Commit ff763866 authored by David Sterba's avatar David Sterba
Browse files

btrfs: export compression buffer limits in a header 



Move the buffer limit definitions out of compress_file_range.

Reviewed-by: default avatarQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 4d3a800e

fs/btrfs/compression.h

+15 −0
Original line number Diff line number Diff line
@@ -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);

fs/btrfs/inode.c

+0 −10
Original line number Diff line number Diff line
@@ -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);