9p: Change p9_fid_create calling convention

Return NULL instead of ERR_PTR when we can't allocate a FID.  The ENOSPC
return value was getting all the way back to userspace, and that's
confusing for a userspace program which isn't expecting read() to tell it
there's no space left on the filesystem.  The best error we can return to
indicate a temporary failure caused by lack of client resources is ENOMEM.

Maybe it would be better to sleep until a FID is available, but that's
not a change I'm comfortable making.

Link: http://lkml.kernel.org/r/20180711210225.19730-3-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Yiwen Jiang <jiangyiwen@huwei.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>

diff --git a/net/9p/client.c b/net/9p/client.c
index cae1fb43bd163ccfb022a5075c03c855521abe25..7c317d39bf6201e807f557ad7508d412b7e98011 100644 (file)
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -914,13 +914,11 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt)
        p9_debug(P9_DEBUG_FID, "clnt %p\n", clnt);
        fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
        if (!fid)
-               return ERR_PTR(-ENOMEM);
+               return NULL;
 
        ret = p9_idpool_get(clnt->fidpool);
-       if (ret < 0) {
-               ret = -ENOSPC;
+       if (ret < 0)
                goto error;
-       }
        fid->fid = ret;
 
        memset(&fid->qid, 0, sizeof(struct p9_qid));
@@ -936,7 +934,7 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt)
 
 error:
        kfree(fid);
-       return ERR_PTR(ret);
+       return NULL;
 }
 
 static void p9_fid_destroy(struct p9_fid *fid)
@@ -1138,9 +1136,8 @@ struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
        p9_debug(P9_DEBUG_9P, ">>> TATTACH afid %d uname %s aname %s\n",
                 afid ? afid->fid : -1, uname, aname);
        fid = p9_fid_create(clnt);
-       if (IS_ERR(fid)) {
-               err = PTR_ERR(fid);
-               fid = NULL;
+       if (!fid) {
+               err = -ENOMEM;
                goto error;
        }
        fid->uid = n_uname;
@@ -1189,9 +1186,8 @@ struct p9_fid *p9_client_walk(struct p9_fid *oldfid, uint16_t nwname,
        clnt = oldfid->clnt;
        if (clone) {
                fid = p9_fid_create(clnt);
-               if (IS_ERR(fid)) {
-                       err = PTR_ERR(fid);
-                       fid = NULL;
+               if (!fid) {
+                       err = -ENOMEM;
                        goto error;
                }
 
@@ -2019,9 +2015,8 @@ struct p9_fid *p9_client_xattrwalk(struct p9_fid *file_fid,
        err = 0;
        clnt = file_fid->clnt;
        attr_fid = p9_fid_create(clnt);
-       if (IS_ERR(attr_fid)) {
-               err = PTR_ERR(attr_fid);
-               attr_fid = NULL;
+       if (!attr_fid) {
+               err = -ENOMEM;
                goto error;
        }
        p9_debug(P9_DEBUG_9P,