9p: introduce the V9fsDir type

If we are to switch back to readdir(), we need a more complex type than
DIR * to be able to serialize concurrent accesses to the directory stream.

This patch introduces a placeholder type and fixes all users.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>

hw/9pfs/9p-handle.c

@@ -112,7 +112,7 @@ static int handle_close(FsContext *ctx, V9fsFidOpenState *fs)
 
 static int handle_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    return closedir(fs->dir);
+    return closedir(fs->dir.stream);
 }
 
 static int handle_open(FsContext *ctx, V9fsPath *fs_path,
@@ -132,8 +132,8 @@ static int handle_opendir(FsContext *ctx,
     if (ret < 0) {
         return -1;
     }
-    fs->dir = fdopendir(ret);
-    if (!fs->dir) {
+    fs->dir.stream = fdopendir(ret);
+    if (!fs->dir.stream) {
         return -1;
     }
     return 0;
@@ -141,24 +141,24 @@ static int handle_opendir(FsContext *ctx,
 
 static void handle_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    rewinddir(fs->dir);
+    rewinddir(fs->dir.stream);
 }
 
 static off_t handle_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    return telldir(fs->dir);
+    return telldir(fs->dir.stream);
 }
 
 static int handle_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
                             struct dirent *entry,
                             struct dirent **result)
 {
-    return readdir_r(fs->dir, entry, result);
+    return readdir_r(fs->dir.stream, entry, result);
 }
 
 static void handle_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 {
-    seekdir(fs->dir, off);
+    seekdir(fs->dir.stream, off);
 }
 
 static ssize_t handle_preadv(FsContext *ctx, V9fsFidOpenState *fs,
@@ -262,7 +262,7 @@ static int handle_fstat(FsContext *fs_ctx, int fid_type,
     int fd;
 
     if (fid_type == P9_FID_DIR) {
-        fd = dirfd(fs->dir);
+        fd = dirfd(fs->dir.stream);
     } else {
         fd = fs->fd;
     }
@@ -409,7 +409,7 @@ static int handle_fsync(FsContext *ctx, int fid_type,
     int fd;
 
     if (fid_type == P9_FID_DIR) {
-        fd = dirfd(fs->dir);
+        fd = dirfd(fs->dir.stream);
     } else {
         fd = fs->fd;
     }

hw/9pfs/9p-local.c

@@ -348,7 +348,7 @@ static int local_close(FsContext *ctx, V9fsFidOpenState *fs)
 
 static int local_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    return closedir(fs->dir);
+    return closedir(fs->dir.stream);
 }
 
 static int local_open(FsContext *ctx, V9fsPath *fs_path,
@@ -370,9 +370,9 @@ static int local_opendir(FsContext *ctx,
     char *path = fs_path->data;
 
     buffer = rpath(ctx, path);
-    fs->dir = opendir(buffer);
+    fs->dir.stream = opendir(buffer);
     g_free(buffer);
-    if (!fs->dir) {
+    if (!fs->dir.stream) {
         return -1;
     }
     return 0;
@@ -380,12 +380,12 @@ static int local_opendir(FsContext *ctx,
 
 static void local_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    rewinddir(fs->dir);
+    rewinddir(fs->dir.stream);
 }
 
 static off_t local_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    return telldir(fs->dir);
+    return telldir(fs->dir.stream);
 }
 
 static int local_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
@@ -395,7 +395,7 @@ static int local_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
     int ret;
 
 again:
-    ret = readdir_r(fs->dir, entry, result);
+    ret = readdir_r(fs->dir.stream, entry, result);
     if (ctx->export_flags & V9FS_SM_MAPPED) {
         entry->d_type = DT_UNKNOWN;
     } else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
@@ -411,7 +411,7 @@ again:
 
 static void local_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 {
-    seekdir(fs->dir, off);
+    seekdir(fs->dir.stream, off);
 }
 
 static ssize_t local_preadv(FsContext *ctx, V9fsFidOpenState *fs,
@@ -610,7 +610,7 @@ static int local_fstat(FsContext *fs_ctx, int fid_type,
     int err, fd;
 
     if (fid_type == P9_FID_DIR) {
-        fd = dirfd(fs->dir);
+        fd = dirfd(fs->dir.stream);
     } else {
         fd = fs->fd;
     }
@@ -998,7 +998,7 @@ static int local_fsync(FsContext *ctx, int fid_type,
     int fd;
 
     if (fid_type == P9_FID_DIR) {
-        fd = dirfd(fs->dir);
+        fd = dirfd(fs->dir.stream);
     } else {
         fd = fs->fd;
     }

hw/9pfs/9p-proxy.c

@@ -633,7 +633,7 @@ static int proxy_close(FsContext *ctx, V9fsFidOpenState *fs)
 
 static int proxy_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    return closedir(fs->dir);
+    return closedir(fs->dir.stream);
 }
 
 static int proxy_open(FsContext *ctx, V9fsPath *fs_path,
@@ -652,14 +652,14 @@ static int proxy_opendir(FsContext *ctx,
 {
     int serrno, fd;
 
-    fs->dir = NULL;
+    fs->dir.stream = NULL;
     fd = v9fs_request(ctx->private, T_OPEN, NULL, "sd", fs_path, O_DIRECTORY);
     if (fd < 0) {
         errno = -fd;
         return -1;
     }
-    fs->dir = fdopendir(fd);
-    if (!fs->dir) {
+    fs->dir.stream = fdopendir(fd);
+    if (!fs->dir.stream) {
         serrno = errno;
         close(fd);
         errno = serrno;
@@ -670,24 +670,24 @@ static int proxy_opendir(FsContext *ctx,
 
 static void proxy_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    rewinddir(fs->dir);
+    rewinddir(fs->dir.stream);
 }
 
 static off_t proxy_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 {
-    return telldir(fs->dir);
+    return telldir(fs->dir.stream);
 }
 
 static int proxy_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
                            struct dirent *entry,
                            struct dirent **result)
 {
-    return readdir_r(fs->dir, entry, result);
+    return readdir_r(fs->dir.stream, entry, result);
 }
 
 static void proxy_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 {
-    seekdir(fs->dir, off);
+    seekdir(fs->dir.stream, off);
 }
 
 static ssize_t proxy_preadv(FsContext *ctx, V9fsFidOpenState *fs,
@@ -791,7 +791,7 @@ static int proxy_fstat(FsContext *fs_ctx, int fid_type,
     int fd;
 
     if (fid_type == P9_FID_DIR) {
-        fd = dirfd(fs->dir);
+        fd = dirfd(fs->dir.stream);
     } else {
         fd = fs->fd;
     }
@@ -936,7 +936,7 @@ static int proxy_fsync(FsContext *ctx, int fid_type,
     int fd;
 
     if (fid_type == P9_FID_DIR) {
-        fd = dirfd(fs->dir);
+        fd = dirfd(fs->dir.stream);
     } else {
         fd = fs->fd;
     }

hw/9pfs/9p.c

@@ -231,7 +231,7 @@ static int v9fs_reopen_fid(V9fsPDU *pdu, V9fsFidState *f)
             } while (err == -EINTR && !pdu->cancelled);
         }
     } else if (f->fid_type == P9_FID_DIR) {
-        if (f->fs.dir == NULL) {
+        if (f->fs.dir.stream == NULL) {
             do {
                 err = v9fs_co_opendir(pdu, f);
             } while (err == -EINTR && !pdu->cancelled);
@@ -345,7 +345,7 @@ static int free_fid(V9fsPDU *pdu, V9fsFidState *fidp)
             retval = v9fs_co_close(pdu, &fidp->fs);
         }
     } else if (fidp->fid_type == P9_FID_DIR) {
-        if (fidp->fs.dir != NULL) {
+        if (fidp->fs.dir.stream != NULL) {
             retval = v9fs_co_closedir(pdu, &fidp->fs);
         }
     } else if (fidp->fid_type == P9_FID_XATTR) {
@@ -443,7 +443,7 @@ void v9fs_reclaim_fd(V9fsPDU *pdu)
                 reclaim_count++;
             }
         } else if (f->fid_type == P9_FID_DIR) {
-            if (f->fs.dir != NULL) {
+            if (f->fs.dir.stream != NULL) {
                 /*
                  * Up the reference count so that
                  * a clunk request won't free this fid
@@ -451,8 +451,8 @@ void v9fs_reclaim_fd(V9fsPDU *pdu)
                 f->ref++;
                 f->rclm_lst = reclaim_list;
                 reclaim_list = f;
-                f->fs_reclaim.dir = f->fs.dir;
-                f->fs.dir = NULL;
+                f->fs_reclaim.dir.stream = f->fs.dir.stream;
+                f->fs.dir.stream = NULL;
                 reclaim_count++;
             }
         }
@@ -1883,7 +1883,7 @@ static void v9fs_readdir(void *opaque)
         retval = -EINVAL;
         goto out_nofid;
     }
-    if (!fidp->fs.dir) {
+    if (!fidp->fs.dir.stream) {
         retval = -EINVAL;
         goto out;
     }

hw/9pfs/9p.h

@@ -167,13 +167,17 @@ typedef struct V9fsXattr
     int flags;
 } V9fsXattr;
 
+typedef struct V9fsDir {
+    DIR *stream;
+} V9fsDir;
+
 /*
  * Filled by fs driver on open and other
  * calls.
  */
 union V9fsFidOpenState {
     int fd;
-    DIR *dir;
+    V9fsDir dir;
     V9fsXattr xattr;
     /*
      * private pointer for fs drivers, that