The previous two patches for this bug worked together so that
no permanent table was memory mapped. The first patch tried to
avoid mapping while a table is in use. It allowed mapping only
if there was exactly one lock on the table, assuming that the
calling thread owned it. During mi_open(), a different call to
memory mapping was coded, which did not have this limitation.

The second patch tried to remove the code duplication and just
called mi_extra() from mi_open() an thus inherited the limitation.
But on open, a thread does not have a lock on the table...

A possible solution would be to check for zero or one lock.
But since I learned that it is safe to memory map a file while
normal file I/O is done on it, I removed the restriction altogether
and allow to memory map while a table is in use.

No test case. I do not see a chance to verify with the test suite
which kind of I/O is used on a table.


storage/myisam/mi_extra.c:
  Bug#25460 - High concurrency MyISAM access causes severe mysqld crash.
  Allow to memory map while table is in use.

into  chilla.local:/home/mydev/mysql-5.1-bug25460

Decreased code duplication by calling memory mapping
function through mi_extra().

into  chilla.local:/home/mydev/mysql-5.1-axmrg


mysys/my_thr_init.c:
  Auto merged

into  chilla.local:/home/mydev/mysql-5.1-axmrg


sql/mysql_priv.h:
  Auto merged

into  chilla.local:/home/mydev/mysql-5.1-axmrg

into  chilla.local:/home/mydev/mysql-5.0-axmrg

into  trift2.:/MySQL/M51/push-5.1

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.1-maint


sql/mysql_priv.h:
  Auto merged

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.0-maint


sql/mysql_priv.h:
  Auto merged

into  chilla.local:/home/mydev/mysql-5.1-axmrg


mysys/my_pthread.c:
  Auto merged
sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/sql_select.cc:
  Auto merged

into  chilla.local:/home/mydev/mysql-5.1-axmrg


mysys/my_pthread.c:
  Auto merged

into  chilla.local:/home/mydev/mysql-5.0-axmrg


sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/sql_select.cc:
  Auto merged

into  chilla.local:/home/mydev/mysql-5.0-axmrg


mysys/my_pthread.c:
  SCCS merged

into  olga.mysql.com:/home/igor/mysql-5.1-opt


BitKeeper/etc/gone:
  auto-union
mysql-test/r/select.result:
  Auto merged
mysql-test/t/select.test:
  Auto merged
mysys/my_getopt.c:
  Auto merged
sql/field.h:
  Auto merged
sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/mysql_priv.h:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged
sql/table.cc:
  Auto merged

into  olga.mysql.com:/home/igor/mysql-5.1-opt


BitKeeper/etc/gone:
  auto-union
mysys/my_getopt.c:
  Auto merged
sql/field.h:
  Auto merged
sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/mysql_priv.h:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged
sql/table.cc:
  Auto merged
mysql-test/r/select.result:
  SCCS merged
mysql-test/t/select.test:
  SCCS merged

into  bk-internal.mysql.com:/data0/bk/mysql-5.1-opt


sql/item.cc:
  Auto merged

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.1-maint

into  bk-internal.mysql.com:/data0/bk/mysql-5.0-opt


BitKeeper/etc/gone:
  auto-union
mysys/my_getopt.c:
  Auto merged
sql/field.h:
  Auto merged
sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/mysql_priv.h:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged
sql/table.cc:
  Auto merged
mysql-test/r/select.result:
  Manual merge
mysql-test/t/select.test:
  Manual merge

into  zippy.cornsilk.net:/home/cmiller/work/mysql/bug25807/my51-bug25807


BitKeeper/etc/collapsed:
  auto-union
mysys/mf_iocache.c:
  Auto merged

Showstopper and regression against 5.0.24.

Previously, we ignored seek() errors (see Bug#22828) and let seek()s
against pipes fail.  Now, since we check that a seek didn't fail,
and return without reading, this bug popped up.

This restores the behavior for file-ish objects that could never be 
seek()ed.


mysys/mf_iocache.c:
  If we detect early that the file is not tell()able, then we should
  assume that it's also not seek()able and therefore we should never
  set the (poorly named) "seek_not_done" flag so that we don't immedi-
  ately try to seek() when reading later.
  
  The problem was that tell() was returning -1, so when we read later, 
  we needlessly tried to seek to position  (unsigned long) -1 . 
  
  Also, if we think we're supposed to seek to a position in a file and 
  the file is un-tell()able, then abort.

into  olga.mysql.com:/home/igor/mysql-5.1-opt


mysql-test/r/view.result:
  Auto merged
sql/sql_select.cc:
  Auto merged
mysql-test/t/view.test:
  Manual merge

into  bk-internal.mysql.com:/data0/bk/mysql-4.1-opt

into  chilla.local:/home/mydev/mysql-5.1-bug25460

into  chilla.local:/home/mydev/mysql-5.1-bug25460-old

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-4.1-maint


sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/sql_select.cc:
  Auto merged

into  zippy.cornsilk.net:/home/cmiller/work/mysql/tmpmerge

Under high load it was possible that memory mapping was started on a table
while other threads were working with the table.

I fixed the start of memory mapping so that it is done at the first table
open or when the requesting thread is using the table exclusively only.


include/my_base.h:
  Bug#25460 - High concurrency MyISAM access causes severe mysqld crash.
  Added a new MyISAM open_flag HA_OPEN_MMAP.
storage/myisam/ha_myisam.cc:
  Bug#25460 - High concurrency MyISAM access causes severe mysqld crash.
  Replaced the call to mi_extra(... HA_EXTRA_MMAP ...) by the new open_flag
  HA_OPEN_MMAP. This effects that the mapping will no longer be done on
  every open of the table but just on the initial open, when the MyISAM
  share is created.
storage/myisam/mi_dynrec.c:
  Bug#25460 - High concurrency MyISAM access causes severe mysqld crash.
  Added a comment with a concern regarding the mmap flag MAP_NORESERVE.
storage/myisam/mi_extra.c:
  Bug#25460 - High concurrency MyISAM access causes severe mysqld crash.
  Limited the start of memory mapping to situations where the requesting
  thread has the table exclusively opened.
storage/myisam/mi_open.c:
  Bug#25460 - High concurrency MyISAM access causes severe mysqld crash.
  Added memory mapping code. Used if the new open_flag HA_OPEN_MMAP is set.

  Rename: BitKeeper/deleted/.del-README.txt -> BitKeeper/deleted/.del-README.txt-renamed


BitKeeper/deleted/.del-README.txt-renamed:
  Rename: BitKeeper/deleted/.del-README.txt -> BitKeeper/deleted/.del-README.txt-renamed

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.1-maint


sql/mysql_priv.h:
  manual merge.

into  zippy.cornsilk.net:/home/cmiller/work/mysql/mysql-5.0-maint


sql/mysql_priv.h:
  Auto merged

BitKeeper/deleted/.del-README.txt~97cdd3dccd3539d2:
  Delete: mysql-test/suite/objects/README.txt
BitKeeper/deleted/.del-drop_all.inc:
  Delete: mysql-test/suite/objects/include/drop_all.inc
BitKeeper/deleted/.del-objects.inc:
  Delete: mysql-test/suite/objects/include/objects.inc
BitKeeper/deleted/.del-tbl01.inc:
  Delete: mysql-test/suite/objects/include/tbl01.inc
BitKeeper/deleted/.del-tbl02.inc:
  Delete: mysql-test/suite/objects/include/tbl02.inc
BitKeeper/deleted/.del-tbl03.inc:
  Delete: mysql-test/suite/objects/include/tbl03.inc
BitKeeper/deleted/.del-tbl04.inc:
  Delete: mysql-test/suite/objects/include/tbl04.inc
BitKeeper/deleted/.del-tbl05.inc:
  Delete: mysql-test/suite/objects/include/tbl05.inc
BitKeeper/deleted/.del-tbl06.inc:
  Delete: mysql-test/suite/objects/include/tbl06.inc
BitKeeper/deleted/.del-tbl07.inc:
  Delete: mysql-test/suite/objects/include/tbl07.inc
BitKeeper/deleted/.del-tbl08.inc:
  Delete: mysql-test/suite/objects/include/tbl08.inc
BitKeeper/deleted/.del-tbl09.inc:
  Delete: mysql-test/suite/objects/include/tbl09.inc
BitKeeper/deleted/.del-tbl10.inc:
  Delete: mysql-test/suite/objects/include/tbl10.inc
BitKeeper/deleted/.del-tbl11.inc:
  Delete: mysql-test/suite/objects/include/tbl11.inc
BitKeeper/deleted/.del-tbl12.inc:
  Delete: mysql-test/suite/objects/include/tbl12.inc
BitKeeper/deleted/.del-tbl13.inc:
  Delete: mysql-test/suite/objects/include/tbl13.inc
BitKeeper/deleted/.del-tbl14.inc:
  Delete: mysql-test/suite/objects/include/tbl14.inc
BitKeeper/deleted/.del-tbl15.inc:
  Delete: mysql-test/suite/objects/include/tbl15.inc
BitKeeper/deleted/.del-tbl16.inc:
  Delete: mysql-test/suite/objects/include/tbl16.inc
BitKeeper/deleted/.del-tbl17.inc:
  Delete: mysql-test/suite/objects/include/tbl17.inc
BitKeeper/deleted/.del-tbl18.inc:
  Delete: mysql-test/suite/objects/include/tbl18.inc
BitKeeper/deleted/.del-tbl19.inc:
  Delete: mysql-test/suite/objects/include/tbl19.inc
BitKeeper/deleted/.del-tbl20.inc:
  Delete: mysql-test/suite/objects/include/tbl20.inc
BitKeeper/deleted/.del-tbl21.inc:
  Delete: mysql-test/suite/objects/include/tbl21.inc
BitKeeper/deleted/.del-tbl22.inc:
  Delete: mysql-test/suite/objects/include/tbl22.inc
BitKeeper/deleted/.del-tbl23.inc:
  Delete: mysql-test/suite/objects/include/tbl23.inc
BitKeeper/deleted/.del-tbl24.inc:
  Delete: mysql-test/suite/objects/include/tbl24.inc
BitKeeper/deleted/.del-tbl25.inc:
  Delete: mysql-test/suite/objects/include/tbl25.inc
BitKeeper/deleted/.del-tbl26.inc:
  Delete: mysql-test/suite/objects/include/tbl26.inc
BitKeeper/deleted/.del-tbl27.inc:
  Delete: mysql-test/suite/objects/include/tbl27.inc
BitKeeper/deleted/.del-tbl28.inc:
  Delete: mysql-test/suite/objects/include/tbl28.inc
BitKeeper/deleted/.del-tbl29.inc:
  Delete: mysql-test/suite/objects/include/tbl29.inc
BitKeeper/deleted/.del-tbl30.inc:
  Delete: mysql-test/suite/objects/include/tbl30.inc
BitKeeper/deleted/.del-tbl31.inc:
  Delete: mysql-test/suite/objects/include/tbl31.inc
BitKeeper/deleted/.del-tbl32.inc:
  Delete: mysql-test/suite/objects/include/tbl32.inc
BitKeeper/deleted/.del-tbl33.inc:
  Delete: mysql-test/suite/objects/include/tbl33.inc
BitKeeper/deleted/.del-tbl34.inc:
  Delete: mysql-test/suite/objects/include/tbl34.inc
BitKeeper/deleted/.del-tbl35.inc:
  Delete: mysql-test/suite/objects/include/tbl35.inc
BitKeeper/deleted/.del-tbl36.inc:
  Delete: mysql-test/suite/objects/include/tbl36.inc
BitKeeper/deleted/.del-tbl37.inc:
  Delete: mysql-test/suite/objects/include/tbl37.inc
BitKeeper/deleted/.del-tbl38.inc:
  Delete: mysql-test/suite/objects/include/tbl38.inc
BitKeeper/deleted/.del-tbl39.inc:
  Delete: mysql-test/suite/objects/include/tbl39.inc
BitKeeper/deleted/.del-tbl40.inc:
  Delete: mysql-test/suite/objects/include/tbl40.inc
BitKeeper/deleted/.del-tbl41.inc:
  Delete: mysql-test/suite/objects/include/tbl41.inc
BitKeeper/deleted/.del-tbl42.inc:
  Delete: mysql-test/suite/objects/include/tbl42.inc
BitKeeper/deleted/.del-tbl43.inc:
  Delete: mysql-test/suite/objects/include/tbl43.inc
BitKeeper/deleted/.del-tbl44.inc:
  Delete: mysql-test/suite/objects/include/tbl44.inc
BitKeeper/deleted/.del-tbl45.inc:
  Delete: mysql-test/suite/objects/include/tbl45.inc
BitKeeper/deleted/.del-tbl46.inc:
  Delete: mysql-test/suite/objects/include/tbl46.inc
BitKeeper/deleted/.del-tbl47.inc:
  Delete: mysql-test/suite/objects/include/tbl47.inc
BitKeeper/deleted/.del-tbl48.inc:
  Delete: mysql-test/suite/objects/include/tbl48.inc
BitKeeper/deleted/.del-view.inc:
  Delete: mysql-test/suite/objects/include/view.inc
BitKeeper/deleted/.del-objects_falcon.result:
  Delete: mysql-test/suite/objects/r/objects_falcon.result
BitKeeper/deleted/.del-objects_falcon.test:
  Delete: mysql-test/suite/objects/t/objects_falcon.test
BitKeeper/deleted/.del-objects_innodb.result:
  Delete: mysql-test/suite/objects/r/objects_innodb.result
BitKeeper/deleted/.del-objects_innodb.test:
  Delete: mysql-test/suite/objects/t/objects_innodb.test

into  olga.mysql.com:/home/igor/mysql-5.1-opt


BitKeeper/etc/gone:
  auto-union
mysql-test/r/insert_select.result:
  Auto merged
mysql-test/r/join_outer.result:
  Auto merged
mysql-test/r/select.result:
  Auto merged
mysql-test/r/view.result:
  Auto merged
mysql-test/t/insert_select.test:
  Auto merged
mysql-test/t/join_outer.test:
  Auto merged
mysql-test/t/select.test:
  Auto merged
mysys/my_getopt.c:
  Auto merged
sql/field.h:
  Auto merged
sql/field_conv.cc:
  Auto merged
sql/item.cc:
  Auto merged
sql/item_cmpfunc.cc:
  Auto merged
sql/item_cmpfunc.h:
  Auto merged
sql/item_func.cc:
  Auto merged
sql/sql_lex.cc:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged
sql/sql_show.cc:
  Auto merged
sql/sql_view.cc:
  Auto merged
sql/table.cc:
  Auto merged
sql/table.h:
  Auto merged
mysql-test/include/mix1.inc:
  Manual merge
mysql-test/r/information_schema.result:
  Manual merge
mysql-test/r/innodb_mysql.result:
  Manual merge
mysql-test/t/information_schema.test:
  Manual merge
mysql-test/t/view.test:
  Manual merge
mysys/my_pthread.c:
  Manual merge
sql/mysql_priv.h:
  Manual merge
sql/opt_range.cc:
  Manual merge
sql/sql_insert.cc:
  Manual merge
sql/sql_update.cc:
  Manual merge

into  pilot.mysql.com:/home/msvensson/mysql/mysql-5.1-new-maint


BitKeeper/etc/gone:
  auto-union
BitKeeper/etc/ignore:
  auto-union
mysys/my_getopt.c:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/table.cc:
  Auto merged
sql/unireg.cc:
  Auto merged
mysql-test/r/type_enum.result:
  Use local
mysql-test/t/type_enum.test:
  Use local

into  pilot.mysql.com:/home/msvensson/mysql/mysql-5.1-new-maint


BitKeeper/etc/ignore:
  auto-union

into  pilot.mysql.com:/home/msvensson/mysql/mysql-5.0-maint


BitKeeper/etc/ignore:
  auto-union