--- /dev/null
+/*
+ * Copyright (C) 2008 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/buffer_head.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/mpage.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/bit_spinlock.h>
+#include <linux/slab.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "volumes.h"
+#include "ordered-data.h"
+#include "compression.h"
+#include "extent_io.h"
+#include "extent_map.h"
+
+struct compressed_bio {
+ /* number of bios pending for this compressed extent */
+ atomic_t pending_bios;
+
+ /* the pages with the compressed data on them */
+ struct page **compressed_pages;
+
+ /* inode that owns this data */
+ struct inode *inode;
+
+ /* starting offset in the inode for our pages */
+ u64 start;
+
+ /* number of bytes in the inode we're working on */
+ unsigned long len;
+
+ /* 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;
+
+ /* IO errors */
+ int errors;
+ int mirror_num;
+
+ /* for reads, this is the bio we are copying the data into */
+ struct bio *orig_bio;
+
+ /*
+ * the start of a variable length array of checksums only
+ * used by reads
+ */
+ u32 sums;
+};
+
+static int btrfs_decompress_biovec(int type, struct page **pages_in,
+ u64 disk_start, struct bio_vec *bvec,
+ int vcnt, size_t srclen);
+
+static inline int compressed_bio_size(struct btrfs_root *root,
+ unsigned long disk_size)
+{
+ u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
+
+ return sizeof(struct compressed_bio) +
+ (DIV_ROUND_UP(disk_size, root->sectorsize)) * csum_size;
+}
+
+static struct bio *compressed_bio_alloc(struct block_device *bdev,
+ u64 first_byte, gfp_t gfp_flags)
+{
+ int nr_vecs;
+
+ nr_vecs = bio_get_nr_vecs(bdev);
+ return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
+}
+
+static int check_compressed_csum(struct inode *inode,
+ struct compressed_bio *cb,
+ u64 disk_start)
+{
+ int ret;
+ struct page *page;
+ unsigned long i;
+ char *kaddr;
+ u32 csum;
+ u32 *cb_sum = &cb->sums;
+
+ if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
+ return 0;
+
+ for (i = 0; i < cb->nr_pages; i++) {
+ page = cb->compressed_pages[i];
+ csum = ~(u32)0;
+
+ kaddr = kmap_atomic(page);
+ csum = btrfs_csum_data(kaddr, csum, PAGE_CACHE_SIZE);
+ btrfs_csum_final(csum, (char *)&csum);
+ kunmap_atomic(kaddr);
+
+ if (csum != *cb_sum) {
+ btrfs_info(BTRFS_I(inode)->root->fs_info,
+ "csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
+ btrfs_ino(inode), disk_start, csum, *cb_sum,
+ cb->mirror_num);
+ ret = -EIO;
+ goto fail;
+ }
+ cb_sum++;
+
+ }
+ ret = 0;
+fail:
+ return ret;
+}
+
+/* when we finish reading compressed pages from the disk, we
+ * decompress them and then run the bio end_io routines on the
+ * decompressed pages (in the inode address space).
+ *
+ * This allows the checksumming and other IO error handling routines
+ * to work normally
+ *
+ * The compressed pages are freed here, and it must be run
+ * in process context
+ */
+static void end_compressed_bio_read(struct bio *bio, int err)
+{
+ struct compressed_bio *cb = bio->bi_private;
+ struct inode *inode;
+ struct page *page;
+ unsigned long index;
+ int ret;
+
+ if (err)
+ cb->errors = 1;
+
+ /* if there are more bios still pending for this compressed
+ * extent, just exit
+ */
+ if (!atomic_dec_and_test(&cb->pending_bios))
+ goto out;
+
+ inode = cb->inode;
+ ret = check_compressed_csum(inode, cb,
+ (u64)bio->bi_iter.bi_sector << 9);
+ if (ret)
+ goto csum_failed;
+
+ /* ok, we're the last bio for this extent, lets start
+ * the decompression.
+ */
+ 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;
+
+ /* release the compressed pages */
+ index = 0;
+ for (index = 0; index < cb->nr_pages; index++) {
+ page = cb->compressed_pages[index];
+ page->mapping = NULL;
+ page_cache_release(page);
+ }
+
+ /* do io completion on the original bio */
+ if (cb->errors) {
+ bio_io_error(cb->orig_bio);
+ } else {
+ int i;
+ struct bio_vec *bvec;
+
+ /*
+ * we have verified the checksum already, set page
+ * checked so the end_io handlers know about it
+ */
+ bio_for_each_segment_all(bvec, cb->orig_bio, i)
+ SetPageChecked(bvec->bv_page);
+
+ bio_endio(cb->orig_bio, 0);
+ }
+
+ /* finally free the cb struct */
+ kfree(cb->compressed_pages);
+ kfree(cb);
+out:
+ bio_put(bio);
+}
+
+/*
+ * Clear the writeback bits on all of the file
+ * pages for a compressed write
+ */
+static noinline void end_compressed_writeback(struct inode *inode,
+ const struct compressed_bio *cb)
+{
+ unsigned long index = cb->start >> PAGE_CACHE_SHIFT;
+ unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_CACHE_SHIFT;
+ struct page *pages[16];
+ unsigned long nr_pages = end_index - index + 1;
+ int i;
+ int ret;
+
+ if (cb->errors)
+ mapping_set_error(inode->i_mapping, -EIO);
+
+ while (nr_pages > 0) {
+ ret = find_get_pages_contig(inode->i_mapping, index,
+ min_t(unsigned long,
+ nr_pages, ARRAY_SIZE(pages)), pages);
+ if (ret == 0) {
+ nr_pages -= 1;
+ index += 1;
+ continue;
+ }
+ for (i = 0; i < ret; i++) {
+ if (cb->errors)
+ SetPageError(pages[i]);
+ end_page_writeback(pages[i]);
+ page_cache_release(pages[i]);
+ }
+ nr_pages -= ret;
+ index += ret;
+ }
+ /* the inode may be gone now */
+}
+
+/*
+ * do the cleanup once all the compressed pages hit the disk.
+ * This will clear writeback on the file pages and free the compressed
+ * pages.
+ *
+ * This also calls the writeback end hooks for the file pages so that
+ * metadata and checksums can be updated in the file.
+ */
+static void end_compressed_bio_write(struct bio *bio, int err)
+{
+ struct extent_io_tree *tree;
+ struct compressed_bio *cb = bio->bi_private;
+ struct inode *inode;
+ struct page *page;
+ unsigned long index;
+
+ if (err)
+ cb->errors = 1;
+
+ /* if there are more bios still pending for this compressed
+ * extent, just exit
+ */
+ if (!atomic_dec_and_test(&cb->pending_bios))
+ goto out;
+
+ /* ok, we're the last bio for this extent, step one is to
+ * call back into the FS and do all the end_io operations
+ */
+ inode = cb->inode;
+ tree = &BTRFS_I(inode)->io_tree;
+ cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
+ tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
+ cb->start,
+ cb->start + cb->len - 1,
+ NULL,
+ err ? 0 : 1);
+ cb->compressed_pages[0]->mapping = NULL;
+
+ end_compressed_writeback(inode, cb);
+ /* note, our inode could be gone now */
+
+ /*
+ * release the compressed pages, these came from alloc_page and
+ * are not attached to the inode at all
+ */
+ index = 0;
+ for (index = 0; index < cb->nr_pages; index++) {
+ page = cb->compressed_pages[index];
+ page->mapping = NULL;
+ page_cache_release(page);
+ }
+
+ /* finally free the cb struct */
+ kfree(cb->compressed_pages);
+ kfree(cb);
+out:
+ bio_put(bio);
+}
+
+/*
+ * worker function to build and submit bios for previously compressed pages.
+ * The corresponding pages in the inode should be marked for writeback
+ * and the compressed pages should have a reference on them for dropping
+ * when the IO is complete.
+ *
+ * This also checksums the file bytes and gets things ready for
+ * the end io hooks.
+ */
+int btrfs_submit_compressed_write(struct inode *inode, u64 start,
+ unsigned long len, u64 disk_start,
+ unsigned long compressed_len,
+ struct page **compressed_pages,
+ unsigned long nr_pages)
+{
+ struct bio *bio = NULL;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct compressed_bio *cb;
+ unsigned long bytes_left;
+ struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+ int pg_index = 0;
+ struct page *page;
+ u64 first_byte = disk_start;
+ struct block_device *bdev;
+ int ret;
+ int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
+
+ WARN_ON(start & ((u64)PAGE_CACHE_SIZE - 1));
+ cb = kmalloc(compressed_bio_size(root, compressed_len), GFP_NOFS);
+ if (!cb)
+ return -ENOMEM;
+ atomic_set(&cb->pending_bios, 0);
+ cb->errors = 0;
+ cb->inode = inode;
+ cb->start = start;
+ cb->len = len;
+ cb->mirror_num = 0;
+ cb->compressed_pages = compressed_pages;
+ cb->compressed_len = compressed_len;
+ cb->orig_bio = NULL;
+ cb->nr_pages = nr_pages;
+
+ bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+
+ bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
+ if (!bio) {
+ kfree(cb);
+ return -ENOMEM;
+ }
+ bio->bi_private = cb;
+ bio->bi_end_io = end_compressed_bio_write;
+ atomic_inc(&cb->pending_bios);
+
+ /* create and submit bios for the compressed pages */
+ bytes_left = compressed_len;
+ for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
+ 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,
+ PAGE_CACHE_SIZE,
+ bio, 0);
+ else
+ ret = 0;
+
+ page->mapping = NULL;
+ if (ret || bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) <
+ PAGE_CACHE_SIZE) {
+ bio_get(bio);
+
+ /*
+ * inc the count before we submit the bio so
+ * we know the end IO handler won't happen before
+ * we inc the count. Otherwise, the cb might get
+ * freed before we're done setting it up
+ */
+ atomic_inc(&cb->pending_bios);
+ ret = btrfs_bio_wq_end_io(root->fs_info, bio,
+ BTRFS_WQ_ENDIO_DATA);
+ BUG_ON(ret); /* -ENOMEM */
+
+ if (!skip_sum) {
+ ret = btrfs_csum_one_bio(root, inode, bio,
+ start, 1);
+ BUG_ON(ret); /* -ENOMEM */
+ }
+
+ ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+ BUG_ON(ret); /* -ENOMEM */
+
+ bio_put(bio);
+
+ bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
+ BUG_ON(!bio);
+ bio->bi_private = cb;
+ bio->bi_end_io = end_compressed_bio_write;
+ bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
+ }
+ if (bytes_left < PAGE_CACHE_SIZE) {
+ btrfs_info(BTRFS_I(inode)->root->fs_info,
+ "bytes left %lu compress len %lu nr %lu",
+ bytes_left, cb->compressed_len, cb->nr_pages);
+ }
+ bytes_left -= PAGE_CACHE_SIZE;
+ first_byte += PAGE_CACHE_SIZE;
+ cond_resched();
+ }
+ bio_get(bio);
+
+ ret = btrfs_bio_wq_end_io(root->fs_info, bio, BTRFS_WQ_ENDIO_DATA);
+ BUG_ON(ret); /* -ENOMEM */
+
+ if (!skip_sum) {
+ ret = btrfs_csum_one_bio(root, inode, bio, start, 1);
+ BUG_ON(ret); /* -ENOMEM */
+ }
+
+ ret = btrfs_map_bio(root, WRITE, bio, 0, 1);
+ BUG_ON(ret); /* -ENOMEM */
+
+ bio_put(bio);
+ return 0;
+}
+
+static noinline int add_ra_bio_pages(struct inode *inode,
+ u64 compressed_end,
+ struct compressed_bio *cb)
+{
+ unsigned long end_index;
+ unsigned long pg_index;
+ u64 last_offset;
+ u64 isize = i_size_read(inode);
+ int ret;
+ struct page *page;
+ unsigned long nr_pages = 0;
+ struct extent_map *em;
+ struct address_space *mapping = inode->i_mapping;
+ struct extent_map_tree *em_tree;
+ struct extent_io_tree *tree;
+ u64 end;
+ int misses = 0;
+
+ page = cb->orig_bio->bi_io_vec[cb->orig_bio->bi_vcnt - 1].bv_page;
+ last_offset = (page_offset(page) + PAGE_CACHE_SIZE);
+ em_tree = &BTRFS_I(inode)->extent_tree;
+ tree = &BTRFS_I(inode)->io_tree;
+
+ if (isize == 0)
+ return 0;
+
+ end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
+
+ while (last_offset < compressed_end) {
+ pg_index = last_offset >> PAGE_CACHE_SHIFT;
+
+ if (pg_index > end_index)
+ break;
+
+ rcu_read_lock();
+ page = radix_tree_lookup(&mapping->page_tree, pg_index);
+ rcu_read_unlock();
+ if (page && !radix_tree_exceptional_entry(page)) {
+ misses++;
+ if (misses > 4)
+ break;
+ goto next;
+ }
+
+ page = __page_cache_alloc(mapping_gfp_mask(mapping) &
+ ~__GFP_FS);
+ if (!page)
+ break;
+
+ if (add_to_page_cache_lru(page, mapping, pg_index,
+ GFP_NOFS)) {
+ page_cache_release(page);
+ goto next;
+ }
+
+ end = last_offset + PAGE_CACHE_SIZE - 1;
+ /*
+ * at this point, we have a locked page in the page cache
+ * for these bytes in the file. But, we have to make
+ * sure they map to this compressed extent on disk.
+ */
+ set_page_extent_mapped(page);
+ lock_extent(tree, last_offset, end);
+ read_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree, last_offset,
+ PAGE_CACHE_SIZE);
+ read_unlock(&em_tree->lock);
+
+ if (!em || last_offset < em->start ||
+ (last_offset + PAGE_CACHE_SIZE > extent_map_end(em)) ||
+ (em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
+ free_extent_map(em);
+ unlock_extent(tree, last_offset, end);
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+ free_extent_map(em);
+
+ if (page->index == end_index) {
+ char *userpage;
+ size_t zero_offset = isize & (PAGE_CACHE_SIZE - 1);
+
+ if (zero_offset) {
+ int zeros;
+ zeros = PAGE_CACHE_SIZE - zero_offset;
+ userpage = kmap_atomic(page);
+ memset(userpage + zero_offset, 0, zeros);
+ flush_dcache_page(page);
+ kunmap_atomic(userpage);
+ }
+ }
+
+ ret = bio_add_page(cb->orig_bio, page,
+ PAGE_CACHE_SIZE, 0);
+
+ if (ret == PAGE_CACHE_SIZE) {
+ nr_pages++;
+ page_cache_release(page);
+ } else {
+ unlock_extent(tree, last_offset, end);
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+next:
+ last_offset += PAGE_CACHE_SIZE;
+ }
+ return 0;
+}
+
+/*
+ * for a compressed read, the bio we get passed has all the inode pages
+ * in it. We don't actually do IO on those pages but allocate new ones
+ * to hold the compressed pages on disk.
+ *
+ * bio->bi_iter.bi_sector points to the compressed extent on disk
+ * bio->bi_io_vec points to all of the inode pages
+ * bio->bi_vcnt is a count of pages
+ *
+ * After the compressed pages are read, we copy the bytes into the
+ * bio we were passed and then call the bio end_io calls
+ */
+int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
+ int mirror_num, unsigned long bio_flags)
+{
+ struct extent_io_tree *tree;
+ struct extent_map_tree *em_tree;
+ struct compressed_bio *cb;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ unsigned long uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
+ unsigned long compressed_len;
+ unsigned long nr_pages;
+ unsigned long pg_index;
+ struct page *page;
+ struct block_device *bdev;
+ struct bio *comp_bio;
+ u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
+ u64 em_len;
+ u64 em_start;
+ struct extent_map *em;
+ int ret = -ENOMEM;
+ int faili = 0;
+ u32 *sums;
+
+ tree = &BTRFS_I(inode)->io_tree;
+ em_tree = &BTRFS_I(inode)->extent_tree;
+
+ /* we need the actual starting offset of this extent in the file */
+ read_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree,
+ page_offset(bio->bi_io_vec->bv_page),
+ PAGE_CACHE_SIZE);
+ read_unlock(&em_tree->lock);
+ if (!em)
+ return -EIO;
+
+ 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->mirror_num = mirror_num;
+ sums = &cb->sums;
+
+ cb->start = em->orig_start;
+ em_len = em->len;
+ em_start = em->start;
+
+ free_extent_map(em);
+ em = NULL;
+
+ cb->len = uncompressed_len;
+ cb->compressed_len = compressed_len;
+ cb->compress_type = extent_compress_type(bio_flags);
+ cb->orig_bio = bio;
+
+ nr_pages = DIV_ROUND_UP(compressed_len, PAGE_CACHE_SIZE);
+ cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
+ GFP_NOFS);
+ if (!cb->compressed_pages)
+ goto fail1;
+
+ bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+
+ for (pg_index = 0; pg_index < nr_pages; pg_index++) {
+ cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
+ __GFP_HIGHMEM);
+ if (!cb->compressed_pages[pg_index]) {
+ faili = pg_index - 1;
+ ret = -ENOMEM;
+ goto fail2;
+ }
+ }
+ faili = nr_pages - 1;
+ cb->nr_pages = nr_pages;
+
+ /* In the parent-locked case, we only locked the range we are
+ * interested in. In all other cases, we can opportunistically
+ * cache decompressed data that goes beyond the requested range. */
+ if (!(bio_flags & EXTENT_BIO_PARENT_LOCKED))
+ add_ra_bio_pages(inode, em_start + em_len, cb);
+
+ /* include any pages we added in add_ra-bio_pages */
+ uncompressed_len = bio->bi_vcnt * PAGE_CACHE_SIZE;
+ 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);
+
+ for (pg_index = 0; pg_index < nr_pages; pg_index++) {
+ page = cb->compressed_pages[pg_index];
+ page->mapping = inode->i_mapping;
+ page->index = em_start >> PAGE_CACHE_SHIFT;
+
+ if (comp_bio->bi_iter.bi_size)
+ ret = tree->ops->merge_bio_hook(READ, page, 0,
+ PAGE_CACHE_SIZE,
+ comp_bio, 0);
+ else
+ ret = 0;
+
+ page->mapping = NULL;
+ if (ret || bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0) <
+ PAGE_CACHE_SIZE) {
+ bio_get(comp_bio);
+
+ ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio,
+ BTRFS_WQ_ENDIO_DATA);
+ BUG_ON(ret); /* -ENOMEM */
+
+ /*
+ * inc the count before we submit the bio so
+ * we know the end IO handler won't happen before
+ * we inc the count. Otherwise, the cb might get
+ * freed before we're done setting it up
+ */
+ atomic_inc(&cb->pending_bios);
+
+ if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
+ ret = btrfs_lookup_bio_sums(root, inode,
+ comp_bio, sums);
+ BUG_ON(ret); /* -ENOMEM */
+ }
+ sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
+ root->sectorsize);
+
+ ret = btrfs_map_bio(root, READ, comp_bio,
+ mirror_num, 0);
+ if (ret)
+ bio_endio(comp_bio, ret);
+
+ bio_put(comp_bio);
+
+ comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
+ GFP_NOFS);
+ BUG_ON(!comp_bio);
+ comp_bio->bi_private = cb;
+ comp_bio->bi_end_io = end_compressed_bio_read;
+
+ bio_add_page(comp_bio, page, PAGE_CACHE_SIZE, 0);
+ }
+ cur_disk_byte += PAGE_CACHE_SIZE;
+ }
+ bio_get(comp_bio);
+
+ ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio,
+ BTRFS_WQ_ENDIO_DATA);
+ BUG_ON(ret); /* -ENOMEM */
+
+ if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
+ ret = btrfs_lookup_bio_sums(root, inode, comp_bio, sums);
+ BUG_ON(ret); /* -ENOMEM */
+ }
+
+ ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
+ if (ret)
+ bio_endio(comp_bio, ret);
+
+ bio_put(comp_bio);
+ return 0;
+
+fail2:
+ while (faili >= 0) {
+ __free_page(cb->compressed_pages[faili]);
+ faili--;
+ }
+
+ 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];
+
+static const struct btrfs_compress_op * const btrfs_compress_op[] = {
+ &btrfs_zlib_compress,
+ &btrfs_lzo_compress,
+};
+
+void __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]);
+ }
+}
+
+/*
+ * 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(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:
+ smp_mb();
+ 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 PTR_ERR(workspace);
+
+ 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.
+ */
+static 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 PTR_ERR(workspace);
+
+ 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 PTR_ERR(workspace);
+
+ 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 *pg_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[*pg_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);
+ memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);
+ kunmap_atomic(kaddr);
+ 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) {
+ (*pg_index)++;
+ if (*pg_index >= vcnt)
+ return 0;
+
+ page_out = bvec[*pg_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;
+}
+
+/*
+ * When uncompressing data, we need to make sure and zero any parts of
+ * the biovec that were not filled in by the decompression code. pg_index
+ * and pg_offset indicate the last page and the last offset of that page
+ * that have been filled in. This will zero everything remaining in the
+ * biovec.
+ */
+void btrfs_clear_biovec_end(struct bio_vec *bvec, int vcnt,
+ unsigned long pg_index,
+ unsigned long pg_offset)
+{
+ while (pg_index < vcnt) {
+ struct page *page = bvec[pg_index].bv_page;
+ unsigned long off = bvec[pg_index].bv_offset;
+ unsigned long len = bvec[pg_index].bv_len;
+
+ if (pg_offset < off)
+ pg_offset = off;
+ if (pg_offset < off + len) {
+ unsigned long bytes = off + len - pg_offset;
+ char *kaddr;
+
+ kaddr = kmap_atomic(page);
+ memset(kaddr + pg_offset, 0, bytes);
+ kunmap_atomic(kaddr);
+ }
+ pg_index++;
+ pg_offset = 0;
+ }
+}
Code Review / kvmfornfv.git / blobdiff