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btrfs: reduce stack usage for btrfsic_process_written_block

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btrfsic_process_written_block() cals btrfsic_process_metablock(),
which has a fairly large stack usage due to the btrfsic_stack_frame
variable. It also calls btrfsic_test_for_metadata(), which now
needs several hundreds of bytes for its SHASH_DESC_ON_STACK().

In some configurations, we end up with both functions on the
same stack, and gcc warns about the excessive stack usage that
might cause the available stack space to run out:

fs/btrfs/check-integrity.c:1743:13: error: stack frame size of 1152 bytes in function 'btrfsic_process_written_block' [-Werror,-Wframe-larger-than=]

Marking both child functions as noinline_for_stack helps because
this guarantees that the large variables are not on the same
stack frame.

Fixes: d5178578bc ("btrfs: directly call into crypto framework for checksumming")
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Arnd Bergmann 2019-07-08 14:40:09 +02:00 committed by David Sterba
parent 99fccf33c2
commit 8ddc319706
1 changed files with 4 additions and 3 deletions
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7
fs/btrfs/check-integrity.c
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@ -940,7 +940,7 @@ static void btrfsic_stack_frame_free(struct btrfsic_stack_frame *sf)
kfree(sf);
}
static int btrfsic_process_metablock(
static noinline_for_stack int btrfsic_process_metablock(
struct btrfsic_state *state,
struct btrfsic_block *const first_block,
struct btrfsic_block_data_ctx *const first_block_ctx,
@ -1706,8 +1706,9 @@ static void btrfsic_dump_database(struct btrfsic_state *state)
* Test whether the disk block contains a tree block (leaf or node)
* (note that this test fails for the super block)
*/
static int btrfsic_test_for_metadata(struct btrfsic_state *state,
char **datav, unsigned int num_pages)
static noinline_for_stack int btrfsic_test_for_metadata(
struct btrfsic_state *state,
char **datav, unsigned int num_pages)
{
struct btrfs_fs_info *fs_info = state->fs_info;
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);