Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758858AbXJXVZx (ORCPT ); Wed, 24 Oct 2007 17:25:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753749AbXJXVZm (ORCPT ); Wed, 24 Oct 2007 17:25:42 -0400 Received: from mx1.redhat.com ([66.187.233.31]:41201 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757446AbXJXVZl (ORCPT ); Wed, 24 Oct 2007 17:25:41 -0400 Message-ID: <471FB852.8090802@ce.jp.nec.com> Date: Wed, 24 Oct 2007 17:25:38 -0400 From: "Jun'ichi Nomura" User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: device-mapper development CC: linux-kernel@vger.kernel.org Subject: [PATCH] dm: noflush resizing (1/3) Add bdlookup() Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3750 Lines: 111 This patch adds bdlookup() and bdlookup_disk(). They are lookup-only variant of bdget()/bdget_disk(). The function can be used when - the caller wants to get bdev only if somebody already got it (i.e. there is already bd_inode allocated in memory) - the race between bdlookup() and bdget() is acceptable The patch is a preparation for the 2nd part of this patchset. Background: inode is initialized with I_LOCK and I_NEW turned on. After initialization, both flags are turned off. bdget() uses iget5_locked(), which waits until I_LOCK is removed. It could take so long or forever. Signed-off-by: Jun'ichi Nomura --- fs/block_dev.c | 27 +++++++++++++++++++++++++++ include/linux/fs.h | 4 +++- include/linux/genhd.h | 6 ++++++ 3 files changed, 36 insertions(+), 1 deletion(-) Index: linux-2.6.23.work/fs/block_dev.c =================================================================== --- linux-2.6.23.work.orig/fs/block_dev.c +++ linux-2.6.23.work/fs/block_dev.c @@ -586,6 +586,33 @@ struct block_device *bdget(dev_t dev) EXPORT_SYMBOL(bdget); +/* + * Variant of bdget(), which returns bdev only when it is already gotten. + * + * The function can be used when: + * - the caller wants to get bdev only if somebody already got it + * (i.e. there is already bd_inode allocated in memory) + * and + * - the race between bdlookup() and bdget() is acceptable + */ +struct block_device *bdlookup(dev_t dev) +{ + struct inode *inode; + + might_sleep(); + + /* Use _nowait because we don't want to wait for I_LOCK */ + inode = ilookup5_nowait(bd_mnt->mnt_sb, hash(dev), bdev_test, &dev); + + if (!inode) + return NULL; + + wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); + + return &BDEV_I(inode)->bdev; +} +EXPORT_SYMBOL(bdlookup); + long nr_blockdev_pages(void) { struct block_device *bdev; Index: linux-2.6.23.work/include/linux/fs.h =================================================================== --- linux-2.6.23.work.orig/include/linux/fs.h +++ linux-2.6.23.work/include/linux/fs.h @@ -1211,10 +1211,11 @@ struct super_operations { #define I_DIRTY_DATASYNC 2 /* Data-related inode changes pending */ #define I_DIRTY_PAGES 4 /* Data-related inode changes pending */ #define __I_LOCK 3 +#define __I_NEW 6 #define I_LOCK (1 << __I_LOCK) #define I_FREEING 16 #define I_CLEAR 32 -#define I_NEW 64 +#define I_NEW (1 << __I_NEW) #define I_WILL_FREE 128 #define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES) @@ -1431,6 +1432,7 @@ extern void putname(const char *name); extern int register_blkdev(unsigned int, const char *); extern void unregister_blkdev(unsigned int, const char *); extern struct block_device *bdget(dev_t); +extern struct block_device *bdlookup(dev_t); extern void bd_set_size(struct block_device *, loff_t size); extern void bd_forget(struct inode *inode); extern void bdput(struct block_device *); Index: linux-2.6.23.work/include/linux/genhd.h =================================================================== --- linux-2.6.23.work.orig/include/linux/genhd.h +++ linux-2.6.23.work/include/linux/genhd.h @@ -435,6 +435,12 @@ static inline struct block_device *bdget return bdget(MKDEV(disk->major, disk->first_minor) + index); } +static inline struct block_device *bdlookup_disk(struct gendisk *disk, + int index) +{ + return bdlookup(MKDEV(disk->major, disk->first_minor) + index); +} + #endif #else /* CONFIG_BLOCK */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/