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block/file-posix: Extract raw_regular_truncate() 

This functionality is part of raw_create() which we will be able to
reuse nicely in raw_truncate().

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20170613202107.10125-7-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2017-06-13 22:20:57 +02:00
parent 7dacd8bd3d
commit 9f63b07ee7
1 changed files with 78 additions and 66 deletions
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144
block/file-posix.c
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@ -1624,6 +1624,81 @@ static void raw_close(BlockDriverState *bs)
}
}
static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc,
Error **errp)
{
int result = 0;
char *buf;
switch (prealloc) {
#ifdef CONFIG_POSIX_FALLOCATE
case PREALLOC_MODE_FALLOC:
/*
* Truncating before posix_fallocate() makes it about twice slower on
* file systems that do not support fallocate(), trying to check if a
* block is allocated before allocating it, so don't do that here.
*/
result = -posix_fallocate(fd, 0, offset);
if (result != 0) {
/* posix_fallocate() doesn't set errno. */
error_setg_errno(errp, -result,
"Could not preallocate data for the new file");
}
return result;
#endif
case PREALLOC_MODE_FULL:
{
int64_t num = 0, left = offset;
/*
* Knowing the final size from the beginning could allow the file
* system driver to do less allocations and possibly avoid
* fragmentation of the file.
*/
if (ftruncate(fd, offset) != 0) {
result = -errno;
error_setg_errno(errp, -result, "Could not resize file");
return result;
}
buf = g_malloc0(65536);
while (left > 0) {
num = MIN(left, 65536);
result = write(fd, buf, num);
if (result < 0) {
result = -errno;
error_setg_errno(errp, -result,
"Could not write to the new file");
break;
}
left -= result;
}
if (result >= 0) {
result = fsync(fd);
if (result < 0) {
result = -errno;
error_setg_errno(errp, -result,
"Could not flush new file to disk");
}
}
g_free(buf);
return result;
}
case PREALLOC_MODE_OFF:
if (ftruncate(fd, offset) != 0) {
result = -errno;
error_setg_errno(errp, -result, "Could not resize file");
}
return result;
default:
result = -ENOTSUP;
error_setg(errp, "Unsupported preallocation mode: %s",
PreallocMode_lookup[prealloc]);
return result;
}
}
static int raw_truncate(BlockDriverState *bs, int64_t offset,
PreallocMode prealloc, Error **errp)
{
@ -1892,72 +1967,9 @@ static int raw_create(const char *filename, QemuOpts *opts, Error **errp)
#endif
}
switch (prealloc) {
#ifdef CONFIG_POSIX_FALLOCATE
case PREALLOC_MODE_FALLOC:
/*
* Truncating before posix_fallocate() makes it about twice slower on
* file systems that do not support fallocate(), trying to check if a
* block is allocated before allocating it, so don't do that here.
*/
result = -posix_fallocate(fd, 0, total_size);
if (result != 0) {
/* posix_fallocate() doesn't set errno. */
error_setg_errno(errp, -result,
"Could not preallocate data for the new file");
}
break;
#endif
case PREALLOC_MODE_FULL:
{
int64_t num = 0, left = total_size;
/*
* Knowing the final size from the beginning could allow the file
* system driver to do less allocations and possibly avoid
* fragmentation of the file.
*/
if (ftruncate(fd, total_size) != 0) {
result = -errno;
error_setg_errno(errp, -result, "Could not resize file");
goto out_close;
}
buf = g_malloc0(65536);
while (left > 0) {
num = MIN(left, 65536);
result = write(fd, buf, num);
if (result < 0) {
result = -errno;
error_setg_errno(errp, -result,
"Could not write to the new file");
break;
}
left -= result;
}
if (result >= 0) {
result = fsync(fd);
if (result < 0) {
result = -errno;
error_setg_errno(errp, -result,
"Could not flush new file to disk");
}
}
g_free(buf);
break;
}
case PREALLOC_MODE_OFF:
if (ftruncate(fd, total_size) != 0) {
result = -errno;
error_setg_errno(errp, -result, "Could not resize file");
}
break;
default:
result = -ENOTSUP;
error_setg(errp, "Unsupported preallocation mode: %s",
PreallocMode_lookup[prealloc]);
break;
result = raw_regular_truncate(fd, total_size, prealloc, errp);
if (result < 0) {
goto out_close;
}
out_close: