9pfs: Convert V9fsFidState::fid_list to QSIMPLEQ

The fid_list is currently open-coded. This doesn't seem to serve any
purpose that cannot be met with QEMU's generic lists. Let's go for a
QSIMPLEQ : this will allow to add new fids at the end of the list and
to improve the logic in v9fs_mark_fids_unreclaim().

Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <20210118142300.801516-3-groug@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>

hw/9pfs/9p.c

@@ -260,7 +260,7 @@ static V9fsFidState *coroutine_fn get_fid(V9fsPDU *pdu, int32_t fid)
     V9fsFidState *f;
     V9fsState *s = pdu->s;
 
-    for (f = s->fid_list; f; f = f->next) {
+    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
         BUG_ON(f->clunked);
         if (f->fid == fid) {
             /*
@@ -295,7 +295,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
 {
     V9fsFidState *f;
 
-    for (f = s->fid_list; f; f = f->next) {
+    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
         /* If fid is already there return NULL */
         BUG_ON(f->clunked);
         if (f->fid == fid) {
@@ -311,8 +311,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
      * reclaim won't close the file descriptor
      */
     f->flags |= FID_REFERENCED;
-    f->next = s->fid_list;
-    s->fid_list = f;
+    QSIMPLEQ_INSERT_HEAD(&s->fid_list, f, next);
 
     v9fs_readdir_init(s->proto_version, &f->fs.dir);
     v9fs_readdir_init(s->proto_version, &f->fs_reclaim.dir);
@@ -401,20 +400,16 @@ static int coroutine_fn put_fid(V9fsPDU *pdu, V9fsFidState *fidp)
 
 static V9fsFidState *clunk_fid(V9fsState *s, int32_t fid)
 {
-    V9fsFidState **fidpp, *fidp;
+    V9fsFidState *fidp;
 
-    for (fidpp = &s->fid_list; *fidpp; fidpp = &(*fidpp)->next) {
-        if ((*fidpp)->fid == fid) {
-            break;
+    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
+        if (fidp->fid == fid) {
+            QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
+            fidp->clunked = true;
+            return fidp;
         }
     }
-    if (*fidpp == NULL) {
-        return NULL;
-    }
-    fidp = *fidpp;
-    *fidpp = fidp->next;
-    fidp->clunked = true;
-    return fidp;
+    return NULL;
 }
 
 void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
@@ -423,7 +418,7 @@ void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
     V9fsState *s = pdu->s;
     V9fsFidState *f, *reclaim_list = NULL;
 
-    for (f = s->fid_list; f; f = f->next) {
+    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
         /*
          * Unlink fids cannot be reclaimed. Check
          * for them and skip them. Also skip fids
@@ -505,7 +500,7 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path)
     V9fsFidState *fidp;
 
 again:
-    for (fidp = s->fid_list; fidp; fidp = fidp->next) {
+    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
         if (fidp->path.size != path->size) {
             continue;
         }
@@ -537,13 +532,13 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu)
     V9fsFidState *fidp;
 
     /* Free all fids */
-    while (s->fid_list) {
+    while (!QSIMPLEQ_EMPTY(&s->fid_list)) {
         /* Get fid */
-        fidp = s->fid_list;
+        fidp = QSIMPLEQ_FIRST(&s->fid_list);
         fidp->ref++;
 
         /* Clunk fid */
-        s->fid_list = fidp->next;
+        QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
         fidp->clunked = true;
 
         put_fid(pdu, fidp);
@@ -3121,7 +3116,7 @@ static int coroutine_fn v9fs_complete_rename(V9fsPDU *pdu, V9fsFidState *fidp,
      * Fixup fid's pointing to the old name to
      * start pointing to the new name
      */
-    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
+    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
         if (v9fs_path_is_ancestor(&fidp->path, &tfidp->path)) {
             /* replace the name */
             v9fs_fix_path(&tfidp->path, &new_path, strlen(fidp->path.data));
@@ -3215,7 +3210,7 @@ static int coroutine_fn v9fs_fix_fid_paths(V9fsPDU *pdu, V9fsPath *olddir,
      * Fixup fid's pointing to the old name to
      * start pointing to the new name
      */
-    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
+    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
         if (v9fs_path_is_ancestor(&oldpath, &tfidp->path)) {
             /* replace the name */
             v9fs_fix_path(&tfidp->path, &newpath, strlen(oldpath.data));
@@ -4081,7 +4076,7 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t,
     s->ctx.fmode = fse->fmode;
     s->ctx.dmode = fse->dmode;
 
-    s->fid_list = NULL;
+    QSIMPLEQ_INIT(&s->fid_list);
     qemu_co_rwlock_init(&s->rename_lock);
 
     if (s->ops->init(&s->ctx, errp) < 0) {

hw/9pfs/9p.h

@@ -280,7 +280,7 @@ struct V9fsFidState {
     uid_t uid;
     int ref;
     bool clunked;
-    V9fsFidState *next;
+    QSIMPLEQ_ENTRY(V9fsFidState) next;
     V9fsFidState *rclm_lst;
 };
 
@@ -339,7 +339,7 @@ typedef struct {
 struct V9fsState {
     QLIST_HEAD(, V9fsPDU) free_list;
     QLIST_HEAD(, V9fsPDU) active_list;
-    V9fsFidState *fid_list;
+    QSIMPLEQ_HEAD(, V9fsFidState) fid_list;
     FileOperations *ops;
     FsContext ctx;
     char *tag;