From 019d6b8ff0d495ded6977f24a4e8fd1c7fec09e0 Mon Sep 17 00:00:00 2001 From: Anthony Liguori Date: Sat, 9 May 2009 17:14:19 -0500 Subject: Move block drivers into their own directory Signed-off-by: Anthony Liguori --- block/cow.c | 275 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 275 insertions(+) create mode 100644 block/cow.c (limited to 'block/cow.c') diff --git a/block/cow.c b/block/cow.c new file mode 100644 index 0000000000..94b3549389 --- /dev/null +++ b/block/cow.c @@ -0,0 +1,275 @@ +/* + * Block driver for the COW format + * + * Copyright (c) 2004 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#ifndef _WIN32 +#include "qemu-common.h" +#include "block_int.h" +#include "module.h" +#include + +/**************************************************************/ +/* COW block driver using file system holes */ + +/* user mode linux compatible COW file */ +#define COW_MAGIC 0x4f4f4f4d /* MOOO */ +#define COW_VERSION 2 + +struct cow_header_v2 { + uint32_t magic; + uint32_t version; + char backing_file[1024]; + int32_t mtime; + uint64_t size; + uint32_t sectorsize; +}; + +typedef struct BDRVCowState { + int fd; + uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */ + uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */ + int cow_bitmap_size; + int64_t cow_sectors_offset; +} BDRVCowState; + +static int cow_probe(const uint8_t *buf, int buf_size, const char *filename) +{ + const struct cow_header_v2 *cow_header = (const void *)buf; + + if (buf_size >= sizeof(struct cow_header_v2) && + be32_to_cpu(cow_header->magic) == COW_MAGIC && + be32_to_cpu(cow_header->version) == COW_VERSION) + return 100; + else + return 0; +} + +static int cow_open(BlockDriverState *bs, const char *filename, int flags) +{ + BDRVCowState *s = bs->opaque; + int fd; + struct cow_header_v2 cow_header; + 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 (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) { + goto fail; + } + + if (be32_to_cpu(cow_header.magic) != COW_MAGIC || + be32_to_cpu(cow_header.version) != COW_VERSION) { + goto fail; + } + + /* cow image found */ + size = be64_to_cpu(cow_header.size); + bs->total_sectors = size / 512; + + pstrcpy(bs->backing_file, sizeof(bs->backing_file), + cow_header.backing_file); + + /* mmap the bitmap */ + s->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header); + s->cow_bitmap_addr = (void *)mmap(get_mmap_addr(s->cow_bitmap_size), + s->cow_bitmap_size, + PROT_READ | PROT_WRITE, + MAP_SHARED, s->fd, 0); + if (s->cow_bitmap_addr == MAP_FAILED) + goto fail; + s->cow_bitmap = s->cow_bitmap_addr + sizeof(cow_header); + s->cow_sectors_offset = (s->cow_bitmap_size + 511) & ~511; + return 0; + fail: + close(fd); + return -1; +} + +static inline void cow_set_bit(uint8_t *bitmap, int64_t bitnum) +{ + bitmap[bitnum / 8] |= (1 << (bitnum%8)); +} + +static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum) +{ + return !!(bitmap[bitnum / 8] & (1 << (bitnum%8))); +} + + +/* Return true if first block has been changed (ie. current version is + * in COW file). Set the number of continuous blocks for which that + * is true. */ +static inline int is_changed(uint8_t *bitmap, + int64_t sector_num, int nb_sectors, + int *num_same) +{ + int changed; + + if (!bitmap || nb_sectors == 0) { + *num_same = nb_sectors; + return 0; + } + + changed = is_bit_set(bitmap, sector_num); + for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) { + if (is_bit_set(bitmap, sector_num + *num_same) != changed) + break; + } + + return changed; +} + +static int cow_is_allocated(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, int *pnum) +{ + BDRVCowState *s = bs->opaque; + return is_changed(s->cow_bitmap, sector_num, nb_sectors, pnum); +} + +static int cow_read(BlockDriverState *bs, int64_t sector_num, + uint8_t *buf, int nb_sectors) +{ + BDRVCowState *s = bs->opaque; + int ret, n; + + while (nb_sectors > 0) { + if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) { + lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET); + ret = read(s->fd, buf, n * 512); + if (ret != n * 512) + return -1; + } else { + if (bs->backing_hd) { + /* read from the base image */ + ret = bdrv_read(bs->backing_hd, sector_num, buf, n); + if (ret < 0) + return -1; + } else { + memset(buf, 0, n * 512); + } + } + nb_sectors -= n; + sector_num += n; + buf += n * 512; + } + return 0; +} + +static int cow_write(BlockDriverState *bs, int64_t sector_num, + const uint8_t *buf, int nb_sectors) +{ + BDRVCowState *s = bs->opaque; + int ret, i; + + lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET); + ret = write(s->fd, buf, nb_sectors * 512); + if (ret != nb_sectors * 512) + return -1; + for (i = 0; i < nb_sectors; i++) + cow_set_bit(s->cow_bitmap, sector_num + i); + return 0; +} + +static void cow_close(BlockDriverState *bs) +{ + BDRVCowState *s = bs->opaque; + munmap((void *)s->cow_bitmap_addr, s->cow_bitmap_size); + close(s->fd); +} + +static int cow_create(const char *filename, int64_t image_sectors, + const char *image_filename, int flags) +{ + int fd, cow_fd; + struct cow_header_v2 cow_header; + struct stat st; + + if (flags) + return -ENOTSUP; + + cow_fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, + 0644); + if (cow_fd < 0) + return -1; + memset(&cow_header, 0, sizeof(cow_header)); + cow_header.magic = cpu_to_be32(COW_MAGIC); + cow_header.version = cpu_to_be32(COW_VERSION); + if (image_filename) { + /* Note: if no file, we put a dummy mtime */ + cow_header.mtime = cpu_to_be32(0); + + fd = open(image_filename, O_RDONLY | O_BINARY); + if (fd < 0) { + close(cow_fd); + goto mtime_fail; + } + if (fstat(fd, &st) != 0) { + close(fd); + goto mtime_fail; + } + close(fd); + cow_header.mtime = cpu_to_be32(st.st_mtime); + mtime_fail: + pstrcpy(cow_header.backing_file, sizeof(cow_header.backing_file), + image_filename); + } + cow_header.sectorsize = cpu_to_be32(512); + cow_header.size = cpu_to_be64(image_sectors * 512); + write(cow_fd, &cow_header, sizeof(cow_header)); + /* resize to include at least all the bitmap */ + ftruncate(cow_fd, sizeof(cow_header) + ((image_sectors + 7) >> 3)); + close(cow_fd); + return 0; +} + +static void cow_flush(BlockDriverState *bs) +{ + BDRVCowState *s = bs->opaque; + fsync(s->fd); +} + +static BlockDriver bdrv_cow = { + .format_name = "cow", + .instance_size = sizeof(BDRVCowState), + .bdrv_probe = cow_probe, + .bdrv_open = cow_open, + .bdrv_read = cow_read, + .bdrv_write = cow_write, + .bdrv_close = cow_close, + .bdrv_create = cow_create, + .bdrv_flush = cow_flush, + .bdrv_is_allocated = cow_is_allocated, +}; + +static void bdrv_cow_init(void) +{ + bdrv_register(&bdrv_cow); +} + +block_init(bdrv_cow_init); +#endif -- cgit v1.2.1