ error = mnt_want_write(file->f_vfsmnt);
+ if (error)
+ goto out_fput;
dentry = file->f_path.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;
_