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Re: [PATCH 1/2] migration/compress: compress QEMUFile is not writable
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH 1/2] migration/compress: compress QEMUFile is not writable |
Date: |
Thu, 7 Nov 2019 11:59:10 +0000 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
* Wei Yang (address@hidden) wrote:
> We open a file with empty_ops for compress QEMUFile, which means this is
> not writable.
That explanation sounds reasonable; but I'm confused by the history of
this; the code was added by Liang Li in :
b3be289 qemu-file: Fix qemu_put_compression_data flaw
( https://www.mail-archive.com/address@hidden/msg368974.html )
with almost exactly the opposite argument; can we figure out why?
Dave
> Signed-off-by: Wei Yang <address@hidden>
> ---
> migration/qemu-file.c | 16 +++-------------
> 1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index 26fb25ddc1..f3d99a96ec 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -744,11 +744,8 @@ static int qemu_compress_data(z_stream *stream, uint8_t
> *dest, size_t dest_len,
> /* Compress size bytes of data start at p and store the compressed
> * data to the buffer of f.
> *
> - * When f is not writable, return -1 if f has no space to save the
> - * compressed data.
> - * When f is wirtable and it has no space to save the compressed data,
> - * do fflush first, if f still has no space to save the compressed
> - * data, return -1.
> + * Since the file is dummy file with empty_ops, return -1 if f has no space
> to
> + * save the compressed data.
> */
> ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
> const uint8_t *p, size_t size)
> @@ -756,14 +753,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream
> *stream,
> ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
>
> if (blen < compressBound(size)) {
> - if (!qemu_file_is_writable(f)) {
> - return -1;
> - }
> - qemu_fflush(f);
> - blen = IO_BUF_SIZE - sizeof(int32_t);
> - if (blen < compressBound(size)) {
> - return -1;
> - }
> + return -1;
> }
>
> blen = qemu_compress_data(stream, f->buf + f->buf_index +
> sizeof(int32_t),
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [PATCH 1/2] migration/compress: compress QEMUFile is not writable,
Dr. David Alan Gilbert <=