Reduce stack usage in dsl_deleg_get, gcc flagged it as consuming a
whopping 1040 bytes or potentially 1/4 of a 4K stack. This patch
moves all the large structures and buffer off the stack and on to
the heap. This includes 2 zap_cursor_t structs each 52 bytes in
size, 2 zap_attribute_t structs each 280 bytes in size, and 1
256 byte char array. The total saves on the stack is 880 bytes
after you account for the 5 new pointers added.
Also the source buffer length has been increased from MAXNAMELEN
to MAXNAMELEN+strlen(MOS_DIR_NAME)+1 as described by the comment in
dsl_dir_name(). A buffer overrun may have been possible with the
slightly smaller buffer.
The upstream ZFS code has correctly moved to a faster native sha2
implementation. Unfortunately, under Linux that's going to be a little
problematic so we revert the code to the more portable version contained
in earlier ZFS releases. Using the native sha2 implementation in Linux
is possible but the API is slightly different in kernel version user
space depending on which libraries are used. Ideally, we need a fast
implementation of SHA256 which builds as part of ZFS this shouldn't be
that hard to do but it will take some effort.
Reduce kernel stack usage by lzjb_compress() by moving uint16 array
off the stack and on to the heap. The exact performance implications
of this I have not measured but we absolutely need to keep stack
usage to a minimum. If/when this becomes and issue we optimize.
Move xiou stat structures from a header to the dmu.c source as is
done with all the other kstat interfaces. This information is local
to dmu.c registered the xuio kstat and should stay that way.
If your only going to allow one allocator to be used and it is defined
at compile time there is no point including the others in the build.
This patch could/should be refined for Linux to make the metaslab
configurable at run time. That might be a bit tricky however since
you would need to quiese all IO. Short of that making it configurable
as a module load option would be a reasonable compromise.
In the linux kernel 'current' is defined to mean the current process
and can never be used as a local variable in a function. Simply
replace all usage of 'current' with 'curr' in this function.
Updated fix to detect if we are in an interrupt and only sleep if it
is safe to do some. I guess it must be safe to sleep under Solaris
this must be handled in a sort interrupt handler there
Almost exclusively this patch handled the addition of another char
array to the zfs_cmd_t structure. Unfortunately c90 doesn't allow
zero filling the entire struct with the '= { 0 };' shorthand.
Originally these changes were on other gcc-* topic branches but
because c90 touches the same bit of code and I'd like to keep all
the gcc-* branches completely parallel I've moved these few bits
over here. This is one of the downsides of not just having one
big patch stack.
Fix new instances or changes in gcc flagged unused code. These are
mostly related to variables which are not used when debugging is
disabled and the ASSERTs are compiled out.
Brian Behlendorf