btrfs: Allow to add new compression algorithm

Make the code aware of compression type, instead of always assuming
zlib compression.

Also make the zlib workspace function as common code for all
compression types.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

fs/btrfs/btrfs_inode.h

@@ -157,7 +157,7 @@ struct btrfs_inode {
 	/*
 	 * always compress this one file
 	 */
-	unsigned force_compress:1;
+	unsigned force_compress:4;
 
 	struct inode vfs_inode;
 };

fs/btrfs/compression.c

@@ -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;
 
@@ -173,11 +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.
 	 */
-	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;
@@ -588,6 +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) /
@@ -677,3 +682,224 @@ 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,
+};
+
+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();
+}

fs/btrfs/compression.h

@@ -19,24 +19,22 @@
 #ifndef __BTRFS_COMPRESSION_
 #define __BTRFS_COMPRESSION_
 
-int btrfs_zlib_decompress(unsigned char *data_in,
-			  struct page *dest_page,
-			  unsigned long start_byte,
-			  size_t srclen, size_t destlen);
-int btrfs_zlib_compress_pages(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);
-int btrfs_zlib_decompress_biovec(struct page **pages_in,
-			      u64 disk_start,
-			      struct bio_vec *bvec,
-			      int vcnt,
-			      size_t srclen);
-void btrfs_zlib_exit(void);
+int btrfs_init_compress(void);
+void btrfs_exit_compress(void);
+
+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);
+int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
+			    struct bio_vec *bvec, int vcnt, size_t srclen);
+int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
+		     unsigned long start_byte, size_t srclen, size_t destlen);
+
 int btrfs_submit_compressed_write(struct inode *inode, u64 start,
 				  unsigned long len, u64 disk_start,
 				  unsigned long compressed_len,
@@ -44,4 +42,36 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start,
 				  unsigned long nr_pages);
 int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 				 int mirror_num, unsigned long bio_flags);
+
+struct btrfs_compress_op {
+	struct list_head *(*alloc_workspace)(void);
+
+	void (*free_workspace)(struct list_head *workspace);
+
+	int (*compress_pages)(struct list_head *workspace,
+			      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);
+
+	int (*decompress_biovec)(struct list_head *workspace,
+				 struct page **pages_in,
+				 u64 disk_start,
+				 struct bio_vec *bvec,
+				 int vcnt,
+				 size_t srclen);
+
+	int (*decompress)(struct list_head *workspace,
+			  unsigned char *data_in,
+			  struct page *dest_page,
+			  unsigned long start_byte,
+			  size_t srclen, size_t destlen);
+};
+
+extern struct btrfs_compress_op btrfs_zlib_compress;
+
 #endif

fs/btrfs/ctree.h

@@ -551,9 +551,10 @@ struct btrfs_timespec {
 } __attribute__ ((__packed__));
 
 enum btrfs_compression_type {
-	BTRFS_COMPRESS_NONE = 0,
-	BTRFS_COMPRESS_ZLIB = 1,
-	BTRFS_COMPRESS_LAST = 2,
+	BTRFS_COMPRESS_NONE  = 0,
+	BTRFS_COMPRESS_ZLIB  = 1,
+	BTRFS_COMPRESS_TYPES = 1,
+	BTRFS_COMPRESS_LAST  = 2,
 };
 
 struct btrfs_inode_item {
@@ -895,7 +896,8 @@ struct btrfs_fs_info {
 	 */
 	u64 last_trans_log_full_commit;
 	u64 open_ioctl_trans;
-	unsigned long mount_opt;
+	unsigned long mount_opt:20;
+	unsigned long compress_type:4;
 	u64 max_inline;
 	u64 alloc_start;
 	struct btrfs_transaction *running_transaction;

fs/btrfs/extent_io.c

@@ -2028,8 +2028,11 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
 		BUG_ON(extent_map_end(em) <= cur);
 		BUG_ON(end < cur);
 
-		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
+		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
 			this_bio_flag = EXTENT_BIO_COMPRESSED;
+			extent_set_compress_type(&this_bio_flag,
+						 em->compress_type);
+		}
 
 		iosize = min(extent_map_end(em) - cur, end - cur + 1);
 		cur_end = min(extent_map_end(em) - 1, end);

fs/btrfs/extent_io.h

@@ -20,8 +20,12 @@
 #define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
 #define EXTENT_CTLBITS (EXTENT_DO_ACCOUNTING | EXTENT_FIRST_DELALLOC)
 
-/* flags for bio submission */
+/*
+ * flags for bio submission. The high bits indicate the compression
+ * type for this bio
+ */
 #define EXTENT_BIO_COMPRESSED 1
+#define EXTENT_BIO_FLAG_SHIFT 16
 
 /* these are bit numbers for test/set bit */
 #define EXTENT_BUFFER_UPTODATE 0
@@ -135,6 +139,17 @@ struct extent_buffer {
 	wait_queue_head_t lock_wq;
 };
 
+static inline void extent_set_compress_type(unsigned long *bio_flags,
+					    int compress_type)
+{
+	*bio_flags |= compress_type << EXTENT_BIO_FLAG_SHIFT;
+}
+
+static inline int extent_compress_type(unsigned long bio_flags)
+{
+	return bio_flags >> EXTENT_BIO_FLAG_SHIFT;
+}
+
 struct extent_map_tree;
 
 static inline struct extent_state *extent_state_next(struct extent_state *state)

fs/btrfs/extent_map.c

@@ -3,6 +3,7 @@
 #include <linux/module.h>
 #include <linux/spinlock.h>
 #include <linux/hardirq.h>
+#include "ctree.h"
 #include "extent_map.h"
 
 
@@ -54,6 +55,7 @@ struct extent_map *alloc_extent_map(gfp_t mask)
 		return em;
 	em->in_tree = 0;
 	em->flags = 0;
+	em->compress_type = BTRFS_COMPRESS_NONE;
 	atomic_set(&em->refs, 1);
 	return em;
 }

fs/btrfs/extent_map.h

@@ -26,7 +26,8 @@ struct extent_map {
 	unsigned long flags;
 	struct block_device *bdev;
 	atomic_t refs;
-	int in_tree;
+	unsigned int in_tree:1;
+	unsigned int compress_type:4;
 };
 
 struct extent_map_tree {

fs/btrfs/file.c

@@ -224,6 +224,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 
 			split->bdev = em->bdev;
 			split->flags = flags;
+			split->compress_type = em->compress_type;
 			ret = add_extent_mapping(em_tree, split);
 			BUG_ON(ret);
 			free_extent_map(split);
@@ -238,6 +239,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 			split->len = em->start + em->len - (start + len);
 			split->bdev = em->bdev;
 			split->flags = flags;
+			split->compress_type = em->compress_type;
 
 			if (compressed) {
 				split->block_len = em->block_len;

fs/btrfs/inode.c

@@ -122,10 +122,10 @@ static noinline int insert_inline_extent(struct btrfs_trans_handle *trans,
 	size_t cur_size = size;
 	size_t datasize;
 	unsigned long offset;
-	int use_compress = 0;
+	int compress_type = BTRFS_COMPRESS_NONE;
 
 	if (compressed_size && compressed_pages) {
-		use_compress = 1;
+		compress_type = root->fs_info->compress_type;
 		cur_size = compressed_size;
 	}
 
@@ -159,7 +159,7 @@ static noinline int insert_inline_extent(struct btrfs_trans_handle *trans,
 	btrfs_set_file_extent_ram_bytes(leaf, ei, size);
 	ptr = btrfs_file_extent_inline_start(ei);
 
-	if (use_compress) {
+	if (compress_type != BTRFS_COMPRESS_NONE) {
 		struct page *cpage;
 		int i = 0;
 		while (compressed_size > 0) {
@@ -176,7 +176,7 @@ static noinline int insert_inline_extent(struct btrfs_trans_handle *trans,
 			compressed_size -= cur_size;
 		}
 		btrfs_set_file_extent_compression(leaf, ei,
-						  BTRFS_COMPRESS_ZLIB);
+						  compress_type);
 	} else {
 		page = find_get_page(inode->i_mapping,
 				     start >> PAGE_CACHE_SHIFT);
@@ -263,6 +263,7 @@ struct async_extent {
 	u64 compressed_size;
 	struct page **pages;
 	unsigned long nr_pages;
+	int compress_type;
 	struct list_head list;
 };
 
@@ -280,7 +281,8 @@ static noinline int add_async_extent(struct async_cow *cow,
 				     u64 start, u64 ram_size,
 				     u64 compressed_size,
 				     struct page **pages,
-				     unsigned long nr_pages)
+				     unsigned long nr_pages,
+				     int compress_type)
 {
 	struct async_extent *async_extent;
 
@@ -290,6 +292,7 @@ static noinline int add_async_extent(struct async_cow *cow,
 	async_extent->compressed_size = compressed_size;
 	async_extent->pages = pages;
 	async_extent->nr_pages = nr_pages;
+	async_extent->compress_type = compress_type;
 	list_add_tail(&async_extent->list, &cow->extents);
 	return 0;
 }
@@ -332,6 +335,7 @@ static noinline int compress_file_range(struct inode *inode,
 	unsigned long max_uncompressed = 128 * 1024;
 	int i;
 	int will_compress;
+	int compress_type = root->fs_info->compress_type;
 
 	actual_end = min_t(u64, isize, end + 1);
 again:
@@ -381,12 +385,16 @@ static noinline int compress_file_range(struct inode *inode,
 		WARN_ON(pages);
 		pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
 
-		ret = btrfs_zlib_compress_pages(inode->i_mapping, start,
-						total_compressed, pages,
-						nr_pages, &nr_pages_ret,
-						&total_in,
-						&total_compressed,
-						max_compressed);
+		if (BTRFS_I(inode)->force_compress)
+			compress_type = BTRFS_I(inode)->force_compress;
+
+		ret = btrfs_compress_pages(compress_type,
+					   inode->i_mapping, start,
+					   total_compressed, pages,
+					   nr_pages, &nr_pages_ret,
+					   &total_in,
+					   &total_compressed,
+					   max_compressed);
 
 		if (!ret) {
 			unsigned long offset = total_compressed &
@@ -493,7 +501,8 @@ static noinline int compress_file_range(struct inode *inode,
 		 * and will submit them to the elevator.
 		 */
 		add_async_extent(async_cow, start, num_bytes,
-				 total_compressed, pages, nr_pages_ret);
+				 total_compressed, pages, nr_pages_ret,
+				 compress_type);
 
 		if (start + num_bytes < end) {
 			start += num_bytes;
@@ -515,7 +524,8 @@ static noinline int compress_file_range(struct inode *inode,
 			__set_page_dirty_nobuffers(locked_page);
 			/* unlocked later on in the async handlers */
 		}
-		add_async_extent(async_cow, start, end - start + 1, 0, NULL, 0);
+		add_async_extent(async_cow, start, end - start + 1,
+				 0, NULL, 0, BTRFS_COMPRESS_NONE);
 		*num_added += 1;
 	}
 
@@ -640,6 +650,7 @@ static noinline int submit_compressed_extents(struct inode *inode,
 		em->block_start = ins.objectid;
 		em->block_len = ins.offset;
 		em->bdev = root->fs_info->fs_devices->latest_bdev;
+		em->compress_type = async_extent->compress_type;
 		set_bit(EXTENT_FLAG_PINNED, &em->flags);
 		set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 
@@ -656,11 +667,13 @@ static noinline int submit_compressed_extents(struct inode *inode,
 						async_extent->ram_size - 1, 0);
 		}
 
-		ret = btrfs_add_ordered_extent(inode, async_extent->start,
-					       ins.objectid,
-					       async_extent->ram_size,
-					       ins.offset,
-					       BTRFS_ORDERED_COMPRESSED);
+		ret = btrfs_add_ordered_extent_compress(inode,
+						async_extent->start,
+						ins.objectid,
+						async_extent->ram_size,
+						ins.offset,
+						BTRFS_ORDERED_COMPRESSED,
+						async_extent->compress_type);
 		BUG_ON(ret);
 
 		/*
@@ -1670,7 +1683,7 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
 	struct btrfs_ordered_extent *ordered_extent = NULL;
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct extent_state *cached_state = NULL;
-	int compressed = 0;
+	int compress_type = 0;
 	int ret;
 	bool nolock = false;
 
@@ -1711,9 +1724,9 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
 	trans->block_rsv = &root->fs_info->delalloc_block_rsv;
 
 	if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
-		compressed = 1;
+		compress_type = ordered_extent->compress_type;
 	if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
-		BUG_ON(compressed);
+		BUG_ON(compress_type);
 		ret = btrfs_mark_extent_written(trans, inode,
 						ordered_extent->file_offset,
 						ordered_extent->file_offset +
@@ -1727,7 +1740,7 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
 						ordered_extent->disk_len,
 						ordered_extent->len,
 						ordered_extent->len,
-						compressed, 0, 0,
+						compress_type, 0, 0,
 						BTRFS_FILE_EXTENT_REG);
 		unpin_extent_cache(&BTRFS_I(inode)->extent_tree,
 				   ordered_extent->file_offset,
@@ -1829,6 +1842,8 @@ static int btrfs_io_failed_hook(struct bio *failed_bio,
 		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
 			logical = em->block_start;
 			failrec->bio_flags = EXTENT_BIO_COMPRESSED;
+			extent_set_compress_type(&failrec->bio_flags,
+						 em->compress_type);
 		}
 		failrec->logical = logical;
 		free_extent_map(em);
@@ -4930,8 +4945,10 @@ static noinline int uncompress_inline(struct btrfs_path *path,
 	size_t max_size;
 	unsigned long inline_size;
 	unsigned long ptr;
+	int compress_type;
 
 	WARN_ON(pg_offset != 0);
+	compress_type = btrfs_file_extent_compression(leaf, item);
 	max_size = btrfs_file_extent_ram_bytes(leaf, item);
 	inline_size = btrfs_file_extent_inline_item_len(leaf,
 					btrfs_item_nr(leaf, path->slots[0]));
@@ -4941,8 +4958,8 @@ static noinline int uncompress_inline(struct btrfs_path *path,
 	read_extent_buffer(leaf, tmp, ptr, inline_size);
 
 	max_size = min_t(unsigned long, PAGE_CACHE_SIZE, max_size);
-	ret = btrfs_zlib_decompress(tmp, page, extent_offset,
-				    inline_size, max_size);
+	ret = btrfs_decompress(compress_type, tmp, page,
+			       extent_offset, inline_size, max_size);
 	if (ret) {
 		char *kaddr = kmap_atomic(page, KM_USER0);
 		unsigned long copy_size = min_t(u64,
@@ -4984,7 +5001,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_trans_handle *trans = NULL;
-	int compressed;
+	int compress_type;
 
 again:
 	read_lock(&em_tree->lock);
@@ -5043,7 +5060,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 
 	found_type = btrfs_file_extent_type(leaf, item);
 	extent_start = found_key.offset;
-	compressed = btrfs_file_extent_compression(leaf, item);
+	compress_type = btrfs_file_extent_compression(leaf, item);
 	if (found_type == BTRFS_FILE_EXTENT_REG ||
 	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
 		extent_end = extent_start +
@@ -5089,8 +5106,9 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 			em->block_start = EXTENT_MAP_HOLE;
 			goto insert;
 		}
-		if (compressed) {
+		if (compress_type != BTRFS_COMPRESS_NONE) {
 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+			em->compress_type = compress_type;
 			em->block_start = bytenr;
 			em->block_len = btrfs_file_extent_disk_num_bytes(leaf,
 									 item);
@@ -5124,12 +5142,14 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 		em->len = (copy_size + root->sectorsize - 1) &
 			~((u64)root->sectorsize - 1);
 		em->orig_start = EXTENT_MAP_INLINE;
-		if (compressed)
+		if (compress_type) {
 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+			em->compress_type = compress_type;
+		}
 		ptr = btrfs_file_extent_inline_start(item) + extent_offset;
 		if (create == 0 && !PageUptodate(page)) {
-			if (btrfs_file_extent_compression(leaf, item) ==
-			    BTRFS_COMPRESS_ZLIB) {
+			if (btrfs_file_extent_compression(leaf, item) !=
+			    BTRFS_COMPRESS_NONE) {
 				ret = uncompress_inline(path, inode, page,
 							pg_offset,
 							extent_offset, item);
@@ -6479,7 +6499,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 	ei->ordered_data_close = 0;
 	ei->orphan_meta_reserved = 0;
 	ei->dummy_inode = 0;
-	ei->force_compress = 0;
+	ei->force_compress = BTRFS_COMPRESS_NONE;
 
 	inode = &ei->vfs_inode;
 	extent_map_tree_init(&ei->extent_tree, GFP_NOFS);

fs/btrfs/ioctl.c

@@ -683,7 +683,7 @@ static int btrfs_defrag_file(struct file *file,
 		total_read++;
 		mutex_lock(&inode->i_mutex);
 		if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)
-			BTRFS_I(inode)->force_compress = 1;
+			BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_ZLIB;
 
 		ret  = btrfs_delalloc_reserve_space(inode, PAGE_CACHE_SIZE);
 		if (ret)
@@ -781,7 +781,7 @@ static int btrfs_defrag_file(struct file *file,
 		atomic_dec(&root->fs_info->async_submit_draining);
 
 		mutex_lock(&inode->i_mutex);
-		BTRFS_I(inode)->force_compress = 0;
+		BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;
 		mutex_unlock(&inode->i_mutex);
 	}
 

fs/btrfs/ordered-data.c

@@ -172,7 +172,7 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
  */
 static int __btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 				      u64 start, u64 len, u64 disk_len,
-				      int type, int dio)
+				      int type, int dio, int compress_type)
 {
 	struct btrfs_ordered_inode_tree *tree;
 	struct rb_node *node;
@@ -189,6 +189,7 @@ static int __btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 	entry->disk_len = disk_len;
 	entry->bytes_left = len;
 	entry->inode = inode;
+	entry->compress_type = compress_type;
 	if (type != BTRFS_ORDERED_IO_DONE && type != BTRFS_ORDERED_COMPLETE)
 		set_bit(type, &entry->flags);
 
@@ -220,14 +221,25 @@ int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 			     u64 start, u64 len, u64 disk_len, int type)
 {
 	return __btrfs_add_ordered_extent(inode, file_offset, start, len,
-					  disk_len, type, 0);
+					  disk_len, type, 0,
+					  BTRFS_COMPRESS_NONE);
 }
 
 int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
 				 u64 start, u64 len, u64 disk_len, int type)
 {
 	return __btrfs_add_ordered_extent(inode, file_offset, start, len,
-					  disk_len, type, 1);
+					  disk_len, type, 1,
+					  BTRFS_COMPRESS_NONE);
+}
+
+int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
+				      u64 start, u64 len, u64 disk_len,
+				      int type, int compress_type)
+{
+	return __btrfs_add_ordered_extent(inode, file_offset, start, len,
+					  disk_len, type, 0,
+					  compress_type);
 }
 
 /*

fs/btrfs/ordered-data.h

@@ -68,7 +68,7 @@ struct btrfs_ordered_sum {
 
 #define BTRFS_ORDERED_NOCOW 2 /* set when we want to write in place */
 
-#define BTRFS_ORDERED_COMPRESSED 3 /* writing a compressed extent */
+#define BTRFS_ORDERED_COMPRESSED 3 /* writing a zlib compressed extent */
 
 #define BTRFS_ORDERED_PREALLOC 4 /* set when writing to prealloced extent */
 
@@ -93,6 +93,9 @@ struct btrfs_ordered_extent {
 	/* flags (described above) */
 	unsigned long flags;
 
+	/* compression algorithm */
+	int compress_type;
+
 	/* reference count */
 	atomic_t refs;
 
@@ -148,6 +151,9 @@ int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 			     u64 start, u64 len, u64 disk_len, int type);
 int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
 				 u64 start, u64 len, u64 disk_len, int type);
+int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
+				      u64 start, u64 len, u64 disk_len,
+				      int type, int compress_type);
 int btrfs_add_ordered_sum(struct inode *inode,
 			  struct btrfs_ordered_extent *entry,
 			  struct btrfs_ordered_sum *sum);

fs/btrfs/super.c

@@ -69,9 +69,9 @@ enum {
 	Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 	Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 	Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
-	Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
-	Opt_discard, Opt_space_cache, Opt_clear_cache, Opt_err,
-	Opt_user_subvol_rm_allowed,
+	Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
+	Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
+	Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -86,7 +86,9 @@ static match_table_t tokens = {
 	{Opt_alloc_start, "alloc_start=%s"},
 	{Opt_thread_pool, "thread_pool=%d"},
 	{Opt_compress, "compress"},
+	{Opt_compress_type, "compress=%s"},
 	{Opt_compress_force, "compress-force"},
+	{Opt_compress_force_type, "compress-force=%s"},
 	{Opt_ssd, "ssd"},
 	{Opt_ssd_spread, "ssd_spread"},
 	{Opt_nossd, "nossd"},
@@ -112,6 +114,8 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 	char *p, *num, *orig;
 	int intarg;
 	int ret = 0;
+	char *compress_type;
+	bool compress_force = false;
 
 	if (!options)
 		return 0;
@@ -154,14 +158,29 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 			btrfs_set_opt(info->mount_opt, NODATACOW);
 			btrfs_set_opt(info->mount_opt, NODATASUM);
 			break;
-		case Opt_compress:
-			printk(KERN_INFO "btrfs: use compression\n");
-			btrfs_set_opt(info->mount_opt, COMPRESS);
-			break;
 		case Opt_compress_force:
-			printk(KERN_INFO "btrfs: forcing compression\n");
-			btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
+		case Opt_compress_force_type:
+			compress_force = true;
+		case Opt_compress:
+		case Opt_compress_type:
+			if (token == Opt_compress ||
+			    token == Opt_compress_force ||
+			    strcmp(args[0].from, "zlib") == 0) {
+				compress_type = "zlib";
+				info->compress_type = BTRFS_COMPRESS_ZLIB;
+			} else {
+				ret = -EINVAL;
+				goto out;
+			}
+
 			btrfs_set_opt(info->mount_opt, COMPRESS);
+			if (compress_force) {
+				btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
+				pr_info("btrfs: force %s compression\n",
+					compress_type);
+			} else
+				pr_info("btrfs: use %s compression\n",
+					compress_type);
 			break;
 		case Opt_ssd:
 			printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
@@ -898,10 +917,14 @@ static int __init init_btrfs_fs(void)
 	if (err)
 		return err;
 
-	err = btrfs_init_cachep();
+	err = btrfs_init_compress();
 	if (err)
 		goto free_sysfs;
 
+	err = btrfs_init_cachep();
+	if (err)
+		goto free_compress;
+
 	err = extent_io_init();
 	if (err)
 		goto free_cachep;
@@ -929,6 +952,8 @@ static int __init init_btrfs_fs(void)
 	extent_io_exit();
 free_cachep:
 	btrfs_destroy_cachep();
+free_compress:
+	btrfs_exit_compress();
 free_sysfs:
 	btrfs_exit_sysfs();
 	return err;
@@ -943,7 +968,7 @@ static void __exit exit_btrfs_fs(void)
 	unregister_filesystem(&btrfs_fs_type);
 	btrfs_exit_sysfs();
 	btrfs_cleanup_fs_uuids();
-	btrfs_zlib_exit();
+	btrfs_exit_compress();
 }
 
 module_init(init_btrfs_fs)

fs/btrfs/zlib.c

@@ -32,15 +32,6 @@
 #include <linux/bio.h>
 #include "compression.h"
 
-/* Plan: call deflate() with avail_in == *sourcelen,
-	avail_out = *dstlen - 12 and flush == Z_FINISH.
-	If it doesn't manage to finish,	call it again with
-	avail_in == 0 and avail_out set to the remaining 12
-	bytes for it to clean up.
-   Q: Is 12 bytes sufficient?
-*/
-#define STREAM_END_SPACE 12
-
 struct workspace {
 	z_stream inf_strm;
 	z_stream def_strm;
@@ -48,155 +39,51 @@ struct workspace {
 	struct list_head list;
 };
 
-static LIST_HEAD(idle_workspace);
-static DEFINE_SPINLOCK(workspace_lock);
-static unsigned long num_workspace;
-static atomic_t alloc_workspace = ATOMIC_INIT(0);
-static DECLARE_WAIT_QUEUE_HEAD(workspace_wait);
+static void zlib_free_workspace(struct list_head *ws)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
 
-/*
- * this finds an available zlib workspace or allocates a new one
- * NULL or an ERR_PTR is returned if things go bad.
- */
-static struct workspace *find_zlib_workspace(void)
+	vfree(workspace->def_strm.workspace);
+	vfree(workspace->inf_strm.workspace);
+	kfree(workspace->buf);
+	kfree(workspace);
+}
+
+static struct list_head *zlib_alloc_workspace(void)
 {
 	struct workspace *workspace;
-	int ret;
-	int cpus = num_online_cpus();
-
-again:
-	spin_lock(&workspace_lock);
-	if (!list_empty(&idle_workspace)) {
-		workspace = list_entry(idle_workspace.next, struct workspace,
-				       list);
-		list_del(&workspace->list);
-		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 = kzalloc(sizeof(*workspace), GFP_NOFS);
-	if (!workspace) {
-		ret = -ENOMEM;
-		goto fail;
-	}
+	if (!workspace)
+		return ERR_PTR(-ENOMEM);
 
 	workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize());
-	if (!workspace->def_strm.workspace) {
-		ret = -ENOMEM;
-		goto fail;
-	}
 	workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
-	if (!workspace->inf_strm.workspace) {
-		ret = -ENOMEM;
-		goto fail_inflate;
-	}
 	workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
-	if (!workspace->buf) {
-		ret = -ENOMEM;
-		goto fail_kmalloc;
-	}
-	return workspace;
-
-fail_kmalloc:
-	vfree(workspace->inf_strm.workspace);
-fail_inflate:
-	vfree(workspace->def_strm.workspace);
-fail:
-	kfree(workspace);
-	atomic_dec(&alloc_workspace);
-	wake_up(&workspace_wait);
-	return ERR_PTR(ret);
-}
-
-/*
- * put a workspace struct back on the list or free it if we have enough
- * idle ones sitting around
- */
-static int free_workspace(struct workspace *workspace)
-{
-	spin_lock(&workspace_lock);
-	if (num_workspace < num_online_cpus()) {
-		list_add_tail(&workspace->list, &idle_workspace);
-		num_workspace++;
-		spin_unlock(&workspace_lock);
-		if (waitqueue_active(&workspace_wait))
-			wake_up(&workspace_wait);
-		return 0;
-	}
-	spin_unlock(&workspace_lock);
-	vfree(workspace->def_strm.workspace);
-	vfree(workspace->inf_strm.workspace);
-	kfree(workspace->buf);
-	kfree(workspace);
+	if (!workspace->def_strm.workspace ||
+	    !workspace->inf_strm.workspace || !workspace->buf)
+		goto fail;
 
-	atomic_dec(&alloc_workspace);
-	if (waitqueue_active(&workspace_wait))
-		wake_up(&workspace_wait);
-	return 0;
-}
+	INIT_LIST_HEAD(&workspace->list);
 
-/*
- * cleanup function for module exit
- */
-static void free_workspaces(void)
-{
-	struct workspace *workspace;
-	while (!list_empty(&idle_workspace)) {
-		workspace = list_entry(idle_workspace.next, struct workspace,
-				       list);
-		list_del(&workspace->list);
-		vfree(workspace->def_strm.workspace);
-		vfree(workspace->inf_strm.workspace);
-		kfree(workspace->buf);
-		kfree(workspace);
-		atomic_dec(&alloc_workspace);
-	}
+	return &workspace->list;
+fail:
+	zlib_free_workspace(&workspace->list);
+	return ERR_PTR(-ENOMEM);
 }
 
-/*
- * 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_zlib_compress_pages(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)
+static int zlib_compress_pages(struct list_head *ws,
+			       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 workspace *workspace = list_entry(ws, struct workspace, list);
 	int ret;
-	struct workspace *workspace;
 	char *data_in;
 	char *cpage_out;
 	int nr_pages = 0;
@@ -208,10 +95,6 @@ int btrfs_zlib_compress_pages(struct address_space *mapping,
 	*total_out = 0;
 	*total_in = 0;
 
-	workspace = find_zlib_workspace();
-	if (IS_ERR(workspace))
-		return -1;
-
 	if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
 		printk(KERN_WARNING "deflateInit failed\n");
 		ret = -1;
@@ -325,35 +208,18 @@ int btrfs_zlib_compress_pages(struct address_space *mapping,
 		kunmap(in_page);
 		page_cache_release(in_page);
 	}
-	free_workspace(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_zlib_decompress_biovec(struct page **pages_in,
-			      u64 disk_start,
-			      struct bio_vec *bvec,
-			      int vcnt,
-			      size_t srclen)
+static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
+				  u64 disk_start,
+				  struct bio_vec *bvec,
+				  int vcnt,
+				  size_t srclen)
 {
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
 	int ret = 0;
 	int wbits = MAX_WBITS;
-	struct workspace *workspace;
 	char *data_in;
 	size_t total_out = 0;
 	unsigned long page_bytes_left;
@@ -371,10 +237,6 @@ int btrfs_zlib_decompress_biovec(struct page **pages_in,
 	unsigned long current_buf_start;
 	char *kaddr;
 
-	workspace = find_zlib_workspace();
-	if (IS_ERR(workspace))
-		return -ENOMEM;
-
 	data_in = kmap(pages_in[page_in_index]);
 	workspace->inf_strm.next_in = data_in;
 	workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
@@ -400,8 +262,7 @@ int btrfs_zlib_decompress_biovec(struct page **pages_in,
 
 	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
 		printk(KERN_WARNING "inflateInit failed\n");
-		ret = -1;
-		goto out;
+		return -1;
 	}
 	while (workspace->inf_strm.total_in < srclen) {
 		ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
@@ -527,35 +388,21 @@ int btrfs_zlib_decompress_biovec(struct page **pages_in,
 	zlib_inflateEnd(&workspace->inf_strm);
 	if (data_in)
 		kunmap(pages_in[page_in_index]);
-out:
-	free_workspace(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_zlib_decompress(unsigned char *data_in,
-			  struct page *dest_page,
-			  unsigned long start_byte,
-			  size_t srclen, size_t destlen)
+static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
+			   struct page *dest_page,
+			   unsigned long start_byte,
+			   size_t srclen, size_t destlen)
 {
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
 	int ret = 0;
 	int wbits = MAX_WBITS;
-	struct workspace *workspace;
 	unsigned long bytes_left = destlen;
 	unsigned long total_out = 0;
 	char *kaddr;
 
-	if (destlen > PAGE_CACHE_SIZE)
-		return -ENOMEM;
-
-	workspace = find_zlib_workspace();
-	if (IS_ERR(workspace))
-		return -ENOMEM;
-
 	workspace->inf_strm.next_in = data_in;
 	workspace->inf_strm.avail_in = srclen;
 	workspace->inf_strm.total_in = 0;
@@ -576,8 +423,7 @@ int btrfs_zlib_decompress(unsigned char *data_in,
 
 	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
 		printk(KERN_WARNING "inflateInit failed\n");
-		ret = -1;
-		goto out;
+		return -1;
 	}
 
 	while (bytes_left > 0) {
@@ -627,12 +473,13 @@ int btrfs_zlib_decompress(unsigned char *data_in,
 		ret = 0;
 
 	zlib_inflateEnd(&workspace->inf_strm);
-out:
-	free_workspace(workspace);
 	return ret;
 }
 
-void btrfs_zlib_exit(void)
-{
-    free_workspaces();
-}
+struct btrfs_compress_op btrfs_zlib_compress = {
+	.alloc_workspace	= zlib_alloc_workspace,
+	.free_workspace		= zlib_free_workspace,
+	.compress_pages		= zlib_compress_pages,
+	.decompress_biovec	= zlib_decompress_biovec,
+	.decompress		= zlib_decompress,
+};