From 8c7d9fe06f5bb87dce356dcc9ea7c003b529e6ba Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Fri, 21 Aug 2020 00:39:52 -0700 Subject: btrfs: send: avoid copying file data send_write() currently copies from the page cache to sctx->read_buf, and then from sctx->read_buf to sctx->send_buf. Similarly, send_hole() zeroes sctx->read_buf and then copies from sctx->read_buf to sctx->send_buf. However, if we write the TLV header manually, we can copy to sctx->send_buf directly and get rid of sctx->read_buf. Reviewed-by: Filipe Manana Reviewed-by: Josef Bacik Signed-off-by: Omar Sandoval Signed-off-by: David Sterba --- fs/btrfs/send.c | 65 ++++++++++++++++++++++++++++++++++----------------------- fs/btrfs/send.h | 1 - 2 files changed, 39 insertions(+), 27 deletions(-) diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 8af5e867e4ca..491c486e3960 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -122,8 +122,6 @@ struct send_ctx { struct file_ra_state ra; - char *read_buf; - /* * We process inodes by their increasing order, so if before an * incremental send we reverse the parent/child relationship of @@ -4794,7 +4792,25 @@ out: return ret; } -static int fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len) +static inline u64 max_send_read_size(const struct send_ctx *sctx) +{ + return sctx->send_max_size - SZ_16K; +} + +static int put_data_header(struct send_ctx *sctx, u32 len) +{ + struct btrfs_tlv_header *hdr; + + if (sctx->send_max_size - sctx->send_size < sizeof(*hdr) + len) + return -EOVERFLOW; + hdr = (struct btrfs_tlv_header *)(sctx->send_buf + sctx->send_size); + put_unaligned_le16(BTRFS_SEND_A_DATA, &hdr->tlv_type); + put_unaligned_le16(len, &hdr->tlv_len); + sctx->send_size += sizeof(*hdr); + return 0; +} + +static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len) { struct btrfs_root *root = sctx->send_root; struct btrfs_fs_info *fs_info = root->fs_info; @@ -4804,8 +4820,11 @@ static int fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len) pgoff_t index = offset >> PAGE_SHIFT; pgoff_t last_index; unsigned pg_offset = offset_in_page(offset); - int ret = 0; - size_t read = 0; + int ret; + + ret = put_data_header(sctx, len); + if (ret) + return ret; inode = btrfs_iget(fs_info->sb, sctx->cur_ino, root); if (IS_ERR(inode)) @@ -4851,14 +4870,15 @@ static int fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len) } addr = kmap(page); - memcpy(sctx->read_buf + read, addr + pg_offset, cur_len); + memcpy(sctx->send_buf + sctx->send_size, addr + pg_offset, + cur_len); kunmap(page); unlock_page(page); put_page(page); index++; pg_offset = 0; len -= cur_len; - read += cur_len; + sctx->send_size += cur_len; } iput(inode); return ret; @@ -4880,10 +4900,6 @@ static int send_write(struct send_ctx *sctx, u64 offset, u32 len) btrfs_debug(fs_info, "send_write offset=%llu, len=%d", offset, len); - ret = fill_read_buf(sctx, offset, len); - if (ret < 0) - goto out; - ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE); if (ret < 0) goto out; @@ -4894,7 +4910,9 @@ static int send_write(struct send_ctx *sctx, u64 offset, u32 len) TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p); TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset); - TLV_PUT(sctx, BTRFS_SEND_A_DATA, sctx->read_buf, len); + ret = put_file_data(sctx, offset, len); + if (ret < 0) + goto out; ret = send_cmd(sctx); @@ -5013,8 +5031,8 @@ out: static int send_hole(struct send_ctx *sctx, u64 end) { struct fs_path *p = NULL; + u64 read_size = max_send_read_size(sctx); u64 offset = sctx->cur_inode_last_extent; - u64 len; int ret = 0; /* @@ -5041,16 +5059,19 @@ static int send_hole(struct send_ctx *sctx, u64 end) ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p); if (ret < 0) goto tlv_put_failure; - memset(sctx->read_buf, 0, BTRFS_SEND_READ_SIZE); while (offset < end) { - len = min_t(u64, end - offset, BTRFS_SEND_READ_SIZE); + u64 len = min(end - offset, read_size); ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE); if (ret < 0) break; TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p); TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset); - TLV_PUT(sctx, BTRFS_SEND_A_DATA, sctx->read_buf, len); + ret = put_data_header(sctx, len); + if (ret < 0) + break; + memset(sctx->send_buf + sctx->send_size, 0, len); + sctx->send_size += len; ret = send_cmd(sctx); if (ret < 0) break; @@ -5066,17 +5087,16 @@ static int send_extent_data(struct send_ctx *sctx, const u64 offset, const u64 len) { + u64 read_size = max_send_read_size(sctx); u64 sent = 0; if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA) return send_update_extent(sctx, offset, len); while (sent < len) { - u64 size = len - sent; + u64 size = min(len - sent, read_size); int ret; - if (size > BTRFS_SEND_READ_SIZE) - size = BTRFS_SEND_READ_SIZE; ret = send_write(sctx, offset + sent, size); if (ret < 0) return ret; @@ -7145,12 +7165,6 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) goto out; } - sctx->read_buf = kvmalloc(BTRFS_SEND_READ_SIZE, GFP_KERNEL); - if (!sctx->read_buf) { - ret = -ENOMEM; - goto out; - } - sctx->pending_dir_moves = RB_ROOT; sctx->waiting_dir_moves = RB_ROOT; sctx->orphan_dirs = RB_ROOT; @@ -7354,7 +7368,6 @@ out: kvfree(sctx->clone_roots); kvfree(sctx->send_buf); - kvfree(sctx->read_buf); name_cache_free(sctx); diff --git a/fs/btrfs/send.h b/fs/btrfs/send.h index ead397f7034f..de91488b7cd0 100644 --- a/fs/btrfs/send.h +++ b/fs/btrfs/send.h @@ -13,7 +13,6 @@ #define BTRFS_SEND_STREAM_VERSION 1 #define BTRFS_SEND_BUF_SIZE SZ_64K -#define BTRFS_SEND_READ_SIZE (48 * SZ_1K) enum btrfs_tlv_type { BTRFS_TLV_U8, -- cgit v1.2.3