On 7/8/20 6:28 AM, Richard W.M. Jones wrote:
On Tue, Jul 07, 2020 at 05:22:46PM -0500, Eric Blake wrote: [...]+/* Compute aligned extents on behalf of a filter. */ +int +nbdkit_extents_aligned (struct nbdkit_next_ops *next_ops, + nbdkit_backend *nxdata, + uint32_t count, uint64_t offset, + uint32_t flags, uint32_t align, + struct nbdkit_extents *exts, int *err) +{ + size_t i; + struct nbdkit_extent e, e2;
Found my bug. Unless these are a pointers...
+ + if (!IS_ALIGNED(count | offset, align)) { + nbdkit_error ("nbdkit_extents_aligned: unaligned request"); + *err = EINVAL; + return -1; + }I wonder if this also should be an assert? This is less clear to me than the vector case however.
I'm fine with an assert.
+ /* Perform an initial query, then scan for the first unaligned extent. */ + if (next_ops->extents (nxdata, count, offset, flags, exts, err) == -1) + return -1; + for (i = 0; i < exts->extents.size; ++i) { + e = exts->extents.ptr[i];
...then this merely copies data,
+ if (!IS_ALIGNED(e.length, align)) { + /* If the unalignment is past align, just truncate and return early */ + if (e.offset + e.length > offset + align) { + e.length = ROUND_DOWN (e.length, align);
...and manipulating the copy doesn't affect what gets returned. With that fixed, my tests are now working as desired.
So we're intersecting (&) the types defined as: #define NBDKIT_EXTENT_HOLE (1<<0) /* Same as NBD_STATE_HOLE */ #define NBDKIT_EXTENT_ZERO (1<<1) /* Same as NBD_STATE_ZERO */ If all extents are holes, then it's a hole. If all extents are zero, then it's a zero. Otherwise it's non-zero data. This seems correct.
I'll add a comment somewhere why intersection is correct.
All looks good to me, so ACK. Rich.
-- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org _______________________________________________ Libguestfs mailing list Libguestfs@redhat.com https://www.redhat.com/mailman/listinfo/libguestfs
