btrfs: export compression buffer limits in a header
Move the buffer limit definitions out of compress_file_range.
Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index cfcec70..619e64c 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -19,6 +19,21 @@
#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);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 83bbe1e..77fb24b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -471,16 +471,6 @@ static noinline void compress_file_range(struct inode *inode,
(start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))
goto cleanup_and_bail_uncompressed;
- /* 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.
- */
total_compressed = min(total_compressed, max_uncompressed);
num_bytes = ALIGN(end - start + 1, blocksize);
num_bytes = max(blocksize, num_bytes);
