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Revert "kvm tools: Use mmap by default for disk images"

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This reverts commit ca8dc9130dd89ca790a7c0830d1129dfa6c5c69e.

As pointed out by Christoph Helwig, shared writeable mappings are error prone
and don't handle I/O errors nor ENOSPC properly.
This commit is contained in:
Pekka Enberg
2015-06-01 16:39:42 +01:00
committed by Will Deacon
parent 9aa4a0eb7e
commit fffb37a932
2 changed files with 11 additions and 45 deletions
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disk-image.c
+10 -44
View File
@@ -13,31 +13,21 @@
#include <unistd.h>
#include <fcntl.h>
static int raw_image__read_sector_mmap(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)
struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_operations *ops)
{
uint64_t offset = sector << SECTOR_SHIFT;
struct disk_image *self;
if (offset + dst_len > self->size)
return -1;
self = malloc(sizeof *self);
if (!self)
return NULL;
memcpy(dst, self->priv + offset, dst_len);
self->fd = fd;
self->size = size;
self->ops = ops;
return 0;
return self;
}
static int raw_image__write_sector_mmap(struct disk_image *self, uint64_t sector, void *src, uint32_t src_len)
{
uint64_t offset = sector << SECTOR_SHIFT;
if (offset + src_len > self->size)
return -1;
memcpy(self->priv + offset, src, src_len);
return 0;
}
static int raw_image__read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)
{
uint64_t offset = sector << SECTOR_SHIFT;
@@ -69,27 +59,6 @@ static struct disk_image_operations raw_image_ops = {
.write_sector = raw_image__write_sector,
};
static struct disk_image_operations raw_image_mmap_ops = {
.read_sector = raw_image__read_sector_mmap,
.write_sector = raw_image__write_sector_mmap,
};
struct disk_image *disk_image__new(int fd, uint64_t size)
{
struct disk_image *self;
self = malloc(sizeof *self);
if (!self)
return NULL;
self->fd = fd;
self->size = size;
self->priv = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
self->ops = (self->priv == MAP_FAILED) ? &raw_image_ops : &raw_image_mmap_ops;
return self;
}
static struct disk_image *raw_image__probe(int fd)
{
struct stat st;
@@ -97,7 +66,7 @@ static struct disk_image *raw_image__probe(int fd)
if (fstat(fd, &st) < 0)
return NULL;
return disk_image__new(fd, st.st_size);
return disk_image__new(fd, st.st_size, &raw_image_ops);
}
struct disk_image *disk_image__open(const char *filename)
@@ -128,9 +97,6 @@ void disk_image__close(struct disk_image *self)
if (self->ops->close)
self->ops->close(self);
if (self->priv != MAP_FAILED)
munmap(self->priv, self->size);
if (close(self->fd) < 0)
warning("close() failed");
include/kvm/disk-image.h
+1 -1
View File
@@ -22,7 +22,7 @@ struct disk_image {
};
struct disk_image *disk_image__open(const char *filename);
struct disk_image *disk_image__new(int fd, uint64_t size);
struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_operations *ops);
void disk_image__close(struct disk_image *self);
static inline int disk_image__read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)