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Jens Axboe 1e42807918 block: reduce stack footprint of blk_recount_segments() 
blk_recalc_rq_segments() requires a request structure passed in, which
we don't have from blk_recount_segments(). So the latter allocates one on
the stack, using > 400 bytes of stack for that. This can cause us to spill
over one page of stack from ext4 at least:

 0)     4560     400   blk_recount_segments+0x43/0x62
 1)     4160      32   bio_phys_segments+0x1c/0x24
 2)     4128      32   blk_rq_bio_prep+0x2a/0xf9
 3)     4096      32   init_request_from_bio+0xf9/0xfe
 4)     4064     112   __make_request+0x33c/0x3f6
 5)     3952     144   generic_make_request+0x2d1/0x321
 6)     3808      64   submit_bio+0xb9/0xc3
 7)     3744      48   submit_bh+0xea/0x10e
 8)     3696     368   ext4_mb_init_cache+0x257/0xa6a [ext4]
 9)     3328     288   ext4_mb_regular_allocator+0x421/0xcd9 [ext4]
10)     3040     160   ext4_mb_new_blocks+0x211/0x4b4 [ext4]
11)     2880     336   ext4_ext_get_blocks+0xb61/0xd45 [ext4]
12)     2544      96   ext4_get_blocks_wrap+0xf2/0x200 [ext4]
13)     2448      80   ext4_da_get_block_write+0x6e/0x16b [ext4]
14)     2368     352   mpage_da_map_blocks+0x7e/0x4b3 [ext4]
15)     2016     352   ext4_da_writepages+0x2ce/0x43c [ext4]
16)     1664      32   do_writepages+0x2d/0x3c
17)     1632     144   __writeback_single_inode+0x162/0x2cd
18)     1488      96   generic_sync_sb_inodes+0x1e3/0x32b
19)     1392      16   sync_sb_inodes+0xe/0x10
20)     1376      48   writeback_inodes+0x69/0xb3
21)     1328     208   balance_dirty_pages_ratelimited_nr+0x187/0x2f9
22)     1120     224   generic_file_buffered_write+0x1d4/0x2c4
23)      896     176   __generic_file_aio_write_nolock+0x35f/0x393
24)      720      80   generic_file_aio_write+0x6c/0xc8
25)      640      80   ext4_file_write+0xa9/0x137 [ext4]
26)      560     320   do_sync_write+0xf0/0x137
27)      240      48   vfs_write+0xb3/0x13c
28)      192      64   sys_write+0x4c/0x74
29)      128     128   system_call_fastpath+0x16/0x1b

Split the segment counting out into a __blk_recalc_rq_segments() helper
to avoid allocating an onstack request just for checking the physical
segment count.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-02-26 10:45:48 +01:00
..
as-iosched.c block: get rid of elevator_t typedef 2008-12-29 08:29:50 +01:00
blk-barrier.c block: Fix documentation for blkdev_issue_flush() 2009-01-30 12:34:37 +01:00
blk-core.c block: fix oops in blk_queue_io_stat() 2009-02-02 08:42:32 +01:00
blk-exec.c Add some block/ source files to the kernel-api docbook. Fix kernel-doc notation in them as needed. Fix changed function parameter names. Fix typos/spellos. In comments, change REQ_SPECIAL to REQ_TYPE_SPECIAL and REQ_BLOCK_PC to REQ_TYPE_BLOCK_PC. 2008-10-09 08:56:03 +02:00
blk-integrity.c block: Allow empty integrity profile 2009-01-30 12:34:36 +01:00
blk-ioc.c cfq-iosched: fix RCU race in the cfq io_context destructor handling 2008-05-07 09:28:57 +02:00
blk-map.c [SCSI] block: make blk_rq_map_user take a NULL user-space buffer for WRITE 2009-01-02 11:10:35 -06:00
blk-merge.c block: reduce stack footprint of blk_recount_segments() 2009-02-26 10:45:48 +01:00
blk-settings.c block: use min_not_zero in blk_queue_stack_limits 2008-12-29 08:29:51 +01:00
blk-softirq.c block: make blk_softirq_init() static 2008-12-29 08:29:51 +01:00
blk-sysfs.c block: add sysfs file for controlling io stats accounting 2009-01-30 12:34:38 +01:00
blk-tag.c block/blk-tag.c: cleanup kernel-doc 2008-12-29 08:28:43 +01:00
blk-timeout.c block: fix deadlock in blk_abort_queue() for drivers that readd to timeout list 2009-02-18 10:34:16 +01:00
blk.h block: fix oops in blk_queue_io_stat() 2009-02-02 08:42:32 +01:00
blktrace.c block: fix bad definition of BIO_RW_SYNC 2009-02-18 10:32:00 +01:00
bsg.c bsg: Fix sense buffer bug in SG_IO 2009-02-18 10:32:00 +01:00
cfq-iosched.c cfq-iosched: Allow RT requests to pre-empt ongoing BE timeslice 2009-01-30 12:47:33 +01:00
cmd-filter.c [PATCH] introduce fmode_t, do annotations 2008-10-21 07:47:06 -04:00
compat_ioctl.c block: don't take lock on changing ra_pages 2008-12-29 08:28:43 +01:00
deadline-iosched.c block: get rid of elevator_t typedef 2008-12-29 08:29:50 +01:00
elevator.c block: get rid of elevator_t typedef 2008-12-29 08:29:50 +01:00
genhd.c block: add documentation for register_blkdev() 2009-02-26 10:45:48 +01:00
ioctl.c block: don't take lock on changing ra_pages 2008-12-29 08:28:43 +01:00
Kconfig block: Add Kconfig help which notes that ext4 needs CONFIG_LBD 2009-01-06 15:16:33 -05:00
Kconfig.iosched update I/O sched Kconfig help texts - CFQ is now default, not AS. 2007-02-17 20:08:22 +01:00
Makefile block: unify request timeout handling 2008-10-09 08:56:13 +02:00
noop-iosched.c block: get rid of elevator_t typedef 2008-12-29 08:29:50 +01:00
scsi_ioctl.c scsi-ioctl: use clock_t <> jiffies 2008-12-29 08:28:42 +01:00