Messages in this thread Patch in this message | | | Date | Fri, 21 Jan 2005 18:15:03 +0000 | From | Alasdair G Kergon <> | Subject | device-mapper: optionally bypass a bdget |
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Improve performance by optionally bypassing some code that uses bdget.
Signed-Off-By: Alasdair G Kergon <agk@redhat.com> --- diff/drivers/md/dm-ioctl.c 2005-01-12 20:50:16.000000000 +0000 +++ source/drivers/md/dm-ioctl.c 2005-01-12 20:50:07.000000000 +0000 @@ -1,6 +1,6 @@ /* * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. - * Copyright (C) 2004 Red Hat, Inc. All rights reserved. + * Copyright (C) 2004 - 2005 Red Hat, Inc. All rights reserved. * * This file is released under the GPL. */ @@ -520,19 +520,22 @@ if (dm_suspended(md)) param->flags |= DM_SUSPEND_FLAG; - bdev = bdget_disk(disk, 0); - if (!bdev) - return -ENXIO; - param->dev = huge_encode_dev(MKDEV(disk->major, disk->first_minor)); - /* - * Yes, this will be out of date by the time it gets back - * to userland, but it is still very useful ofr - * debugging. - */ - param->open_count = bdev->bd_openers; - bdput(bdev); + if (!(param->flags & DM_SKIP_BDGET_FLAG)) { + bdev = bdget_disk(disk, 0); + if (!bdev) + return -ENXIO; + + /* + * Yes, this will be out of date by the time it gets back + * to userland, but it is still very useful for + * debugging. + */ + param->open_count = bdev->bd_openers; + bdput(bdev); + } else + param->open_count = -1; if (disk->policy) param->flags |= DM_READONLY_FLAG; --- diff/include/linux/dm-ioctl.h 2005-01-12 20:50:16.000000000 +0000 +++ source/include/linux/dm-ioctl.h 2005-01-12 20:49:42.000000000 +0000 @@ -1,6 +1,6 @@ /* * Copyright (C) 2001 - 2003 Sistina Software (UK) Limited. - * Copyright (C) 2004 Red Hat, Inc. All rights reserved. + * Copyright (C) 2004 - 2005 Red Hat, Inc. All rights reserved. * * This file is released under the LGPL. */ @@ -272,9 +272,9 @@ #define DM_TARGET_MSG _IOWR(DM_IOCTL, DM_TARGET_MSG_CMD, struct dm_ioctl) #define DM_VERSION_MAJOR 4 -#define DM_VERSION_MINOR 3 +#define DM_VERSION_MINOR 4 #define DM_VERSION_PATCHLEVEL 0 -#define DM_VERSION_EXTRA "-ioctl (2004-09-30)" +#define DM_VERSION_EXTRA "-ioctl (2005-01-12)" /* Status bits */ #define DM_READONLY_FLAG (1 << 0) /* In/Out */ @@ -300,4 +300,9 @@ */ #define DM_BUFFER_FULL_FLAG (1 << 8) /* Out */ +/* + * Set this to improve performance when you aren't going to use open_count + */ +#define DM_SKIP_BDGET_FLAG (1 << 9) /* In */ + #endif /* _LINUX_DM_IOCTL_H */ - 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/
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