linux-kernel - [PATCH] [6/18] BKL-removal: Convert ext4 to use unlocked

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Message-Id: <20080127021712.8275914D2E@wotan.suse.de>
Date:	Sun, 27 Jan 2008 03:17:12 +0100 (CET)
From:	Andi Kleen <ak@...e.de>
To:	sct@...hat.com, adilger@...sterfs.com,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	akpm@...l.org
Subject: [PATCH] [6/18] BKL-removal: Convert ext4 to use unlocked_ioctl


I checked ext4_ioctl and it looked largely safe to not be used
without BKL.  So convert it over to unlocked_ioctl.

The only case where I wasn't quite sure was for the
dynamic fs grow ioctls versus umounting -- I kept the BKL for those. 

Cc: sct@...hat.com
Cc: adilger@...sterfs.com

Signed-off-by: Andi Kleen <ak@...e.de>

---
 fs/ext4/dir.c           |    2 +-
 fs/ext4/file.c          |    2 +-
 fs/ext4/ioctl.c         |   20 +++++++++++---------
 include/linux/ext4_fs.h |    3 +--
 4 files changed, 14 insertions(+), 13 deletions(-)

Index: linux/fs/ext4/dir.c
===================================================================
--- linux.orig/fs/ext4/dir.c
+++ linux/fs/ext4/dir.c
@@ -42,7 +42,7 @@ const struct file_operations ext4_dir_op
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
 	.readdir	= ext4_readdir,		/* we take BKL. needed?*/
-	.ioctl		= ext4_ioctl,		/* BKL held */
+	.unlocked_ioctl = ext4_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext4_compat_ioctl,
 #endif
Index: linux/fs/ext4/file.c
===================================================================
--- linux.orig/fs/ext4/file.c
+++ linux/fs/ext4/file.c
@@ -112,7 +112,7 @@ const struct file_operations ext4_file_o
 	.write		= do_sync_write,
 	.aio_read	= generic_file_aio_read,
 	.aio_write	= ext4_file_write,
-	.ioctl		= ext4_ioctl,
+	.unlocked_ioctl = ext4_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext4_compat_ioctl,
 #endif
Index: linux/fs/ext4/ioctl.c
===================================================================
--- linux.orig/fs/ext4/ioctl.c
+++ linux/fs/ext4/ioctl.c
@@ -17,9 +17,9 @@
 #include <linux/smp_lock.h>
 #include <asm/uaccess.h>
 
-int ext4_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
-		unsigned long arg)
+long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
+	struct inode *inode = filp->f_dentry->d_inode;
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	unsigned int flags;
 	unsigned short rsv_window_size;
@@ -224,10 +224,14 @@ flags_err:
 		if (get_user(n_blocks_count, (__u32 __user *)arg))
 			return -EFAULT;
 
+		/* AK: not sure the BKL is needed, but this might prevent
+		 * races against umount. */
+		lock_kernel();
 		err = ext4_group_extend(sb, EXT4_SB(sb)->s_es, n_blocks_count);
 		jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
 		jbd2_journal_flush(EXT4_SB(sb)->s_journal);
 		jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+		unlock_kernel();
 
 		return err;
 	}
@@ -246,10 +250,14 @@ flags_err:
 				sizeof(input)))
 			return -EFAULT;
 
+		/* AK: not sure the BKL is needed, but this might prevent
+		 * races against umount. */
+		lock_kernel();
 		err = ext4_group_add(sb, &input);
 		jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
 		jbd2_journal_flush(EXT4_SB(sb)->s_journal);
 		jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+		unlock_kernel();
 
 		return err;
 	}
@@ -262,9 +270,6 @@ flags_err:
 #ifdef CONFIG_COMPAT
 long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
-	int ret;
-
 	/* These are just misnamed, they actually get/put from/to user an int */
 	switch (cmd) {
 	case EXT4_IOC32_GETFLAGS:
@@ -304,9 +309,6 @@ long ext4_compat_ioctl(struct file *file
 	default:
 		return -ENOIOCTLCMD;
 	}
-	lock_kernel();
-	ret = ext4_ioctl(inode, file, cmd, (unsigned long) compat_ptr(arg));
-	unlock_kernel();
-	return ret;
+	return ext4_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
 }
 #endif
Index: linux/include/linux/ext4_fs.h
===================================================================
--- linux.orig/include/linux/ext4_fs.h
+++ linux/include/linux/ext4_fs.h
@@ -939,8 +939,7 @@ extern int ext4_block_truncate_page(hand
 		struct address_space *mapping, loff_t from);
 
 /* ioctl.c */
-extern int ext4_ioctl (struct inode *, struct file *, unsigned int,
-		       unsigned long);
+extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
 extern long ext4_compat_ioctl (struct file *, unsigned int, unsigned long);
 
 /* namei.c */
--
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