linux/fs/ecryptfs/kthread.c

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/**
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 2008 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <linux/kthread.h>
#include <linux/freezer.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/mount.h>
#include "ecryptfs_kernel.h"
struct kmem_cache *ecryptfs_open_req_cache;
static struct ecryptfs_kthread_ctl {
#define ECRYPTFS_KTHREAD_ZOMBIE 0x00000001
u32 flags;
struct mutex mux;
struct list_head req_list;
wait_queue_head_t wait;
} ecryptfs_kthread_ctl;
static struct task_struct *ecryptfs_kthread;
/**
* ecryptfs_threadfn
* @ignored: ignored
*
* The eCryptfs kernel thread that has the responsibility of getting
* the lower file with RW permissions.
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_threadfn(void *ignored)
{
set_freezable();
while (1) {
struct ecryptfs_open_req *req;
wait_event_freezable(
ecryptfs_kthread_ctl.wait,
(!list_empty(&ecryptfs_kthread_ctl.req_list)
|| kthread_should_stop()));
mutex_lock(&ecryptfs_kthread_ctl.mux);
if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) {
mutex_unlock(&ecryptfs_kthread_ctl.mux);
goto out;
}
while (!list_empty(&ecryptfs_kthread_ctl.req_list)) {
req = list_first_entry(&ecryptfs_kthread_ctl.req_list,
struct ecryptfs_open_req,
kthread_ctl_list);
mutex_lock(&req->mux);
list_del(&req->kthread_ctl_list);
if (!(req->flags & ECRYPTFS_REQ_ZOMBIE)) {
dget(req->lower_dentry);
mntget(req->lower_mnt);
(*req->lower_file) = dentry_open(
req->lower_dentry, req->lower_mnt,
(O_RDWR | O_LARGEFILE), current_cred());
req->flags |= ECRYPTFS_REQ_PROCESSED;
}
wake_up(&req->wait);
mutex_unlock(&req->mux);
}
mutex_unlock(&ecryptfs_kthread_ctl.mux);
}
out:
return 0;
}
int __init ecryptfs_init_kthread(void)
{
int rc = 0;
mutex_init(&ecryptfs_kthread_ctl.mux);
init_waitqueue_head(&ecryptfs_kthread_ctl.wait);
INIT_LIST_HEAD(&ecryptfs_kthread_ctl.req_list);
ecryptfs_kthread = kthread_run(&ecryptfs_threadfn, NULL,
"ecryptfs-kthread");
if (IS_ERR(ecryptfs_kthread)) {
rc = PTR_ERR(ecryptfs_kthread);
printk(KERN_ERR "%s: Failed to create kernel thread; rc = [%d]"
"\n", __func__, rc);
}
return rc;
}
void ecryptfs_destroy_kthread(void)
{
struct ecryptfs_open_req *req;
mutex_lock(&ecryptfs_kthread_ctl.mux);
ecryptfs_kthread_ctl.flags |= ECRYPTFS_KTHREAD_ZOMBIE;
list_for_each_entry(req, &ecryptfs_kthread_ctl.req_list,
kthread_ctl_list) {
mutex_lock(&req->mux);
req->flags |= ECRYPTFS_REQ_ZOMBIE;
wake_up(&req->wait);
mutex_unlock(&req->mux);
}
mutex_unlock(&ecryptfs_kthread_ctl.mux);
kthread_stop(ecryptfs_kthread);
wake_up(&ecryptfs_kthread_ctl.wait);
}
/**
* ecryptfs_privileged_open
* @lower_file: Result of dentry_open by root on lower dentry
* @lower_dentry: Lower dentry for file to open
* @lower_mnt: Lower vfsmount for file to open
*
* This function gets a r/w file opened againt the lower dentry.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_privileged_open(struct file **lower_file,
struct dentry *lower_dentry,
struct vfsmount *lower_mnt,
const struct cred *cred)
{
struct ecryptfs_open_req *req;
int flags = O_LARGEFILE;
int rc = 0;
/* Corresponding dput() and mntput() are done when the
* lower file is fput() when all eCryptfs files for the inode are
* released. */
dget(lower_dentry);
mntget(lower_mnt);
flags |= IS_RDONLY(lower_dentry->d_inode) ? O_RDONLY : O_RDWR;
(*lower_file) = dentry_open(lower_dentry, lower_mnt, flags, cred);
if (!IS_ERR(*lower_file))
goto out;
if ((flags & O_ACCMODE) == O_RDONLY) {
rc = PTR_ERR((*lower_file));
goto out;
}
req = kmem_cache_alloc(ecryptfs_open_req_cache, GFP_KERNEL);
if (!req) {
rc = -ENOMEM;
goto out;
}
mutex_init(&req->mux);
req->lower_file = lower_file;
req->lower_dentry = lower_dentry;
req->lower_mnt = lower_mnt;
init_waitqueue_head(&req->wait);
req->flags = 0;
mutex_lock(&ecryptfs_kthread_ctl.mux);
if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) {
rc = -EIO;
mutex_unlock(&ecryptfs_kthread_ctl.mux);
printk(KERN_ERR "%s: We are in the middle of shutting down; "
"aborting privileged request to open lower file\n",
__func__);
goto out_free;
}
list_add_tail(&req->kthread_ctl_list, &ecryptfs_kthread_ctl.req_list);
mutex_unlock(&ecryptfs_kthread_ctl.mux);
wake_up(&ecryptfs_kthread_ctl.wait);
wait_event(req->wait, (req->flags != 0));
mutex_lock(&req->mux);
BUG_ON(req->flags == 0);
if (req->flags & ECRYPTFS_REQ_DROPPED
|| req->flags & ECRYPTFS_REQ_ZOMBIE) {
rc = -EIO;
printk(KERN_WARNING "%s: Privileged open request dropped\n",
__func__);
goto out_unlock;
}
if (IS_ERR(*req->lower_file))
rc = PTR_ERR(*req->lower_file);
out_unlock:
mutex_unlock(&req->mux);
out_free:
kmem_cache_free(ecryptfs_open_req_cache, req);
out:
return rc;
}