For devices smaller than 4096 the current code results in a blockdevice
size of 0.
For devices with a different blocksize than 4096 the code potentially
leads to more dropped blocks at the end of the file than necessary. For
example a device with size 6144 would have only 4096 bytes available on
client side even if the blocksize is set to 512.
This patch tries to use the user-given blocksize if possible. Otherwise
it falls back to using 4096.
Signed-off-by: Markus Pargmann <m...@pengutronix.de>
---
nbd-client.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/nbd-client.c b/nbd-client.c
index 2c387f8c8c4c..40d6b7abac3c 100644
--- a/nbd-client.c
+++ b/nbd-client.c
@@ -462,14 +462,25 @@ void setsizes(int nbd, u64 size64, int blocksize, u32
flags) {
if (size64>>12 > (uint64_t)~0UL)
err("Device too large.\n");
else {
- if (ioctl(nbd, NBD_SET_BLKSIZE, 4096UL) < 0)
+ int tmp_blocksize = 4096;
+ if (size64 / (u64)blocksize <= (uint64_t)~0UL)
+ tmp_blocksize = blocksize;
+ if (ioctl(nbd, NBD_SET_BLKSIZE, tmp_blocksize) < 0) {
+ fprintf(stderr, "Failed to set blocksize %d\n",
+ tmp_blocksize);
err("Ioctl/1.1a failed: %m\n");
- size = (unsigned long)(size64>>12);
+ }
+ size = (unsigned long)(size64 / (u64)tmp_blocksize);
if (ioctl(nbd, NBD_SET_SIZE_BLOCKS, size) < 0)
err("Ioctl/1.1b failed: %m\n");
- if (ioctl(nbd, NBD_SET_BLKSIZE, (unsigned long)blocksize) < 0)
- err("Ioctl/1.1c failed: %m\n");
- fprintf(stderr, "bs=%d, sz=%llu bytes\n", blocksize,
4096ULL*size);
+ if (tmp_blocksize != blocksize) {
+ if (ioctl(nbd, NBD_SET_BLKSIZE, (unsigned
long)blocksize) < 0) {
+ fprintf(stderr, "Failed to set blocksize %d\n",
+ blocksize);
+ err("Ioctl/1.1c failed: %m\n");
+ }
+ }
+ fprintf(stderr, "bs=%d, sz=%llu bytes\n", blocksize,
(u64)tmp_blocksize * size);
}
ioctl(nbd, NBD_CLEAR_SOCK);
--
2.7.0.rc3
------------------------------------------------------------------------------
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