/* number of bytes on disk */
unsigned long compressed_len;
+ /* the compression algorithm for this bio */
+ int compress_type;
+
/* number of compressed pages in the array */
unsigned long nr_pages;
/* ok, we're the last bio for this extent, lets start
* the decompression.
*/
- ret = btrfs_zlib_decompress_biovec(cb->compressed_pages,
- cb->start,
- cb->orig_bio->bi_io_vec,
- cb->orig_bio->bi_vcnt,
- cb->compressed_len);
+ ret = btrfs_decompress_biovec(cb->compress_type,
+ cb->compressed_pages,
+ cb->start,
+ cb->orig_bio->bi_io_vec,
+ cb->orig_bio->bi_vcnt,
+ cb->compressed_len);
csum_failed:
if (ret)
cb->errors = 1;
u64 em_len;
u64 em_start;
struct extent_map *em;
- int ret;
+ int ret = -ENOMEM;
u32 *sums;
tree = &BTRFS_I(inode)->io_tree;
compressed_len = em->block_len;
cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
+ if (!cb)
+ goto out;
+
atomic_set(&cb->pending_bios, 0);
cb->errors = 0;
cb->inode = inode;
cb->len = uncompressed_len;
cb->compressed_len = compressed_len;
+ cb->compress_type = extent_compress_type(bio_flags);
cb->orig_bio = bio;
nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
PAGE_CACHE_SIZE;
- cb->compressed_pages = kmalloc(sizeof(struct page *) * nr_pages,
+ cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
GFP_NOFS);
+ if (!cb->compressed_pages)
+ goto fail1;
+
bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
for (page_index = 0; page_index < nr_pages; page_index++) {
cb->compressed_pages[page_index] = alloc_page(GFP_NOFS |
__GFP_HIGHMEM);
+ if (!cb->compressed_pages[page_index])
+ goto fail2;
}
cb->nr_pages = nr_pages;
cb->len = uncompressed_len;
comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
+ if (!comp_bio)
+ goto fail2;
comp_bio->bi_private = cb;
comp_bio->bi_end_io = end_compressed_bio_read;
atomic_inc(&cb->pending_bios);
bio_put(comp_bio);
return 0;
+
+fail2:
+ for (page_index = 0; page_index < nr_pages; page_index++)
+ free_page((unsigned long)cb->compressed_pages[page_index]);
+
+ kfree(cb->compressed_pages);
+fail1:
+ kfree(cb);
+out:
+ free_extent_map(em);
+ return ret;
+}
+
+static struct list_head comp_idle_workspace[BTRFS_COMPRESS_TYPES];
+static spinlock_t comp_workspace_lock[BTRFS_COMPRESS_TYPES];
+static int comp_num_workspace[BTRFS_COMPRESS_TYPES];
+static atomic_t comp_alloc_workspace[BTRFS_COMPRESS_TYPES];
+static wait_queue_head_t comp_workspace_wait[BTRFS_COMPRESS_TYPES];
+
+struct btrfs_compress_op *btrfs_compress_op[] = {
+ &btrfs_zlib_compress,
+ &btrfs_lzo_compress,
+};
+
+int __init btrfs_init_compress(void)
+{
+ int i;
+
+ for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
+ INIT_LIST_HEAD(&comp_idle_workspace[i]);
+ spin_lock_init(&comp_workspace_lock[i]);
+ atomic_set(&comp_alloc_workspace[i], 0);
+ init_waitqueue_head(&comp_workspace_wait[i]);
+ }
+ return 0;
+}
+
+/*
+ * this finds an available workspace or allocates a new one
+ * ERR_PTR is returned if things go bad.
+ */
+static struct list_head *find_workspace(int type)
+{
+ struct list_head *workspace;
+ int cpus = num_online_cpus();
+ int idx = type - 1;
+
+ struct list_head *idle_workspace = &comp_idle_workspace[idx];
+ spinlock_t *workspace_lock = &comp_workspace_lock[idx];
+ atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
+ wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
+ int *num_workspace = &comp_num_workspace[idx];
+again:
+ spin_lock(workspace_lock);
+ if (!list_empty(idle_workspace)) {
+ workspace = idle_workspace->next;
+ list_del(workspace);
+ (*num_workspace)--;
+ spin_unlock(workspace_lock);
+ return workspace;
+
+ }
+ if (atomic_read(alloc_workspace) > cpus) {
+ DEFINE_WAIT(wait);
+
+ spin_unlock(workspace_lock);
+ prepare_to_wait(workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
+ if (atomic_read(alloc_workspace) > cpus && !*num_workspace)
+ schedule();
+ finish_wait(workspace_wait, &wait);
+ goto again;
+ }
+ atomic_inc(alloc_workspace);
+ spin_unlock(workspace_lock);
+
+ workspace = btrfs_compress_op[idx]->alloc_workspace();
+ if (IS_ERR(workspace)) {
+ atomic_dec(alloc_workspace);
+ wake_up(workspace_wait);
+ }
+ return workspace;
+}
+
+/*
+ * put a workspace struct back on the list or free it if we have enough
+ * idle ones sitting around
+ */
+static void free_workspace(int type, struct list_head *workspace)
+{
+ int idx = type - 1;
+ struct list_head *idle_workspace = &comp_idle_workspace[idx];
+ spinlock_t *workspace_lock = &comp_workspace_lock[idx];
+ atomic_t *alloc_workspace = &comp_alloc_workspace[idx];
+ wait_queue_head_t *workspace_wait = &comp_workspace_wait[idx];
+ int *num_workspace = &comp_num_workspace[idx];
+
+ spin_lock(workspace_lock);
+ if (*num_workspace < num_online_cpus()) {
+ list_add_tail(workspace, idle_workspace);
+ (*num_workspace)++;
+ spin_unlock(workspace_lock);
+ goto wake;
+ }
+ spin_unlock(workspace_lock);
+
+ btrfs_compress_op[idx]->free_workspace(workspace);
+ atomic_dec(alloc_workspace);
+wake:
+ if (waitqueue_active(workspace_wait))
+ wake_up(workspace_wait);
+}
+
+/*
+ * cleanup function for module exit
+ */
+static void free_workspaces(void)
+{
+ struct list_head *workspace;
+ int i;
+
+ for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
+ while (!list_empty(&comp_idle_workspace[i])) {
+ workspace = comp_idle_workspace[i].next;
+ list_del(workspace);
+ btrfs_compress_op[i]->free_workspace(workspace);
+ atomic_dec(&comp_alloc_workspace[i]);
+ }
+ }
+}
+
+/*
+ * given an address space and start/len, compress the bytes.
+ *
+ * pages are allocated to hold the compressed result and stored
+ * in 'pages'
+ *
+ * out_pages is used to return the number of pages allocated. There
+ * may be pages allocated even if we return an error
+ *
+ * total_in is used to return the number of bytes actually read. It
+ * may be smaller then len if we had to exit early because we
+ * ran out of room in the pages array or because we cross the
+ * max_out threshold.
+ *
+ * total_out is used to return the total number of compressed bytes
+ *
+ * max_out tells us the max number of bytes that we're allowed to
+ * stuff into pages
+ */
+int btrfs_compress_pages(int type, struct address_space *mapping,
+ u64 start, unsigned long len,
+ struct page **pages,
+ unsigned long nr_dest_pages,
+ unsigned long *out_pages,
+ unsigned long *total_in,
+ unsigned long *total_out,
+ unsigned long max_out)
+{
+ struct list_head *workspace;
+ int ret;
+
+ workspace = find_workspace(type);
+ if (IS_ERR(workspace))
+ return -1;
+
+ ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
+ start, len, pages,
+ nr_dest_pages, out_pages,
+ total_in, total_out,
+ max_out);
+ free_workspace(type, workspace);
+ return ret;
+}
+
+/*
+ * pages_in is an array of pages with compressed data.
+ *
+ * disk_start is the starting logical offset of this array in the file
+ *
+ * bvec is a bio_vec of pages from the file that we want to decompress into
+ *
+ * vcnt is the count of pages in the biovec
+ *
+ * srclen is the number of bytes in pages_in
+ *
+ * The basic idea is that we have a bio that was created by readpages.
+ * The pages in the bio are for the uncompressed data, and they may not
+ * be contiguous. They all correspond to the range of bytes covered by
+ * the compressed extent.
+ */
+int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
+ struct bio_vec *bvec, int vcnt, size_t srclen)
+{
+ struct list_head *workspace;
+ int ret;
+
+ workspace = find_workspace(type);
+ if (IS_ERR(workspace))
+ return -ENOMEM;
+
+ ret = btrfs_compress_op[type-1]->decompress_biovec(workspace, pages_in,
+ disk_start,
+ bvec, vcnt, srclen);
+ free_workspace(type, workspace);
+ return ret;
+}
+
+/*
+ * a less complex decompression routine. Our compressed data fits in a
+ * single page, and we want to read a single page out of it.
+ * start_byte tells us the offset into the compressed data we're interested in
+ */
+int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
+ unsigned long start_byte, size_t srclen, size_t destlen)
+{
+ struct list_head *workspace;
+ int ret;
+
+ workspace = find_workspace(type);
+ if (IS_ERR(workspace))
+ return -ENOMEM;
+
+ ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
+ dest_page, start_byte,
+ srclen, destlen);
+
+ free_workspace(type, workspace);
+ return ret;
+}
+
+void btrfs_exit_compress(void)
+{
+ free_workspaces();
+}
+
+/*
+ * Copy uncompressed data from working buffer to pages.
+ *
+ * buf_start is the byte offset we're of the start of our workspace buffer.
+ *
+ * total_out is the last byte of the buffer
+ */
+int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
+ unsigned long total_out, u64 disk_start,
+ struct bio_vec *bvec, int vcnt,
+ unsigned long *page_index,
+ unsigned long *pg_offset)
+{
+ unsigned long buf_offset;
+ unsigned long current_buf_start;
+ unsigned long start_byte;
+ unsigned long working_bytes = total_out - buf_start;
+ unsigned long bytes;
+ char *kaddr;
+ struct page *page_out = bvec[*page_index].bv_page;
+
+ /*
+ * start byte is the first byte of the page we're currently
+ * copying into relative to the start of the compressed data.
+ */
+ start_byte = page_offset(page_out) - disk_start;
+
+ /* we haven't yet hit data corresponding to this page */
+ if (total_out <= start_byte)
+ return 1;
+
+ /*
+ * the start of the data we care about is offset into
+ * the middle of our working buffer
+ */
+ if (total_out > start_byte && buf_start < start_byte) {
+ buf_offset = start_byte - buf_start;
+ working_bytes -= buf_offset;
+ } else {
+ buf_offset = 0;
+ }
+ current_buf_start = buf_start;
+
+ /* copy bytes from the working buffer into the pages */
+ while (working_bytes > 0) {
+ bytes = min(PAGE_CACHE_SIZE - *pg_offset,
+ PAGE_CACHE_SIZE - buf_offset);
+ bytes = min(bytes, working_bytes);
+ kaddr = kmap_atomic(page_out, KM_USER0);
+ memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
+ kunmap_atomic(kaddr, KM_USER0);
+ flush_dcache_page(page_out);
+
+ *pg_offset += bytes;
+ buf_offset += bytes;
+ working_bytes -= bytes;
+ current_buf_start += bytes;
+
+ /* check if we need to pick another page */
+ if (*pg_offset == PAGE_CACHE_SIZE) {
+ (*page_index)++;
+ if (*page_index >= vcnt)
+ return 0;
+
+ page_out = bvec[*page_index].bv_page;
+ *pg_offset = 0;
+ start_byte = page_offset(page_out) - disk_start;
+
+ /*
+ * make sure our new page is covered by this
+ * working buffer
+ */
+ if (total_out <= start_byte)
+ return 1;
+
+ /*
+ * the next page in the biovec might not be adjacent
+ * to the last page, but it might still be found
+ * inside this working buffer. bump our offset pointer
+ */
+ if (total_out > start_byte &&
+ current_buf_start < start_byte) {
+ buf_offset = start_byte - buf_start;
+ working_bytes = total_out - start_byte;
+ current_buf_start = buf_start + buf_offset;
+ }
+ }
+ }
+
+ return 1;
}
projects / mv-sheeva.git / blobdiff