Merge remote-tracking branch 'regulator/topic/vctrl' into regulator-next

[karo-tx-linux.git] / fs / btrfs / compression.h

diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 09879579fbc83d29ac9e199fa4507ff75fc5b244..39ec43ab8df1b72bf9a7cc57b0a90ea4e5fb8602 100644 (file)
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -19,20 +19,32 @@
 #ifndef __BTRFS_COMPRESSION_
 #define __BTRFS_COMPRESSION_
 
+/*
+ * We want to make sure that amount of RAM required to uncompress an extent is
+ * reasonable, so we limit the total size in ram of a compressed extent to
+ * 128k.  This is a crucial number because it also controls how easily we can
+ * spread reads across cpus for decompression.
+ *
+ * We also want to make sure the amount of IO required to do a random read is
+ * reasonably small, so we limit the size of a compressed extent to 128k.
+ */
+
+/* Maximum length of compressed data stored on disk */
+#define BTRFS_MAX_COMPRESSED           (SZ_128K)
+/* Maximum size of data before compression */
+#define BTRFS_MAX_UNCOMPRESSED         (SZ_128K)
+
 void 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,
+                        u64 start, struct page **pages,
                         unsigned long *out_pages,
                         unsigned long *total_in,
-                        unsigned long *total_out,
-                        unsigned long max_out);
+                        unsigned long *total_out);
 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_decompress_buf2page(char *buf, unsigned long buf_start,
+int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
                              unsigned long total_out, u64 disk_start,
                              struct bio *bio);
 
@@ -59,13 +71,11 @@ struct btrfs_compress_op {
 
        int (*compress_pages)(struct list_head *workspace,
                              struct address_space *mapping,
-                             u64 start, unsigned long len,
+                             u64 start,
                              struct page **pages,
-                             unsigned long nr_dest_pages,
                              unsigned long *out_pages,
                              unsigned long *total_in,
-                             unsigned long *total_out,
-                             unsigned long max_out);
+                             unsigned long *total_out);
 
        int (*decompress_bio)(struct list_head *workspace,
                                 struct page **pages_in,