1 files changed, 330 insertions, 39 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index a11a32058b50..f745287fbf2e 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -31,7 +31,7 @@
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/bit_spinlock.h>
-#include <linux/pagevec.h>
+#include <linux/slab.h>
 #include "compat.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -62,6 +62,9 @@ struct compressed_bio {
         /* 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;
 
@@ -91,23 +94,10 @@ static inline int compressed_bio_size(struct btrfs_root *root,
 static struct bio *compressed_bio_alloc(struct block_device *bdev,
                                         u64 first_byte, gfp_t gfp_flags)
 {
-        struct bio *bio;
         int nr_vecs;
 
         nr_vecs = bio_get_nr_vecs(bdev);
-        bio = bio_alloc(gfp_flags, nr_vecs);
-
-        if (bio == NULL && (current->flags & PF_MEMALLOC)) {
-                while (!bio && (nr_vecs /= 2))
-                        bio = bio_alloc(gfp_flags, nr_vecs);
-        }
-
-        if (bio) {
-                bio->bi_size = 0;
-                bio->bi_bdev = bdev;
-                bio->bi_sector = first_byte >> 9;
-        }
-        return bio;
+        return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
 }
 
 static int check_compressed_csum(struct inode *inode,
@@ -163,7 +153,6 @@ fail:
  */
 static void end_compressed_bio_read(struct bio *bio, int err)
 {
-        struct extent_io_tree *tree;
         struct compressed_bio *cb = bio->bi_private;
         struct inode *inode;
         struct page *page;
@@ -187,12 +176,12 @@ static void end_compressed_bio_read(struct bio *bio, int err)
         /* ok, we're the last bio for this extent, lets start
          * the decompression.
          */
-        tree = &BTRFS_I(inode)->io_tree;
-        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;
@@ -445,7 +434,6 @@ static noinline int add_ra_bio_pages(struct inode *inode,
         unsigned long nr_pages = 0;
         struct extent_map *em;
         struct address_space *mapping = inode->i_mapping;
-        struct pagevec pvec;
         struct extent_map_tree *em_tree;
         struct extent_io_tree *tree;
         u64 end;
@@ -461,7 +449,6 @@ static noinline int add_ra_bio_pages(struct inode *inode,
 
         end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 
-        pagevec_init(&pvec, 0);
         while (last_offset < compressed_end) {
                 page_index = last_offset >> PAGE_CACHE_SHIFT;
 
@@ -478,26 +465,17 @@ static noinline int add_ra_bio_pages(struct inode *inode,
                         goto next;
                 }
 
-                page = alloc_page(mapping_gfp_mask(mapping) | GFP_NOFS);
+                page = __page_cache_alloc(mapping_gfp_mask(mapping) &
+                                                                ~__GFP_FS);
                 if (!page)
                         break;
 
-                page->index = page_index;
-                /*
-                 * what we want to do here is call add_to_page_cache_lru,
-                 * but that isn't exported, so we reproduce it here
-                 */
-                if (add_to_page_cache(page, mapping,
-                                      page->index, GFP_NOFS)) {
+                if (add_to_page_cache_lru(page, mapping, page_index,
+                                                                GFP_NOFS)) {
                         page_cache_release(page);
                         goto next;
                 }
 
-                /* open coding of lru_cache_add, also not exported */
-                page_cache_get(page);
-                if (!pagevec_add(&pvec, page))
-                        __pagevec_lru_add_file(&pvec);
-
                 end = last_offset + PAGE_CACHE_SIZE - 1;
                 /*
                  * at this point, we have a locked page in the page cache
@@ -551,8 +529,6 @@ static noinline int add_ra_bio_pages(struct inode *inode,
 next:
                 last_offset += PAGE_CACHE_SIZE;
         }
-        if (pagevec_count(&pvec))
-                __pagevec_lru_add_file(&pvec);
         return 0;
 }
 
@@ -616,6 +592,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 
         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) /
@@ -705,3 +682,317 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
         bio_put(comp_bio);
         return 0;
 }
+
+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 __exit 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;
+}