From patchwork Mon Jun 7 10:06:47 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 54843 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 7951AB7D1F for ; Mon, 7 Jun 2010 20:08:45 +1000 (EST) Received: from localhost ([127.0.0.1]:54916 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OLZG5-0004r9-81 for incoming@patchwork.ozlabs.org; Mon, 07 Jun 2010 06:08:41 -0400 Received: from [140.186.70.92] (port=38309 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OLZEH-0004ou-NF for qemu-devel@nongnu.org; Mon, 07 Jun 2010 06:06:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OLZEG-0008Vs-FT for qemu-devel@nongnu.org; Mon, 07 Jun 2010 06:06:49 -0400 Received: from verein.lst.de ([213.95.11.210]:36380) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OLZEG-0008Ve-64 for qemu-devel@nongnu.org; Mon, 07 Jun 2010 06:06:48 -0400 Received: from verein.lst.de (localhost [127.0.0.1]) by verein.lst.de (8.12.3/8.12.3/Debian-7.1) with ESMTP id o57A6lXt002234 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO) for ; Mon, 7 Jun 2010 12:06:47 +0200 Received: (from hch@localhost) by verein.lst.de (8.12.3/8.12.3/Debian-7.2) id o57A6lHO002233 for qemu-devel@nongnu.org; Mon, 7 Jun 2010 12:06:47 +0200 Date: Mon, 7 Jun 2010 12:06:47 +0200 From: Christoph Hellwig To: qemu-devel@nongnu.org Message-ID: <20100607100647.GC2176@lst.de> Mime-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.3.28i X-Scanned-By: MIMEDefang 2.39 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) Subject: [Qemu-devel] [PATCH 3/3] cow: use qemu block API X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Use bdrv_pwrite to access the backing device instead of pread, and convert the driver to implementing the bdrv_open method which gives it an already opened BlockDriverState for the underlying device. Signed-off-by: Christoph Hellwig Index: qemu/block/cow.c =================================================================== --- qemu.orig/block/cow.c 2010-05-07 17:07:56.000000000 +0200 +++ qemu/block/cow.c 2010-05-07 17:11:11.498255489 +0200 @@ -42,7 +42,6 @@ struct cow_header_v2 { }; typedef struct BDRVCowState { - int fd; int64_t cow_sectors_offset; } BDRVCowState; @@ -58,23 +57,16 @@ static int cow_probe(const uint8_t *buf, return 0; } -static int cow_open(BlockDriverState *bs, const char *filename, int flags) +static int cow_open(BlockDriverState *bs, int flags) { BDRVCowState *s = bs->opaque; - int fd; struct cow_header_v2 cow_header; int bitmap_size; int64_t size; - fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE); - if (fd < 0) { - fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE); - if (fd < 0) - return -1; - } - s->fd = fd; /* see if it is a cow image */ - if (pread(fd, &cow_header, sizeof(cow_header), 0) != sizeof(cow_header)) { + if (bdrv_pread(bs->file, 0, &cow_header, sizeof(cow_header)) != + sizeof(cow_header)) { goto fail; } @@ -94,7 +86,6 @@ static int cow_open(BlockDriverState *bs s->cow_sectors_offset = (bitmap_size + 511) & ~511; return 0; fail: - close(fd); return -1; } @@ -104,18 +95,17 @@ static int cow_open(BlockDriverState *bs */ static inline int cow_set_bit(BlockDriverState *bs, int64_t bitnum) { - BDRVCowState *s = bs->opaque; uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8; uint8_t bitmap; - if (pread(s->fd, &bitmap, sizeof(bitmap), offset) != + if (bdrv_pread(bs->file, offset, &bitmap, sizeof(bitmap)) != sizeof(bitmap)) { return -errno; } bitmap |= (1 << (bitnum % 8)); - if (pwrite(s->fd, &bitmap, sizeof(bitmap), offset) != + if (bdrv_pwrite(bs->file, offset, &bitmap, sizeof(bitmap)) != sizeof(bitmap)) { return -errno; } @@ -124,11 +114,10 @@ static inline int cow_set_bit(BlockDrive static inline int is_bit_set(BlockDriverState *bs, int64_t bitnum) { - BDRVCowState *s = bs->opaque; uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8; uint8_t bitmap; - if (pread(s->fd, &bitmap, sizeof(bitmap), offset) != + if (bdrv_pread(bs->file, offset, &bitmap, sizeof(bitmap)) != sizeof(bitmap)) { return -errno; } @@ -186,8 +175,9 @@ static int cow_read(BlockDriverState *bs while (nb_sectors > 0) { if (cow_is_allocated(bs, sector_num, nb_sectors, &n)) { - ret = pread(s->fd, buf, n * 512, - s->cow_sectors_offset + sector_num * 512); + ret = bdrv_pread(bs->file, + s->cow_sectors_offset + sector_num * 512, + buf, n * 512); if (ret != n * 512) return -1; } else { @@ -213,8 +203,8 @@ static int cow_write(BlockDriverState *b BDRVCowState *s = bs->opaque; int ret; - ret = pwrite(s->fd, buf, nb_sectors * 512, - s->cow_sectors_offset + sector_num * 512); + ret = bdrv_pwrite(bs->file, s->cow_sectors_offset + sector_num * 512, + buf, nb_sectors * 512); if (ret != nb_sectors * 512) return -1; @@ -223,8 +213,6 @@ static int cow_write(BlockDriverState *b static void cow_close(BlockDriverState *bs) { - BDRVCowState *s = bs->opaque; - close(s->fd); } static int cow_create(const char *filename, QEMUOptionParameter *options) @@ -294,8 +282,7 @@ exit: static void cow_flush(BlockDriverState *bs) { - BDRVCowState *s = bs->opaque; - qemu_fdatasync(s->fd); + bdrv_flush(bs->file); } static QEMUOptionParameter cow_create_options[] = { @@ -316,7 +303,7 @@ static BlockDriver bdrv_cow = { .format_name = "cow", .instance_size = sizeof(BDRVCowState), .bdrv_probe = cow_probe, - .bdrv_file_open = cow_open, + .bdrv_open = cow_open, .bdrv_read = cow_read, .bdrv_write = cow_write, .bdrv_close = cow_close,