Re: [Qemu-devel] [PATCH] dump: Show custom message for ENOSPC

[Murilo Opsfelder Araujo <muriloo@linux.vnet.ibm.com>]

Hi, Yasmin.

Congratulations on your first patch!

On 02/09/2018 05:31 PM, Yasmin Beatriz wrote:
> This patch intends to make a more specific message for when
> the system has not enough space to save guest memory.
> 
> Reported-by: yilzhang@redhat.com
> Cc: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
> Signed-off-by: Yasmin Beatriz <yasmins@linux.vnet.ibm.com>
> ---
>  dump.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/dump.c b/dump.c
> index e9dfed060a..eb56ff53f6 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -106,6 +106,9 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
> 
>      written_size = qemu_write_full(s->fd, buf, size);
>      if (written_size != size) {
> +        if (errno == ENOSPC) {
> +            return -ENOSPC;
> +        }
>          return -1;
>      }
> 
> @@ -364,7 +367,11 @@ static void write_data(DumpState *s, void *buf, int length, Error **errp)
> 
>      ret = fd_write_vmcore(buf, length, s);
>      if (ret < 0) {
> -        error_setg(errp, "dump: failed to save memory");
> +        if (ret == -ENOSPC) {
> +            error_setg(errp, "dump: not enough space to save memory");
> +        } else {
> +            error_setg(errp, "dump: failed to save memory");
> +        }

If fd_write_vmcore() returned -errno, as Daniel Barboza suggested, it
could be used in error_setg_errno(). Something like this:

diff --git a/dump.c b/dump.c
index e9dfed060a..313a7460a7 100644
--- a/dump.c
+++ b/dump.c
@@ -106,7 +106,7 @@ static int fd_write_vmcore(const void *buf, size_t
size, void *opaque)

     written_size = qemu_write_full(s->fd, buf, size);
     if (written_size != size) {
-        return -1;
+        return -errno;
     }

     return 0;
@@ -364,7 +364,7 @@ static void write_data(DumpState *s, void *buf, int
length, Error **errp)

     ret = fd_write_vmcore(buf, length, s);
     if (ret < 0) {
-        error_setg(errp, "dump: failed to save memory");
+        error_setg_errno(errp, ret, "dump: failed to save memory");
     } else {
         s->written_size += length;
     }

With this, other reasons of errno would also be considered, not only ENOSPC.

Cheers
Murilo