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dm integrity: only allocate recalculate buffer when needed

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dm-integrity preallocated 8MiB buffer for recalculating in the
constructor and freed it in the destructor. This wastes memory when
the user has many dm-integrity devices.

Fix dm-integrity so that the buffer is only allocated when
recalculation is in progress; allocate the buffer at the beginning of
integrity_recalc() and free it at the end.

Note that integrity_recalc() doesn't hold any locks when allocating
the buffer, so it shouldn't cause low-memory deadlock.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mikulas Patocka 2023-06-26 16:46:00 +02:00 committed by Mike Snitzer
parent 6d50eb4725
commit da8b4fc1f6
1 changed files with 26 additions and 26 deletions
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52
drivers/md/dm-integrity.c
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@ -251,8 +251,6 @@ struct dm_integrity_c {
struct workqueue_struct *recalc_wq;
struct work_struct recalc_work;
u8 *recalc_buffer;
u8 *recalc_tags;
struct bio_list flush_bio_list;
@ -2646,6 +2644,9 @@ static void recalc_write_super(struct dm_integrity_c *ic)
static void integrity_recalc(struct work_struct *w)
{
struct dm_integrity_c *ic = container_of(w, struct dm_integrity_c, recalc_work);
size_t recalc_tags_size;
u8 *recalc_buffer = NULL;
u8 *recalc_tags = NULL;
struct dm_integrity_range range;
struct dm_io_request io_req;
struct dm_io_region io_loc;
@ -2658,6 +2659,20 @@ static void integrity_recalc(struct work_struct *w)
int r;
unsigned int super_counter = 0;
recalc_buffer = __vmalloc(RECALC_SECTORS << SECTOR_SHIFT, GFP_NOIO);
if (!recalc_buffer) {
DMCRIT("out of memory for recalculate buffer - recalculation disabled");
goto free_ret;
}
recalc_tags_size = (RECALC_SECTORS >> ic->sb->log2_sectors_per_block) * ic->tag_size;
if (crypto_shash_digestsize(ic->internal_hash) > ic->tag_size)
recalc_tags_size += crypto_shash_digestsize(ic->internal_hash) - ic->tag_size;
recalc_tags = kvmalloc(recalc_tags_size, GFP_NOIO);
if (!recalc_tags) {
DMCRIT("out of memory for recalculate buffer - recalculation disabled");
goto free_ret;
}
DEBUG_print("start recalculation... (position %llx)\n", le64_to_cpu(ic->sb->recalc_sector));
spin_lock_irq(&ic->endio_wait.lock);
@ -2720,7 +2735,7 @@ next_chunk:
io_req.bi_opf = REQ_OP_READ;
io_req.mem.type = DM_IO_VMA;
io_req.mem.ptr.addr = ic->recalc_buffer;
io_req.mem.ptr.addr = recalc_buffer;
io_req.notify.fn = NULL;
io_req.client = ic->io;
io_loc.bdev = ic->dev->bdev;
@ -2733,15 +2748,15 @@ next_chunk:
goto err;
}
t = ic->recalc_tags;
t = recalc_tags;
for (i = 0; i < n_sectors; i += ic->sectors_per_block) {
integrity_sector_checksum(ic, logical_sector + i, ic->recalc_buffer + (i << SECTOR_SHIFT), t);
integrity_sector_checksum(ic, logical_sector + i, recalc_buffer + (i << SECTOR_SHIFT), t);
t += ic->tag_size;
}
metadata_block = get_metadata_sector_and_offset(ic, area, offset, &metadata_offset);
r = dm_integrity_rw_tag(ic, ic->recalc_tags, &metadata_block, &metadata_offset, t - ic->recalc_tags, TAG_WRITE);
r = dm_integrity_rw_tag(ic, recalc_tags, &metadata_block, &metadata_offset, t - recalc_tags, TAG_WRITE);
if (unlikely(r)) {
dm_integrity_io_error(ic, "writing tags", r);
goto err;
@ -2769,12 +2784,16 @@ advance_and_next:
err:
remove_range(ic, &range);
return;
goto free_ret;
unlock_ret:
spin_unlock_irq(&ic->endio_wait.lock);
recalc_write_super(ic);
free_ret:
vfree(recalc_buffer);
kvfree(recalc_tags);
}
static void bitmap_block_work(struct work_struct *w)
@ -4439,8 +4458,6 @@ try_smaller_buffer:
}
if (ic->internal_hash) {
size_t recalc_tags_size;
ic->recalc_wq = alloc_workqueue("dm-integrity-recalc", WQ_MEM_RECLAIM, 1);
if (!ic->recalc_wq) {
ti->error = "Cannot allocate workqueue";
@ -4448,21 +4465,6 @@ try_smaller_buffer:
goto bad;
}
INIT_WORK(&ic->recalc_work, integrity_recalc);
ic->recalc_buffer = vmalloc(RECALC_SECTORS << SECTOR_SHIFT);
if (!ic->recalc_buffer) {
ti->error = "Cannot allocate buffer for recalculating";
r = -ENOMEM;
goto bad;
}
recalc_tags_size = (RECALC_SECTORS >> ic->sb->log2_sectors_per_block) * ic->tag_size;
if (crypto_shash_digestsize(ic->internal_hash) > ic->tag_size)
recalc_tags_size += crypto_shash_digestsize(ic->internal_hash) - ic->tag_size;
ic->recalc_tags = kvmalloc(recalc_tags_size, GFP_KERNEL);
if (!ic->recalc_tags) {
ti->error = "Cannot allocate tags for recalculating";
r = -ENOMEM;
goto bad;
}
} else {
if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING)) {
ti->error = "Recalculate can only be specified with internal_hash";
@ -4606,8 +4608,6 @@ static void dm_integrity_dtr(struct dm_target *ti)
destroy_workqueue(ic->writer_wq);
if (ic->recalc_wq)
destroy_workqueue(ic->recalc_wq);
vfree(ic->recalc_buffer);
kvfree(ic->recalc_tags);
kvfree(ic->bbs);
if (ic->bufio)
dm_bufio_client_destroy(ic->bufio);