At 02/18/2017 02:05 AM, David Sterba wrote:
Move the buffer limit definitions out of compress_file_range.
Nice one. No longer need to dig the codes to know the 128K limit now. Reviewed-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> Thanks, Qu
Signed-off-by: David Sterba <dsterba@xxxxxxxx> --- fs/btrfs/compression.h | 15 +++++++++++++++ fs/btrfs/inode.c | 10 ---------- 2 files changed, 15 insertions(+), 10 deletions(-) diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h index e453f42b3bbf..c9d7e552cfa8 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 801d1b3fd9d7..bc547608ff1a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -470,16 +470,6 @@ 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);
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