kfree(cb);
return -ENOMEM;
}
+ bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
bio->bi_private = cb;
bio->bi_end_io = end_compressed_bio_write;
atomic_inc(&cb->pending_bios);
page = compressed_pages[pg_index];
page->mapping = inode->i_mapping;
if (bio->bi_iter.bi_size)
- ret = io_tree->ops->merge_bio_hook(WRITE, page, 0,
+ ret = io_tree->ops->merge_bio_hook(page, 0,
PAGE_SIZE,
bio, 0);
else
BUG_ON(ret); /* -ENOMEM */
}
- ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+ ret = btrfs_map_bio(root, bio, 0, 1);
BUG_ON(ret); /* -ENOMEM */
bio_put(bio);
bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
BUG_ON(!bio);
+ bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
bio->bi_private = cb;
bio->bi_end_io = end_compressed_bio_write;
bio_add_page(bio, page, PAGE_SIZE, 0);
BUG_ON(ret); /* -ENOMEM */
}
- ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+ ret = btrfs_map_bio(root, bio, 0, 1);
BUG_ON(ret); /* -ENOMEM */
bio_put(bio);
comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
if (!comp_bio)
goto fail2;
+ bio_set_op_attrs (comp_bio, REQ_OP_READ, 0);
comp_bio->bi_private = cb;
comp_bio->bi_end_io = end_compressed_bio_read;
atomic_inc(&cb->pending_bios);
page->index = em_start >> PAGE_SHIFT;
if (comp_bio->bi_iter.bi_size)
- ret = tree->ops->merge_bio_hook(READ, page, 0,
+ ret = tree->ops->merge_bio_hook(page, 0,
PAGE_SIZE,
comp_bio, 0);
else
sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
root->sectorsize);
- ret = btrfs_map_bio(root, READ, comp_bio,
- mirror_num, 0);
+ ret = btrfs_map_bio(root, comp_bio, mirror_num, 0);
if (ret) {
bio->bi_error = ret;
bio_endio(comp_bio);
comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
GFP_NOFS);
BUG_ON(!comp_bio);
+ bio_set_op_attrs(comp_bio, REQ_OP_READ, 0);
comp_bio->bi_private = cb;
comp_bio->bi_end_io = end_compressed_bio_read;
BUG_ON(ret); /* -ENOMEM */
}
- ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
+ ret = btrfs_map_bio(root, comp_bio, mirror_num, 0);
if (ret) {
bio->bi_error = ret;
bio_endio(comp_bio);
static struct {
struct list_head idle_ws;
spinlock_t ws_lock;
- int num_ws;
- atomic_t alloc_ws;
+ /* Number of free workspaces */
+ int free_ws;
+ /* Total number of allocated workspaces */
+ atomic_t total_ws;
+ /* Waiters for a free workspace */
wait_queue_head_t ws_wait;
} btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
int i;
for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
+ struct list_head *workspace;
+
INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
spin_lock_init(&btrfs_comp_ws[i].ws_lock);
- atomic_set(&btrfs_comp_ws[i].alloc_ws, 0);
+ atomic_set(&btrfs_comp_ws[i].total_ws, 0);
init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
+
+ /*
+ * Preallocate one workspace for each compression type so
+ * we can guarantee forward progress in the worst case
+ */
+ workspace = btrfs_compress_op[i]->alloc_workspace();
+ if (IS_ERR(workspace)) {
+ printk(KERN_WARNING
+ "BTRFS: cannot preallocate compression workspace, will try later");
+ } else {
+ atomic_set(&btrfs_comp_ws[i].total_ws, 1);
+ btrfs_comp_ws[i].free_ws = 1;
+ list_add(workspace, &btrfs_comp_ws[i].idle_ws);
+ }
}
}
/*
- * this finds an available workspace or allocates a new one
- * ERR_PTR is returned if things go bad.
+ * This finds an available workspace or allocates a new one.
+ * If it's not possible to allocate a new one, waits until there's one.
+ * Preallocation makes a forward progress guarantees and we do not return
+ * errors.
*/
static struct list_head *find_workspace(int type)
{
struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
- atomic_t *alloc_ws = &btrfs_comp_ws[idx].alloc_ws;
+ atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
- int *num_ws = &btrfs_comp_ws[idx].num_ws;
+ int *free_ws = &btrfs_comp_ws[idx].free_ws;
again:
spin_lock(ws_lock);
if (!list_empty(idle_ws)) {
workspace = idle_ws->next;
list_del(workspace);
- (*num_ws)--;
+ (*free_ws)--;
spin_unlock(ws_lock);
return workspace;
}
- if (atomic_read(alloc_ws) > cpus) {
+ if (atomic_read(total_ws) > cpus) {
DEFINE_WAIT(wait);
spin_unlock(ws_lock);
prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
- if (atomic_read(alloc_ws) > cpus && !*num_ws)
+ if (atomic_read(total_ws) > cpus && !*free_ws)
schedule();
finish_wait(ws_wait, &wait);
goto again;
}
- atomic_inc(alloc_ws);
+ atomic_inc(total_ws);
spin_unlock(ws_lock);
workspace = btrfs_compress_op[idx]->alloc_workspace();
if (IS_ERR(workspace)) {
- atomic_dec(alloc_ws);
+ atomic_dec(total_ws);
wake_up(ws_wait);
+
+ /*
+ * Do not return the error but go back to waiting. There's a
+ * workspace preallocated for each type and the compression
+ * time is bounded so we get to a workspace eventually. This
+ * makes our caller's life easier.
+ *
+ * To prevent silent and low-probability deadlocks (when the
+ * initial preallocation fails), check if there are any
+ * workspaces at all.
+ */
+ if (atomic_read(total_ws) == 0) {
+ static DEFINE_RATELIMIT_STATE(_rs,
+ /* once per minute */ 60 * HZ,
+ /* no burst */ 1);
+
+ if (__ratelimit(&_rs)) {
+ printk(KERN_WARNING
+ "no compression workspaces, low memory, retrying");
+ }
+ }
+ goto again;
}
return workspace;
}
int idx = type - 1;
struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
- atomic_t *alloc_ws = &btrfs_comp_ws[idx].alloc_ws;
+ atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
- int *num_ws = &btrfs_comp_ws[idx].num_ws;
+ int *free_ws = &btrfs_comp_ws[idx].free_ws;
spin_lock(ws_lock);
- if (*num_ws < num_online_cpus()) {
+ if (*free_ws < num_online_cpus()) {
list_add(workspace, idle_ws);
- (*num_ws)++;
+ (*free_ws)++;
spin_unlock(ws_lock);
goto wake;
}
spin_unlock(ws_lock);
btrfs_compress_op[idx]->free_workspace(workspace);
- atomic_dec(alloc_ws);
+ atomic_dec(total_ws);
wake:
/*
* Make sure counter is updated before we wake up waiters.
workspace = btrfs_comp_ws[i].idle_ws.next;
list_del(workspace);
btrfs_compress_op[i]->free_workspace(workspace);
- atomic_dec(&btrfs_comp_ws[i].alloc_ws);
+ atomic_dec(&btrfs_comp_ws[i].total_ws);
}
}
}
int ret;
workspace = find_workspace(type);
- if (IS_ERR(workspace))
- return PTR_ERR(workspace);
ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
start, len, pages,
int ret;
workspace = find_workspace(type);
- if (IS_ERR(workspace))
- return PTR_ERR(workspace);
ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
disk_start,
int ret;
workspace = find_workspace(type);
- if (IS_ERR(workspace))
- return PTR_ERR(workspace);
ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
dest_page, start_byte,
projects / karo-tx-linux.git / blobdiff