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Brian Behlendorf a168788053 Reduce stack for traverse_visitbp() recursion
During pool import stack overflows may still occur due to the
potentially deep recursion of traverse_visitbp().  This is most
likely to occur when additional layers are added to the block
device stack such as DM multipath.  To minimize the stack usage
for this call path the following changes were made:

1) Added the keywork 'noinline' to the vdev_*_map_alloc() functions
   to prevent them from being inlined by gcc.  This reduced the
   stack usage of vdev_raidz_io_start() from 208 to 128 bytes, and
   vdev_mirror_io_start() from 144 to 128 bytes.

2) The 'saved_poolname' charater array in zfsdev_ioctl() was moved
   from the stack to the heap.  This reduced the stack usage of
   zfsdev_ioctl() from 368 to 112 bytes.

3) The major saving came from slimming down traverse_visitbp() from
   from 224 to 144 bytes.  Since this function is called recursively
   the 80 bytes saved per invokation adds up.  The following changes
   were made:

  a) The 'hard' local variable was replaced by a TD_HARD() macro.

  b) The 'pd' local variable was replaced by 'td->td_pfd' references.

  c) The zbookmark_t was moved to the heap.  This does cost us an
     additional memory allocation per recursion by that cost should
     still be minimal.  The cost could be further reduced by adding
     a dedicated zbookmark_t slab cache.

  d) The variable declarations in 'if (BP_GET_LEVEL()) { }' were
     restructured to use the minimum amount of stack.  This includes
     removing the 'cbp' local variable.

Overall for the offending use case roughly 1584 of total stack space
has been saved.  This is enough to avoid overflowing the stack on
stock kernels with 8k stacks.  See #1778 for additional details.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #1778
2013-11-14 14:28:12 -08:00
cmd Python 3 fixes 2013-11-08 14:30:29 -08:00
config Posix ACL Support 2013-10-29 14:54:26 -07:00
dracut Refresh dracut module setup 2013-03-21 12:51:06 -07:00
etc Updating init scripts to have more robust grepping 2013-11-08 10:55:20 -08:00
include Honor CONFIG_FS_POSIX_ACL kernel option 2013-11-05 16:22:05 -08:00
lib Handle concurrent snapshot automounts failing due to EBUSY. 2013-11-08 10:45:14 -08:00
man Explain 'zfs list -t snap -o name -s name' speedup 2013-11-08 14:21:58 -08:00
module Reduce stack for traverse_visitbp() recursion 2013-11-14 14:28:12 -08:00
patches Adding grub2 mkconfig support patch 2012-07-30 16:17:23 -07:00
rpm Fix libzfs_core changes to follow GNU libtool guidelines 2013-10-10 16:56:51 -07:00
scripts Add cstyle.pl utility and cstyle.1 man page 2013-10-30 11:36:30 -07:00
udev Open pools asynchronously after module load 2013-07-03 09:24:38 -07:00
.gitignore Ignore *.{deb,rpm,tar.gz} files in the top directory. 2013-04-24 16:18:59 -07:00
AUTHORS Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
autogen.sh build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
configure.ac Add dbufstat.py command 2013-10-25 14:52:45 -07:00
copy-builtin Consistent menuconfig name 2012-08-26 13:49:37 -07:00
COPYRIGHT Refresh links to web site 2013-03-06 15:46:41 -08:00
DISCLAIMER Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
Makefile.am Add cstyle.pl utility and cstyle.1 man page 2013-10-30 11:36:30 -07:00
META Tag zfs-0.6.2 2013-08-22 13:33:26 -07:00
OPENSOLARIS.LICENSE Add CDDL license file 2008-12-01 14:49:34 -08:00
README.markdown Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
zfs-script-config.sh.in Retire zpool_id infrastructure 2013-01-29 12:23:17 -08:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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