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loop-util: insist on setting the sector size correctly

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If we attach a disk image to a loopback device the sector size of the
image must match the one of the loopback device, hence be more careful
here.
This commit is contained in:
Lennart Poettering
2023-01-18 10:10:57 +01:00
parent 65046b92dc
commit 1163ddb386
1 changed files with 19 additions and 1 deletions
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src/shared/loop-util.c
+19 -1
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@@ -131,8 +131,10 @@ static int loop_configure_verify(int fd, const struct loop_config *c) {
if (r < 0)
return r;
if (ssz != c->block_size)
if (ssz != c->block_size) {
log_debug("LOOP_CONFIGURE didn't honour requested block size %" PRIu32 ", got %" PRIu32 " instead. Ignoring.", c->block_size, ssz);
broken = true;
}
}
if (c->info.lo_sizelimit != 0) {
@@ -173,6 +175,7 @@ static int loop_configure_verify(int fd, const struct loop_config *c) {
static int loop_configure_fallback(int fd, const struct loop_config *c) {
struct loop_info64 info_copy;
int r;
assert(fd >= 0);
assert(c);
@@ -220,6 +223,21 @@ static int loop_configure_fallback(int fd, const struct loop_config *c) {
if (ioctl(fd, BLKFLSBUF, 0) < 0)
log_debug_errno(errno, "Failed to issue BLKFLSBUF ioctl, ignoring: %m");
/* If a block size is requested then try to configure it. If that doesn't work, ignore errors, but
* afterwards, let's validate what is in effect, and if it doesn't match what we want, fail */
if (c->block_size != 0) {
uint32_t ssz;
if (ioctl(fd, LOOP_SET_BLOCK_SIZE, (unsigned long) c->block_size) < 0)
log_debug_errno(errno, "Failed to set sector size, ignoring: %m");
r = blockdev_get_sector_size(fd, &ssz);
if (r < 0)
return log_debug_errno(r, "Failed to read sector size: %m");
if (ssz != c->block_size)
return log_debug_errno(SYNTHETIC_ERRNO(EIO), "Sector size of loopback device doesn't match what we requested, refusing.");
}
/* LO_FLAGS_DIRECT_IO is a flags we need to configure via explicit ioctls. */
if (FLAGS_SET(c->info.lo_flags, LO_FLAGS_DIRECT_IO))
if (ioctl(fd, LOOP_SET_DIRECT_IO, 1UL) < 0)