ext4: add EXT4_IOC_GOINGDOWN ioctl

This ioctl is modeled after the xfs's XFS_IOC_GOINGDOWN ioctl.  (In
fact, it uses the same code points.)

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

3 files changed, 61 insertions, 1 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 35d93ab7f3fb..55b7a77a0444 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -679,6 +679,16 @@ struct fsxattr {
 #define EXT4_IOC_FSGETXATTR             FS_IOC_FSGETXATTR
 #define EXT4_IOC_FSSETXATTR             FS_IOC_FSSETXATTR
 
+#define EXT4_IOC_GOINGDOWN _IOR ('X', 125, __u32)
+
+/*
+ * Flags for going down operation
+ */
+#define EXT4_GOING_FLAGS_DEFAULT                0x0     /* going down */
+#define EXT4_GOING_FLAGS_LOGFLUSH               0x1     /* flush log but not data */
+#define EXT4_GOING_FLAGS_NOLOGFLUSH             0x2     /* don't flush log nor data */
+
+
 #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
 /*
  * ioctl commands in 32 bit emulation
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index d534399cf607..b383ebf4020c 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -16,6 +16,7 @@
 #include <linux/quotaops.h>
 #include <linux/uuid.h>
 #include <linux/uaccess.h>
+#include <linux/delay.h>
 #include "ext4_jbd2.h"
 #include "ext4.h"
 
@@ -442,6 +443,52 @@ static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
         return iflags;
 }
 
+int ext4_goingdown(struct super_block *sb, unsigned long arg)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        __u32 flags;
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        if (get_user(flags, (__u32 __user *)arg))
+                return -EFAULT;
+
+        if (flags > EXT4_GOING_FLAGS_NOLOGFLUSH)
+                return -EINVAL;
+
+        if (ext4_forced_shutdown(sbi))
+                return 0;
+
+        ext4_msg(sb, KERN_ALERT, "shut down requested (%d)", flags);
+
+        switch (flags) {
+        case EXT4_GOING_FLAGS_DEFAULT:
+                freeze_bdev(sb->s_bdev);
+                set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);
+                thaw_bdev(sb->s_bdev, sb);
+                break;
+        case EXT4_GOING_FLAGS_LOGFLUSH:
+                set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);
+                if (sbi->s_journal && !is_journal_aborted(sbi->s_journal)) {
+                        (void) ext4_force_commit(sb);
+                        jbd2_journal_abort(sbi->s_journal, 0);
+                }
+                break;
+        case EXT4_GOING_FLAGS_NOLOGFLUSH:
+                set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);
+                if (sbi->s_journal && !is_journal_aborted(sbi->s_journal)) {
+                        msleep(100);
+                        jbd2_journal_abort(sbi->s_journal, 0);
+                }
+                break;
+        default:
+                return -EINVAL;
+        }
+        clear_opt(sb, DISCARD);
+        return 0;
+}
+
 long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
         struct inode *inode = file_inode(filp);
@@ -893,6 +940,8 @@ resizefs_out:
 
                 return 0;
         }
+        case EXT4_IOC_GOINGDOWN:
+                return ext4_goingdown(sb, arg);
         default:
                 return -ENOTTY;
         }
@@ -959,6 +1008,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         case EXT4_IOC_SET_ENCRYPTION_POLICY:
         case EXT4_IOC_GET_ENCRYPTION_PWSALT:
         case EXT4_IOC_GET_ENCRYPTION_POLICY:
+        case EXT4_IOC_GOINGDOWN:
                 break;
         default:
                 return -ENOIOCTLCMD;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index cfa4ce5a1f80..3db5b6491513 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4821,7 +4821,7 @@ out:
  */
 static int ext4_unfreeze(struct super_block *sb)
 {
-        if (sb->s_flags & MS_RDONLY)
+        if ((sb->s_flags & MS_RDONLY) || ext4_forced_shutdown(EXT4_SB(sb)))
                 return 0;
 
         if (EXT4_SB(sb)->s_journal) {