btrfs: extract the max compression chunk size into a macro

We have two locations using open-coded 512K size, as the async chunk
size.

For compression we have not only the max size a compressed extent can
represent (128K), but also how large an async chunk can be (512K).

Although we have a macro for the maximum compressed extent size, we do
not have any macro for the async chunk size.

Add such a macro and replace the two open-coded SZ_512K.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 84600b284e1e28bd2419fc21ea558b431f38b176..973530e9ce6c28ebe8fd12e9392ad0afbd0a645c 100644 (file)
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -36,6 +36,9 @@ struct btrfs_ordered_extent;
 #define BTRFS_MAX_COMPRESSED_PAGES     (BTRFS_MAX_COMPRESSED / PAGE_SIZE)
 static_assert((BTRFS_MAX_COMPRESSED % PAGE_SIZE) == 0);
 
+/* The max size for a single worker to compress. */
+#define BTRFS_COMPRESSION_CHUNK_SIZE   (SZ_512K)
+
 /* Maximum size of data before compression */
 #define BTRFS_MAX_UNCOMPRESSED         (SZ_128K)
 

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ea3746c14760b008b5235ab86e717e10a46a7ccb..89ab33c5b9403d886ca4e1e1ed656db03550d877 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1691,7 +1691,7 @@ static bool run_delalloc_compressed(struct btrfs_inode *inode,
        struct async_cow *ctx;
        struct async_chunk *async_chunk;
        unsigned long nr_pages;
-       u64 num_chunks = DIV_ROUND_UP(end - start, SZ_512K);
+       u64 num_chunks = DIV_ROUND_UP(end - start, BTRFS_COMPRESSION_CHUNK_SIZE);
        int i;
        unsigned nofs_flag;
        const blk_opf_t write_flags = wbc_to_write_flags(wbc);
@@ -1708,7 +1708,7 @@ static bool run_delalloc_compressed(struct btrfs_inode *inode,
        atomic_set(&ctx->num_chunks, num_chunks);
 
        for (i = 0; i < num_chunks; i++) {
-               u64 cur_end = min(end, start + SZ_512K - 1);
+               u64 cur_end = min(end, start + BTRFS_COMPRESSION_CHUNK_SIZE - 1);
 
                /*
                 * igrab is called higher up in the call chain, take only the