Revision 38d78e587d4960d0db94add518d27ee74bad2301 authored by Vladimir Davydov on 22 March 2013, 22:04:51 UTC, committed by Linus Torvalds on 22 March 2013, 23:41:21 UTC
mnt_drop_write() must be called only if mnt_want_write() succeeded, otherwise the mnt_writers counter will diverge. mnt_writers counters are used to check if remounting FS as read-only is OK, so after an extra mnt_drop_write() call, it would be impossible to remount mqueue FS as read-only. Besides, on umount a warning would be printed like this one: ===================================== [ BUG: bad unlock balance detected! ] 3.9.0-rc3 #5 Not tainted ------------------------------------- a.out/12486 is trying to release lock (sb_writers) at: mnt_drop_write+0x1f/0x30 but there are no more locks to release! Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Doug Ledford <dledford@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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generic_acl.c
/*
* (C) 2005 Andreas Gruenbacher <agruen@suse.de>
*
* This file is released under the GPL.
*
* Generic ACL support for in-memory filesystems.
*/
#include <linux/sched.h>
#include <linux/gfp.h>
#include <linux/fs.h>
#include <linux/generic_acl.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
static size_t
generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
const char *name, size_t name_len, int type)
{
struct posix_acl *acl;
const char *xname;
size_t size;
acl = get_cached_acl(dentry->d_inode, type);
if (!acl)
return 0;
posix_acl_release(acl);
switch (type) {
case ACL_TYPE_ACCESS:
xname = POSIX_ACL_XATTR_ACCESS;
break;
case ACL_TYPE_DEFAULT:
xname = POSIX_ACL_XATTR_DEFAULT;
break;
default:
return 0;
}
size = strlen(xname) + 1;
if (list && size <= list_size)
memcpy(list, xname, size);
return size;
}
static int
generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
size_t size, int type)
{
struct posix_acl *acl;
int error;
if (strcmp(name, "") != 0)
return -EINVAL;
acl = get_cached_acl(dentry->d_inode, type);
if (!acl)
return -ENODATA;
error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
posix_acl_release(acl);
return error;
}
static int
generic_acl_set(struct dentry *dentry, const char *name, const void *value,
size_t size, int flags, int type)
{
struct inode *inode = dentry->d_inode;
struct posix_acl *acl = NULL;
int error;
if (strcmp(name, "") != 0)
return -EINVAL;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (!inode_owner_or_capable(inode))
return -EPERM;
if (value) {
acl = posix_acl_from_xattr(&init_user_ns, value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
}
if (acl) {
error = posix_acl_valid(acl);
if (error)
goto failed;
switch (type) {
case ACL_TYPE_ACCESS:
error = posix_acl_equiv_mode(acl, &inode->i_mode);
if (error < 0)
goto failed;
inode->i_ctime = CURRENT_TIME;
if (error == 0) {
posix_acl_release(acl);
acl = NULL;
}
break;
case ACL_TYPE_DEFAULT:
if (!S_ISDIR(inode->i_mode)) {
error = -EINVAL;
goto failed;
}
break;
}
}
set_cached_acl(inode, type, acl);
error = 0;
failed:
posix_acl_release(acl);
return error;
}
/**
* generic_acl_init - Take care of acl inheritance at @inode create time
*
* Files created inside a directory with a default ACL inherit the
* directory's default ACL.
*/
int
generic_acl_init(struct inode *inode, struct inode *dir)
{
struct posix_acl *acl = NULL;
int error;
if (!S_ISLNK(inode->i_mode))
acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
if (acl) {
if (S_ISDIR(inode->i_mode))
set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
if (error < 0)
return error;
if (error > 0)
set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
} else {
inode->i_mode &= ~current_umask();
}
error = 0;
posix_acl_release(acl);
return error;
}
/**
* generic_acl_chmod - change the access acl of @inode upon chmod()
*
* A chmod also changes the permissions of the owner, group/mask, and
* other ACL entries.
*/
int
generic_acl_chmod(struct inode *inode)
{
struct posix_acl *acl;
int error = 0;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
if (acl) {
error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
if (error)
return error;
set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
posix_acl_release(acl);
}
return error;
}
const struct xattr_handler generic_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.flags = ACL_TYPE_ACCESS,
.list = generic_acl_list,
.get = generic_acl_get,
.set = generic_acl_set,
};
const struct xattr_handler generic_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.flags = ACL_TYPE_DEFAULT,
.list = generic_acl_list,
.get = generic_acl_get,
.set = generic_acl_set,
};
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