[PATCH 3/3] Add timeout feature

Takashi Sato
2008-07-22T09:37:42Z

The timeout feature is added to freeze ioctl. And new ioctl
to reset the timeout period is added.
o Freeze the filesystem
int ioctl(int fd, int FIFREEZE, long *timeout_sec)
fd: The file descriptor of the mountpoint
FIFREEZE: request code for the freeze
timeout_sec: the timeout period in seconds
If it's 0 or 1, the timeout isn't set.
This special case of "1" is implemented to keep
the compatibility with XFS applications.
Return value: 0 if the operation succeeds. Otherwise, -1

o Reset the timeout period
int ioctl(int fd, int FIFREEZE_RESET_TIMEOUT, long *timeout_sec)
fd:file descriptor of mountpoint
FIFREEZE_RESET_TIMEOUT: request code for reset of timeout period
timeout_sec: new timeout period in seconds
Return value: 0 if the operation succeeds. Otherwise, -1
Error number: If the filesystem has already been unfrozen,
errno is set to EINVAL.

Signed-off-by: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Masayuki Hamaguchi <m-hamaguchi@ys.jp.nec.com>
---
drivers/md/dm.c | 2 -
fs/block_dev.c | 2 +
fs/buffer.c | 16 +++++++--
fs/ioctl.c | 77 ++++++++++++++++++++++++++++++++++++++++++--
fs/super.c | 57 ++++++++++++++++++++++++++++++++
fs/xfs/xfs_fsops.c | 2 -
include/linux/buffer_head.h | 3 +
include/linux/fs.h | 10 +++++
8 files changed, 160 insertions(+), 9 deletions(-)

diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/drivers/md/dm.c linux-2.6.26-timeout/drivers/md/d
m.c
--- linux-2.6.26-xfs/drivers/md/dm.c 2008-07-17 11:33:03.000000000 +0900
+++ linux-2.6.26-timeout/drivers/md/dm.c 2008-07-17 11:36:00.000000000 +0900
@@ -1407,7 +1407,7 @@ static int lock_fs(struct mapped_device

WARN_ON(md->frozen_sb);

- md->frozen_sb = freeze_bdev(md->suspended_bdev);
+ md->frozen_sb = freeze_bdev(md->suspended_bdev, 0);
if (IS_ERR(md->frozen_sb)) {
r = PTR_ERR(md->frozen_sb);
md->frozen_sb = NULL;
diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/fs/block_dev.c linux-2.6.26-timeout/fs/block_dev.
c
--- linux-2.6.26-xfs/fs/block_dev.c 2008-07-18 15:53:51.000000000 +0900
+++ linux-2.6.26-timeout/fs/block_dev.c 2008-07-18 17:12:22.000000000 +0900
@@ -287,6 +287,8 @@ static void init_once(struct kmem_cache
inode_init_once(&ei->vfs_inode);
/* Initialize semaphore for freeze. */
sema_init(&bdev->bd_freeze_sem, 1);
+ /* Setup freeze timeout function. */
+ INIT_DELAYED_WORK(&bdev->bd_freeze_timeout, freeze_timeout);
}

static inline void __bd_forget(struct inode *inode)
diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/fs/buffer.c linux-2.6.26-timeout/fs/buffer.c
--- linux-2.6.26-xfs/fs/buffer.c 2008-07-18 15:53:51.000000000 +0900
+++ linux-2.6.26-timeout/fs/buffer.c 2008-07-18 17:17:50.000000000 +0900
@@ -190,14 +190,18 @@ int fsync_bdev(struct block_device *bdev

/**
* freeze_bdev -- lock a filesystem and force it into a consistent state
- * @bdev: blockdevice to lock
+ * @bdev: blockdevice to lock
+ * @timeout_msec: timeout period
*
* This takes the block device bd_mount_sem to make sure no new mounts
* happen on bdev until thaw_bdev() is called.
* If a superblock is found on this device, we take the s_umount semaphore
* on it to make sure nobody unmounts until the snapshot creation is done.
+ * If timeout_msec is bigger than 0, this registers the delayed work for
+ * timeout of the freeze feature.
*/
-struct super_block *freeze_bdev(struct block_device *bdev)
+struct super_block *freeze_bdev(struct block_device *bdev,
+ unsigned int timeout_msec)
{
struct super_block *sb;

@@ -228,8 +232,11 @@ struct super_block *freeze_bdev(struct b
}

sync_blockdev(bdev);
- up(&bdev->bd_freeze_sem);
+ /* Setup unfreeze timer. */
+ if (timeout_msec > 0)
+ add_freeze_timeout(bdev, timeout_msec);

+ up(&bdev->bd_freeze_sem);
return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */
}
EXPORT_SYMBOL(freeze_bdev);
@@ -255,6 +262,9 @@ int thaw_bdev(struct block_device *bdev,
return 0;
}

+ /* Delete unfreeze timer. */
+ del_freeze_timeout(bdev);
+
if (sb) {
BUG_ON(sb->s_bdev != bdev);

diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/fs/ioctl.c linux-2.6.26-timeout/fs/ioctl.c
--- linux-2.6.26-xfs/fs/ioctl.c 2008-07-18 21:57:20.000000000 +0900
+++ linux-2.6.26-timeout/fs/ioctl.c 2008-07-22 11:50:42.000000000 +0900
@@ -145,12 +145,16 @@ static int ioctl_fioasync(unsigned int f
* ioctl_freeze - Freeze the filesystem.
*
* @filp: target file
+ * @argp: timeout value(sec)
*
* Call freeze_bdev() to freeze the filesystem.
*/
-static int ioctl_freeze(struct file *filp)
+static int ioctl_freeze(struct file *filp, int __user *argp)
{
+ int timeout_sec;
+ unsigned int timeout_msec;
struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
+ int error;

if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -163,8 +167,25 @@ static int ioctl_freeze(struct file *fil
if (sb->s_bdev == NULL)
return -EINVAL;

+ /* arg(sec) to tick value. */
+ error = get_user(timeout_sec, argp);
+ if (error != 0)
+ return error;
+
+ if (timeout_sec < 0 || timeout_sec > UINT_MAX/1000)
+ return -EINVAL;
+
+ /*
+ * If 1 is specified as the timeout period it is changed into 0
+ * to retain compatibility with XFS's xfs_freeze.
+ */
+ if (timeout_sec == 1)
+ timeout_sec = 0;
+
+ timeout_msec = timeout_sec * 1000;
+
/* Freeze */
- sb = freeze_bdev(sb->s_bdev);
+ sb = freeze_bdev(sb->s_bdev, timeout_msec);
if (IS_ERR(sb))
return PTR_ERR(sb);
return 0;
@@ -193,6 +214,52 @@ static int ioctl_thaw(struct file *filp)
}

/*
+ * ioctl_freeze_reset_timeout - Reset timeout for freeze.
+ *
+ * @filp: target file
+ * @argp: timeout value(sec)
+ *
+ * Reset timeout for freeze.
+ */
+static int
+ioctl_freeze_reset_timeout(struct file *filp, int __user *argp)
+{
+ int timeout_sec;
+ unsigned int timeout_msec;
+ struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
+ struct block_device *bdev = sb->s_bdev;
+ int error;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* If a regular file or a directory isn't specified, return EINVAL. */
+ if (bdev == NULL)
+ return -EINVAL;
+
+ /* arg(sec) to tick value */
+ error = get_user(timeout_sec, argp);
+ if (error)
+ return error;
+
+ if (timeout_sec <= 0 || timeout_sec > UINT_MAX/1000)
+ return -EINVAL;
+
+ timeout_msec = timeout_sec * 1000;
+
+ down(&bdev->bd_freeze_sem);
+ if (!bdev->bd_freeze_count) {
+ up(&bdev->bd_freeze_sem);
+ return -EINVAL;
+ }
+ /* setup unfreeze timer */
+ add_freeze_timeout(bdev, timeout_msec);
+ up(&bdev->bd_freeze_sem);
+
+ return 0;
+}
+
+/*
* When you add any new common ioctls to the switches above and below
* please update compat_sys_ioctl() too.
*
@@ -235,13 +302,17 @@ int do_vfs_ioctl(struct file *filp, unsi
break;

case FIFREEZE:
- error = ioctl_freeze(filp);
+ error = ioctl_freeze(filp, argp);
break;

case FITHAW:
error = ioctl_thaw(filp);
break;

+ case FIFREEZE_RESET_TIMEOUT:
+ error = ioctl_freeze_reset_timeout(filp, argp);
+ break;
+
default:
if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
error = file_ioctl(filp, cmd, arg);
diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/fs/super.c linux-2.6.26-timeout/fs/super.c
--- linux-2.6.26-xfs/fs/super.c 2008-07-17 11:33:13.000000000 +0900
+++ linux-2.6.26-timeout/fs/super.c 2008-07-17 11:36:00.000000000 +0900
@@ -980,3 +980,60 @@ struct vfsmount *kern_mount_data(struct
}

EXPORT_SYMBOL_GPL(kern_mount_data);
+
+/*
+ * freeze_timeout - Thaw the filesystem.
+ *
+ * @work: work queue (delayed_work.work)
+ *
+ * Called by the delayed work when elapsing the timeout period.
+ * Thaw the filesystem.
+ */
+void freeze_timeout(struct work_struct *work)
+{
+ struct block_device *bd = container_of(work,
+ struct block_device, bd_freeze_timeout.work);
+ struct super_block *sb = get_super(bd);
+
+ thaw_bdev(bd, sb);
+
+ if (sb)
+ drop_super(sb);
+}
+EXPORT_SYMBOL_GPL(freeze_timeout);
+
+/*
+ * add_freeze_timeout - Add timeout for freeze.
+ *
+ * @bdev: block device struct
+ * @timeout_msec: timeout period
+ *
+ * Add the delayed work for freeze timeout to the delayed work queue.
+ */
+void add_freeze_timeout(struct block_device *bdev, unsigned int timeout_msec)
+{
+ s64 timeout_jiffies = msecs_to_jiffies(timeout_msec);
+
+ /* Set delayed work queue */
+ cancel_delayed_work_sync(&bdev->bd_freeze_timeout);
+ schedule_delayed_work(&bdev->bd_freeze_timeout, timeout_jiffies);
+}
+
+/*
+ * del_freeze_timeout - Delete timeout for freeze.
+ *
+ * @bdev: block device struct
+ *
+ * Delete the delayed work for freeze timeout from the delayed work queue.
+ */
+void del_freeze_timeout(struct block_device *bdev)
+{
+ /*
+ * It's possible that the delayed work task (freeze_timeout()) calls
+ * del_freeze_timeout(). If the delayed work task calls
+ * cancel_delayed_work_sync((), the deadlock will occur.
+ * So we need this check (delayed_work_pending()).
+ */
+ if (delayed_work_pending(&bdev->bd_freeze_timeout))
+ cancel_delayed_work_sync(&bdev->bd_freeze_timeout);
+}
diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/fs/xfs/xfs_fsops.c linux-2.6.26-timeout/fs/xfs/xf
s_fsops.c
--- linux-2.6.26-xfs/fs/xfs/xfs_fsops.c 2008-07-17 11:33:13.000000000 +0900
+++ linux-2.6.26-timeout/fs/xfs/xfs_fsops.c 2008-07-17 11:36:00.000000000 +0900
@@ -619,7 +619,7 @@ xfs_fs_goingdown(
{
switch (inflags) {
case XFS_FSOP_GOING_FLAGS_DEFAULT: {
- struct super_block *sb = freeze_bdev(mp->m_super->s_bdev);
+ struct super_block *sb = freeze_bdev(mp->m_super->s_bdev, 0);

if (sb && !IS_ERR(sb)) {
xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/include/linux/buffer_head.h linux-2.6.26-timeout/
include/linux/buffer_head.h
--- linux-2.6.26-xfs/include/linux/buffer_head.h 2008-07-17 11:33:14.000000000 +0900
+++ linux-2.6.26-timeout/include/linux/buffer_head.h 2008-07-17 11:36:00.000000000 +0900
@@ -170,7 +170,8 @@ int sync_blockdev(struct block_device *b
void __wait_on_buffer(struct buffer_head *);
wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
int fsync_bdev(struct block_device *);
-struct super_block *freeze_bdev(struct block_device *);
+struct super_block *freeze_bdev(struct block_device *,
+ unsigned int timeout_msec);
int thaw_bdev(struct block_device *, struct super_block *);
int fsync_super(struct super_block *);
int fsync_no_super(struct block_device *);
diff -uprN -X linux-2.6.26.org/Documentation/dontdiff linux-2.6.26-xfs/include/linux/fs.h linux-2.6.26-timeout/include/l
inux/fs.h
--- linux-2.6.26-xfs/include/linux/fs.h 2008-07-18 15:53:51.000000000 +0900
+++ linux-2.6.26-timeout/include/linux/fs.h 2008-07-18 21:51:41.000000000 +0900
@@ -8,6 +8,7 @@

#include <linux/limits.h>
#include <linux/ioctl.h>
+#include <linux/workqueue.h>

/*
* It's silly to have NR_OPEN bigger than NR_FILE, but you can change
@@ -226,6 +227,7 @@ extern int dir_notify_enable;
#define FIGETBSZ _IO(0x00,2) /* get the block size used for bmap */
#define FIFREEZE _IOWR('X', 119, int) /* Freeze */
#define FITHAW _IOWR('X', 120, int) /* Thaw */
+#define FIFREEZE_RESET_TIMEOUT _IO(0x00, 3) /* Reset freeze timeout */

#define FS_IOC_GETFLAGS _IOR('f', 1, long)
#define FS_IOC_SETFLAGS _IOW('f', 2, long)
@@ -550,10 +552,13 @@ struct block_device {
* care to not mess up bd_private for that case.
*/
unsigned long bd_private;
+
/* The counter of freeze processes */
int bd_freeze_count;
/* Semaphore for freeze */
struct semaphore bd_freeze_sem;
+ /* Delayed work for freeze */
+ struct delayed_work bd_freeze_timeout;
};

/*
@@ -2140,5 +2145,10 @@ int proc_nr_files(struct ctl_table *tabl

int get_filesystem_list(char * buf);

+extern void add_freeze_timeout(struct block_device *bdev,
+ unsigned int timeout_msec);
+extern void del_freeze_timeout(struct block_device *bdev);
+extern void freeze_timeout(struct work_struct *work);
+
#endif /* __KERNEL__ */
#endif /* _LINUX_FS_H */