Re: [PATCH v2 01/21] block: Fixes nfs compiling error on msys2/mingw

[Peter Lieven]

> Am 10.09.2020 um 09:14 schrieb 罗勇刚(Yonggang Luo) <luoyonggang@gmail.com>:
> 
> 
> 
> On Thu, Sep 10, 2020 at 3:01 PM Peter Lieven <pl@kamp.de> wrote:
> 
> 
> > Am 09.09.2020 um 11:45 schrieb Yonggang Luo <luoyonggang@gmail.com>:
> > 
> > These compiling errors are fixed:
> > ../block/nfs.c:27:10: fatal error: poll.h: No such file or directory
> >   27 | #include <poll.h>
> >      |          ^~~~~~~~
> > compilation terminated.
> > 
> > ../block/nfs.c:63:5: error: unknown type name 'blkcnt_t'
> >   63 |     blkcnt_t st_blocks;
> >      |     ^~~~~~~~
> > ../block/nfs.c: In function 'nfs_client_open':
> > ../block/nfs.c:550:27: error: 'struct _stat64' has no member named 
> > 'st_blocks'
> >  550 |     client->st_blocks = st.st_blocks;
> >      |                           ^
> > ../block/nfs.c: In function 'nfs_get_allocated_file_size':
> > ../block/nfs.c:751:41: error: 'struct _stat64' has no member named 
> > 'st_blocks'
> >  751 |     return (task.ret < 0 ? task.ret : st.st_blocks * 512);
> >      |                                         ^
> > ../block/nfs.c: In function 'nfs_reopen_prepare':
> > ../block/nfs.c:805:31: error: 'struct _stat64' has no member named 
> > 'st_blocks'
> >  805 |         client->st_blocks = st.st_blocks;
> >      |                               ^
> > ../block/nfs.c: In function 'nfs_get_allocated_file_size':
> > ../block/nfs.c:752:1: error: control reaches end of non-void function 
> > [-Werror=return-type]
> >  752 | }
> >      | ^
> > 
> > On msys2/mingw, there is no st_blocks in struct _stat64, so we use 
> > consistence st_size instead.
> > 
> > Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
> > ---
> > block/nfs.c | 26 +++++++++++++++++---------
> > 1 file changed, 17 insertions(+), 9 deletions(-)
> > 
> > diff --git a/block/nfs.c b/block/nfs.c
> > index 61a249a9fc..34b2cd5708 100644
> > --- a/block/nfs.c
> > +++ b/block/nfs.c
> > @@ -24,7 +24,9 @@
> > 
> > #include "qemu/osdep.h"
> > 
> > +#if !defined(_WIN32)
> > #include <poll.h>
> > +#endif
> > #include "qemu/config-file.h"
> > #include "qemu/error-report.h"
> > #include "qapi/error.h"
> > @@ -51,6 +53,12 @@
> > #define QEMU_NFS_MAX_PAGECACHE_SIZE (8388608 / NFS_BLKSIZE)
> > #define QEMU_NFS_MAX_DEBUG_LEVEL 2
> > 
> > +#if defined (_WIN32)
> > +#define nfs_stat __stat64
> > +#else
> > +#define nfs_stat stat
> > +#endif
> > +
> > typedef struct NFSClient {
> >     struct nfs_context *context;
> >     struct nfsfh *fh;
> > @@ -58,7 +66,7 @@ typedef struct NFSClient {
> >     bool has_zero_init;
> >     AioContext *aio_context;
> >     QemuMutex mutex;
> > -    blkcnt_t st_blocks;
> > +    int64_t st_size;
> >     bool cache_used;
> >     NFSServer *server;
> >     char *path;
> > @@ -70,7 +78,7 @@ typedef struct NFSRPC {
> >     int ret;
> >     int complete;
> >     QEMUIOVector *iov;
> > -    struct stat *st;
> > +    struct nfs_stat *st;
> >     Coroutine *co;
> >     NFSClient *client;
> > } NFSRPC;
> > @@ -419,7 +427,7 @@ static int64_t nfs_client_open(NFSClient *client, 
> > BlockdevOptionsNfs *opts,
> >                                int flags, int open_flags, Error **errp)
> > {
> >     int64_t ret = -EINVAL;
> > -    struct stat st;
> > +    struct nfs_stat st;
> >     char *file = NULL, *strp = NULL;
> > 
> >     qemu_mutex_init(&client->mutex);
> > @@ -545,7 +553,7 @@ static int64_t nfs_client_open(NFSClient *client, 
> > BlockdevOptionsNfs *opts,
> >     }
> > 
> >     ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
> > -    client->st_blocks = st.st_blocks;
> > +    client->st_size = st.st_size;
> >     client->has_zero_init = S_ISREG(st.st_mode);
> >     *strp = '/';
> >     goto out;
> > @@ -729,11 +737,11 @@ static int64_t 
> > nfs_get_allocated_file_size(BlockDriverState *bs)
> > {
> >     NFSClient *client = bs->opaque;
> >     NFSRPC task = {0};
> > -    struct stat st;
> > +    struct nfs_stat st;
> > 
> >     if (bdrv_is_read_only(bs) &&
> >         !(bs->open_flags & BDRV_O_NOCACHE)) {
> > -        return client->st_blocks * 512;
> > +        return client->st_size;
> I am using   client->st_size instead client->st_blocks * 512, anything wrong 
> with this?
> >     }
> > 
> >     task.bs = bs;
> > @@ -746,7 +754,7 @@ static int64_t 
> > nfs_get_allocated_file_size(BlockDriverState *bs)
> >     nfs_set_events(client);
> >     BDRV_POLL_WHILE(bs, !task.complete);
> > 
> > -    return (task.ret < 0 ? task.ret : st.st_blocks * 512);
> > +    return (task.ret < 0 ? task.ret : st.st_size);
> > }
> > 
> > static int coroutine_fn
> > @@ -778,7 +786,7 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
> >                               BlockReopenQueue *queue, Error **errp)
> > {
> >     NFSClient *client = state->bs->opaque;
> > -    struct stat st;
> > +    struct nfs_stat st;
> >     int ret = 0;
> > 
> >     if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
> > @@ -800,7 +808,7 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
> >                        nfs_get_error(client->context));
> >             return ret;
> >         }
> > -        client->st_blocks = st.st_blocks;
> > +        client->st_size = st.st_size;
> >     }
> > 
> >     return 0;
> > -- 
> > 2.28.0.windows.1
> > 
> 
> 
> NACK. st_blocks and st_size is not the same. st_blocks is the number of 
> allocated blocks on disk. st_size is the virtual size of a file as it may 
> contain holes.
> I think the appropriate fix is to not implement nfs_get_allocated_file_size 
> on WIN32. Its not mandatory.
> 
> Please look at the   st_size, it's equivalant to  st_blocks * 512;

It is definitely not. Where do you have this info from?

Please have a look at libnfs/lib/nfs_v3.c in function nfs3_stat_1_cb.


        st.st_size    = res->GETATTR3res_u.resok.obj_attributes.size;
#ifndef WIN32
        st.st_blksize = NFS_BLKSIZE;
        st.st_blocks  = (res->GETATTR3res_u.resok.obj_attributes.used + 512 - 
1) / 512;
#endif//WIN32


Your patch will eliminate this difference for non WIN32 systems. Please change 
your patch to not implement nfs_get_allocated_file_size and qemu will handle 
this case properly.
Put everything that involves st_blocks and nfs_get_allocated_file_size in 
#ifndef _WIN32 conditions.


Peter