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https://github.com/kdave/btrfs-progs
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btrfs-progs: receive: dynamically allocate sctx->read_buf
In send stream v2, write commands can now be an arbitrary size. For that reason, we can no longer allocate a fixed array in sctx for read_cmd. Instead, read_cmd dynamically allocates sctx->read_buf. To avoid needless reallocations, we reuse read_buf between read_cmd calls by also keeping track of the size of the allocated buffer in sctx->read_buf_sz. We do the first allocation of the old default size at the start of processing the stream, and we only reallocate if we encounter a command that needs a larger buffer. Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
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@ -35,11 +35,11 @@ struct btrfs_send_attribute {
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};
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struct btrfs_send_stream {
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char read_buf[BTRFS_SEND_BUF_SIZE];
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char *read_buf;
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size_t read_buf_size;
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int fd;
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int cmd;
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struct btrfs_cmd_header *cmd_hdr;
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struct btrfs_send_attribute cmd_attrs[BTRFS_SEND_A_MAX + 1];
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u32 version;
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@ -111,11 +111,12 @@ static int read_cmd(struct btrfs_send_stream *sctx)
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u32 pos;
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u32 crc;
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u32 crc2;
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struct btrfs_cmd_header *cmd_hdr;
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size_t buf_len;
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memset(sctx->cmd_attrs, 0, sizeof(sctx->cmd_attrs));
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ASSERT(sizeof(*sctx->cmd_hdr) <= sizeof(sctx->read_buf));
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ret = read_buf(sctx, sctx->read_buf, sizeof(*sctx->cmd_hdr));
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ret = read_buf(sctx, sctx->read_buf, sizeof(*cmd_hdr));
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if (ret < 0)
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goto out;
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if (ret) {
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@ -124,18 +125,26 @@ static int read_cmd(struct btrfs_send_stream *sctx)
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goto out;
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}
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sctx->cmd_hdr = (struct btrfs_cmd_header *)sctx->read_buf;
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cmd = le16_to_cpu(sctx->cmd_hdr->cmd);
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cmd_len = le32_to_cpu(sctx->cmd_hdr->len);
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cmd_hdr = (struct btrfs_cmd_header *)sctx->read_buf;
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cmd_len = le32_to_cpu(cmd_hdr->len);
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cmd = le16_to_cpu(cmd_hdr->cmd);
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buf_len = sizeof(*cmd_hdr) + cmd_len;
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if (sctx->read_buf_size < buf_len) {
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void *new_read_buf;
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if (cmd_len + sizeof(*sctx->cmd_hdr) >= sizeof(sctx->read_buf)) {
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ret = -EINVAL;
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error("command length %u too big for buffer %zu",
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cmd_len, sizeof(sctx->read_buf));
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goto out;
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new_read_buf = realloc(sctx->read_buf, buf_len);
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if (!new_read_buf) {
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ret = -ENOMEM;
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errno = -ret;
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error("failed to reallocate read buffer for cmd: %m");
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goto out;
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}
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sctx->read_buf = new_read_buf;
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sctx->read_buf_size = buf_len;
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/* We need to reset cmd_hdr after realloc of sctx->read_buf */
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cmd_hdr = (struct btrfs_cmd_header *)sctx->read_buf;
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}
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data = sctx->read_buf + sizeof(*sctx->cmd_hdr);
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data = sctx->read_buf + sizeof(*cmd_hdr);
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ret = read_buf(sctx, data, cmd_len);
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if (ret < 0)
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goto out;
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@ -145,11 +154,12 @@ static int read_cmd(struct btrfs_send_stream *sctx)
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goto out;
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}
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crc = le32_to_cpu(sctx->cmd_hdr->crc);
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sctx->cmd_hdr->crc = 0;
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crc = le32_to_cpu(cmd_hdr->crc);
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/* In send, CRC is computed with header crc = 0, replicate that */
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cmd_hdr->crc = 0;
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crc2 = crc32c(0, (unsigned char*)sctx->read_buf,
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sizeof(*sctx->cmd_hdr) + cmd_len);
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sizeof(*cmd_hdr) + cmd_len);
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if (crc != crc2) {
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ret = -EINVAL;
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@ -537,19 +547,29 @@ int btrfs_read_and_process_send_stream(int fd,
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goto out;
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}
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sctx.read_buf = malloc(BTRFS_SEND_BUF_SIZE_V1);
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if (!sctx.read_buf) {
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ret = -ENOMEM;
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errno = -ret;
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error("unable to allocate send stream read buffer: %m");
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goto out;
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}
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sctx.read_buf_size = BTRFS_SEND_BUF_SIZE_V1;
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while (1) {
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ret = read_and_process_cmd(&sctx);
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if (ret < 0) {
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last_err = ret;
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errors++;
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if (max_errors > 0 && errors >= max_errors)
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goto out;
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break;
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} else if (ret > 0) {
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if (!honor_end_cmd)
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ret = 0;
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goto out;
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break;
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}
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}
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free(sctx.read_buf);
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out:
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if (last_err && !ret)
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@ -25,7 +25,11 @@
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#define BTRFS_SEND_STREAM_MAGIC "btrfs-stream"
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#define BTRFS_SEND_STREAM_VERSION 1
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#define BTRFS_SEND_BUF_SIZE (64 * 1024)
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/*
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* In send stream v1, no command is larger than 64KiB. In send stream v2, no limit
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* should be assumed.
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*/
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#define BTRFS_SEND_BUF_SIZE_V1 (64 * 1024)
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#define BTRFS_SEND_READ_SIZE (1024 * 48)
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enum btrfs_tlv_type {
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