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Date: Mon, 27 Oct 2008 22:40:07 +1100
From: Nigel Cunningham <ncunningham@...a.org.au>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Miklos Szeredi <miklos@...redi.hu>,
linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [linux-pm] Freezer: Don't count threads waiting for frozen
filesystems.
Hi.
On Mon, 2008-10-27 at 12:37 +0100, Rafael J. Wysocki wrote:
> On Monday, 27 of October 2008, Nigel Cunningham wrote:
> > Hi Miklos.
> >
> > On Mon, 2008-10-27 at 12:12 +0100, Miklos Szeredi wrote:
> > > On Sun, 26 Oct 2008, Rafael J. Wysocki wrote:
> > > > On Saturday, 25 of October 2008, Nigel Cunningham wrote:
> > > > > While working on freezing fuse filesystems, I found that if a filesystem
> > > > > is frozen when we try to freeze processes, freezing can fail because
> > > > > threads are waiting in vfs_check_frozen for the filesystem to be thawed.
> > > > > We should thus not count such threads.
> > > > >
> > > > > The check will be safe if a filesystem is thawed while we're freezing
> > > > > processes because filesystem thaws are only invoked from userspace. Any
> > > > > waiting processes will be woken and frozen prior to us completing the
> > > > > freezing of userspace (the caller invoking the filesystem thaw will be
> > > > > freezing) or - in the worst case - together with kernel threads.
> > >
> > > The description is missing some details: why is the filesystem frozen
> > > before suspend? AFAICS this can happen when DM calls bdev_freeze() on
> > > the device before the task freezing begins. Is this the case?
> >
> > It doesn't matter why a process is sitting in that wait_event call. What
> > does matter is that one can be there. In the case where I saw it, I was
> > working on fuse freezing. I don't remember the details, as it's a year
> > since I made this patch, but I don't think I wasn't using fuse or DM.
> >
> > > Also, while the patch might solve some of the symptoms of the fuse
> > > vs. process freezer interaction, it will not fully fix that problem.
> > > As such it's just a hack to hide the problem, making it less likely to
> > > appear.
> >
> > No, it's part of the solution. I haven't posted the full fuse freezing
> > patch because I thought this could be profitably merged without the rest
> > of the patch.
>
> Well, I guess it's better if you post the entire thing so that we can see
> what the role of the $subject patch is in it, even if this patch finally gets
> merged separately.
Ah.. that makes me see how vfs_check_frozen was getting triggered...
(fs/namei.c, below).
Regards,
Nigel
fs/buffer.c | 87 ++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/control.c | 1
fs/fuse/dev.c | 7 +++
fs/fuse/dir.c | 35 +++++++++++++++--
fs/fuse/file.c | 14 +++++++
fs/fuse/fuse.h | 13 ++++++
fs/fuse/inode.c | 4 +-
fs/namei.c | 2 +
include/linux/buffer_head.h | 5 ++
include/linux/freezer.h | 15 +++++++
include/linux/fs.h | 10 ++++-
kernel/power/process.c | 48 +++++++++++++++++++++---
12 files changed, 227 insertions(+), 14 deletions(-)
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/buffer.c 700-BRANCH-fuse-freezing.patch-new/fs/buffer.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/buffer.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/buffer.c 2008-10-21 13:16:08.000000000 +1100
@@ -247,6 +247,93 @@ void thaw_bdev(struct block_device *bdev
}
EXPORT_SYMBOL(thaw_bdev);
+#if 0
+#define FS_PRINTK(fmt, args...) printk(fmt, ## args)
+#else
+#define FS_PRINTK(fmt, args...)
+#endif
+
+/* #define DEBUG_FS_FREEZING */
+
+/**
+ * freeze_filesystems - lock all filesystems and force them into a consistent
+ * state
+ * @which: What combination of fuse & non-fuse to freeze.
+ */
+void freeze_filesystems(int which)
+{
+ struct super_block *sb;
+
+ lockdep_off();
+
+ /*
+ * Freeze in reverse order so filesystems dependant upon others are
+ * frozen in the right order (eg. loopback on ext3).
+ */
+ list_for_each_entry_reverse(sb, &super_blocks, s_list) {
+ FS_PRINTK(KERN_INFO "Considering %s.%s: (root %p, bdev %x)",
+ sb->s_type->name ? sb->s_type->name : "?",
+ sb->s_subtype ? sb->s_subtype : "", sb->s_root,
+ sb->s_bdev ? sb->s_bdev->bd_dev : 0);
+
+ if (sb->s_type->fs_flags & FS_IS_FUSE &&
+ sb->s_frozen == SB_UNFROZEN &&
+ which & FS_FREEZER_FUSE) {
+ sb->s_frozen = SB_FREEZE_TRANS;
+ sb->s_flags |= MS_FROZEN;
+ FS_PRINTK("Fuse filesystem done.\n");
+ continue;
+ }
+
+ if (!sb->s_root || !sb->s_bdev ||
+ (sb->s_frozen == SB_FREEZE_TRANS) ||
+ (sb->s_flags & MS_RDONLY) ||
+ (sb->s_flags & MS_FROZEN) ||
+ !(which & FS_FREEZER_NORMAL)) {
+ FS_PRINTK(KERN_INFO "Nope.\n");
+ continue;
+ }
+
+ FS_PRINTK(KERN_INFO "Freezing %x... ", sb->s_bdev->bd_dev);
+ freeze_bdev(sb->s_bdev);
+ sb->s_flags |= MS_FROZEN;
+ FS_PRINTK(KERN_INFO "Done.\n");
+ }
+
+ lockdep_on();
+}
+
+/**
+ * thaw_filesystems - unlock all filesystems
+ * @which: What combination of fuse & non-fuse to thaw.
+ */
+void thaw_filesystems(int which)
+{
+ struct super_block *sb;
+
+ lockdep_off();
+
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (!(sb->s_flags & MS_FROZEN))
+ continue;
+
+ if (sb->s_type->fs_flags & FS_IS_FUSE) {
+ if (!(which & FS_FREEZER_FUSE))
+ continue;
+
+ sb->s_frozen = SB_UNFROZEN;
+ } else {
+ if (!(which & FS_FREEZER_NORMAL))
+ continue;
+
+ thaw_bdev(sb->s_bdev, sb);
+ }
+ sb->s_flags &= ~MS_FROZEN;
+ }
+
+ lockdep_on();
+}
+
/*
* Various filesystems appear to want __find_get_block to be non-blocking.
* But it's the page lock which protects the buffers. To get around this,
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/fuse/control.c 700-BRANCH-fuse-freezing.patch-new/fs/fuse/control.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/fuse/control.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/fuse/control.c 2008-10-21 13:12:40.000000000 +1100
@@ -207,6 +207,7 @@ static void fuse_ctl_kill_sb(struct supe
static struct file_system_type fuse_ctl_fs_type = {
.owner = THIS_MODULE,
.name = "fusectl",
+ .fs_flags = FS_IS_FUSE,
.get_sb = fuse_ctl_get_sb,
.kill_sb = fuse_ctl_kill_sb,
};
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/fuse/dev.c 700-BRANCH-fuse-freezing.patch-new/fs/fuse/dev.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/fuse/dev.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/fuse/dev.c 2008-10-21 13:12:40.000000000 +1100
@@ -7,6 +7,7 @@
*/
#include "fuse_i.h"
+#include "fuse.h"
#include <linux/init.h>
#include <linux/module.h>
@@ -16,6 +17,7 @@
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/slab.h>
+#include <linux/freezer.h>
MODULE_ALIAS_MISCDEV(FUSE_MINOR);
@@ -743,6 +745,8 @@ static ssize_t fuse_dev_read(struct kioc
if (!fc)
return -EPERM;
+ FUSE_MIGHT_FREEZE(file->f_mapping->host->i_sb, "fuse_dev_read");
+
restart:
spin_lock(&fc->lock);
err = -EAGAIN;
@@ -869,6 +873,9 @@ static ssize_t fuse_dev_write(struct kio
if (!fc)
return -EPERM;
+ FUSE_MIGHT_FREEZE(iocb->ki_filp->f_mapping->host->i_sb,
+ "fuse_dev_write");
+
fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
if (nbytes < sizeof(struct fuse_out_header))
return -EINVAL;
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/fuse/dir.c 700-BRANCH-fuse-freezing.patch-new/fs/fuse/dir.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/fuse/dir.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/fuse/dir.c 2008-10-21 13:12:40.000000000 +1100
@@ -7,12 +7,14 @@
*/
#include "fuse_i.h"
+#include "fuse.h"
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/gfp.h>
#include <linux/sched.h>
#include <linux/namei.h>
+#include <linux/freezer.h>
#if BITS_PER_LONG >= 64
static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
@@ -174,6 +176,9 @@ static int fuse_dentry_revalidate(struct
return 0;
fc = get_fuse_conn(inode);
+
+ FUSE_MIGHT_FREEZE(inode->i_sb, "fuse_dentry_revalidate");
+
req = fuse_get_req(fc);
if (IS_ERR(req))
return 0;
@@ -273,6 +278,8 @@ int fuse_lookup_name(struct super_block
if (IS_ERR(req))
goto out;
+ FUSE_MIGHT_FREEZE(sb, "fuse_lookup");
+
forget_req = fuse_get_req(fc);
err = PTR_ERR(forget_req);
if (IS_ERR(forget_req)) {
@@ -402,6 +409,8 @@ static int fuse_create_open(struct inode
if (IS_ERR(forget_req))
return PTR_ERR(forget_req);
+ FUSE_MIGHT_FREEZE(dir->i_sb, "fuse_create_open");
+
req = fuse_get_req(fc);
err = PTR_ERR(req);
if (IS_ERR(req))
@@ -488,6 +497,8 @@ static int create_new_entry(struct fuse_
int err;
struct fuse_req *forget_req;
+ FUSE_MIGHT_FREEZE(dir->i_sb, "create_new_entry");
+
forget_req = fuse_get_req(fc);
if (IS_ERR(forget_req)) {
fuse_put_request(fc, req);
@@ -585,7 +596,11 @@ static int fuse_mkdir(struct inode *dir,
{
struct fuse_mkdir_in inarg;
struct fuse_conn *fc = get_fuse_conn(dir);
- struct fuse_req *req = fuse_get_req(fc);
+ struct fuse_req *req;
+
+ FUSE_MIGHT_FREEZE(dir->i_sb, "fuse_mkdir");
+
+ req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -605,7 +620,11 @@ static int fuse_symlink(struct inode *di
{
struct fuse_conn *fc = get_fuse_conn(dir);
unsigned len = strlen(link) + 1;
- struct fuse_req *req = fuse_get_req(fc);
+ struct fuse_req *req;
+
+ FUSE_MIGHT_FREEZE(dir->i_sb, "fuse_symlink");
+
+ req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -622,7 +641,11 @@ static int fuse_unlink(struct inode *dir
{
int err;
struct fuse_conn *fc = get_fuse_conn(dir);
- struct fuse_req *req = fuse_get_req(fc);
+ struct fuse_req *req;
+
+ FUSE_MIGHT_FREEZE(dir->i_sb, "fuse_unlink");
+
+ req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -653,7 +676,11 @@ static int fuse_rmdir(struct inode *dir,
{
int err;
struct fuse_conn *fc = get_fuse_conn(dir);
- struct fuse_req *req = fuse_get_req(fc);
+ struct fuse_req *req;
+
+ FUSE_MIGHT_FREEZE(dir->i_sb, "fuse_rmdir");
+
+ req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/fuse/file.c 700-BRANCH-fuse-freezing.patch-new/fs/fuse/file.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/fuse/file.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/fuse/file.c 2008-10-21 13:12:40.000000000 +1100
@@ -7,11 +7,13 @@
*/
#include "fuse_i.h"
+#include "fuse.h"
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/sched.h>
+#include <linux/freezer.h>
static const struct file_operations fuse_direct_io_file_operations;
@@ -23,6 +25,8 @@ static int fuse_send_open(struct inode *
struct fuse_req *req;
int err;
+ FUSE_MIGHT_FREEZE(inode->i_sb, "fuse_send_open");
+
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -674,6 +678,8 @@ static int fuse_buffered_write(struct fi
if (is_bad_inode(inode))
return -EIO;
+ FUSE_MIGHT_FREEZE(inode->i_sb, "fuse_commit_write");
+
/*
* Make sure writepages on the same page are not mixed up with
* plain writes.
@@ -962,6 +968,8 @@ static ssize_t fuse_direct_io(struct fil
if (is_bad_inode(inode))
return -EIO;
+ FUSE_MIGHT_FREEZE(file->f_mapping->host->i_sb, "fuse_direct_io");
+
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -1315,6 +1323,8 @@ static int fuse_getlk(struct file *file,
struct fuse_lk_out outarg;
int err;
+ FUSE_MIGHT_FREEZE(file->f_mapping->host->i_sb, "fuse_getlk");
+
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -1350,6 +1360,8 @@ static int fuse_setlk(struct file *file,
if (fl->fl_flags & FL_CLOSE)
return 0;
+ FUSE_MIGHT_FREEZE(file->f_mapping->host->i_sb, "fuse_setlk");
+
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
@@ -1416,6 +1428,8 @@ static sector_t fuse_bmap(struct address
if (!inode->i_sb->s_bdev || fc->no_bmap)
return 0;
+ FUSE_MIGHT_FREEZE(inode->i_sb, "fuse_bmap");
+
req = fuse_get_req(fc);
if (IS_ERR(req))
return 0;
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/fuse/fuse.h 700-BRANCH-fuse-freezing.patch-new/fs/fuse/fuse.h
--- 700-BRANCH-fuse-freezing.patch-old/fs/fuse/fuse.h 1970-01-01 10:00:00.000000000 +1000
+++ 700-BRANCH-fuse-freezing.patch-new/fs/fuse/fuse.h 2008-10-21 13:12:40.000000000 +1100
@@ -0,0 +1,13 @@
+#define FUSE_MIGHT_FREEZE(superblock, desc) \
+do { \
+ int printed = 0; \
+ while (superblock->s_frozen != SB_UNFROZEN) { \
+ if (!printed) { \
+ printk(KERN_INFO "%d frozen in " desc ".\n", \
+ current->pid); \
+ printed = 1; \
+ } \
+ try_to_freeze(); \
+ yield(); \
+ } \
+} while (0)
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/fuse/inode.c 700-BRANCH-fuse-freezing.patch-new/fs/fuse/inode.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/fuse/inode.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/fuse/inode.c 2008-10-21 13:12:40.000000000 +1100
@@ -914,7 +914,7 @@ static int fuse_get_sb(struct file_syste
static struct file_system_type fuse_fs_type = {
.owner = THIS_MODULE,
.name = "fuse",
- .fs_flags = FS_HAS_SUBTYPE,
+ .fs_flags = FS_HAS_SUBTYPE | FS_IS_FUSE,
.get_sb = fuse_get_sb,
.kill_sb = kill_anon_super,
};
@@ -933,7 +933,7 @@ static struct file_system_type fuseblk_f
.name = "fuseblk",
.get_sb = fuse_get_sb_blk,
.kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
+ .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE | FS_IS_FUSE,
};
static inline int register_fuseblk(void)
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/fs/namei.c 700-BRANCH-fuse-freezing.patch-new/fs/namei.c
--- 700-BRANCH-fuse-freezing.patch-old/fs/namei.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/fs/namei.c 2008-10-21 13:12:40.000000000 +1100
@@ -2223,6 +2223,8 @@ int vfs_unlink(struct inode *dir, struct
if (!dir->i_op || !dir->i_op->unlink)
return -EPERM;
+ vfs_check_frozen(dir->i_sb, SB_FREEZE_WRITE);
+
DQUOT_INIT(dir);
mutex_lock(&dentry->d_inode->i_mutex);
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/include/linux/buffer_head.h 700-BRANCH-fuse-freezing.patch-new/include/linux/buffer_head.h
--- 700-BRANCH-fuse-freezing.patch-old/include/linux/buffer_head.h 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/include/linux/buffer_head.h 2008-10-21 13:12:40.000000000 +1100
@@ -171,6 +171,11 @@ wait_queue_head_t *bh_waitq_head(struct
int fsync_bdev(struct block_device *);
struct super_block *freeze_bdev(struct block_device *);
void thaw_bdev(struct block_device *, struct super_block *);
+#define FS_FREEZER_FUSE 1
+#define FS_FREEZER_NORMAL 2
+#define FS_FREEZER_ALL (FS_FREEZER_FUSE | FS_FREEZER_NORMAL)
+void freeze_filesystems(int which);
+void thaw_filesystems(int which);
int fsync_super(struct super_block *);
int fsync_no_super(struct block_device *);
struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/include/linux/freezer.h 700-BRANCH-fuse-freezing.patch-new/include/linux/freezer.h
--- 700-BRANCH-fuse-freezing.patch-old/include/linux/freezer.h 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/include/linux/freezer.h 2008-10-21 13:16:08.000000000 +1100
@@ -136,6 +136,19 @@ static inline void set_freezable_with_si
current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
}
+extern int freezer_state;
+#define FREEZER_OFF 0
+#define FREEZER_FILESYSTEMS_FROZEN 1
+#define FREEZER_USERSPACE_FROZEN 2
+#define FREEZER_FULLY_ON 3
+
+static inline int freezer_is_on(void)
+{
+ return freezer_state == FREEZER_FULLY_ON;
+}
+
+extern void thaw_kernel_threads(void);
+
/*
* Freezer-friendly wrappers around wait_event_interruptible() and
* wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
@@ -178,6 +191,8 @@ static inline int freeze_processes(void)
static inline void thaw_processes(void) {}
static inline int try_to_freeze(void) { return 0; }
+static inline int freezer_is_on(void) { return 0; }
+static inline void thaw_kernel_threads(void) { }
static inline void freezer_do_not_count(void) {}
static inline void freezer_count(void) {}
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/include/linux/fs.h 700-BRANCH-fuse-freezing.patch-new/include/linux/fs.h
--- 700-BRANCH-fuse-freezing.patch-old/include/linux/fs.h 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/include/linux/fs.h 2008-10-21 13:12:40.000000000 +1100
@@ -8,6 +8,7 @@
#include <linux/limits.h>
#include <linux/ioctl.h>
+#include <linux/freezer.h>
/*
* It's silly to have NR_OPEN bigger than NR_FILE, but you can change
@@ -96,6 +97,7 @@ extern int dir_notify_enable;
#define FS_REQUIRES_DEV 1
#define FS_BINARY_MOUNTDATA 2
#define FS_HAS_SUBTYPE 4
+#define FS_IS_FUSE 8 /* Fuse filesystem - bdev freeze these too */
#define FS_REVAL_DOT 16384 /* Check the paths ".", ".." for staleness */
#define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move()
* during rename() internally.
@@ -128,6 +130,7 @@ extern int dir_notify_enable;
#define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */
#define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */
#define MS_I_VERSION (1<<23) /* Update inode I_version field */
+#define MS_FROZEN (1<<24) /* Frozen by freeze_filesystems() */
#define MS_ACTIVE (1<<30)
#define MS_NOUSER (1<<31)
@@ -1141,8 +1144,11 @@ enum {
SB_FREEZE_TRANS = 2,
};
-#define vfs_check_frozen(sb, level) \
- wait_event((sb)->s_wait_unfrozen, ((sb)->s_frozen < (level)))
+#define vfs_check_frozen(sb, level) do { \
+ freezer_do_not_count(); \
+ wait_event((sb)->s_wait_unfrozen, ((sb)->s_frozen < (level))); \
+ freezer_count(); \
+} while (0)
#define get_fs_excl() atomic_inc(¤t->fs_excl)
#define put_fs_excl() atomic_dec(¤t->fs_excl)
diff -ruNp 700-BRANCH-fuse-freezing.patch-old/kernel/power/process.c 700-BRANCH-fuse-freezing.patch-new/kernel/power/process.c
--- 700-BRANCH-fuse-freezing.patch-old/kernel/power/process.c 2008-10-19 04:57:22.000000000 +1100
+++ 700-BRANCH-fuse-freezing.patch-new/kernel/power/process.c 2008-10-21 13:16:08.000000000 +1100
@@ -13,6 +13,9 @@
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
+#include <linux/buffer_head.h>
+
+int freezer_state;
/*
* Timeout for stopping processes
@@ -201,7 +204,8 @@ static int try_to_freeze_tasks(bool sig_
do_each_thread(g, p) {
task_lock(p);
if (freezing(p) && !freezer_should_skip(p))
- printk(KERN_ERR " %s\n", p->comm);
+ printk(KERN_ERR " %s (%d) failed to freeze.\n",
+ p->comm, p->pid);
cancel_freezing(p);
task_unlock(p);
} while_each_thread(g, p);
@@ -221,17 +225,25 @@ int freeze_processes(void)
{
int error;
- printk("Freezing user space processes ... ");
+ printk(KERN_INFO "Stopping fuse filesystems.\n");
+ freeze_filesystems(FS_FREEZER_FUSE);
+ freezer_state = FREEZER_FILESYSTEMS_FROZEN;
+ printk(KERN_INFO "Freezing user space processes ... ");
error = try_to_freeze_tasks(true);
if (error)
goto Exit;
- printk("done.\n");
+ printk(KERN_INFO "done.\n");
- printk("Freezing remaining freezable tasks ... ");
+ sys_sync();
+ printk(KERN_INFO "Stopping normal filesystems.\n");
+ freeze_filesystems(FS_FREEZER_NORMAL);
+ freezer_state = FREEZER_USERSPACE_FROZEN;
+ printk(KERN_INFO "Freezing remaining freezable tasks ... ");
error = try_to_freeze_tasks(false);
if (error)
goto Exit;
printk("done.");
+ freezer_state = FREEZER_FULLY_ON;
Exit:
BUG_ON(in_atomic());
printk("\n");
@@ -257,11 +269,35 @@ static void thaw_tasks(bool nosig_only)
void thaw_processes(void)
{
- printk("Restarting tasks ... ");
- thaw_tasks(true);
+ int old_state = freezer_state;
+
+ if (old_state == FREEZER_OFF)
+ return;
+
+ /*
+ * Change state beforehand because thawed tasks might submit I/O
+ * immediately.
+ */
+ freezer_state = FREEZER_OFF;
+
+ printk(KERN_INFO "Restarting all filesystems ...\n");
+ thaw_filesystems(FS_FREEZER_ALL);
+
+ printk(KERN_INFO "Restarting tasks ... ");
+
+ if (old_state == FREEZER_FULLY_ON)
+ thaw_tasks(true);
thaw_tasks(false);
schedule();
printk("done.\n");
}
EXPORT_SYMBOL(refrigerator);
+
+void thaw_kernel_threads(void)
+{
+ freezer_state = FREEZER_USERSPACE_FROZEN;
+ printk(KERN_INFO "Restarting normal filesystems.\n");
+ thaw_filesystems(FS_FREEZER_NORMAL);
+ thaw_tasks(true);
+}
--
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