Commit Graph

4 Commits

Author SHA1 Message Date
sterlingjensen
2ab24dfded Use the correct return type for getopt
Use the correct return type for getopt otherwise clang complains
about tautological-constant-out-of-range-compare.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Sterling Jensen <sterlingjensen@users.noreply.github.com>
Closes #11359
2020-12-23 14:34:59 -08:00
Brian Behlendorf
6de3e59bdd
Fix unitialized variable in zstream redup command
Fix uninitialized variable in `zstream redup` command.  The compiler
may determine the 'stream_offset' variable can be uninitialized
because not all rdt_lookup() exit paths set it.  This should never
happen in practice as documented by the assert, but initialize it
regardless to resolve the warning.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #10241
Closes #10244
2020-04-23 15:54:38 -07:00
Brian Behlendorf
8080848254
Minor zstream redup command fixes
* Fix uninitialized variable in `zstream redup` command.  The
  'rdt.ddt_count' variable is uninitialized because it was
  allocated from the stack and not globally.  Initialize it.
  This was reported by gcc when compiling with debugging enabled.

    zstream_redup.c:157:16: error: 'rdt.ddt_count' may be used
    uninitialized in this function [-Werror=maybe-uninitialized]

* Remove the cmd/zstreamdump/.gitignore file.  It's no longer
  needed now that the zstreamdump command is a script.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #10192
2020-04-10 21:10:09 -07:00
Matthew Ahrens
c618f87cd2
Add zstream redup command to convert deduplicated send streams
Deduplicated send and receive is deprecated.  To ease migration to the
new dedup-send-less world, the commit adds a `zstream redup` utility to
convert deduplicated send streams to normal streams, so that they can
continue to be received indefinitely.

The new `zstream` command also replaces the functionality of
`zstreamdump`, by way of the `zstream dump` subcommand.  The
`zstreamdump` command is replaced by a shell script which invokes
`zstream dump`.

The way that `zstream redup` works under the hood is that as we read the
send stream, we build up a hash table which maps from `<GUID, object,
offset> -> <file_offset>`.

Whenever we see a WRITE record, we add a new entry to the hash table,
which indicates where in the stream file to find the WRITE record for
this block. (The key is `drr_toguid, drr_object, drr_offset`.)

For entries other than WRITE_BYREF, we pass them through unchanged
(except for the running checksum, which is recalculated).

For WRITE_BYREF records, we change them to WRITE records.  We find the
referenced WRITE record by looking in the hash table (for the record
with key `drr_refguid, drr_refobject, drr_refoffset`), and then reading
the record header and payload from the specified offset in the stream
file.  This is why the stream can not be a pipe.  The found WRITE record
replaces the WRITE_BYREF record, with its `drr_toguid`, `drr_object`,
and `drr_offset` fields changed to be the same as the WRITE_BYREF's
(i.e. we are writing the same logical block, but with the data supplied
by the previous WRITE record).

This algorithm requires memory proportional to the number of WRITE
records (same as `zfs send -D`), but the size per WRITE record is
relatively low (40 bytes, vs. 72 for `zfs send -D`).  A 1TB send stream
with 8KB blocks (`recordsize=8k`) would use around 5GB of RAM to
"redup".

Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10124 
Closes #10156
2020-04-10 10:39:55 -07:00