btrfs: send add define for v2 buffer size

Add a define for the data buffer size (though the maximum size is not
limited by it) BTRFS_SEND_BUF_SIZE_V2 so it's more visible.

Signed-off-by: Wang Yugui <wangyugui@e16-tech.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 1c4b693..80104b5 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -7901,7 +7901,7 @@ long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg)
        if (sctx->proto >= 2) {
                u32 send_buf_num_pages;
 
-               sctx->send_max_size = ALIGN(SZ_16K + BTRFS_MAX_COMPRESSED, PAGE_SIZE);
+               sctx->send_max_size = BTRFS_SEND_BUF_SIZE_V2;
                sctx->send_buf = vmalloc(sctx->send_max_size);
                if (!sctx->send_buf) {
                        ret = -ENOMEM;

diff --git a/fs/btrfs/send.h b/fs/btrfs/send.h
index f7585cf..4f5509c 100644 (file)
--- a/fs/btrfs/send.h
+++ b/fs/btrfs/send.h
@@ -18,10 +18,12 @@
 #endif
 
 /*
- * In send stream v1, no command is larger than 64K. In send stream v2, no limit
- * should be assumed.
+ * In send stream v1, no command is larger than 64K. In send stream v2, no
+ * limit should be assumed, the buffer size is set to be a header with
+ * compressed extent size.
  */
 #define BTRFS_SEND_BUF_SIZE_V1                         SZ_64K
+#define BTRFS_SEND_BUF_SIZE_V2 ALIGN(SZ_16K + BTRFS_MAX_COMPRESSED, PAGE_SIZE)
 
 struct inode;
 struct btrfs_ioctl_send_args;