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[PATCH 3/3] Add timeout feature

To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: [PATCH 3/3] Add timeout feature
From: Takashi Sato <t-sato@xxxxxxxxxxxxx>
Date: Mon, 18 Aug 2008 21:28:56 +0900
Cc: "linux-fsdevel@xxxxxxxxxxxxxxx" <linux-fsdevel@xxxxxxxxxxxxxxx>, "dm-devel@xxxxxxxxxx" <dm-devel@xxxxxxxxxx>, "viro@xxxxxxxxxxxxxxxxxx" <viro@xxxxxxxxxxxxxxxxxx>, "linux-ext4@xxxxxxxxxxxxxxx" <linux-ext4@xxxxxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, "axboe@xxxxxxxxx" <axboe@xxxxxxxxx>, "mtk.manpages@xxxxxxxxxxxxxx" <mtk.manpages@xxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
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@xxxxxxxxxxxxx>
Signed-off-by: Masayuki Hamaguchi <m-hamaguchi@xxxxxxxxxxxxx>
---
 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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/drivers/md/dm.c linux-2.6.27-rc2-timeout/
drivers/md/dm.c
--- linux-2.6.27-rc2-xfs/drivers/md/dm.c        2008-08-07 09:00:27.000000000 
+0900
+++ linux-2.6.27-rc2-timeout/drivers/md/dm.c    2008-08-07 09:14:30.000000000 
+0900
@@ -1451,7 +1451,7 @@ 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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/fs/block_dev.c linux-2.6.27-rc2-timeout/f
s/block_dev.c
--- linux-2.6.27-rc2-xfs/fs/block_dev.c 2008-08-07 09:00:29.000000000 +0900
+++ linux-2.6.27-rc2-timeout/fs/block_dev.c     2008-08-07 09:14:30.000000000 
+0900
@@ -287,6 +287,8 @@ static void init_once(void *foo)
        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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/fs/buffer.c linux-2.6.27-rc2-timeout/fs/b
uffer.c
--- linux-2.6.27-rc2-xfs/fs/buffer.c    2008-08-07 09:00:29.000000000 +0900
+++ linux-2.6.27-rc2-timeout/fs/buffer.c        2008-08-07 09:14:30.000000000 
+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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/fs/ioctl.c linux-2.6.27-rc2-timeout/fs/io
ctl.c
--- linux-2.6.27-rc2-xfs/fs/ioctl.c     2008-08-07 09:00:29.000000000 +0900
+++ linux-2.6.27-rc2-timeout/fs/ioctl.c 2008-08-07 09:14:30.000000000 +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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/fs/super.c linux-2.6.27-rc2-timeout/fs/su
per.c
--- linux-2.6.27-rc2-xfs/fs/super.c     2008-08-07 09:00:29.000000000 +0900
+++ linux-2.6.27-rc2-timeout/fs/super.c 2008-08-07 09:14:30.000000000 +0900
@@ -981,3 +981,60 @@ 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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/fs/xfs/xfs_fsops.c linux-2.6.27-rc2-timeo
ut/fs/xfs/xfs_fsops.c
--- linux-2.6.27-rc2-xfs/fs/xfs/xfs_fsops.c     2008-08-07 09:00:29.000000000 
+0900
+++ linux-2.6.27-rc2-timeout/fs/xfs/xfs_fsops.c 2008-08-07 09:14:30.000000000 
+0900
@@ -621,7 +621,7 @@ 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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/include/linux/buffer_head.h linux-2.6.27-
rc2-timeout/include/linux/buffer_head.h
--- linux-2.6.27-rc2-xfs/include/linux/buffer_head.h    2008-08-07 
09:00:39.000000000 +0900
+++ linux-2.6.27-rc2-timeout/include/linux/buffer_head.h        2008-08-07 
09:14:30.000000000 +0900
@@ -169,7 +169,8 @@ 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-2.6.27-rc2.org/Documentation/dontdiff 
linux-2.6.27-rc2-xfs/include/linux/fs.h linux-2.6.27-rc2-timeo
ut/include/linux/fs.h
--- linux-2.6.27-rc2-xfs/include/linux/fs.h     2008-08-07 09:00:39.000000000 
+0900
+++ linux-2.6.27-rc2-timeout/include/linux/fs.h 2008-08-07 09:14:30.000000000 
+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
@@ -228,6 +229,7 @@ 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)
@@ -576,10 +578,13 @@ 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;
 };
 
 /*
@@ -2159,5 +2164,10 @@ 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 */


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