dm integrity: only allocate recalculate buffer when needed

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>

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 0a910bb..16d1aa2 100644 (file)
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -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);