btrfs: export compression buffer limits in a header

#ifndef __BTRFS_COMPRESSION_

#ifndef __BTRFS_COMPRESSION_

#define __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_init_compress(void);

void btrfs_exit_compress(void);

void btrfs_exit_compress(void);

	   (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))

	   (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))

		goto cleanup_and_bail_uncompressed;

		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);

	total_compressed = min(total_compressed, max_uncompressed);

	num_bytes = ALIGN(end - start + 1, blocksize);

	num_bytes = ALIGN(end - start + 1, blocksize);

	num_bytes = max(blocksize,  num_bytes);

	num_bytes = max(blocksize,  num_bytes);