ext4: mark several more functions in mballoc.c as noinline

Ted noticed a stack-deep callchain through
writepages->ext4_mb_regular_allocator->ext4_mb_init_cache->submit_bh ...

With all the static functions in mballoc.c, gcc helpfully
inlines for us, and we get something like this:

ext4_mb_regular_allocator (232 bytes stack)
ext4_mb_init_cache (232 bytes stack)
submit_bh (starts 464 deeper)

the 2 ext4 functions here get several others inlined; by telling
gcc not to inline them, we can save stack space for when we
head off into submit_bh land and associated block layer callchains.
The following noinlined functions are only called once, so this
won't impact any other callchains:

ext4_mb_regular_allocator (104) (was 232)
ext4_mb_find_by_goal (56) (noinlined)
ext4_mb_init_group (24) (noinlined)
ext4_mb_init_cache (136) (was 232)
ext4_mb_generate_buddy (88) (noinlined)
ext4_mb_generate_from_pa (40) (noinlined)
submit_bh
ext4_mb_simple_scan_group (24) (noinlined)
ext4_mb_scan_aligned (56) (noinlined)
ext4_mb_complex_scan_group (40) (noinlined)
ext4_mb_try_best_found (24) (noinlined)

now when we head off into submit_bh() we're only 264 bytes deeper
in stack than when we entered ext4_mb_regular_allocator()
(vs. 464 bytes before). Every 200 bytes helps. :)

Signed-off-by: Eric Sandeen <[e-mail]>
Signed-off-by: "Theodore Ts'o" <[e-mail]>

fs/ext4/mballoc.c

···
 	}
 }
 
-static void ext4_mb_generate_buddy(struct super_block *sb,
+static noinline_for_stack
+void ext4_mb_generate_buddy(struct super_block *sb,
 				void *buddy, void *bitmap, ext4_group_t group)
 {
 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
···
 	ext4_mb_check_limits(ac, e4b, 0);
 }
 
-static int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
+static noinline_for_stack
+int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
 					struct ext4_buddy *e4b)
 {
 	struct ext4_free_extent ex = ac->ac_b_ex;
···
 	return 0;
 }
 
-static int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
+static noinline_for_stack
+int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
 				struct ext4_buddy *e4b)
 {
 	ext4_group_t group = ac->ac_g_ex.fe_group;
···
  * The routine scans buddy structures (not bitmap!) from given order
  * to max order and tries to find big enough chunk to satisfy the req
  */
-static void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
+static noinline_for_stack
+void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
 					struct ext4_buddy *e4b)
 {
 	struct super_block *sb = ac->ac_sb;
···
  * In order to optimize scanning, caller must pass number of
  * free blocks in the group, so the routine can know upper limit.
  */
-static void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
+static noinline_for_stack
+void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
 					struct ext4_buddy *e4b)
 {
 	struct super_block *sb = ac->ac_sb;
···
  * we try to find stripe-aligned chunks for stripe-size requests
  * XXX should do so at least for multiples of stripe size as well
  */
-static void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
+static noinline_for_stack
+void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
 				 struct ext4_buddy *e4b)
 {
 	struct super_block *sb = ac->ac_sb;
···
 
 }
 
-static int ext4_mb_init_group(struct super_block *sb, ext4_group_t group)
+static noinline_for_stack
+int ext4_mb_init_group(struct super_block *sb, ext4_group_t group)
 {
 
 	int ret;
···
  * used in in-core bitmap. buddy must be generated from this bitmap
  * Need to be called with ext4 group lock held
  */
-static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
+static noinline_for_stack
+void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 					ext4_group_t group)
 {
 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);