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dm-verity, dm-crypt: align "struct bvec_iter" correctly

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"struct bvec_iter" is defined with the __packed attribute, so it is
aligned on a single byte. On X86 (and on other architectures that support
unaligned addresses in hardware), "struct bvec_iter" is accessed using the
8-byte and 4-byte memory instructions, however these instructions are less
efficient if they operate on unaligned addresses.

(on RISC machines that don't have unaligned access in hardware, GCC
generates byte-by-byte accesses that are very inefficient - see [1])

This commit reorders the entries in "struct dm_verity_io" and "struct
convert_context", so that "struct bvec_iter" is aligned on 8 bytes.

[1] https://lore.kernel.org/all/ZcLuWUNRZadJr0tQ@fedora/T/

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mikulas Patocka 2024-02-20 19:11:51 +01:00 committed by Mike Snitzer
parent 42e15d1207
commit 787f1b2800
2 changed files with 4 additions and 4 deletions
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4
drivers/md/dm-crypt.c
View File

@ -53,11 +53,11 @@
struct convert_context {
struct completion restart;
struct bio *bio_in;
struct bio *bio_out;
struct bvec_iter iter_in;
struct bio *bio_out;
struct bvec_iter iter_out;
u64 cc_sector;
atomic_t cc_pending;
u64 cc_sector;
union {
struct skcipher_request *req;
struct aead_request *req_aead;

4
drivers/md/dm-verity.h
View File

@ -80,12 +80,12 @@ struct dm_verity_io {
/* original value of bio->bi_end_io */
bio_end_io_t *orig_bi_end_io;
struct bvec_iter iter;
sector_t block;
unsigned int n_blocks;
bool in_tasklet;
struct bvec_iter iter;
struct work_struct work;
char *recheck_buffer;